the voice box, resulting in altered voice production. Patients may have a strained-strangled quality to their voice or, in some cases, a whispering or breathy quality. Cervical dystonia (CD) or spasmodic torticollis is characterized by muscle spasms of the head and neck, which may be painful and cause the neck to twist into unusual positions or postures. Writer's cramp and musician's cramp is a task-specific dystonia, meaning that it only occurs when performing certain tasks. Writer's cramp is a contraction of hand and/or arm muscles that happens only when a patient is writing. It does not occur in other situations, such as when a patient is typing or eating. Musician's cramp occurs only when a musician plays an instrument, and the type of cramp experienced is specific to the instrument. For example, pianists may experience cramping of their hands when playing, while brass players may have cramping or contractions of their mouth muscles. Hemiballismus Typically caused by damage to the subthalamic nucleus or nuclei, hemiballismus movements are nonrhythmic, rapid, nonsuppressible, and violent. They usually occur in an isolated body part, such as the proximal arm. Hemifacial spasm Hemifacial spasm (HFS) is characterized by involuntary contraction of facial muscles, typically occurring only on one side of the face. Like blepharospasm, the frequency of contractions in hemifacial spasm may range from intermittent to frequent and constant. The unilateral blepharospasm of HFS may interfere with routine tasks such as driving. In addition to medication, patients may respond well to treatment with Botox. HFS may be due to vascular compression of the nerves going to the muscles of the face. For these patients, surgical decompression may be a viable option for the improvement of symptoms. Myoclonus Myoclonus is defined as a sequence of repeated, often nonrhythmic, brief, shock-like jerks due to sudden involuntary contraction or relaxation of one or more muscles. These movements may be asynchronous, in which several muscles contract variably in time, synchronous, in which muscles contract simultaneously, or spreading, in which several muscles contract sequentially. It is characterized by a sudden, unidirectional movement due to muscle contraction, followed by a relaxation period in which the muscle is no longer contracted. However, when this relaxation phase is decreased, as when muscle contractions become faster, a myoclonic tremor results. Myoclonus can often be associated with seizures, delirium, dementia, and other signs of neurological disease and gray matter damage. Stereotypies Stereotypies are repetitive, rhythmic,