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[Primary progressive limb-kinetic apraxia: a case report with an electrophysiological study]
Y Shimo-Nakanishi1, H Miwa, H Kobayashi
1Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan.
No to Shinkei = Brain and Nerve
|July 9, 1999
Summary
Primary progressive limb-kinetic apraxia is linked to increased motor cortex excitability. This may stem from reduced cortico-cortical inhibition due to focal neuronal degeneration.
Area of Science:
- Neuroscience
- Neurology
Background:
- Primary progressive limb-kinetic apraxia is a rare neurological disorder characterized by progressive clumsiness.
- The underlying physiological mechanisms remain incompletely understood.
Observation:
- A 53-year-old woman presented with a 5-year history of right-hand clumsiness and mild dysarthria.
- Brain imaging revealed focal atrophy in the left precentral gyrus.
- Electrophysiological studies showed co-contraction of antagonistic muscles, myoclonic discharges, and a positive C-reflex in the affected limb.
Findings:
- Jerk-locked averaging demonstrated a premyoclonus spike.
- Transcranial magnetic stimulation revealed decreased cortico-cortical inhibition in the affected motor cortex.
- Abnormal facilitation of motor evoked potentials was observed with median nerve stimulation.
Implications:
- Findings suggest increased motor cortical neuron excitability in primary progressive limb-kinetic apraxia.
- This excitability may result from impaired cortico-cortical inhibitory mechanisms due to focal cortical neuron degeneration.
- Further research into these mechanisms could inform therapeutic strategies for apraxia.