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 What is Dystonia? Dystonia is a movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. Dystonia refers to an involuntary movement resulting in a sustained posture which may be painful. Dystonia may affect a single muscle, group of muscles, or the entire body. Dystonia is classified according to the parts of the body affected. What causes Dystonia? Dystonia is classified into 3 areas based upon the cause: primary, secondary, or dystonia plus syndromes. Primary dystonia is defined by the existence of dystonia alone without an underlying condition. There are two forms of primary: hereditary (familial) and sporadic. Secondary dystonia results from such causes as birth injury, trauma, toxins, or stroke. Dystonia plus refers to dystonia which are part of another syndrome as Lubag or X linked dystonia parkinsonism, Pelizaeus-Merzbacher disease, Parkinson's disease, Progressive Supranuclear Palsy, Corticobasal Ganglionic Degeneration, Huntington's disease, Machado-Joseph disease or Wilson's disease. Some patterns of dystonia are referred to as specific syndromes. Treating Dystonia Pharmacologic therapy: Dopaminergic therapy is indicated for dopa-responsive dystonia. Many movement disorder specialists advocate a trial for all young adults presenting with focal dystonia, particularly limb dystonia. Antidopaminergic therapy has also been used. This includes medications such as reserpine, tetrabenazine, and clozapine. Although the use of these medication is limited by side effects. Anticholinergic medications as trihexyphenidyl have been useful in focal and generalized dystonia. Children are able to tolerate large doses well, however adults tend to have more problems with side effects, in particular difficulties with short term memory. Other pharmacologic therapies inclue lioresal, tizznidine, and clonazepam. Chemical Denervation: One of the greatest breakthroughs in the treatment of focal dysontia is botulinum toxin. This was introduced into clinical practice in the 1980's. It is a purified form of toxin produced by Clostridium botulimum. It inhibits the presynaptic release of acetylcholine at the neuromuscular junction. It produces a temporary paralysis of the skeletal muscles that are injected. There are two commercially available forms, Botox (botulinum toxin type A) and Myobloc (botulinum toxin type B). It is extremely effective in treating focal dystonias, both in reducing the abnormal movement and controlling the pain. One of the limiting factors in using botulinum toxin is the development of immunoresistence. This is believed to occur from the use of large doses given frequently. Therefore, it is recommended that the toxin be give at least at three month intervals at the lowest effective dose. Surgical Therapy: Peripheral denervation has shown some success for cervical dystonia. Patients may have recurrence of their symptoms. Deep brain stimulation appears to be most effective in patients with the inherited from of generalized dystonia. There are a handful of reports showing benefit in cases of torticollis. The success rate is lower for secondary focal dystonias than for either inherited generalized dystonia or torticollis. |
