4. Subjects with past or present medical history of (a) neurological disorders, such as stroke, movement disorders (other than cervical dystonia in the patient group), brain tumors, traumatic brain injury with loss of consciousness lasting more than a few seconds, ataxias, myopathies, myasthenia gravis, demyelinating diseases, alcoholism, drug dependence; (b) psychiatric disorders, such as schizophrenia, major depressive and/or bipolar disorder, obsessive-compulsive disorder; (c) ventricular arrhythmias, renal and hepatic insufficiency, vascular headache, or carcinoid syndrome.