Myoclonus.

Myoclonus can be classified as physiologic, essential, epileptic, and symptomatic. Animal models of myoclonus include DDT and posthypoxic myoclonus in the rat. 5-Hydrotryptophan, clonazepam, and valproic acid suppress myoclonus induced by posthypoxia. The diagnostic evaluation of myoclonus is complex and involves an extensive work-up including basic electrolytes, glucose, renal and hepatic function tests, paraneoplastic antibodies, drug and toxicology screens, thyroid antibody and function studies, neurophysiology testing, imaging, and tests for malabsorption disorders, assays for enzyme deficiencies, tissue biopsy, copper studies, alpha-fetoprotein, cytogenetic analysis, radiosensitivity DNA synthesis, genetic testing for inherited disorders, and mitochondrial function studies. Treatment of myoclonus is targeted to the underlying disorder. If myoclonus physiology cannot be demonstrated, treatment should be aimed at the common pattern of symptoms. If the diagnosis is not known, treatment could be directed empirically at cortical myoclonus as the most common physiology. In cortical myoclonus, the most effective drugs are sodium valproic acid, clonazepam, levetiracetam, and piracetam. For cortical-subcortical myoclonus, valproic acid is the drug of choice. Here, lamotrigine can be used either alone or in combination with valproic acid. Ethosuximide, levetiracetam, or zonisamide can also be used as adjunct therapy with valproic acid. A ketogenic diet can be considered if everything else fails. Subcortical-nonsegmental myoclonus may respond to clonazepam and deep-brain stimulation. Rituximab, adrenocorticotropic hormone, high-dose dexamethasone pulse, or plasmapheresis have been reported to improve opsoclonus myoclonus syndrome. Reticular reflex myoclonus can be treated with clonazepam, diazepam and 5-hydrotryptophan. For palatal myoclonus, a variety of drugs have been used.

"Dystonic" body perception in childhood dystonia.

Dystonia refers to a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures. Although the pathophysiology of the abnormal posture is still unknown and a wide variety of abnormal postures can be observed, recent psychophysical studies have revealed abnormalities in the way patients with focal and generalized dystonia judge the position of their bodies in space [Bove M, Brichetto G, Abbruzzese G, Marchese R, Schieppati M. Neck proprioception and spatial orientation in cervical dystonia. Brain 2004;127(Pt 12):2764-78; Molloy FM, Carr TD, Zeuner KE, Dambrosia JM, Hallett M. Abnormalities of spatial discrimination in focal and generalized dystonia. Brain 2003;126(Pt 10):2175-82; Anastasopoulos D, Nasios G, Psilas K, Mergner T, Maurer C, Lucking CH. What is straight ahead to a patient with torticollis? Brain 1998;121(Pt 1):91-101]. Most intriguingly, patients do not always recognize "straight ahead" in the way normal individuals do [Anastasopoulos D, Nasios G, Psilas K, Mergner T, Maurer C, Lucking CH. What is straight ahead to a patient with torticollis? Brain 1998;121(Pt 1):91-101]. We describe a patient with childhood-onset dystonia who consistently drew images of his unaffected family members with 'dystonic' postures without being aware that this posture is abnormal.

Posthypoxic myoclonus animal models.

The animal model presented here resembles several of the key features of human myoclonus. Further study of the neuropathology and pharmacology of this animal model will hopefully increase our knowledge of the brain structures and systems affected in this disease and permit testing of therapeutic agents for the significant number of patients who do not respond to current treatments.