Dystonia is a rare neurological movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The cause(s) of dystonia are not yet known or understood. Primary dystonia is suspected to be caused by a pathology of the central nervous system, likely originating in those parts of the brain concerned with motor function, such as the basal ganglia, and the GABA ( gamma-aminobutyric acid) producing Purkinje neurons in the cerebellum. In most cases it involve some genetic predisposition towards the disorder combined with environmental conditions.
Secondary dystonia refers to dystonia brought on by some identified cause, such as traumatic brain injury, drug induced chemical imbalance or diseases of the central nervous system such as Wilson’s disease.
Symptoms vary according to the kind of dystonia involved. In most cases, dystonia tends to lead to abnormal posturing, particularly on movement. Many sufferers have continuous pain, cramping and relentless muscle spasms due to involuntary muscle movements.
Early symptoms may include loss of precision muscle coordination (sometimes first manifested in declining penmanship, frequent small injuries to the hands, dropped items and a noticeable increase in dropped or chipped dishes), cramping pain with sustained use and trembling. It may become difficult to find a comfortable position for arms and legs with even the minor exertions associated with holding arms crossed causing significant pain similar to restless leg syndrome. Affected persons may notice trembling in the diaphragm while breathing, or the need to place hands in pockets, under legs while sitting or under pillows while sleeping to keep them still and to reduce pain. In some cases, symptoms may progress and then plateau for years, or stop progressing entirely. In others, the symptoms may progress to total disability, making some of the more risky forms of treatment worth considering.
Treatment has been limited to minimizing the symptoms of the disorder, as there is yet no cure. Physicians may prescribe a series of different medications on a trial basis in an effort to find a combination that is effective for a specific patient. Drugs such as anticholinergics, which act as inhibitors of the neurotransmitter acetylcholine, may provide some relief. Clonazepam, an anti-seizure medicine, is also sometimes prescribed. However, for most sufferers their effects are limited and side effects like often occur.
Botulinum toxin (Botox) injections into affected muscles have proved quite successful in providing some relief. The injections have to be repeated as the effects wear off after a few months.
Surgery, such as the denervation of selected muscles, may also provide some relief; however, the destruction of nerves in the limbs or brain is not reversible and should only be considered in the most extreme cases. Recently, the procedure of deep brain stimulation (DBS) has proved successful in a number of cases of severe generalized dystonia.