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Electrophysiological studies of early stage corticobasal degeneration
Author(s) -
Lu C. S.,
Ikeda A.,
Terada K.,
Mima T.,
Nagamine T.,
Fukuyama H.,
Kohara N.,
Kojima Y.,
Yonekura Y.,
Chen R. S.,
Tsai C. H.,
Chu N. S.,
Kimura J.,
Shibasaki H.
Publication year - 1998
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.870130126
Subject(s) - somatosensory evoked potential , myoclonus , motor cortex , evoked potential , neuroscience , corticobasal degeneration , transcranial magnetic stimulation , electromyography , silent period , psychology , parkinsonism , electrophysiology , sensory cortex , medicine , cortex (anatomy) , sensory system , stimulation , progressive supranuclear palsy , pathology , atrophy , disease
We conducted electrophysiological studies in two Asian patients with probable corticobasal degeneration (CBD). The duration of illness from onset was 16 and 20 months, respectively. The clinical manifestations were markedly asymmetric and characterized by cortical sensory loss, apraxia, action myoclonus, action tremor, and akinetic‐rigid parkinsonism. Neither patient responded to levodopa therapy. Simple photon‐emission computed tomography (SPECT) study showed significantly decreased regional cerebral blood flow in the frontoparietal areas and thalamus opposite to the predominantly affected limb. A series of electrophysiological studies failed to identify giant somatosensory evoked potentials (SEPs), enhanced long latency electromyography (EMG) reflex, and cortical spikes preceding myoclonic jerk. However, the earliest cortical component of the median nerve SEP was exclusively enlarged in one patient and preserved with depression of the subsequent components in the other patient. Significantly shorter postmotor‐evoked potential (MEP) silent period was found after the transcranial magnetic stimulation of the motor cortex in both patients. CBD is a unique clinical entity characterized by action myoclonus probably the result of the pathologic hyperexcitability of the motor cortex, based on a loss of inhibitory input form the sensory cortex.