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Arnold-Chiari Malformation

Arnold-Chiari malformation

Arnold-Chiari malformation, sometimes referred to as 'Chiari malformation' or ACM, is a congenital anomaly of the brain in which the cerebellar tonsils are elongated and pushed down through the opening of the base of the skull (see foramen magnum), blocking the flow of cerebrospinal fluid (CSF). The brainstem, cranial nerves and the lower portion of the cerebellum may be stretched or compressed. Therefore, any of the functions controlled by these areas may be affected. The blockage of CSF flow may also cause a syrinx to form (syringomyelia). In infants, the most common symptoms are stridor and swallowing difficulties. In older children, upper limb weakness and breathing difficulties may occur. Patients may experience no symptoms or remain asymptomatic until early adulthood, at which point they will often experience severe headaches and neck pain. Fatigue, dizziness, vertigo, neuropathic pain, visual disturbances, difficulty swallowing, ringing in the ears, impaired fine motor skills, muscle weakness, and palpitations are other common symptoms. Because of the complex combination of symptoms and the lack of experience with ACM1 had by many, even outstanding neurologists and neurosurgeons, many patients are frequently misdiagnosed. Some patients may go an entire lifetime without having noticeable symptoms. Or, symptoms can be minimal, then turn severe suddenly due to head trauma which alters the condition of the spine, brain, or cerebellar tonsils and begins to cause more difficulties. Once these "onset of symptoms" occurs, the most frequent treatment is decompression surgery, in which a neurosurgeon seeks to open the base of the skull and through various methods unrestrict CSF flow to the spine. Arnold-Chiari Malformation II occurs in almost all children born with both spina bifida and hydrocephalus, but ACM I is typically seen in children and adults without spina bifida. The scale of severity is rates I - IV, with IV being the most severe.

History

An Austrian pathologist, Professor Hans Chiari, first described these hindbrain malformations in the 1890s. A colleague of Professor Chiari, Dr. Arnold, later contributed to the definition of the condition, and students of Dr. Arnold suggested the term "Arnold-Chiari malformation" to henceforth refer to the condition.

External links


- [http://www.wacma.com/ World Arnold Chiari Malformation Association]
- [http://www.asap.org/ American Syringomyelia Alliance Project]
- [http://www.chiariinstitute.com/ The Chiari Institute] Category:Neurology Category:Eponymous diseases

Brain

In the anatomy of animals, the brain, or encephalon (Greek for "in the head"), is the higher, supervisory center of the nervous system. The term 'brain' is typically used in connection with vertebrate nervous systems, and less often with regard to the nervous system of invertebrates. In the latter, neural control is performed by collections of ganglia. The brain is an extremely complex organ: the human brain is a collection of 100 billion neurons, each linked with up to 25,000 others. This huge number of interconnecting neurons, often referred to as a neural ensemble, is what makes the brain intelligent—enabling humans to analyze sensory signals, control the body, and think. In most animals, the brain is located in the head, close to the primary sensory apparatus and the mouth. Hippocrates considered the brain to be the seat of thought, while Aristotle believed it to be a cooling system for the blood. Today the study of the mind and brain consists of Neuroscience, the field of biology that studies the brain at its various levels of organization (from single neurons to functional systems such as visual system, auditory system, motor system and others); and psychology, the study of the cognition that arises from the neural function of the brain. Attempts have also been made to directly "read" the brain, which has been accomplished in a rudimentary manner through a brain-computer interface. In recent years, several institutions and bodies have undertaken research on recreating the neural structure of the brain with aim to produce human-like cognition and intelligence in computers. The brain controls and coordinates most movement, behavior and homeostatic body functions (such as heartbeat, blood pressure, fluid balance and body temperature). The brain is responsible for cognition, emotion, memory, motor learning and other kinds of learning. However, many behaviors, such as simple reflexes and basic locomotion, can be executed under spinal cord control alone.

The importance of the brain

The brain in animals

Three groups of animals, with some exceptions, have notably complex brains: the arthropods (insects and crustaceans), the cephalopods (octopuses, squid, and similar mollusks), and the craniates (vertebrates and their cousins). The brain of arthropods and cephalopods arises from twin parallel nerve cords that extend through the body of the animal. In arthropod, the brain consists of a central brain with three divisions and large optical lobes behind each eye for visual processing. eye The brain of craniates develops from the anterior section of a single dorsal nerve cord, which later becomes the spinal cord. In craniates, the brain is protected by the bones of the skull. In vertebrates, increasing complexity in the cerebral cortex correlates with height on the phylogenetic and evolutionary tree. Primitive vertebrates, like fish, reptiles, and amphibians have cortices with fewer than six layers of neurons, a structure known as allocortex (also named heterotypic cortex) (Martin, 1996). More complex vertebrates such as mammals have developed a six-layered neocortex (other terms: homotypic cortex, neocortex, neopallium), in addition to having some parts of the brain that are allocortex (Martin, 1996). In mammals, increasing convolutions of the brain, called gyri, are characteristic of animals with more advanced brains. These convolutions evolved to provide a larger surface area for a greater number of neurons, while keeping the volume of the brain compact enough to fit inside the skull.

The human brain

The structure of the human brain is different from that of other animals in several significant ways. These differences have allowed for many abilities over and above those of other animals, such as advanced cognitive skills. Human encephalization is especially pronounced in the neocortex, the most complex part of the cerebral cortex. The proportion of the human brain that is devoted to the neocortex—and the most advanced part within it, the prefrontal cortex—is larger than in all other animals. Humans enjoy unique neural capacities, but much of the human neuroarchitecture is shared with ancient species. Basic systems that alert the nervous system to stimulus, that sense events in the environment, and that monitor the condition of the body are similar to those of the most basic vertebrates. The neural circuitry underlying human consciousness includes both the advanced neocortex and protypical structures of the brain stem. The human brain also has a a million billion synaptic connections, making it one of the most densely connected network systems in the known universe; however, more complex structures may exist.

Pathology of the brain

The loss of function in the brain fulfills some definitions of death. Injuries to the brain tend to affect large areas of the organ, sometimes causing major deficits in intelligence, memory and control of the body. Head trauma, caused, for example, by vehicle and industrial accidents, is a leading cause of death in youth and middle age. In these cases, more damage is typically caused by resultant swelling (edema) than by the impact itself. Stroke, caused by the blockage of blood vessels in the brain, is another major cause of death from brain damage. Other problems in the brain can be more accurately classified as diseases rather than injuries. Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, motor neurone disease, and Huntington's disease, are caused by the gradual death of individual neurons, leading to decrements in movement control, memory, and cognition. Currently, only the symptoms of these diseases can be treated, but stem cell research may offer a cure. Mental illness, such as clinical depression, schizophrenia, bipolar disorder, and post-traumatic stress disorder, are brain diseases that impact on the personality and typically on other aspects of mental and somatic function. These disorders may be treated by psychiatric therapy, by pharmaceutical intervention, or by a combination of treatments; therapeutic effectiveness varies significantly among individuals. pharmaceutical Some infectious diseases affecting the brain are caused by viral and bacterial infection(s). Infection of the meninges, the membrane that covers the brain, can lead to meningitis. Bovine spongiform encephalopathy (also known as mad cow disease), is deadly in cattle and is linked to prions. Kuru is a similar prion-borne degenerative brain disease affecting humans. Both are linked to the ingestion of neural tissue, and may be an evolutionary defense against cannibalism. Viral or bacterial causes have been substantiated in multiple sclerosis, Parkinson's disease, Lyme disease, encephalopathy and encephalomyelitis. Some brain disorders are congenital. Tay-Sachs disease, Fragile X syndrome, Down syndrome, and Tourette syndrome are all linked to genetic and chromosomal errors. Malfunctions in the embryonic development of the brain can be caused by genetic factors, by drug use, and disease during a mother's pregnancy.

