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Reduction in the motor unit number estimate (MUNE) after cerebral infarction

Keisuke Arasaki1, Osamu Igarashi, Toru Machida

  • 1Stroke Care Unit, Department of Neurology, NTT East Kanto Medical Center, Tokyo 141-0022, Japan. arasaki@aikawanaika.or.jp

Supplements to Clinical Neurophysiology
|August 19, 2010
PubMed

Insights

Motor unit number estimates (MUNEs) decrease in patients with cerebral infarction, particularly with hand weakness. This reduction, observed within 30 hours post-infarction, correlates with upper extremity weakness severity.

Area of Science:

  • Neurology
  • Neurophysiology

Background:

  • Cerebral infarction can lead to motor deficits.
  • The early electrophysiological changes following stroke are not fully understood.

Purpose of the Study:

  • To investigate the relationship between motor unit number estimates (MUNEs) and clinical features in patients with cerebral infarction.
  • To determine the temporal profile of MUNE changes after stroke.

Main Methods:

  • Motor unit number estimates (MUNEs) of the hypothenar muscle were measured using a multiple-point stimulation technique.
  • Patients underwent neurological assessment using the Japan Stroke Scale (JSS) and brain imaging (MR, MR angiography, SPECT).
  • Data were collected from 30 patients with cerebral infarction and 13 age-matched controls.

Main Results:

  • A decrease in hypothenar MUNE was observed in 24 patients with cerebral infarction and hand weakness.
  • MUNE reduction began 4 to 30 hours post-infarction, even when initial MR images were normal.
  • The degree of MUNE decrease correlated with the severity of upper extremity weakness on the JSS.

Conclusions:

  • Early MUNE reduction in cerebral infarction may indicate transsynaptic inhibition of spinal alpha motor neurons.
  • MUNE assessment could serve as an early electrophysiological marker for motor deficits post-stroke.
  • This finding provides insights into the pathophysiology of motor impairment following cerebral infarction.

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