Dystonia is increased muscle tone, but it results from a different alteration in the nervous system than rigidity or spasticity. Dystonia usually results in your neck, arm, leg, or trunk becoming twisted or turned. An electromyogram (EMG), an electrical recording of the muscle firing, usually reveals a distinct pattern, one entirely different from rigidity or spasticity. Dystonia may be a symptom of PD or of one of the PD-like dis-orders. The cramps that PD patients experience when levodopa is wearing off or when they awaken in the morning are usually leg dystonias.
Acute dystonia, consisting of sustained, sometimes painful muscle spasms that result in abnormal twisting or turning, usually of the head and neck, but sometimes of an arm or a leg, the whole body (ophistotonus), or the eyes (oculogyric crisis), may occur within hours of injecting a neuroleptic (a drug used to treat behavioral disorders such as psychosis or schizophrenia). The acute dystonia may last several hours and is relieved by injecting Benadryl, an antihistamine. About 3–10% of patients treated with a neuroleptic may have an acute dystonia. The risk is higher with drugs such as Haldol or Thorazine, but may occur with other neuroleptics such as Compazine (a drug used to treat nausea).
Dystonia may occur unassociated with any other dis-ease. It may affect only a single muscle, called focal dystonia. A common form of this is one that affects the sternocleidomastoid muscles, the muscles that turn the neck, resulting in a disorder called toritcollis. Another relatively common form of focal dystonia affects selected muscles of the forearm, resulting in an inability to write, called writer’s cramp. Torticollis, writer’s cramp, and other focal dystonias can be treated by injections of Botox. Dystonia may affect an entire group of muscles, called segmental dystonia, and rarely, it may affect most of the muscles in the body and is called generalized dystonia. Generalized dystonia usually starts in childhood and is inherited.