Other matters

Some philosophers consider that "brain" is synonymous with "mind", while others (such as strong AI theorists) believe that the mind is analogous to software and the brain to hardware. This issue—related to the mind-body problem—and many other issues, are the subjects of the area of the philosophy of mind. Questions asked in this field typically relate to the nature of consciousness and whether non-human animals are conscious beings. Computer scientists have produced computer systems called neural networks, loosely based on the structure of neuron connections in the brain. Artificial intelligence seeks to replicate brain function—although not necessarily brain mechanisms—but as yet is an immature science. Creating algorithms to mimic a biological brain is extremely difficult because the brain is not a static arrangement of circuits, but a network of vastly interconnected neurons that are constantly changing their connectivity and sensitivity. More recent work in both neuroscience and artificial intelligence models the brain using the mathematical tools of chaos theory and dynamical systems. Brain activity can be detected by electrodes, raising the possibility of "brain-computer interface". The reverse path has been demonstrated: brain implants have been used to generate artificial hearing and (crude and experimental) artificial vision for deaf and blind people; brain pacemakers are now commonly used to regulate brain activity in conditions such as Parkinson's disease. Both of these avenues of research are confronted with potentially serious ethical implications. For example, by placing electrodes in the brain and using a remote control, researchers have been able to remotely control the movements of a rat, combining commands of what to do with the stimulation of the brain pleasure centers. This raises the possibility of creating an electronically controlled biological "ratbot" that could be used in dangerous circumstances.

The biology of the brain

Despite the variance of the species in which the brain is found there are many common features in its cellular make-up, its structure and its function. On a cellular level, the brain is composed of two classes of cell, neurons and glia, both of which contain several different cell types which perform different functions. Interconnected neurons form neural networks (or neural ensembles). These networks are similar to man-made electrical circuits in that they contain circuit elements (neurons) connected by biological wires (nerve fibers). Of course, these do not form simple one-to-one electrical circuits (as is the case in many man-made circuits), neurons typically connect to at least a thousand other neurons. These highly specialized circuits make up systems which are the basis of perception, action and higher cognitive function. The brain contains anatomical and functional divides. In mammals, the most obvious partitioning of the brain is into the cerebrum (Latin for "brain", a large, anterior part that consists of two convoluted hemispheres and deep nuclei), cerebellum (Latin for "small brain", a smaller, structure behind the cerebrum with two rippled hemispheres and deep cerebellar nuclei), and brain stem (an elongated structure connecting the brain to the spinal cord). These parts are further divided into hemispheres, lobes, gyri, cortices, cytoarchitectonic and functional areas, nuclei, layers, fiber tracks and so forth. In summary, the chemical and electrical impulses continually passing through the cells of the brain produce all control, action and cognitive function in the body.

Histology

lobe Neurons, the cells that generate action potentials and convey them to other cells, constitute the chief class of brain cells. In each particular brain area, input (or afferent) neurons, output (or efferent) neurons and interneurons are typically found. Input neurons are recipients of projections from other brain areas. Output neurons project to the other areas. Interneurons are the neurons which do not leave the area. In addition to neurons, the brain contains glial cells in the proportion roughly 10 glial cells to every neuron; these are traditionally seen to perform supportive roles to neurons and fill out the space between them (hence its name, Greek for 'glue'). Most types of glia in the brain (and the rest of the central nervous system) are present in the entire nervous system, exceptions include oligodendrocytes which insulate neural axons (a role performed by Schwann cells in the peripheral nervous system). Oligosaccharides are the defining factor between white matter and grey matter in the brain—white matter is composed of myelinated (insulated) axons, whereas grey matter contains mostly cell soma, dendrites and unmyelinated portions of axons and glia and a smaller proportion of myelinated axons. In mammals, the brain also contains a certain amount of connective tissue called the meninges which is a system of membranes that separate the skull from the brain. The three-layered covering is made of, from the outside in, dura mater, arachnoid and pia mater (the latter two are connected and thus often considered as a single layer, the pia-arachnoid). Below the arachnoid is the subarachnoid space which contains cerebrospinal fluid which protects the nervous system. Blood vessels enter the central nervous system through the perivascular space above the pia mater. A blood-brain barrier protects the brain from unwanted substances that might enter it through the blood. The brain is suspended in cerebrospinal fluid, which circulates between layers of the meninges and through cavities in the brain called ventricles. It is important both chemically (metabolism) and mechanically (shock-prevention).

Anatomy

Although the histology of the brain is common to all those who have one, the structural anatomy is not. Apart from the general nature of the brain to order into lobes and suchforth, the lobes into which it has evolved are not common across the vertebrate/invertebrate divide. There are further dissimilarities within invertebrates, though vertebrates tend to share certain commonalities.

Invertebrates

In insects, the brain can be divided into four parts, the optical lobes, the protocerebrum, the deutocerebrum, and the tritocerebrum. The optical lobes are positioned behind each eye and process visual stimuli (Butler, 2000). The protocerebrum contains the mushroom bodies, which respond to smell, and the central body complex. The deutocerebrum includes the antennal lobes, which are similar to the mammalian olfactory bulb, and the mechanosensory neuropils which receive information from touch receptors on the head and antennae. The antennal lobes of flies and moths are quite complex. In cephalopods, the brain is divided into two regions: the supraesophageal mass and the subesophageal mass. These parts are divided by the animal's esophagus. The supra- and subesophageal masses are connected to each other on either side of the esophagus by the basal lobes and the dorsal magnocellular lobes. The large optic lobes are sometimes not considered to be part of the brain proper since the optic lobes anatomically separate from the brain and are joined to the brain by the optic stalks. However, the optic lobes perform much of the visual processing and can be functionally considered to be a part of the brain.

Vertebrates

In vertebrates, a gross division into three major parts is used: hindbrain (medulla oblongata and metencephalon), midbrain (mesencephalon) and forebrain (diencephalon and telencephalon). Varied taxonomies have been used by assorted schools at various times in history for the study of diverse species. An anterior part of the telencephalon called the cerebrum makes up the largest section of the mammalian brain and in humans, its surface has many deep fissures (sulci) and convolutions (gyri), giving a wrinkled appearance to the brain. In most vertebrates the metencephalon is the highest integration center in the brain, whereas in mammals this role has been adopted by the cerebrum. Behind (or in humans, below) the cerebrum is the cerebellum, a convoluted structure whose neural circuitry is often compared with crystal structure. Cerebellum participates in the control of movement. The cerebellum attaches to the hindbrain in a structure called the pons. The cerebrum and the cerebellum consist each of two halves (hemispheres). The corpus callosum connects the two hemispheres of the cerebrum. An outgrowth of the telencephalon called the olfactory bulb is a major structure in many animals, but in humans and other primates, it is relatively small. Vertebrate nervous systems are distinguished by encephalization and bilateral symmetry. Encephalization refers to the tendency for more complex organisms to gain a larger-size brains through evolutionary time. Larger vertebrates develop a complex of layered, networked and convoluted grey matter and white matter. Grey matter refers to tissue mostly comprised of neurons and can be found on the surface of cerebral cortex, as well as in clusters called nuclei deep within the brain. White matter refers to axons and their surrounding myelin insulation, which gives this tissue its white color. White matter is found in bundles of fibers known as tracts which connect the different parts of the brain. In modern species most closely related to the first vertebrates, brains are covered with gray matter that has a three-layer structure. Their brains also contain deep brain nucleus and fiber tracks forming the white matter. Most regions of the human cerebral cortex have six layers of neurons, a structure known as neocortex.

