Dystonia is a neurological disorder characterized by sustained, involuntary muscle contractions which cause twisting, repetitive movements or abnormal body postures. The symptoms may be generalized or involve specific body parts (focal dystonia). When dystonia begins in childhood it is usually generalized and can be inherited. Adult onset dystonia usually occurs in a sporadic fashion (not inherited) and usually remains restricted to one body region (focal). Examples of focal dystonia include:
- Blepharospasm – forceful contractions of the eyelid muscles causing involuntary blinking or sustained eyelid closure.
- Cervical dystonia (spasmodic torticollis) – forceful contractions of the neck muscles which are often painful and cause twisting or jerking motions of the head and neck. This is the most common type of dystonia.
- Spasmodic dysphonia (laryngeal dystonia) – involuntary contractions of the vocal cords causing the voice to be harsh, broken up, whispery or tremulous.
- Oro-mandibular dystonia – forceful contractions of the lower facial muscles causing jaw opening or closing, chewing motions and tongue movements.
- Writer’s cramp – muscular spasm in the hand and forearm muscles triggered by handwriting.
Dystonia can be treated with medications but the benefits are usually modest and there are often bothersome side effects. The current treatment of choice for focal dystonia is botulinum toxin injections into the affected muscles.