Juvenile Muscular Amyotrophy of Distal Upper Limbs: A Case Report

平山症(Hirayama disease)爲一罕見的疾病，主要影響年輕男性的頭髓前角細胞，其特徵爲因頭部屈曲動作壓迫頭部前方脊髓，造成一種緩慢發生，且以單側上肢遠端肌肉無力及萎縮爲主的頭髓病變。臨床上不易與如運動神經元疾病等，其它具類似症狀的疾病區分。頭部屈曲時的核磁共振影像有助確認診斷。本病例報告一名21歲男性，在三年前右肩部拉扯性傷害後，開始出現進展性的右前臂及手部肌肉的無力及萎縮。肌電學檢查顯示，右側萎縮肌肉處出現急性及慢性的去神經變化，常規頭部核磁共振檢查顯示下頭髓的前角細胞信號強度增加。因懷疑爲平山症，我們安排屈頭核磁共振檢查，發現典型的下頭髓腔後方硬腦膜前移，証實了平山症的診斷。病患開始穿戴頭圈，同時補充維它命B12。治療三個月後的追蹤檢查顯示症狀沒有惡化。雖然平山症爲一自限性疾病，早期診斷卻非常重要，因早期使用頭圈避免頭部前屈動作可阻止病程進展。臨床上若遇有年輕男性因單側遠端上肢無力就診，伴有冷麻痺(cold paresis)及收縮性肌顫動(contractile fasciculation)現象，同時常規頭部核磁共振檢查顯示下頭髓非對稱性萎縮，應考慮平山症的可能，並安排屈頭核磁共振檢查以確定診斷。

關鍵字

平山症；青少年肌萎縮；單肢性肌萎縮

並列摘要

Juvenile muscular amyotrophy of distal upper limbs (Hirayama disease) is a rare disease predominantly affecting the anterior horn cells of the cervical cord in young men. It is a kind of cervical myelopathy characterized by insidious onset of unilateral distal dominant upper limbs muscle weakness and atrophy due to anterior cervical cord compression. It is difficult to differentiate this disease from other diseases with similar symptoms such as motor neuron disease. Cervical magnetic resonance (MR) study in flexed position is helpful to confirm the diagnosis. We reported a 21-year-old man who complained of slowly progressed muscle atrophy and weakness of right hand and forearm after right shoulder stretching injury three years ago. Electrodiagnostic study revealed acute and chronic denervative change in the right side atrophied muscles. Routine cervical MR images showed high signal intensity over the anterior horn cells of the lower cervical cord. With the suspicion of Hirayama disease, flexion MR was performed and the striking and pathognomonic picture of anterior shifting of posterior dura at the lower cervical spinal canal was noted. He received neck collar therapy and vitamin B12 supplement. No further progression of symptoms was noted at the 3 months follow-up study. Though Hirayama disease is spontaneous arrested, early diagnosis is necessary because early cervical collar application by preventing neck flexion has been shown to stop disease progression. Surgical managements are preserved to late stage. In cases of early onset of distal upper limb weakness with cold paresis and contractile fasciculation, the finding of asymmetric lower cervical cord atrophy on routine cervical MR study raise the suspicion of Hirayama disease. A flexion MR study should be performed to confirm the diagnosis.

並列關鍵字

Hirayama disease ； juvenile muscular atrophy ； monomelic amyotrophy

國際替代計量

Juvenile Muscular Amyotrophy of Distal Upper Limbs: A Case Report

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