Brain Regions in Vertebrates

According to the hierarchy based on embryonic and evolutionary development, chordate brains are composed of the following regions:
- RHOMBENCEPHALON (Greek for "rhomboid brain")
  - Myelencephalon (Greek for "brain marrow", also called medulla oblongata which means "long marrow" in Latin)
  - Metencephalon (Greek for "after the brain"; also called hindbrain)
    - pons
    - cerebellum
- MESENCEPHALON (Greek for "middle brain", also called midbrain)
  - tectum
  - midbrain tegmentum
  - substantia nigra
  - crus cerebri (also called cerebral peduncles and pedunculus cerebri)
- PROSENCEPHALON
  - Diencephalon (Greek for "brain in between")
    - thalamus
    - hypothalamus (Greek for "under the thalamus")
    - pituitary gland
    - epithalamus
    - pineal gland
  - Telencephalon (Greek for "end brain", i.e. the most rostral part of the brain; also called forebrain)
    - TELENCEPHALON NUCLEI
      - putamen
      - caudate nucleus
      - putamen
      - globus pallidus
      - amygdala
    - CEREBRAL CORTEX
    - Archipallium (Greek for "first cloak", i.e. cortex that developed first; also called archeocortex)
      - hippocampus
    - Paleopallium (Greek for "ancient cloak"; also called "paleocortex")
      - priform(olfactory) cortex
      - parahippocampal gyrus
    - Neopallium (Greek for "new cloak"; also called "paleocortex"; also called neocortex and isocortex)
      - frontal lobe
      - temporal lobe
      - parietal lobe
      - occipital lobe
      - insula
      - cingulate cortex In addition, the brain is often subdivided into the following major parts:
- BRAINSTEM
  - Medulla
  - Pons
  - Midbrain
- CEREBELLUM
  - Cerebellar cortex
  - Cerebellar nuclei
- BASAL GANGLIA (some midbrain nuclei, such as substantia nigra are usually considered as basal ganglia)
  - Striatum (caudate nucleus and putamen)
  - Globus pallidus
- HIPPOCAMPUS
- AMYGDALA
- THALAMUS
- HYPOTHALAMUS
- CEREBRAL CORTEX Yet alternative classifications arrange brain areas into functional systems:
- Limbic system
- Sensory systems
  - Visual system
  - Olfactory system
  - Gustatory system
  - Auditory system
  - Somatosensory system
- Motor system
- Associative areas

Function

Associative areas Vertebrate brains receive signals through nerves arriving from the sensors of the organism, interpret those signals and formulate reactions based on built-in programs and learned experiences. A similarly extensive nerve network delivers signals from a brain to control muscles throughout a body. Anatomically, the majority of afferent and efferent nerves (with the exception of cranial nerves) are connected to the spinal cord, which then transfers the signals to the brain. Sensory input is processed by the brain to recognize danger, find food, identify potential mates and perform more sophisticated functions. Visual, touch, and auditory sensory pathways of vertebrates are routed to specific nuclei of the thalamus and then to regions of the cerebral cortex that are specific to each sensory system: the visual system, the auditory system and the somatosensory system. Olfactory pathways are routed to the olfactory bulb, then to various parts of the olfactory system. Taste is routed through the brainstem and then to other portions of the gustatory system. To control movement, the brain has several parallel systems of muscle control. The motor system controls voluntary muscle movement, aided by motor areas of the cerebral cortex, the cerebellum and the basal ganglia — the system that eventually projects to the spinal cord. Nuclei in the brainstem control many involuntary muscle functions such as heartrate and breathing. In addition, many automatic acts (simple reflexes, locomotion) can be controlled by the spinal cord alone. Brains also produce hormones that can influence organs and glands elsewhere in a body - conversely, brains also react to hormones produced elsewhere in the body. In mammals, most of these hormones are released into the circulatory system by a structure called the pituitary gland. It is hypothesized that developed brains derive consciousness from interaction among numerous systems within the brain. Cognitive processing in mammals occurs in the cerebral cortex but relies on mid-brain and limbic functions as well, especially those of the thalamus and hippocampus. Among "younger" (in an evolutionary sense) vertebrates, advanced processing involves progressively rostral (forward) regions of the brain. Hormones, incoming sensory information, and cognitive processing performed by the brain determine the brain state. Stimulus from any source can trigger a general arousal process that focuses cortical operations to processing of the new information. Cognitive priorities are constantly shifted by a variety of factors, such as hunger, fatigue, beliefs, unfamiliar information or threats. The simplest dichotomy related to processing of threats is the fight-or-flight response mediated by the amygdala, among other structures.

The study of the brain

Fields of study

Several areas of science specifically study the brain. Neuroscience seeks to understand the nervous system, including the brain, from a biological perspective. Psychology seeks to understand behavior and the brain. The terms neurology and psychiatry usually refer to medical applications of neuroscience and psychology, respectively. Cognitive science seeks to unify neuroscience and psychology with other fields that concern themselves with the brain, such as computer science (in Artificial intelligence and similar fields) and philosophy.

Methods of observation

Each method for observing activity in the brain has its advantages and drawbacks. Electrophysiology, in which wire electrodes are implanted in the brain, allows scientists to record the electrical activity of individual neurons or fields of neurons, but since it requires invasive surgery, this is a technique usually reserved for lab animals. By placing electrodes on the scalp, electroencephalography (EEG) measures brain waves, which are the mass changes in electrical current from the cerebral cortex, but can only detect changes over large areas of the brain and very little sub-cortical activity. Functional magnetic resonance imaging (fMRI) measures changes in blood flow in the brain, but the activity of neurons is not directly measured, nor can it be distinguished whether this activity is inhibitory or excitatory. Similarly, a PET (Positron Emission Tomography) Scan, is able to monitor glucose intake in different areas within the brain which is correlated the level of activity in that region. Behavioral tests can measure symptoms of disease and mental performance, but only provide indirect measurements of brain function and may not be practical in all animals. Finally, post-mortem analysis of the brain allows for the study of anatomy and protein expression patterns, but is only possible after the human or animal is dead.

History

Ancient Greeks had differing views on the function of the brain. Hippocrates believed the brain to be the seat of intelligence, but Aristotle held that the brain was a cooling mechanism for the blood, while the heart was the seat of intelligence. He reasoned that humans are more rational than the beasts because they have a proportionally larger brain to cool their hot-bloodedness (Bear, 2001). During the Roman Empire, the anatomist Galen dissected the brains of sheep. He concluded that since the cerebellum was hard on touch, it must control the muscles, while since the cerebrum was soft, it must be where the senses were processed. Galen further theorized that the brain functioned by movement of fluids through the ventricles (Bear, 2001). In the Age of Reason, René Descartes espoused a fluid mechanical view of the brain similar to Galen's theories. However, Descartes thought that although this explanation was adequate to explain the brain functions of animals, the higher mental functions of humans were accomplished by the soul. This theoretical separation of the mind and brain became known as the mind-body problem (Bear, 2001). In the mid-1600s, however, great progress in describing the anatomy of the brain was achieved with the works of English anatomist Thomas Willis and Flemish anatomist Vesalius. They dispelled many of the notions of Galen and Descartes and discovered many facts about the macro structure of the brain of animals and humans. In the 1700s, Luigi Galvani showed that electrically stimulating the sciatic nerve of a dissected frog caused movement of the attached muscle. His experiments led scientists away from the fluid mechanical theory of the brain and toward an electrical theory. In the 19th century, Galvani's work led to the development of research in bioelectricity and to the discovery of the membrane potential and action potential by researchers such as Emil du Bois-Reymond. The scientists of the 1800s debated whether areas of the brain corresponded to specific functions or if the brain functioned as a whole (the "aggregate field theory"). Jean Pierre Flourens championed the aggregate field theory in opposition to the pseudoscience of phrenology, founded by Franz Joseph Gall. However, the work of Paul Pierre Broca, Karl Wernicke, and Korbinian Brodmann eventually helped to show that areas of the brain had specific functions, though some functions were repeated, an idea known as parallel distributed processing (Kandel, 2001). As the 20th century approached, the anatomical works of Santiago Ramon y Cajal and Camillo Golgi laid the foundation for the study of individual neurons in the brain. Charles Scott Sherrington and Edgar Douglas Adrian furthered the study of neurons with the new techniques of electrodes and the electroencephalogram (EEG). Neurotransmitters were discovered and investigated by a number of scientists, including Otto Loewi, Henry Hallett Dale, Arvid Carlsson and many others. Modern Neuroscience experiences rapid development. The scientists use a variety of approaches to study the brain at different levels — from the molecules to systems. Extensive knowledge has been accumulated about the electrophysiological properties of different types of neurons and their responsiveness to neurotransmitters. Recordings from the brain of awake, behaving animals pioneered by Edward Evarts help to decode neuronal firing during different behaviors and cognitive processes. Miguel Nicolelis introduce multielectrode recording techniques which led to creation of brain-computer interfaces. Rapidly developing brain imaging allows scientists to study the brain in living humans and animals in ways that their predecessors could not.

