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Hyporeflexia
Hyporeflexia is the reduction or absence of normal bodily reflexes (areflexia). It can be detected through the use of a reflex hammer and is the opposite of hyperreflexia. Hyporeflexia is generally associated with a deficit in the lower motor neurons (at the alpha motor neurons from spinal cord to muscle), whereas hyperreflexia is often attributed to lesions in the upper motor neurons (along the long, motor tracts from the brain). The upper motor neurons are thought to inhibit the reflex arc, which is formed by sensory neurons from intrafusal fibers of muscles, lower motor neurons (including alpha and gamma motor fibers) and appurtenant interneurons. Therefore, damage to lower motor neurons will subsequently result in hyporeflexia and/or areflexia. In spinal shock, which is commonly seen in the transection of the spinal cord (Spinal cord injury), areflexia can transiently occur below the level of the lesion and can later become hyperreflexic. Cases of severe muscle atrophy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflex Hammer
A reflex hammer is a medical instrument used by practitioners to test deep tendon reflexes. Testing for reflexes is an important part of the neurological physical examination in order to detect abnormalities in the central or peripheral nervous system. Reflex hammers can also be used for chest percussion.Swartz MH. ''Textbook of Physical Diagnosis: History and Examination.'' Third edition. Philadelphia: WB Saunders; 1998 Models of reflex hammer Prior to the development of specialized reflex hammers, hammers specific for percussion of the chest were used to elicit reflexes.Lanska DJ. The history of reflex hammers. ''Neurology''. 1989 Nov;39(11):1542-9. However, this proved to be cumbersome, as the weight of the chest percussion hammer was insufficient to generate an adequate stimulus for a reflex. Starting in the late 19th century, several models of specific reflex hammers were created: *The Taylor or tomahawk reflex hammer was designed by John Madison Taylor in 1888 and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Motor Neurons
Alpha (α) motor neurons (also called alpha motoneurons), are large, multipolar lower motor neurons of the brainstem and spinal cord. They innervate extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction. Alpha motor neurons are distinct from gamma motor neurons, which innervate intrafusal muscle fibers of muscle spindles. While their cell bodies are found in the central nervous system (CNS), α motor neurons are also considered part of the somatic nervous system—a branch of the peripheral nervous system (PNS)—because their axons extend into the periphery to innervate skeletal muscles. An alpha motor neuron and the muscle fibers it innervates is a motor unit. A motor neuron pool contains the cell bodies of all the alpha motor neurons involved in contracting a single muscle. Location Alpha motor neurons (α-MNs) innervating the head and neck are found in the brainstem; the remaining α-MNs innervate the rest of the bod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Shock
Spinal shock was first explored by Whytt in 1750 as a loss of sensation accompanied by motor paralysis with initial loss but gradual recovery of reflexes, following a spinal cord injury (SCI) – most often a complete transection. Reflexes in the spinal cord below the level of injury are depressed (hyporeflexia) or absent (areflexia), while those above the level of the injury remain unaffected. The 'shock' in spinal shock does not refer to circulatory collapse, and should not be confused with neurogenic shock, which is life-threatening. The term “spinal shock” was introduced more than 150 years ago in an attempt to distinguish arterial hypotension due to a hemorrhagic source from arterial hypotension due to loss of sympathetic tone resulting from spinal cord injury. Whytt, however, may have discussed the same phenomenon a century earlier, although no descriptive term was assigned. __TOC__ Phases of spinal shock Ditunno et al. proposed a four-phase model for spinal shock in 2004 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guillain–Barré Syndrome
Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation or pain often in the back along with muscle weakness, beginning in the feet and hands, often spreading to the arms and upper body. The symptoms may develop over hours to a few weeks. During the acute phase, the disorder can be life-threatening, with about 15% of people developing weakness of the breathing muscles and, therefore, requiring mechanical ventilation. Some are affected by changes in the function of the autonomic nervous system, which can lead to dangerous abnormalities in heart rate and blood pressure. Although the cause is unknown, the underlying mechanism involves an autoimmune disorder in which the body's immune system mistakenly attacks the peripheral nerves and damages their myelin insulation. Sometimes this immune dysfunction i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurology
Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal cord and the peripheral nerves. Neurological practice relies heavily on the field of neuroscience, the scientific study of the nervous system. A neurologist is a physician specializing in neurology and trained to investigate, diagnose and treat neurological disorders. Neurologists treat a myriad of neurologic conditions, including stroke, seizures, movement disorders such as Parkinson's disease, autoimmune neurologic disorders such as multiple sclerosis, headache disorders like migraine and dementias such as Alzheimer's disease. Neurologists may also be involved in clinical research, clinical trials, and basic or translational research. While neurology is a nonsurgical specialty, its corresponding surgical specialty is neurosurger ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperreflexia
Hyperreflexia is overactive or overresponsive bodily reflexes. Examples of this include twitching and spastic tendencies, which indicate upper disease of the upper motor neurons and the lessening or loss of control ordinarily exerted by higher brain centers of lower neural pathways (disinhibition). The most common cause of hyperreflexia is spinal-cord injury (''see'' "Autonomic dysreflexia"). Standard stimuli, such as the filling of the bladder, can cause excessive responses from the nervous system; the causes are not known. Hyperreflexia also has many other causes, including the side effects of drugs and stimulants; hyperthyroidism; electrolyte imbalance; serotonin syndrome; severe brain trauma; multiple sclerosis; Reye syndrome; and preeclampsia. Treatment depends on the cause of the hyperreflexia. If drugs cause it, treatment may require that they not be used. Recovery from hyperreflexia can occur several hours to several months after a spinal-cord injury; the phase of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lesion
A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classification or naming convention for lesions. Since lesions can occur anywhere in the body and the definition of a lesion is so broad, the varieties of lesions are virtually endless. Generally, lesions may be classified by their patterns, their sizes, their locations, or their causes. They can also be named after the person who discovered them. For example, Ghon lesions, which are found in the lungs of those with tuberculosis, are named after the lesion's discoverer, Anton Ghon. The characteristic skin lesions of a varicella zoster virus infection are called '' chickenpox''. Lesions of the teeth are usually called dental caries. Location Lesions are often classified by their tissue types or locations. For example, a "skin lesion" or a " b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflex Arc
A reflex arc is a neural pathway that controls a reflex. In vertebrates, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This allows for faster reflex actions to occur by activating spinal motor neurons without the delay of routing signals through the brain. The brain will receive the input while the reflex is being carried out and the analysis of the signal takes place after the reflex action. There are two types: autonomic reflex arc (affecting inner organs) and somatic reflex arc (affecting muscles). Autonomic reflexes sometimes involve the spinal cord and some somatic reflexes are mediated more by the brain than the spinal cord. During a somatic reflex, nerve signals travel along the following pathway: # ''Somatic receptors'' in the skin, muscles and tendons # ''Afferent nerve fibers'' carry signals from the somatic receptors to the posterior horn of the spinal cord or to the brainstem # An ''integrating center'', the point at whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Cord Injury
A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. Symptoms may include loss of muscle function, sensation, or autonomic function in the parts of the body served by the spinal cord below the level of the injury. Injury can occur at any level of the spinal cord and can be ''complete'', with a total loss of sensation and muscle function at lower sacral segments, or ''incomplete'', meaning some nervous signals are able to travel past the injured area of the cord up to the Sacral S4-5 spinal cord segments. Depending on the location and severity of damage, the symptoms vary, from numbness to paralysis, including bowel or bladder incontinence. Long term outcomes also range widely, from full recovery to permanent tetraplegia (also called quadriplegia) or paraplegia. Complications can include muscle atrophy, loss of voluntary motor control, spasticity, pressure sores, infections, and breathing problems. In the major ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzodiazepine
Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, insomnia, and seizures. The first benzodiazepine, chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955 and was made available in 1960 by Hoffmann–La Roche, who soon followed with diazepam (Valium) in 1963. By 1977, benzodiazepines were the most prescribed medications globally; the introduction of selective serotonin reuptake inhibitors (SSRIs), among other factors, decreased rates of prescription, but they remain frequently used worldwide. Benzodiazepines are depressants that enhance the effect of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABAA receptor, resulting in sedative, hypnotic ( sleep-inducing), anxiolytic (anti-anxiety), anticonvulsant, and muscle relaxant properties. High d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centronuclear Myopathy
Centronuclear myopathies (CNM) are a group of congenital myopathies where cell nuclei are abnormally located in the center of muscle cells instead of their normal location at the periphery. Symptoms of CNM include severe hypotonia, hypoxia-requiring breathing assistance, and scaphocephaly. Among centronuclear myopathies, the X-linked myotubular myopathy form typically presents at birth, and is thus considered a congenital myopathy. However, some centronuclear myopathies may present later in life. Presentation As with other myopathies, the clinical manifestations of MTM/CNM are most notably muscle weakness and associated disabilities. Congenital forms often present with neonatal low muscle tone, severe weakness, delayed developmental milestones (particularly gross motor milestones such as head control, crawling, and walking) and pulmonary complications (presumably due to weakness of the muscles responsible for respiration). Involvement of the facial muscles may cause ophthalm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambert–Eaton Myasthenic Syndrome
Lambert–Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder characterized by muscle weakness of the limbs. Around 60% of those with LEMS have an underlying malignancy, most commonly small-cell lung cancer; it is therefore regarded as a paraneoplastic syndrome (a condition that arises as a result of cancer elsewhere in the body). It is the result of antibodies against presynaptic voltage-gated calcium channels, and likely other nerve terminal proteins, in the neuromuscular junction (the connection between nerves and the muscle that they supply). The diagnosis is usually confirmed with electromyography and blood tests; these also distinguish it from myasthenia gravis, a related autoimmune neuromuscular disease. If the disease is associated with cancer, direct treatment of the cancer often relieves the symptoms of LEMS. Other treatments often used are steroids, azathioprine, which suppress the immune system, intravenous immunoglobulin, which outcompetes autorea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
