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Epileptic negative myoclonus. Subdural EEG recordings indicate a postcentral generator
S Noachtar1, H Holthausen, H O Lüders
1Department of Neurology, University of Munich, Germany.
Neurology
|December 31, 1997
Summary
Epileptic negative myoclonus (ENM) in the arm resulted from a cortical malformation. Epileptic spikes in the postcentral cortex triggered an EMG silent period, indicating inhibition of motor neuron activity.
Area of Science:
- Neurology
- Epileptology
- Neurophysiology
Background:
- Epileptic negative myoclonus (ENM) is a rare epilepsy syndrome.
- Cortical malformations are a known etiology for various epilepsy types.
Observation:
- A patient presented with status epilepticus characterized by right arm ENM.
- The underlying cause was identified as a cortical malformation in the left postcentral gyrus.
- Electrical stimulation revealed abnormal somatosensory evoked potentials.
Findings:
- Subdural recordings localized the epileptogenic zone to the left postcentral gyrus.
- Repetitive spikes from this region consistently preceded a silent period in the right arm's EMG.
- The duration of this EMG silent period, reflecting ENM, correlated with the extent of cortical spike involvement.
Implications:
- These findings suggest that epileptic activation of the postcentral cortex can inhibit motor neuron activity.
- Focal ENM may stem from hyperexcitability within the postcentral cortex.
- Understanding this mechanism could inform epilepsy surgery planning and treatment strategies.