The brain as a food

Like most other internal organs, the brain can serve as nourishment. For example, in the Southern United States canned pork brain in gravy can be purchased for consumption as food. This form of brain is often fried with scrambled egg to produce the famous "Eggs n' Brains". The brain of animals also features in the cuisine of France such as in the dish tête de veau, or head of calf. Although it might consist only of the outer meat of the skull and jaw, the full meal includes the brain, tongue and glands (the latter form being the favorite food of president Jacques Chirac). Similar delicacies from around the world include Mexican tacos de sesos (tacos made with cattle brain) and squirrel brain in the US South. The Anyang tribe of Cameroon practiced a tradition in which a new chief would consume the brain of a hunted gorilla while another senior member of the tribe would eat the heart. Consuming the brain and other nerve tissue of animals is not without its risks. The first problem is that the brain is made up of 60% fat due to the myelin (which by itself is 70% fat) insulating the axons of neurons and glia. As an example, a 5 oz. (0.14 kg) can of "Pork Brains in Milk Gravy", a single serving, contains 3500 milligrams of cholesterol, 1170% of our recommended daily intake. More importantly, humans can contract fatal transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease and other (prion diseases), as well as Bovine Spongiform Encephalopathy (colloquially known as "mad cow" disease) through the consumption of the infected nerve tissue of cattle and other animals - However, "there is no evidence that people can get mad cow disease from eating muscle meat". Another prion disease called kuru has been traced to a mourning ritual among the Fore people of Papua New Guinea in which those close to the dead would eat their brain to create a sense of immortality. Some archaeological evidence suggests that the mourning rituals of European neanderthals also involved the consumption of the brain. The practice of eating another human's brain has been depicted by Hollywood in Hannibal (film) and countless zombie movies. It is not only humans who eat the brains of other animals. The two species of chimpanzee, though generally vegetarian, are known to eat the brains of monkeys to obtain fat in their diet.

External links


- [http://www.stanford.edu/group/hopes/basics/braintut/ab0.html Brain Tutorial]
- [http://brainmuseum.org/ Comparative Mammalian Brain Collection]
- [http://www.rmcybernetics.com/science/cybernetics/ai_vision_perception_brain.htm RMCybernetics - The Brain and Artificial Intelligence]
- [http://braininfo.rprc.washington.edu BrainInfo for Neuroanatomy]
- [http://faculty.washington.edu/chudler/neurok.html Neuroscience for kids]
- [http://3dscience.com/advancedsearch.asp?stS=brain&cboMatch=Any&selectcategory=0&txtMinPrice=&txtMaxPrice= Free Brain Medical Clip Art].
- [http://purl.net/net/neurowiki neuroscience wiki]
- [http://www.brainmaps.org/ BrainMaps.org], interactive high-resolution digital brain atlas based on scanned images of serial sections of both primate and non-primate brains

Related topics


- A/S ratio
- Avian pallium
- Brain damage
- Brain-computer interface
- Coma
- Human brain
- Persistent vegetative state
- Regions in the human brain
- The Memory-Prediction Framework
- Metastability in the brain
- Neuroendocrinology
- Traumatic brain injury

References


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Notes

The following are the sources for individual facts, statistics and information included in the article:
- Statistic from page 161 of Basic Histology: Text and Atlas, 10th ed. by L.C. Junqueira, and J. Carneiro.
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- Category:Central nervous system Category:Cerebrum ja:脳 ko:뇌 simple:Brain th:สมอง

Foramen magnum

In anatomy, the foramen magnum is the large hole through the occipital bone in the base of the skull, through which the medulla oblongata (an extension of the spinal cord) exits the skull vault. In humans the foramen magnum is farther underneath the head than in great apes. Thus, the neck muscles do not need to be as robust in order to hold the head upright. Comparisons of the position of the foramen magnum in early hominid species are useful to determine how comfortable a particular species was when walking on two limbs ( bipedality) rather than four. Category:Skull

Cerebrospinal fluid

Cerebrospinal fluid (CSF) is a clear bodily fluid that occupies the subarachnoid space in the brain (the space between the skull and the cerebral cortex—more specifically, between the arachnoid and pia layers of the meninges). It is basically a saline solution and acts as a "cushion" or buffer for the cortex.

Physiology

Cerebrospinal fluid also occupies the ventricular system of the brain and the spinal cord. It is mainly produced by the choroid plexus, but also by the ependymal lining of the brain's ventricles. The CSF is formed by the choroid plexus of the ventricles circulates through the interventricular foramina into the third ventricle and then via the mesencephalic duct (cerebral aqueduct) into the fourth ventricle. From there, the fluid passes to the subarachnoid space through two lateral apertures and one median aperature and is then absorbed by the venous system to the blood circulation. The total amount of cerebrospinal fluid is about 150 ml, and about 500 ml is produced every day, which indicates its very active circulation.

Pathology

The cerebrospinal fluid has many putative roles including mechanical protection of the brain, distribution of neuroendocrine factors, and facilitation of pulsatile cerebral blood flow. Understanding cardiovascular dynamics is valuable as the flow pattern of arterial blood must be tightly regulated within the brain in order to assure consistent brain oxygenation. CSF movement allows arterial expansion and contraction by acting like a spring, which prevents wide changes in intracranial blood flow. When disorders of CSF flow occur, they may therefore impact not only CSF movement, but may also impact intracranial blood flow and subsequent neuronal and glial vulnerabilities. The venous system is also important in this equation. Infants and patients shunted as small children may have particularly unexpected relationships between pressure and ventricular size, possibly due in part to venous pressure dynamics. This may have significant treatment implications but the underlying pathophysiology needs to be further explored. CSF connections with the lymphatic system have been demonstrated in several mammalian systems. Preliminary data suggest that these CSF-lymph connections form around the time that the CSF secretory capacity of the choroid plexus is developing (in utero). There may be some relationship between CSF disorders, including hydrocephalus and impaired CSF lymphatic transport.

Diagnosis and therapy

Cerebrospinal fluid can be tested for the diagnosis of a variety of neurological diseases. Usually, it is obtained by a procedure called lumbar puncture in an attempt to count the cells in the fluid and to detect the levels of protein and glucose. These parameters alone may be extremely beneficial in the diagnosis of central nervous system infections (especially meningitis and subarachnoid hemorrhage). Moreover, a cerebrospinal fluid culture examination may yield the microorganism that has caused the infection. By using more sophisticated methods, such as the detection of the oligoclonal bands, an ongoing inflammatory condition (for example, multiple sclerosis) can be recognized. Lumbar puncture can also be performed to measure the intracranial pressure, which might be increased in certain types of hydrocephalus. Category:Central nervous system Category:Neurology ja:脳脊髄液

Brainstem

The term brain stem refers to a composite substructure of the brain. It includes the midbrain, the pons and the medulla oblongata. Some authors include the cerebellum and/or parts of the diencephalon. A discussion of differences in the use of this term is presented in Anthoney-94. medulla oblongata The lower part of the brain stem is the medulla oblongata, grossly comprising the medullary pyramids and the olivary bodies or olives. The pons is a knob above the medulla. The reticular activating system is situated in between the medulla and metencephalon, and is considered to be at the "core." Differentiation of the brain stem from the cerebrum is complex, both anatomically and taxonomically. Some taxonomies describe the brain stem as the pons, medulla and mesencephalon while others include diencephaletic regions. The adult human brainstem emerges from parts of all three vesicles in the neural tube.

