Neuromuscular disease

Neuromuscular disease is a very broad term that encompasses many diseases and ailments that either directly (via intrinsic muscle pathology) or indirectly (via nerve pathology) impair the functioning of muscle. It tends to be particularly associated with human muscle, although most pathologies apply to animal muscle in general.

Neuromuscular diseases are those that affect the muscles and/or their nervous control. In general, problems with nervous control can cause spasticity or paralysis, depending on the location and nature of the problem. A large proportion of neurological disorders leads to problems with movement, ranging from cerebrovascular accident (stroke) and Parkinson's disease to Creutzfeldt-Jakob disease.

Symptoms
Symptoms of muscle disease may include weakness or spasticity/rigidity, myoclonus (twitching, spasming) and myalgia (muscle pain). Diagnostic procedures that may reveal muscular disorders include testing creatine kinase levels in the blood and electromyography (measuring electrical activity in muscles).

Causes
Diseases of the motor end plate include myasthenia gravis, a form of muscle weakness due to antibodies to the acetylcholine receptor, and its related condition Lambert-Eaton myasthenic syndrome (LEMS). Tetanus and botulism are bacterial infections in which bacterial toxins cause increased or decreased muscle tone, respectively.

The myopathies are all diseases affecting the muscle itself, rather than its nervous control.

Muscular dystrophy is a large group of diseases, many of them hereditary, where the muscle integrity is disrupted. It leads to progressive loss of strength, high dependence and decreased life span.

Inflammatory muscle disorders

 * Polymyalgia rheumatica (or "muscle rheumatism") is an inflammatory condition that mainly occurs in the elderly; it is associated with giant-cell arteritis. It often responds dramatically to glucocorticoids (e.g. prednisolone).
 * Polymyositis, dermatomyositis and inclusion body myositis are autoimmune conditions in which the muscle is affected.

Rhabdomyolysis is the breakdown of muscular tissue due to any cause. While it may not lead to any muscular symptoms at all, the myoglobin thus released may cause acute renal failure.

Tumors
Tumors of muscle include:
 * Smooth muscle: leiomyoma (benign, very common in the uterus), leiomyosarcoma (malignant, very rare)
 * Striated muscle: rhabdomyoma (benign) and rhabdomyosarcoma (malignant) - both very rare
 * Metastasis from elsewhere (e.g. lung cancer)

Smooth muscle has been implicated to play a role in a large number of diseases affecting blood vessels, the respiratory tract (e.g., asthma), the digestive system (e.g. irritable bowel syndrome) and the urinary tract (e.g., urinary incontinence). These disease processes are not usually confined to the muscular tissue.

Injury
Injuries of muscles include wounds and strains.