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Hyporeflexia
Hyporeflexia is the reduction or absence of normal bodily reflexes. 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 the spinal cord to a 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, hyporeflexia can transiently occur below the level of the lesion and can later become hyperreflexic. Cases of severe muscle atrophy or destruction may ren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Spinal Shock
Spinal shock was first explored by Robert 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Reflex Hammer
A reflex hammer is a medical instrument used by practitioners to test deep tendon reflexes, the best known possibly being the patellar reflex. Testing for reflexes is an important part of the neurological examination, neurological physical examination in order to detect abnormalities in the central nervous system, central or peripheral nervous system, peripheral nervous system. Reflex hammers can also be used for chest percussion (medicine), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Lower Motor Neuron
Lower motor neurons (LMNs) are motor neurons located in either the anterior grey column, anterior nerve roots (spinal lower motor neurons) or the cranial nerve nuclei of the brainstem and cranial nerves with motor function (cranial nerve lower motor neurons). Many voluntary movements rely on spinal lower motor neurons, which innervate skeletal muscle fibers and act as a link between upper motor neurons and muscles. Cranial nerve lower motor neurons also control some voluntary movements of the eyes, face and tongue, and contribute to chewing, swallowing and vocalization. Damage to lower motor neurons often leads to hypotonia, hyporeflexia, flaccid paralysis as well as muscle atrophy and fasciculations. Classification Lower motor neurons are classified based on the type of muscle fiber they innervate: * Alpha motor neurons (α-MNs) innervate extrafusal muscle fibers, the most numerous type of muscle fiber and the one involved in muscle contraction. * Beta motor neurons (β-M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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 comprise 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 b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Spinal Cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal cord is hollow and contains a structure called the central canal, which contains cerebrospinal fluid. The spinal cord is also covered by meninges and enclosed by the neural arches. Together, the brain and spinal cord make up the central nervous system. In humans, the spinal cord is a continuation of the brainstem and anatomically begins at the occipital bone, passing out of the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it tapers to become the cauda equina. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around long in adult men and around long in adult women. The diam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Guillain–Barré Syndrome
Guillain–Barré syndrome (GBS) is a rapid-onset Paralysis, 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 respiratory system, respiratory muscle weakness requiring mechanical ventilation. Some are affected by dysautonomia, 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 im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Electrolyte Imbalance
Electrolyte imbalance, or water-electrolyte imbalance, is an abnormality in the concentration of electrolytes in the body. Electrolytes play a vital role in maintaining homeostasis in the body. They help to regulate heart and neurological function, fluid balance, oxygen delivery, acid–base balance and much more. Electrolyte imbalances can develop by consuming too little or too much electrolyte as well as excreting too little or too much electrolyte. Examples of electrolytes include calcium, chloride, magnesium, phosphate, potassium, and sodium. Electrolyte disturbances are involved in many disease processes and are an important part of patient management in medicine. The causes, severity, treatment, and outcomes of these disturbances can differ greatly depending on the implicated electrolyte. The most serious electrolyte disturbances involve abnormalities in the levels of sodium, potassium or calcium. Other electrolyte imbalances are less common and often occur in conjunction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hyperreflexia
Hyperreflexia is overactive or overresponsive bodily reflexes. Examples of this include twitching and spastic tendencies, which indicate disease of the upper motor neurons and the lessening or loss of control ordinarily exerted by higher brain centers of lower neural pathways. Spinal cord injury is the most common cause of hyperreflexia. Standard stimuli, such as the filling of the bladder, can cause excessive responses from the nervous system. The causes of hyperreflexia are not known. Hyperreflexia also has many other causes, including the side effects of drugs (e.g., stimulants), hyperthyroidism, electrolyte imbalance, serotonin syndrome, severe brain trauma, multiple sclerosis, Reye syndrome, and pre-eclampsia. Recovery from hyperreflexia can occur several hours to several months after a spinal cord injury; the phase of recovery is likely to occur in stages rather than on a continuum.Little, J., Ditunno, J. F., Stien, S., A., Harris, R. M. (1999). "Incomplete spinal cord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Friedreich's Ataxia
Friedreich's ataxia (FRDA) is a rare, inherited, autosomal recessive neurodegenerative disorder that primarily affects the nervous system, causing progressive damage to the spinal cord, peripheral nerves, and cerebellum, leading to impaired muscle coordination (''ataxia''). The condition typically manifests in childhood or adolescence, with initial symptoms including difficulty walking, loss of balance, and poor coordination. As the disease progresses, it can also impact speech, vision, and hearing. Many individuals with Friedreich's ataxia develop scoliosis, diabetes, and hypertrophic cardiomyopathy, a serious heart condition that is a leading cause of mortality in patients. Friedreich's ataxia is caused by mutations in the ''FXN'' gene, which result in reduced production of frataxin, a protein essential for mitochondrial function, particularly in iron-sulfur cluster biogenesis. The deficiency of frataxin disrupts cellular energy production and leads to oxidative stress, co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Polyneuropathy
Polyneuropathy () is damage or disease affecting peripheral nerves (peripheral neuropathy) in roughly the same areas on both sides of the body, featuring weakness, numbness, and burning pain. It usually begins in the hands and feet and may progress to the arms and legs and sometimes to other parts of the body where it may affect the autonomic nervous system. It may be acute or chronic. A number of different disorders may cause polyneuropathy, including diabetes and some types of Guillain–Barré syndrome. Classification Polyneuropathies may be classified in different ways, such as by ''cause'', by ''presentation'', or by ''classes'' of polyneuropathy, in terms of which part of the nerve cell is affected mainly: the axon, the myelin sheath, or the cell body. * ''Distal axonopathy'', is the result of interrupted function of the peripheral nerves. It is the most common response of neurons to metabolic or toxic disturbances, and may be caused by metabolic diseases such as diabe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hypothyroidism
Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, constipation, slow heart rate, Depression (mood), depression, and weight gain. Occasionally there may be swelling of the front part of the neck due to goiter. Untreated cases of hypothyroidism during pregnancy can lead to delays in child development, growth and intellectual development in the baby or congenital iodine deficiency syndrome. Worldwide, iodine deficiency, too little iodine in the diet is the most common cause of hypothyroidism. Hashimoto's thyroiditis, an autoimmune disease where the body's immune system reacts to the thyroid gland, is the most common cause of hypothyroidism in countries with sufficient dietary iodine. Less common causes include previous treatment with iodine-131, radioactive iodine, injury to the hypothalamus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Lambert–Eaton Myasthenic Syndrome
Lambert–Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder characterized by muscle weakness of the limbs. It is also known as myasthenic syndrome, Eaton–Lambert syndrome, and when related to cancer, carcinomatous myopathy. Around 60% of those with LEMS have an underlying malignancy, most commonly small-cell lung cancer (SCLC); 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