Function

The brain stem is the stalk of the brain below the cerebral hemispheres. It is the major route for communication between the forebrain and the spinal cord and peripheral nerves. It also controls various functions including respiration, regulation of heart rhythms, and primary aspects of sound localization.

Syringomyelia

Syringomyelia (sear-IN-go-my-EEL-ya) is a disorder in which a cyst or tubular cavity forms within the spinal cord. This cyst, called a [http://www.merck.com/mrkshared/mmanual/section14/chapter182/182d.jsp syrinx], expands and elongates over time, destroying the center of the spinal cord. Since the spinal cord connects the brain to nerves in the extremities, this damage results in pain, weakness, and stiffness in the back, shoulders, arms, or legs. Other symptoms may include headaches and a loss of the ability to feel extremes of hot or cold, especially in the hands. Each patient experiences a different combination of symptoms. Other, more common disorders share the early symptoms of syringomyelia. In the past, this has made diagnosis difficult. The advent of one outpatient test, however, called magnetic resonance imaging or MRI, has significantly increased the number of syringomyelia cases diagnosed in the beginning stages of the disorder. About 21,000 American men and women have syringomyelia, with symptoms usually beginning in young adulthood. Signs of the disorder tend to develop slowly, although sudden onset may occur with coughing, straining, or myelopathy. If not treated surgically, syringomyelia often leads to progressive weakness in the arms and legs, loss of hand sensation, and chronic, severe pain.

The Cause

A watery, protective substance known as cerebrospinal fluid normally flows around the spinal cord and brain, transporting nutrients and waste products. It also serves to cushion the brain. A number of medical conditions can cause an obstruction in the normal flow of cerebrospinal fluid, redirecting it into the spinal cord itself. For reasons that are only now becoming clear, this results in syrinx formation. Cerebrospinal fluid fills the syrinx. Pressure differences along the spine cause the fluid to move within the cyst. Physicians believe that it is this continual movement of fluid that results in cyst growth and further damage to the spinal cord.

Different Origins

Generally, there are two forms of syringomyelia. The first major form consists of most cases, whereby the disorder is related to an abnormality of the brain called an Arnold-Chiari malformation, named after the physician who first characterized it. This anatomic abnormality causes the lower part of the cerebellum to protrude from its normal location in the back of the head into the cervical or neck portion of the spinal canal. A syrinx may then develop in the cervical region of the spinal cord. Because of the relationship that was once thought to exist between the brain and spinal cord in this type of syringomyelia, physicians sometimes refer to it as communicating syringomyelia. Here, symptoms usually begin between the ages of 25 and 40 and may worsen with straining or any activity that causes cerebrospinal fluid pressure to fluctuate suddenly. Some patients, however, may have long periods of stability. Some patients with this form of the disorder also have hydrocephalus, in which cerebrospinal fluid accumulates in the skull, or a condition called arachnoiditis, in which a covering of the spinal cord--the arachnoid membrane--is inflamed. The second major form of syringomyelia occurs as a complication of trauma, meningitis, hemorrhage, a tumor, or arachnoiditis. Here, the syrinx or cyst develops in a segment of the spinal cord damaged by one of these conditions. The syrinx then starts to expand. This is sometimes referred to as noncommunicating syringomyelia. Symptoms may appear months or even years after the initial injury, starting with pain, weakness, and sensory impairment originating at the site of trauma. The primary symptom of post-traumatic syringomyelia is pain, which may spread upward from the site of injury. Symptoms, such as pain, numbness, weakness, and disruption in temperature sensation, may be limited to one side of the body. Syringomyelia can also adversely affect sweating, sexual function, and, later, bladder and bowel control. Some cases of syringomyelia are familial, although this is rare. In addition, one form of the disorder involves a part of the brain called the brainstem. The brainstem controls many of our vital functions, such as respiration and heartbeat. When syrinxes affect the brainstem, the condition is called [http://www.emedicine.com/NEURO/topic359.htm syringobulbia].

Diagnosis

Physicians now use magnetic resonance imaging (MRI) to diagnose syringomyelia. The MR imager takes pictures of body structures, such as the brain and spinal cord, in vivid detail. This test will show the syrinx in the spine or any other conditions, such as the presence of a tumor. MRI is safe, painless, and informative and has greatly improved the diagnosis of syringomyelia. The physician may order additional tests to help confirm the diagnosis. One of these is called electromyography (EMG), which measures muscle weakness. The doctor may also wish to test cerebrospinal fluid pressure levels and to analyze the cerebrospinal fluid by performing a lumbar puncture. In addition, computed axial tomography (CT) scans of a patient's head may reveal the presence of tumors and other abnormalities such as hydrocephalus. Like MRI and CT scans, another test, called a [http://www.umm.edu/radiology/myelog.htm myelogram], takes x-ray-like pictures and requires a contrast medium or dye to do so. Since the introduction of MRI this test is rarely necessary to diagnose syringomyelia. The possible causes are trauma, tumors and congenital defects. It is most usually observed in the part of the spinal cord corresponding to the neck area. Symptoms are due to spinal cord damage and are: pain, decreased sensation of touch, weakness and loss of muscle tissue. The diagnosis is confirmed with a spinal CT, myelogram or MRI of the spinal cord. The cavity may be reduced by surgical decompression.

Treatment

The first step after diagnosis is finding a neurosurgeon who is experienced in the treatment of syringomyelia. Finding a specialist is highly recommended. Surgery is the only viable treatment for syringomyelia, but not all patients will advance to the stage where surgery is needed. Evaluation of the condition is often difficult because syringomyelia can remain stationary for long periods of time, and in some cases progress rapidly. Surgery is usually recommended for syringomyelia patients. Treatment is aimed at correcting the condition that allowed the syrinx to form, if possible. In cases involving a Chiari Malformation, the main goal of surgery is to provide more space for the cerebellum at the base of the skull and upper cervical spine without entering the brain or spinal cord. This often results in flattening or disappearance of the primary syrinx or cavity as the normal flow of cerebrospinal fluid is restored. If a tumor is causing syringomyelia, removal of the tumor is the treatment of choice and almost always eliminates the syrinx. Surgery results in stabilization or modest improvement in symptoms for most patients. Delay in treatment may result in irreversible spinal cord injury. Recurrence of syringomyelia after surgery may make additional operations necessary; these may not be completely successful over the long term. In some patients it may be necessary to drain the syrinx, which can be accomplished using a catheter, drainage tubes, and valves. This system is also known as a shunt. Shunts are used in both the communicating and noncommunicating forms of the disorder. First, the surgeon must locate the syrinx. Then, the shunt is placed into it with the other end draining cerebrospinal fluid into a cavity, usually the abdomen. This type of shunt is called a ventriculoperitoneal shunt and is used in cases involving hydrocephalus. By draining syrinx fluid, a shunt can arrest the progression of symptoms and relieve pain, headache, and tightness. Without correction, symptoms generally continue. The decision to use a shunt requires extensive discussion between doctor and patient, as this procedure carries with it the risk of injury to the spinal cord, infection, blockage, or hemorrhage and may not necessarily work for all patients. In the case of trauma-related syringomyelia, the surgeon operates at the level of the initial injury. The cyst collapses at surgery but a tube or shunt is usually necessary to prevent re-expansion. Drugs have no curative value as a treatment for syringomyelia. Radiation is used rarely and is of little benefit except in the presence of a tumor. In these cases, it can halt the extension of a cavity and may help to alleviate pain. In the absence of symptoms, syringomyelia is usually not treated. In addition, a physician may recommend not treating the condition in patients of advanced age or in cases where there is no progression of symptoms. Whether treated or not, many patients will be told to avoid activities that involve straining. Since the natural history of syringomyelia is poorly understood, a conservative approach may be recommended. When surgery is not yet advised, patients should be carefully monitored by a neurologist or neurosurgeon. Periodic MRI's and physical evaluations should be scheduled at the recommendation of a qualified physician.

