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Decreased cortical inhibition and yet cerebellar pathology in ‘familial cortical myoclonic tremor with epilepsy’
Author(s) -
van Rootselaar AnneFleur,
van der Salm Sandra M.A.,
Bour Lo J.,
Edwards Mark J.,
Brown Peter,
Aronica Eleonora,
RozemullerKwakkel Johanna M.,
Koehler Peter J.,
Koelman Johannes H.T.M.,
Rothwell John C.,
Tijssen Marina A.J.
Publication year - 2007
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/mds.21738
Subject(s) - neuroscience , transcranial magnetic stimulation , epilepsy , motor cortex , psychology , cerebellar ataxia , cerebellum , myoclonus , medicine , cerebellar cortex , progressive myoclonus epilepsy , ataxia , stimulation
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