Propriospinal Myoclonus

Propriospinal myoclonus (PSM) is a rare movement disorder first described in 1991. It is characterized by painless, repetitive jerking of the trunk, neck, hips, and knees. The jerking may be spontaneous but may also occur in response to a stimulus. The jerking often gets worse when the person is lying down. In some cases, a strange sensation such as a tingling at the back of the neck, a clicking sensation in the head, or an electrical current-like sensation may precede the jerks. Causes of PSM can include a spinal lesion, infection, or certain medications. In some cases, PSM is thought to have a psychogenic component. In most cases, the cause is not known (idiopathic). The work-up usually includes an MRI to rule out spinal lesions. No current guidelines regarding the treatment of PSM exist. Therapy includes treatment of any underlying disorders. Several medications have been tried with varying success, but larger controlled studies are needed to learn more.