Branchial Myoclonus with Spastic Paraparesis and Cerebellar Ataxia is a rare genetic disorder. Very few cases have been reported. Patients affected with this disease have branchial myoclonus, spastic paraphrases, and cerebellar ataxia. Palatal myoclonus, which also occurs in Machado-Joseph disease and in spinocerebellar ataxia type 2, is characterized by rhythmic oscillations of the soft palate. It is also called branchial myoclonus because it may be associated with synchronous contractions of muscles derived from the branchial arches, including the diaphragm, tongue, and sternomastoids.
The age of onset of Branchial Myoclonus with Spastic Paraparesis and Cerebellar Ataxia ranges from 40 to 50-years. After 5 to 10-years of age of onset, the clinical symptoms may progress, leading to death or severe disability. Treatment with 5-hydroxytryptophan and carbidopa at highest tolerated dose may mildly improve ataxia but it will not modify the myoclonus.
Branchial Myoclonus with Spastic Paraparesis and Cerebellar Ataxia is a unique genetic disorder; reported studies in families affected with this disease suggest that the mode of inheritance is autosomal dominant.