Familial cortical myoclonic tremor (FCMT) is a rare disorder often leading to a wrong clinical diagnosis of essential tremor. Electrophysiological data are usually considered to allow a correct diagnosis. We describe a FCMT French family with previously unreported clinical features such as sensitivi
Decreased cortical inhibition and yet cerebellar pathology in ‘familial cortical myoclonic tremor with epilepsy’
✍ Scribed by Anne-Fleur van Rootselaar; Sandra M.A. van der Salm; Lo J. Bour; Mark J. Edwards; Peter Brown; Eleonora Aronica; Johanna M. Rozemuller-Kwakkel; Peter J. Koehler; Johannes H.T.M. Koelman; John C. Rothwell; Marina A.J. Tijssen
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 339 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0885-3185
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✦ Synopsis
Abstract
Cortical hyperexcitability is a feature of “familial cortical myoclonic tremor with epilepsy” (FCMTE). However, neuropathological investigations in a single FCMTE patient showed isolated cerebellar pathology. Pathological investigations in a second FCMTE patient, reported here, confirmed cerebellar Purkinje cell degeneration and a normal sensorimotor cortex. Subsequently, we sought to explore the nature of cerebellar and motor system pathophysiology in FCMTE. Eye movement recordings and transcranial magnetic stimulation performed in six related FCMTE patients showed impaired saccades and smooth pursuit and downbeat nystagmus upon hyperventilation, as in patients with spinocerebellar ataxia type 6. In FCMTE patients short‐interval intracortical inhibition (SICI) was significantly reduced. Resting motor threshold, recruitment curve, silent period, and intracortical facilitation were normal. The neuropathological and ocular motor abnormalities indicate cerebellar involvement in FCMTE patients. Decreased SICI is compatible with intracortical GABA~A~‐ergic dysfunction. Cerebellar and intracortical functional changes could result from a common mechanism such as a channelopathy. Alternatively, decreased cortical inhibition may be caused by dysfunction of the cerebello‐thalamo‐cortical loop as a result of primary cerebellar pathology. © 2007 Movement Disorder Society
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## Abstract Fifty Japanese and European families with cortical myoclonic tremor and epilepsy have been reported under various names. Unfamiliarity with the syndrome often leads to an initial misdiagnosis of essential tremor or progressive myoclonus epilepsy. A detailed overview of the literature is