頭部外傷により下肢純粋運動性単麻痺をきたした1例

Pure Motor Monoparesis of a Lower Limb due to Head Injury: A Case Report

はじめに

　純粋運動性単麻痺（pure motor monoparesis：PMM）は，その原因疾患としてラクナ梗塞，出血，腫瘍などの報告はあるが¹⁾，外傷が契機となって発症したという報告は非常に稀である^1-4)。今回，筆者らは頭部外傷により下肢のPMMをきたした症例を経験したので，過去の報告例を踏まえ若干の文献的考察を加え報告する。

Abstract

　A 70-year-old woman sustained a head injury after a motor vehicle accident. Physical examination conducted on admission revealed pure motor monoparesis (PMM) and pathological reflexes in the right lower extremity. Her left lower extremity and upper extremities were intact. Computed tomography showed a spotty high-density lesion in the left precentral gyrus and a subgaleal hematoma in the left occipital region. Magnetic resonance imaging was performed on the next day. Fluid-attenuated inversion recovery (FLAIR) imaging demonstrated a high-intensity lesion in the left precentral gyrus, and T₂^* imaging revealed a low-intensity lesion suggesting a small hemorrhage in the same area. The small hemorrhage and perifocal edema were identified on diffusion-weighted images in which low- and high-intensity lesions were observed in the anterior and posterior left precentral gyrus, respectively. Subsequent neurological examinations over 2 weeks showed improvement. We discuss the clinical presentation, diagnosis, and treatment of PMM due to head injury. We concluded that FLAIR and T₂^*- and diffusion-weighted imaging may be useful techniques for diagnosing PMM due to head injury.

(Received: March 26, 2012, Accepted: May 24, 2012)