Neuromuscular disorders are a group of diseases that affect any part of the nerve and muscle. Neuromuscular disorders include motor neuron diseases such as amyotrophic lateral sclerosis and spinal muscular atrophy, which may involve motor neurons in the brain, spinal cord, and periphery, and ultimately weaken the muscle. Neuromuscular disorders also include peripheral neuropathies such as Charcot-Marie-Tooth disease (CMT) that affect not only motor but also sensory nerves.
A list of some Neuromuscular diseases
This includes quite a number of medical conditions: Amyotrophic Lateral Sclerosis - Brachial Plexus Neuritis - Brachial Plexus Neuropathies - Bulbar Palsy, Progressive - Carpal Tunnel Syndrome - Diabetic Neuropathies - Duchenne muscular dystrophy - Dysautonomia, Familial - Guillain-Barre Syndrome - Hereditary Sensory and Autonomic Neuropathies - Kennedy disease - McCardle Disease - Mitochondrial Myopathy - Motor Neuron Disease - Muscular Atrophy, Spinal - Muscular Dystrophy - Myasthenia Gravis - Myopathies, Structural, Congenital - Myotonic Dystrophy - Nerve Compression Syndromes - Neuralgia - Neuromuscular Diseases - Paralyses, Familial Periodic - Peripheral Nervous System Diseases - POEMS Syndrome - Polyneuropathies - Polyradiculopathy - Refsum Disease - Sciatica - Spinal Muscular Atrophies of Childhood - Thoracic Outlet Syndrome - Ulnar Nerve Compression Syndromes, and others.
Statins and Neuromuscular Disease, more common than previously thought
Statins may reveal underlying neuromuscular disease. According to investigators from the University of Athens Medical School, patients with asymptomatic neuromuscular disorders may have their condition precipitated by statin use. Dr. Panagiota Manta and colleagues describe four such cases in Archives of Internal Medicine 2006;166:1519-1524:
Case 1 was a 46-year-old man with a history of hypertension and diabetes mellitus who was prescribed pravastatin for hypercholesterolemia. Three months later, he complained of fatigue, muscle pain and stiffness. Serum creatine kinase levels were persistently elevated. After stopping the drug, creatine kinase levels fell somewhat and there was mild symptom improvement. Mild myopathy was seen on needle electromyography and muscle biopsy showed numerous internal nuclei, nuclear clumps and variations in fiber size. Genetic testing revealed myotonic dystrophy.
Case 2 was a 62-year-old man with a history of MI and diabetes. Hypercholesterolemia was treated with simvastatin. Creatine kinase levels became persistently elevated and did not return to normal after drug discontinuation. Biopsy was positive for muscle enzyme activity. He was eventually diagnosed with McArdle disease.
Case 3 was a 51-year-old man with hypertension and hypercholesterolemia who was hospitalized with acute rhabdomyolytis after taking atorvastatin for 18 months. Exercise intolerance and muscle pain persisted for months after discontinuation of statin therapy. Some time later, he was diagnosed with mitochondrial myopathy.
The last case was a 58-year-old man with a history of hypertension, hyperuricemia and coronary artery disease. He began treatment with pravastatin. Shortly after a dose increase, he developed muscle twitching, muscle cramps and difficulty walking. Like the other cases, there was only mild symptom improvement and a modest decline in creatine kinase levels after the statin was discontinued. He was eventually diagnosed with Kennedy disease.
There are a
number of different types of muscular dystrophy. They are muscle diseases which
have three features in common; they are hereditary, they are progressive; and
each causes a characteristic, selective pattern of muscle wasting and weakness.
Myotonic dystrophy is the most common adult form of muscular dystrophy. Myotonic dystrophy is caused by a defective gene. Unlike any of the other muscular dystrophies, the muscle weakness is accompanied by myotonia (delayed relaxation of muscles after contraction) and by a variety of abnormalities in addition to those of muscle. The disorder is also known as Steinert's disease and dystrophia myotonica. Myotonic dystrophy shows an early pattern of muscle wasting that is unique among the major muscular dystrophies. The first muscles to be affected are those of the face, neck, hands, forearms, and feet (as opposed to the hip and shoulder muscles in the other dystrophies).
McArdle disease: Glycogen storage disease type V and the most common type of glycogen storage disease. McArdle disease is an autosomal recessive disorder caused by mutations in the gene that encodes myophosphorylase, an enzyme that is essential for glycogenolysis. Exercise intolerance usually develops during childhood, along with pain, cramps, and fatigue in exercised muscle. These symptoms are more likely to be induced by brief, intense activities (such as weight lifting or sprinting) but can also occur after prolonged, low-intensity exercises (such as swimming or jogging). Severe muscle damage can lead to myoglobinuria (the release of myoglobin from muscle into the bloodstream) and renal failure. There is variation among patients with McArdle disease. In rare cases, McArdle disease is so severe it causes congenital weakness and progressive respiratory failure.
A group of neuromuscular diseases caused by damage to the mitochondria, energy-producing structures in cells that serve as power plants. Nerve and muscle cells require a great deal of energy and are particularly impaired by mitochondrial dysfunction. Some of the more common mitochondrial myopathies include the Kearns-Sayre syndrome, myoclonic epilepsy with ragged-red fibers, and the MELAS syndrome of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes. The onset of most mitochondrial myopathies is before the age of 20. They often begin with muscle weakness. During physical activity, muscles may become easily fatigued or weak. Muscle cramping is rare, but may occur.
Kennedy disease information
Kennedy Disease is an inherited disorder characterized by degeneration of both motor and sensory neurons. It involves loss of lower motor neurons supplying the limb and bulbar musculature. Extraocular muscles are spared, possibly because of reduced numbers of androgen receptors in these muscles. Autopsy studies show loss of large, medium, and small motor neurons.
Med Clin North Am. 2013 Nov. Patients with neuromuscular disorder. This article describes the preoperative preparation of patients with neuromuscular disorders. These entities are a relatively rare and diverse group of diseases that can affect various organ systems in addition to the central nervous system. The anesthetic implications for the various comorbidities are varied and can be profound. These patients should be optimized before surgery, with the involvement of a multidisciplinary team of specialists.