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Hydranencephaly
Hydranencephaly is a condition in which the brain's cerebral hemispheres are absent to a great degree and the remaining cranial cavity is filled with cerebrospinal fluid. "Cephalic" is the scientific term for "head" or "head end of body". Hydranencephaly is a type of cephalic disorder. These disorders are congenital conditions that derive from damage to, or abnormal development of, the fetal nervous system in the earliest stages of development in utero. These conditions do not have any definitive identifiable cause factor. Instead, they are generally attributed to a variety of hereditary or genetic conditions, but also by environmental factors such as maternal infection, pharmaceutical intake, or even exposure to high levels of radiation. Hydranencephaly should not be confused with hydrocephalus, which is an accumulation of excess cerebrospinal fluid in the ventricles of the brain. In hemihydranencephaly, only half of the cranial cavity is affected. Signs and symptoms An i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemihydranencephaly
Hemihydranencephaly is a severe cephalic disorder characterized by complete or almost complete absence of the cerebral cortex with preservation of meninges, basal ganglia, pons, medulla, cerebellum, and falx. It is a special type of hydranencephaly Hydranencephaly is a condition in which the brain's cerebral hemispheres are absent to a great degree and the remaining cranial cavity is filled with cerebrospinal fluid. "Cephalic" is the scientific term for "head" or "head end of body". Hydrane .... It is a very rare disease. As it stands, only 7 cases have been reported. References * Greco F, Finocchiaro M, Pavone P, Trifiletti RR, Parano E. Hemihydranencephaly: case report and literature review. J Child Neurol. 2001;16 :218–221 Congenital disorders of nervous system Rare diseases {{nervoussystem-disease-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Hemispheres
The vertebrate cerebrum (brain) is formed by two cerebral hemispheres that are separated by a groove, the longitudinal fissure. The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter, the cerebral cortex, that is supported by an inner layer of white matter. In eutherian (placental) mammals, the hemispheres are linked by the corpus callosum, a very large bundle of nerve fibers. Smaller commissures, including the anterior commissure, the posterior commissure and the fornix, also join the hemispheres and these are also present in other vertebrates. These commissures transfer information between the two hemispheres to coordinate localized functions. There are three known poles of the cerebral hemispheres: the ''occipital pole'', the ''frontal pole'', and the ''temporal pole''. The central sulcus is a prominent fissure which separates the parietal lobe from the frontal lobe and the prim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypertonia
Hypertonia is a term sometimes used synonymously with spasticity and rigidity in the literature surrounding damage to the central nervous system, namely upper motor neuron lesions. Impaired ability of damaged motor neurons to regulate descending pathways gives rise to disordered spinal reflexes, increased excitability of muscle spindles, and decreased synaptic inhibition. These consequences result in abnormally increased muscle tone of symptomatic muscles. Some authors suggest that the current definition for spasticity, the velocity-dependent over-activity of the stretch reflex, is not sufficient as it fails to take into account patients exhibiting increased muscle tone in the absence of stretch reflex over-activity. They instead suggest that "reversible hypertonia" is more appropriate and represents a treatable condition that is responsive to various therapy modalities like drug and/or physical therapy. Presentation Symptoms associated with central nervous systems disorders ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxoplasmosis
Toxoplasmosis is a parasitic disease caused by ''Toxoplasma gondii'', an apicomplexan. Infections with toxoplasmosis are associated with a variety of neuropsychiatric and behavioral conditions. Occasionally, people may have a few weeks or months of mild, flu-like illness such as muscle aches and tender lymph nodes. In a small number of people, eye problems may develop. In those with a weak immune system, severe symptoms such as seizures and poor coordination may occur. If a person becomes infected during pregnancy, a condition known as congenital toxoplasmosis may affect the child. Toxoplasmosis is usually spread by eating poorly cooked food that contains cysts, exposure to infected cat feces, and from an infected woman to their baby during pregnancy. Rarely, the disease may be spread by blood transfusion. It is not otherwise spread between people. The parasite is known to reproduce sexually only in the cat family. However, it can infect most types of warm-blooded animals, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pregnancy
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but can also occur through assisted reproductive technology procedures. A pregnancy may end in a live birth, a miscarriage, an induced abortion, or a stillbirth. Childbirth typically occurs around 40 weeks from the start of the last menstrual period (LMP), a span known as the gestational age. This is just over nine months. Counting by fertilization age, the length is about 38 weeks. Pregnancy is "the presence of an implanted human embryo or fetus in the uterus"; implantation occurs on average 8–9 days after fertilization. An '' embryo'' is the term for the developing offspring during the first seven weeks following implantation (i.e. ten weeks' gestational age), after which the term ''fetus'' is used until birth. Signs an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyst
A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble); however, the distinguishing aspect of a cyst is that the cells forming the "shell" of such a sac are distinctly abnormal (in both appearance and behaviour) when compared with all surrounding cells for that given location. A cyst may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, a cyst may resolve on its own. When a cyst fails to resolve, it may need to be removed surgically, but that would depend upon its type and location. Cancer-related cysts are formed as a defense mechanism for the body following the development of mutations that lead to an uncontrolled cellular division. Once that mutation has occurred, the affected cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porencephaly
Porencephaly is an extremely rare cephalic disorder involving encephalomalacia. It is a neurological disorder of the central nervous system characterized by cysts or cavities within the cerebral hemisphere.Parker, J. (2004). The official parent's sourcebook on porencephaly: A revised and updated directory for the internet age. ICON Health Publications. Porencephaly was termed by Heschl in 1859 to describe a cavity in the human brain. Derived from Greek roots, the word ''porencephaly'' means 'holes in the brain'. The cysts and cavities (cystic brain lesions) are more likely to be the result of destructive (encephaloclastic) cause, but can also be from abnormal development (malformative), direct damage, inflammation, or hemorrhage. The cysts and cavities cause a wide range of physiological, physical, and neurological symptoms. Depending on the patient, this disorder may cause only minor neurological problems, without any disruption of intelligence, while others may be severely dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Respiration (physiology)
In physiology, respiration is the movement of oxygen from the outside environment to the cells within Tissue (biology), tissues, and the transport, removal of carbon dioxide in the opposite direction that's to the environment. The physiological definition of respiration differs from the Cellular respiration, biochemical definition, which refers to a metabolic process by which an organism obtains energy (in the form of ATP and NADPH) by oxidizing nutrients and releasing waste products. Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the organism, while physiologic respiration concerns the Diffusion#Diffusion vs. bulk flow diffusion, diffusion and transport of metabolites between the organism and the external environment. Gas exchanges in the lung occurs by ventilation and perfusion. Ventilation refers to the in and out movement of air of the lu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoregulation In Humans
As in other mammals, thermoregulation in humans is an important aspect of homeostasis. In thermoregulation, body heat is generated mostly in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid. High temperatures pose serious stress for the human body, placing it in great danger of injury or even death. For humans, adaptation to varying climatic conditions includes both physiological mechanisms resulting from evolution and behavioural mechanisms resulting from conscious cultural adaptations.Harrison, G.A., Tanner, J.M., Pilbeam, D.R., & Baker, P.T. (1988) ''Human Biology: An introduction to human evolution, variation, growth, and adaptability''. (3rd ed). Oxford: Oxford University PressWeiss, M.L., & Mann, A.E. (1985) ''Human Biology and Behaviour: An anthropological perspective''. (4th ed). Boston: Little Brown There are four avenues of heat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myoclonus
Myoclonus is a brief, involuntary, irregular (lacking rhythm) twitching of a muscle or a group of muscles, different from clonus, which is rhythmic or regular. Myoclonus (myo "muscle", clonic "jerk") describes a medical sign and, generally, is not a diagnosis of a disease. These myoclonic twitches, jerks, or seizures are usually caused by sudden muscle contractions (''positive myoclonus'') or brief lapses of contraction (''negative myoclonus''). The most common circumstance under which they occur is while falling asleep (hypnic jerk). Myoclonic jerks occur in healthy people and are experienced occasionally by everyone. However, when they appear with more persistence and become more widespread they can be a sign of various neurological disorders. Hiccups are a kind of myoclonic jerk specifically affecting the diaphragm. When a spasm is caused by another person it is known as a ''provoked spasm''. Shuddering attacks in babies fall in this category. Myoclonic jerks may occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with loss of consciousness ( tonic-clonic seizure), to shaking movements involving only part of the body with variable levels of consciousness (focal seizure), to a subtle momentary loss of awareness ( absence seizure). Most of the time these episodes last less than two minutes and it takes some time to return to normal. Loss of bladder control may occur. Seizures may be provoked and unprovoked. Provoked seizures are due to a temporary event such as low blood sugar, alcohol withdrawal, abusing alcohol together with prescription medication, low blood sodium, fever, brain infection, or concussion. Unprovoked seizures occur without a known or fixable cause such that ongoing seizures are likely. Unprovoked seizures may be exacerbated by stress or sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paralysis
Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 50 people have been diagnosed with some form of permanent or transient paralysis. The word "paralysis" derives from the Greek παράλυσις, meaning "disabling of the nerves" from παρά (''para'') meaning "beside, by" and λύσις (''lysis'') meaning "making loose". A paralysis accompanied by involuntary tremors is usually called "palsy". Causes Paralysis is most often caused by damage in the nervous system, especially the spinal cord. Other major causes are stroke, trauma with nerve injury, poliomyelitis, cerebral palsy, peripheral neuropathy, Parkinson's disease, ALS, botulism, spina bifida, multiple sclerosis, and Guillain–Barré syndrome. Temporary paralysis occurs during REM sleep, and dysregulation of this system can lead ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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