movement disease paroxysmal dystonia Paroxysmal dystonia (historically known as tonic spasms or tonic seizures) is a type of fluctuating dystonia characterized by repetitive and patterned twisting movements and abnormal postures lasting seconds to hours (Demirkiran and Jankovic, 1995). Bouts of paroxysmal dystonia occur when opposing muscle groups contract simultaneously. Paroxysmal dystonia may affect the face, arm, or leg and is often precipitated by tactile stimulation, voluntary movement, loud noise, or hyperventilation. ICD9:333.99 Orphanet:200037 SCTID:230310003 MONDO:0016058