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Myoclonus in corticobasal degeneration
1University Department of Medicine, Royal Adelaide Hospital, South Australia.
Clinical Neuroscience (New York, N.Y.)
|January 1, 1995
Summary
Myoclonus in corticobasal degeneration (CBD) presents uniquely, differing from typical cortical myoclonus. These differences in reflex responses suggest distinct underlying physiological mechanisms in CBD.
Area of Science:
- Neuroscience
- Neurology
- Clinical Neurophysiology
Background:
- Myoclonus is a common symptom in corticobasal degeneration (CBD), affecting approximately 50% of patients.
- The myoclonus in CBD is typically focal, often involving one arm, and is characterized by action and reflex responses to sensory stimulation.
Purpose of the Study:
- To investigate the physiological characteristics of myoclonus in corticobasal degeneration.
- To compare the neurophysiological features of CBD-associated myoclonus with recognized forms of cortical reflex myoclonus.
Main Methods:
- Clinical assessment of myoclonus characteristics in CBD patients.
- Electrophysiological studies including somatosensory evoked potentials (SEPs) and electroencephalography (EEG) to analyze reflex responses.
Main Results:
- Myoclonus in CBD shows distinct features compared to other cortical reflex myoclonus.
- Specifically, it lacks the enlarged secondary component of SEPs and preceding EEG spikes characteristic of other forms.
- Reflex myoclonus in CBD exhibits a shorter latency (approximately 10 ms shorter) than in cortical reflex myoclonus.
Conclusions:
- The findings suggest that the myoclonus in CBD may arise from preferential enhancement of different components of transcortical reflexes.
- Alterations in cortical excitability, sensory input, and the balance of cortical excitatory/inhibitory influences are likely key factors in the distinct physiology of CBD-related myoclonus.