Research

The precise causes of syringomyelia are still unknown. Scientists at the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland, and at grantee institutions across the country continue to explore the mechanisms that lead to the formation of syrinxes in the spinal cord. For instance, Institute investigators have found that as the heart beats, the syrinx fluid is abruptly forced downward. They have also demonstrated the presence of a block to the free flow of cerebrospinal fluid that normally occurs in and out of the head during each heartbeat. Surgical techniques are also being refined by the neurosurgical research community. In one treatment approach currently being evaluated, neurosurgeons perform a decompressive procedure where the dura mater, a tough membrane covering the cerebellum and spinal cord, is enlarged with a graft. Like altering a suit of clothing, this procedure expands the area around the cerebellum and spinal cord, thus improving the flow of cerebrospinal fluid and eliminating the syrinx. It is also important to understand the role of birth defects in the development of hindbrain malformations that can lead to syringomyelia. Learning when these defects occur during the development of the fetus can help us understand this and similar disorders, and may lead to preventive treatment that can stop the formation of many birth abnormalities. Dietary supplements of folic acid during pregnancy have already been found to reduce the number of cases of certain birth defects. Diagnostic technology is another area for continued research. Already, MRI has enabled scientists to see conditions in the spine, including syringomyelia, even before symptoms appear. A new technology, known as dynamic MRI, allows investigators to view spinal fluid pulsating within the syrinx. CT scans allow physicians to see abnormalities in the brain, and other diagnostic tests have also improved greatly with the availability of new, non-toxic, contrast dyes. Patients can expect even better techniques to become available in the future from the research efforts of scientists today.

Resource Pages

[http://www.emedicine.com/neuro/topic359.htm eMedicine's syringomyelia page] [http://www.websters-online-dictionary.org/definition/english/Sy/Syringomyelia.html Webster's Dictionary entry] [http://www.mayoclinic.com/invoke.cfm?id=AN00464 Mayo Clinic's page] [http://www.syringo.org/ Syringomyelia Facts] [http://www.neuro.wustl.edu/neuromuscular/spinal/syrinx.htm Syringomyelia syndromes, effects and associated disorders] [http://www.nlm.nih.gov/medlineplus/ency/article/001398.htm MedLine Plus' medical encyclopedia entry] [http://sm-acm.com/public_html/index.php SM/ACM Community]

Litigation

[http://www.rosenblumandreisman.com/index.jsp Rosenblum & Reisman] [http://www.lawyers.com/dchlaw/ Deal · Cooper · Holton PLLC] [http://www.ledbetterlawfirm.com Mark Ledbetter] [http://www.cochranfirm.com/firm-memphis.html Johnnie Cochran's firm] [http://www.medifocuslegal.com/guide_detail.asp?gid=XL110&KeyWord=syringomyelia MediFocusLegal.com page on Trauma and Syringomyelia] "For medical malpractice and personal injury attorneys who need authoritative medical literature to support a claim, identify the most notable experts, and build a solid winning case." One must say it looks suspect...

Organizations


- American Syringomyelia Alliance Project (ASAP) P.O. Box 1586 Longview, TX 75606-1586 info@asap.org http://www.asap.org Tel: 903-236-7079 800-ASAP-282 (272-7282) Fax: 903-757-7456
- National Organization for Rare Disorders (NORD) P.O. Box 1968 (55 Kenosia Avenue) Danbury, CT 06813-1968 orphan@rarediseases.org http://www.rarediseases.org Tel: 203-744-0100 Voice Mail 800-999-NORD (6673) Fax: 203-798-2291
- National Spinal Cord Injury Association (NSCIA) 6701 Democracy Blvd. #300-9 Bethesda, MD 20817 info@spinalcord.org http://www.spinalcord.org Tel: 301-214-4006 800-962-9629 Fax: 301-881-9817
- Brain Resources and Information Network (BRAIN) P.O. Box 5801 Bethesda, MD 20824 (800) 352-9424 http://www.ninds.nih.gov

Stridor

Stridor is a high pitched sound heard on inspiration that is indicative of airway obstruction. It may be indicative of severe disease, such as epiglottitis, and is treated as a medical emergency. Category:Sign (medicine)

Spina bifida

Spina bifida describes birth defects caused by an incomplete closure of one or more vertebral arches of the spine, resulting in malformations of the spinal cord. The spinal membranes and spinal cord may protrude through the absence of vertebral arches (called a cleft). These malformations fall into three categories: spina bifida occulta, spina bifida cystica (myelomeningocele) and meningocele. Spina bifida is a type of neural tube defect. Neural tube defects can usually be detected during pregnancy by AFP screening or a detailed fetal ultrasound. Spina bifida may be associated with other malformations as in dysmorphic syndromes, often resulting in spontaneous miscarriage. However, in the majority of cases spina bifida is an isolated malformation. Spina bifida has varying prevalence in different human populations. This and extensive evidence from mouse strains with spina bifida suggests a genetic basis. As with other human diseases such as cancer, hypertension and atherosclerosis (coronary artery disease), spina bifida likely results from the interaction of multiple genes and environmental factors. Despite much research on spina bifida we still do not know what causes the majority of human cases. Nevertheless, there is substantial evidence supporting a significant protective effect of Folic acid (0.4mg/day) when taken by women early in pregnancy. It is important to note that spina bifida occurs by the 4th week of pregnancy before many women will be aware of a pregnancy, thus it is generally recommended that women of child-bearing age take a folic acid supplement (most multivitamins contain 0.4mg folic acid) if they are sexually active. Genetic counseling and further genetic testing, such as amniocentesis, may be offered during the pregnancy as some neural tube defects are associated with genetic disorders such as trisomy 18. The most common locations of the malformations are in the lumbar and sacral areas. The lumbar nerves control the muscles in the hip, leg, knee and foot, and help to keep the body erect. The sacral nerves control some of the muscles in the feet, bowel and bladder and the ability to have an erection. Some degree of impairment can be expected in these areas. Spina bifida is a Latin term meaning "split spine." Occulta means "hidden."

Types of spina bifida

Spina bifida occulta

This is a mild form of spina bifida. There is no opening on the back, but the outer part of some of the vertebrae are not completely closed. The split in the vertebrae is so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, or it may have some hairs growing from it; there may be a dimple in the skin, or a birthmark. People with this form may have incontinence, slight ambulatory problems, and slight loss of sensation.

Spina bifida cystica (myelomeningocele)

In this, the most serious form, the meningeal membranes that cover the spinal cord and part of the spinal cord protrude through a cleft, forming a sac or cyst, and are clearly visible. The opening is surgically repaired, shortly after birth. The sac or cyst not only contains tissue and cerebrospinal fluid but also nerves and part of the spinal cord. The spinal cord is damaged or not properly developed. As a result, there is usually some degree of paralysis and loss of sensation below the damaged vertebrae. The amount of disability depends very much on where the spina bifida is and the amount of nerve damage involved. Many children and adults with this condition experience problems with bowel and bladder control. In approximately 90% of the people with myelomeningocele, hydrocephalus, extra fluid in the ventricles of the brain, will also occur.

Meningocele

In this, the least common form, the outer part of some of the vertebrae are split and the meninges are damaged and pushed out through the opening, appearing as a sac or cyst, which contains both the meninges and cerebrospinal fluid. The nerves are not usually badly damaged and are able to function, therefore there is often little disability present. There are usually no long-term problems, although problems can arise.

