Muscle atrophy in the context of "Carpal tunnel"

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⭐ Core Definition: Muscle atrophy

Muscle atrophy is the loss of skeletal muscle mass. It can be caused by immobility, aging, malnutrition, medications, or a wide range of injuries or diseases that impact the musculoskeletal or nervous system. Muscle atrophy leads to muscle weakness and causes disability.

Disuse causes rapid muscle atrophy and often occurs during injury or illness that requires immobilization of a limb or bed rest. Depending on the duration of disuse and the health of the individual, this may be fully reversed with activity. Malnutrition first causes fat loss but may progress to muscle atrophy in prolonged starvation and can be reversed with nutritional therapy. In contrast, cachexia is a wasting syndrome caused by an underlying disease such as cancer that causes dramatic muscle atrophy and cannot be completely reversed with nutritional therapy. Sarcopenia is age-related muscle atrophy and can be slowed by exercise. Finally, diseases of the muscles such as muscular dystrophy or myopathies can cause atrophy, as well as damage to the nervous system such as in spinal cord injury or stroke. Thus, muscle atrophy is usually a finding (sign or symptom) in a disease rather than being a disease by itself. However, some syndromes of muscular atrophy are classified as disease spectrums or disease entities rather than as clinical syndromes alone, such as the various spinal muscular atrophies.

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Muscle atrophy in the context of World War II casualties of the Soviet Union

World War II losses of the Soviet Union were about 27 million both civilian and military from all war-related causes, although exact figures are disputed. A figure of 20 million was considered official during the Soviet era. The post-Soviet government of Russia puts the Soviet war losses at 26.6 million, on the basis of the 1993 study by the Russian Academy of Sciences, including people dying as a result of effects of the war. This includes 8,668,400 military deaths as calculated by the Russian Ministry of Defence.

The figures published by the Russian Ministry of Defence have been accepted by most historians outside Russia. However, the official figure of 8.7 million military deaths has been disputed by Russian scholars who believe that the number of dead and missing POWs is not correct and new research is necessary to determine actual losses. Officials at the Russian Central Defense Ministry Archive (CDMA) maintain that their database lists the names of roughly 14 million dead and missing service personnel. Russian President Dmitry Medvedev stated in 2009 that more than 2.4 million people are still officially considered missing in action, and that of the 9.5 million persons buried in mass graves, six million are unidentified. Some Russian scholars put the total number of losses in the war, both civilian and military, at over 40 million. In 2020, Mikhail Meltyukhov, who works with the Russian Federal archival project, claimed that 15.9–17.4 million civilians were killed on Soviet territory by Germany and its allies during the war.

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Muscle atrophy in the context of Myopathy

In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Myopathy means muscle disease (Greek : myo- muscle + patheia -pathy : suffering). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("neuropathies" or "neurogenic" disorders) or elsewhere (e.g., the brain).

This muscular defect typically results in myalgia (muscle pain), muscle weakness (reduced muscle force), or premature muscle fatigue (initially normal, but declining muscle force). Muscle cramps, stiffness, spasm, and contracture can also be associated with myopathy. Myopathy experienced over a long period (chronic) may result in the muscle becoming an abnormal size, such as muscle atrophy (abnormally small) or a pseudoathletic appearance (abnormally large).

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Muscle atrophy in the context of Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States and CanadaLou Gehrig's disease (LGD), is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. ALS is the most common form of the broader group of motor neuron diseases. ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the abilities to eat, speak, move, and breathe without mechanical support are lost. While only 15% of people with ALS also develop full-blown frontotemporal dementia, an estimated 50% face at least minor changes in thinking and behavior, and a loss of energy, possibly secondary to metabolic dysfunction, is thought to drive a characteristic loss of empathy. Depending on which of the aforementioned symptoms develops first, ALS is classified as limb-onset (begins with weakness in the arms or legs) or bulbar-onset (begins with difficulty in speaking and/or swallowing). Respiratory onset occurs in approximately 1%–3% of cases.

Most cases of ALS (about 90–95%) have no known cause, and are known as sporadic ALS. However, both genetic and environmental factors are believed to be involved. The remaining 5–10% of cases have a genetic cause, often linked to a family history of the disease, and these are known as familial ALS (hereditary). About half of these genetic cases are due to disease-causing variants in one of four specific genes. The diagnosis is based on a person's signs and symptoms, with testing conducted to rule out other potential causes.

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Muscle atrophy in the context of Spinal injuries

A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. It is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions.

Symptoms of spinal cord injury 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.

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Muscle atrophy in the context of Muscle contracture

Muscle contractures can occur for many reasons, such as paralysis, muscular atrophy, and forms of muscular dystrophy. Fundamentally, the muscle and its tendons shorten, resulting in reduced flexibility.

Various interventions can slow, stop, or even reverse muscle contractures, ranging from physical therapy to surgery.

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Muscle atrophy in the context of Neurofibromatosis

Neurofibromatosis (NF) refers to a group of three distinct genetic conditions in which tumors grow in the nervous system. The tumors are non-cancerous (benign) and often involve the skin or surrounding bone. Although symptoms are often mild, each condition presents differently. Neurofibromatosis type I (NF1) is typically characterized by café au lait spots (light-brown flat patches of skin), neurofibromas (small bumps in or under the skin), scoliosis (side-way curvature of the back), and headaches. Neurofibromatosis type II (NF2), on the other hand, may present with early-onset hearing loss, cataracts, tinnitus, difficulty walking or maintaining balance, and muscle atrophy. The third type is called schwannomatosis and often presents in early adulthood with widespread pain, numbness, or tingling due to nerve compression.

The cause is a genetic mutation in certain oncogenes. These can be inherited, or in about half of cases spontaneously occur during early development. Different mutations result in the three types of NF. Neurofibromatosis arise from the supporting cells of the nervous system rather than the neurons themselves. In NF1, the tumors are neurofibromas (tumors of the peripheral nerves), while in NF2 and schwannomatosis tumors of Schwann cells are more common. Diagnosis is typically based on symptoms, examination, medical imaging, and biopsy. Genetic testing may rarely be done to support the diagnosis.

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Muscle atrophy in the context of 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.

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