尺骨神経脱臼とオーバーテーブルを用いた座位練習が発症の原因として疑われた肘部管症候群の1例

A Case of Cubital Tunnel Syndrome Due to Ulnar Nerve Dislocation Further Affected by Sitting Exercises Using an Over-table

はじめに

　肘部管症候群（cubital tunnel syndrome：CBTS）は，手根管症候群に次いで多い絞扼性神経障害であり，神経生理学的診断の対象であるだけでなく，リハビリテーション治療の臨床場面においてもしばしば認められる疾患である．その発症原因の1つに尺骨神経脱臼が挙げられる^1-7)．

　重度の外傷性脳損傷により中枢性麻痺を呈した患者が，回復期リハビリテーション病棟入院中にCBTSを発症した．その発症機転には，脱臼した尺骨神経に対して反復的なオーバーテーブルからの圧迫が加わった機序が疑われた．

　リハビリテーション診療において，オーバーテーブルは日常的に使用されるものである．座位が不安定な意識障害患者に尺骨神経脱臼があった場合，オーバーテーブル使用というリハビリテーション治療によってCBTSを生じる可能性が考えられたため，本症例の臨床経過を報告する．

Herein, we report a case of a 49-year-old man with a history of bilateral hemiplegia caused by severe traumatic brain injury. During his stay in the convalescent rehabilitation hospital, he developed a flexion deformity of the 4th and 5th fingers of his right hand. Elbow palpation and ultrasonography showed that the ulnar nerve was dislocated from the elbow canal, and a nerve conduction study revealed that the conduction velocity was low in the right elbow. Thus, a diagnosis of cubital tunnel syndrome was made and an ulnar nerve transfer was performed to prevent progression. Prior to onset, an over-table had been used by the patient for daily activities such as sitting, training, and eating. Therefore, it was considered that the repeated use of the over-table plausibly exerted pressure on the dislocated ulnar nerve, leading to the onset of the cubital tunnel syndrome.

As over-tables and wheelchair armrests are often used during rehabilitation, it is imperative to pay attention to elbow compression when using them in patients with ulnar nerve dislocation.