Causes

Spina bifida is caused by the failure of the neural tube to close during embryonic development. Normally the closure of the neural tube occurs around the thirtieth day after fertilization. However, if something interferes and the tube fails to close properly, a neural tube defect will occur. Neural tube defects include the conditions of anencephaly, encephalocele, and spina bifida. Spina bifida occurs in the first month of pregnancy, often before the woman knows that she is pregnant. Spina bifida does not follow direct patterns of heredity like muscular dystrophy or haemophilia. Studies show that a woman who has had one child with a neural tube defects such as spina bifida, have about a 3% risk to have another child with a neural tube defect. This risk can be reduced to about 1% if the woman takes high doses of (0.4mg/day) folic acid before and during pregnancy. It is known that women taking certain medication for epilepsy and women with insulin dependant diabetes have a higher chance of having a child with a neural tube defect. It is also more common among those of Gaelic descent than any other ethnic group.

Effects

Spina bifida results in varying degrees of paralysis, absence of skin sensation, incontinence, and spine and limb problems depending on the severity and location of the lesion damage on the spine. In very rare cases, cognitive problems also result. Most babies born with the condition will need surgeries to correct spinal, foot or leg problems, shunt surgery to drain fluid from the brain, application of techniques to control bladder and bowel function (such as self-catherization or diapers), and braces and other equipment to assist in walking. Tethered cord, with symptoms such as lower body pain, leg weakness, incontinence, scoliosis, numbness, is a common problem associated with spina bifida. Indeed 100% of spina bifida myelomeningocele patients have tethered cord, caused by the spinal cord damage when it is repaired by surgery soon after birth, and the resulting natural scar tissue buildup. However many do not show symptoms of tethered cord until later in life or never at all. Before MRIs were invented Tethered Cord could only be detected through symptoms or surgery and therefore those born before the invention of the MRI, and without symptoms, may not know they have it, or even what it is. If, or when, symptoms show up later in life it can often be a difficult process to discover the correct diagnosis, by which time further damage has been done. According to the Spina Bifida Association of America ([http://www.sbaa.org SBAA]), over 73% of people with spina bifida develop an allergy to latex, ranging from mild to life-threatening. The prevalance of latex in medical facilities makes this a particularly serious concern.

Treatment

There is no cure for spina bifida. To prevent further drying and damage of the nervous tissue and to prevent infection, doctors operate as soon as possible to close the opening on the back, but there is no operation that can fix damaged nerves. During the operation, the spinal cord and its nerve roots are put into place and covered with skin. Doctors are now experimenting and evaluating the efficacy of in-utero surgery to correct the spina bifida lesion. The in-utero surgery occurs in the womb and before birth. In the 4th or 5th month, surgeons have a window of opportunity to perform in-utero surgery by opening the mother's abdomen, and entering the uterus to operate on the spina bifida lesion found on the fetus. Skin grafts are used to cover the exposed spinal cord and protect the spinal cord from further damage caused by prolonged exposure to amniotic fluid. It is believed that the in-utero surgery will decrease some of the damaging effects of the spina bifida lesion, but it is not a cure. The in-utero surgery is currently undergoing NIH clinical trials and the results of these trials and studies ([http://pediatrics.about.com/cs/specialneedskids/a/moms_study_2.htm MOMs study at About.com] and [http://www.spinabifidamoms.com/english/index.html Official MOMs Website]) will not be completed until 2008.

Rate of occurrence

In Canada, spina bifida occurs in about one in every 1,000 births. In Western Australia, up until 1996 around 2 children in every 1000 were born with a neural tube defect. Since 1996, as a result of the folic acid campaign, the figure has dropped to 1.3 children per 1000 births. In the United States, spina bifida occurs in about one in every 1-2,000 births. More children in the U.S. have spina bifida than have muscular dystrophy, multiple sclerosis, and cystic fibrosis combined.

Prevention

Doctors and scientists have found that folic acid can help to prevent spina bifida. It is recommended that all women of childbearing years as well as those women planning to become pregnant should take at least 0.4 mg of folic acid per day from at least one month before conception, and at least 1 mg of folic acid during at least the first three months of pregnancy. Women who have already had a baby with spina bifida or other type of neural tube defect should take extra folic acid - 4mg/day. As yet it is unknown how or why folic acid helps to prevent spina bifida. Sources of folic acid include: Whole grains, fortified breakfast cereals, dried beans, leaf vegetables, fruits.

People

People of note born with spina bifida:
- Olympian and eight-time Boston Marathon winner Jean Driscoll[http://www.jeandriscoll.com]
- 80s Rock Star John Mellencamp
- British Paralympian Tanni Grey-Thompson
- Country music legend Hank Williams

External link


- [http://www.canadian-health-network.ca/servlet/ContentServer2FSearchPageTemplate&c=Page&lang=En&searchStr=spina+bifida&orderBy=ORDER_RANK&searchType=EXACT&x=43&y=12&logSearch=true Canadian Health Network - Search Results for spina bifida]
- http://www.ifglobal.org, the International Federation for Spina Bifida and Hydrocephalus (IF), the umbrella organisation for national spina bifida and hydrocephalus organisations Category:Congenital disorders Category:obstetrics

Hydrocephalus

Hydrocephalus ('water-head', term derived from Greek) is an abnormal accumulation of cerebrospinal fluid in the ventricles of the brain. This increase in intracranial volume results in elevated intracranial pressure.

History

Hydrocephalus was first described by Hippocrates, but it remained an intractable condition until the 20th century, when shunts and other neurosurgical treatment modalities were developed.

Causes

Hydrocephalus is caused by impaired cerebrospinal fluid (CSF) production, flow or resorption. The most common cause of hydrocephalus is a flow obstruction, hindering the free passage of cerebrospinal fluid through the ventricular system and subarachnoid space (e.g. stenosis of the cerebral aqueduct, obstruction of the interventricular foraminae - foramen of Monro). This can be secondary to tumors, hemorrhages, infections or congenital malfomations. It can also be caused by overproduction of cerebrospinal fluid (relative obstruction). Based on its underlying mechanisms, hydrocephalus can be classified into communicating, and non-communicating (obstructive). Both communicating and non-communicating forms can be either congenital, or acquired. Normal pressure hydrocephalus (NPH) is a particular form of communicating hydrocephalus, characterized by enlarged cerebral ventricles, with only intermittently elevated cerebrospinal fluid pressure. The diagnosis of NPH can be established only with the help of continuous intraventricular pressure recordings (over 24 hours or even longer), since more often than not, instant measurements yield normal pressure values. Dynamic compliance studies may be also helpful. Altered compliance (elasticity) of the ventricular walls, as well as increased viscosity of the cerebrospinal fluid may play a role in the genesis of normal pressure hydrocephalus. Brain atrophy, as it occurs in dementias, after traumatic brain injuries and even in some psychiatric disorders, such as schizophrenia, may also result in an enlargement of cerebral ventricles and subarachnoid spaces. As opposed to hydrocephalus, this is a compensatory enlargement of the CSF-spaces in response to brain parenchyma loss - it is not the result of increased CSF pressure.

Communicating hydrocephalus

Communicating hydrocephalus, a.k.a. non-obstructive or communicating hydrocephalus is caused by impaired cerebrospinal fluid resorption, in the absence of any CSF-flow obstruction. It has been theorized that this is due to functional impairment the arachnoid granulations (located along the superior sagittal sinus) - they represent the site of cerebrospinal fluid resorption back into the venous system). Various neurologic conditions may result in communicating hydrocephalus. These include subarachnoid/intraventricular hemorrhage, meningitis, Chiari malformation, and congenital absence of arachnoidal granulations, a.k.a. Pacchioni's granulations.

Non-communicating hydrocephalus

Non-communicating hydrocephalus, or obstructive hydrocephalus, is caused by a CSF-flow obstruction (either due to external compression or intraventricular mass lesions). In many cases, the flow obstruction is located at the level of the cerebral aqueduct (aqueduct stenosis), which connects the third and fourth ventricle. Third ventriculostomy (i.e. a surgical connection between the third ventricle and the subarachnoid space) should be considered as an alternative therapeutic option to traditional CSF-shunting procedures (ventriculo-peritoneal shunt, ventriculo-atrial shunt).

Congenital hydrocephalus

In newborns and toddlers with hydrocephalus, the head circumference is enlarged, since the skull bones are not yet firmly joined together. A bulging, firm fontanelle (soft spot) may be an early sign of hydrocephalus in this age group. About 80-90% of fetuses or newborn infants with spina bifida - often associated with meningocele or myelomeningocele - develop hydrocephalus.

Acquired hydrocephalus

This condition is acquired as a consequence of CNS-infections, brain tumors, head trauma, intracranial hemorrhage (subarachnoid or intraparenchymal).

Clinical presentation

Like various other neurologic conditions (brain tumors, strokes, traumatic brain injury, etc.), hydrocephalus results in elevated intracranial pressure. Possible clinical manifestations include: headaches, vomiting (in some cases not accompanied by nausea), papilledema, somnolence, coma. Elevated intracranial pressure may result in uncal and/or cerebellar tonsill herniation, with resulting life threatening brain stem compression. Normal pressure hydrocephalus (NPH) is distinguished by a relatively typical clinical triad: gait instability, urinary incontinence and dementia. Focal neurologic deficits may also occur, such as abducens nerve palsy and vertical gaze palsy - Parrinaud syndrome (due to compression of the quadrigeminal plate, where the neural centers coordinating the conjugated vertical eye movement are located).

Treatment

State-of-the-art hydrocephalus treatment is surgical. It involves the placement of a ventricular catheter (a tube made of silastic), into the cerebral ventricles to bypass the flow obstruction/malfunctioning arachnoidal granulations and drain the excess fluid into other body cavities, from where it can be resorbed. Most shunts drain the fluid into the peritoneal cavity (ventriculo-peritoneal shunt), but alternative sites include the right atrium (ventriculo-atrial shunt), pleural cavity (ventriculo-pleural shunt), and gallbladder. An alternative treatment is the endoscopic third venstriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction, as in aqueductal stenosis.

Links


- http://www.ifglobal.org, the International Federation for Spina Bifida and Hydrocephalus (IF), the umbrella organisation for national spina bifida and hydrocephalus organisations Category:Medical emergencies Category:Neurological disorders

Pathologist

Pathology (from Greek pathos, feeling, pain, suffering; and logos, study of; see also -ology) is the study of the processes underlying disease and other forms of illness, harmful abnormality, or dysfunction. Within biology, it means specifically the study of the structural and functional changes in cells, tissues and organs that underlie disease. It is a form of science and a branch of medicine that involves testing samples in a medical laboratory and diagnosing health problems from their evidence. Pathologists are trained doctors who have specialized in interpreting test results and physical evidence, and are generally required to take further postgraduate exams and mandatory training before they are able to practice independently. The related term pathological is sometimes used by clinicians, or casually, to signify some aberrant process underlying such a dysfunction, thus a "pathological growth", or casually, a "pathological attitude" or a "pathological woman hater".

Biological and life studies use

The four main aspects of a disease that are studied in pathology are:
- Etiology: what causes the disease
- Pathogenesis: the mechanism by which a certain etiological factor causes disease
- Morphologic changes: the structural changes induced in the cells, tissues and organs
- Clinical significance: the functional consequences of the morphologic changes Fields of pathology include:
- Anatomical pathology
- Chemical pathology
- Cytopathology (Cellular pathology?)
- Cytogenetics
- Experimental Pathology
- Forensic pathology
- Hematology
- Histology (the study of tissues and the effects of disease upon them)
- Histopathology (the microscopic study of diseased tissue)
- Immunology
- Microbiology
- Nosology (the science of classifying diseases)
- Oral and maxillofacial pathology (a specialty of dentistry and pathology)
- Plant pathology

Related uses


- Speech pathology is a quite separate area mostly involved in helping patients with stroke or speech impediments.
- Psychopathology is also used in mental health, denoting the study of mental illness. Pathological is also used to describe a person's actions in such a way as to credit the action to a disease process or a compulsion:
- Pathological purchasing or Pathological consumption
- Pathological narcissism
- Pathological liar

Other uses

Pathological can also be used in data sets in mathematics or statistics to reference an exceptionally (or awkwardly, or inconveniently) atypical example or set of data, often one which does not abide by rules or succumb to treatment that other similar cases usually do:
- Pathological (mathematics)
- Pathological science Computer science uses this term in a slightly different sense with regard to the study of algorithms. Here, an input (or set of inputs) is said to be pathological if it causes atypical behavior from the algorithm, such as a violation of its average case complexity, or even its correctness. For example, hash tables generally have pathological inputs: sets of keys that collide on hash values. The term is often used pejoratively, as a way of dismissing such inputs as being specially designed to break a routine that is otherwise sound in practice.

See also


- Important publications in pathology
- ja:病理学

1890s

The 1890s were sometimes referred to as the "Mauve Decade," because William Henry Perkin's aniline dye allowed the widespread use of that colour in fashion, and also as the "Gay Nineties", under the then-current usage of the word "gay" which referred simply to merriment and frivolity, with no connotation of homosexuality as in current-day usage.

Events and trends

Technology


- Early commercial production of automobiles.

Science


- Henri Becquerel discovers radioactivity
- Discovery of x-rays by Wilhelm Röntgen
- Swedish scientist Svante Arrhenius and US geologist Thomas Crowder Chamberlain independently come to the conclusion that burning fossil fuels might cause global warming due to carbon dioxide emissions

War, peace and politics


- Second Boer War
- Spanish-American War
- Split in Irish nationalism over Irish leader Charles Stewart Parnell's affair with a fellow MP's wife, Kitty O'Shea
- The New Imperialism

Culture, religion


- Motion pictures
- Ragtime music
- Accession of Tsar Nicholas II of Russia in the world's first ever filmed coronation.
- Lynchings of African Americans in the United States averaged 150 per year.
- H. G. Wells creates modern science fiction with his book The War of the Worlds.
- Hale Johnson is a major leader of the temperance movement.
- Department of Scientific Temperance Instruction, under Mary Hunt, achieves de facto control over all alcohol education in the U.S.

Others

People

World leaders


- Prime Minister John Sparrow David Thompson (Canada)
- Prime Minister Sir Wilfrid Laurier (Canada)
- Emperor Franz Josef (Austria-Hungary)
- Kaiser Wilhelm II (Germany)
- Chancellor Leo von Caprivi (Germany)
- King Umberto I (Italy)
- Pope Leo XIII
- Czar Alexander III (Russia)
- Czar Nicholas II (Russia)
- Queen Victoria (United Kingdom)
- Prime Minister Lord Salisbury (United Kingdom)
- Prime Minister William Ewart Gladstone (United Kingdom)
- Prime Minister Lord Rosebery (United Kingdom)
- President Benjamin Harrison (United States)
- President Grover Cleveland (United States)
- President William McKinley (United States)

Important people


- Thomas A. Edison
- Nikola Tesla

Entertainers


- Adelina Patti
- George W. Johnson
- Justin Smith
- Jonathan Booth

Sports


- Bob Fitzsimmons

Books about the 1890s


- The Mauve Decade, by Thomas Beer (1926)

See also

Gay Nineties

External links


- [http://www.mccord-museum.qc.ca/en/keys/games/game_0/ Quiz: Victorian Etiquette] — Educational Game, In the style of the Monty Pythons Category:1890s ja:1890年代

Category:Neurology

Neurology is the branch of medicine that deals with diseases of the nervous system. Category:Medical specialties Category:Neuroscience

211

__NOTOC__ Siglo: Tabla anual siglo III (siglo II - siglo III - siglo IV) Década: Años 180 - Años 190 - Años 200 - Años 210 - Años 220 - Años 230 - Años 240 Años: 206 207 208 209 210 - 211 - 212 213 214 215 216 ----

Acontecimientos:

Nacimientos:

Fallecimientos:


- 4 de febrero - Septimio Severo, emperador de Roma. Categoría: Siglo III ko:211년

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