title: Reduction in the motor unit number estimate (MUNE) after cerebral infarction.
abstract: We examined the relationship between the degree to which motor unit number estimates (MUNEs) decrease in association with the clinical features of patients with the infarction. Using a multiple-point stimulation technique, we obtained the MUNE of the hypothenar muscle group in 13 age-matched control subjects and 30 patients with cerebral infarction. In all patients, we obtained the Japan Stroke Scale (JSS) and head MR images. In 8 patients with acute cerebral infarction, admitted within 24 h after onset, we also obtained head MR angiograms and single-photon emission CT. There was a decrease in the MUNE of the hypothenar muscle group on the affected side of 24 patients with cerebral infarction and hand weakness. The decrease in the MUNE started from 4 to 30 h after the infarction, when T1-weighted MR images of the brain involved were normal. The degree to which the MUNE decreased correlated with the part of the JSS showing the upper extremity weakness. A decrease in the MUNE of the hypothenar muscle group within 30 h after cerebral infarction may be due to transsynaptic inhibition of the spinal alpha motor neurons innervating this muscle.
authors: Stroke Care Unit, Department of Neurology, NTT East Kanto Medical Center, Tokyo 141-0022, Japan. arasaki@aikawanaika.or.jp
authors: Keisuke
authors: K
authors: Arasaki
authors: Osamu
authors: O
authors: Igarashi
authors: Toru
authors: T
authors: Machida
authors: Akira
authors: A
authors: Hyodo
authors: Ryosuke
authors: R
authors: Ushijima
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000473:pathology* / Q000503:physiopathology*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric