鏡視下手根管開放術における不全開放と皮下断端神経腫形成が複合性局所疼痛症候群を生じた1例

Formation of a Subcutaneous Amputation Neuroma after Incomplete Endoscopic Carpal Tunnel Release Resulting in Complex Regional Pain Syndrome:A Case Report

Ⅰ．はじめに

　手根管症候群（carpal tunnel syndrome：CTS）への外科治療は，1930年代の直視下手根管開放術（open carpal tunnel release：OCTR）に始まり¹⁴⁾，1980年代後半には鏡視下手根管開放術（endoscopic carpal tunnel release：ECTR）が加わった．ECTRは，汎用型内視鏡を用いるコンセプトの発案以後²⁵⁾，前腕遠位部のポートと専用器具を用いるsingle-portal technique¹⁾，前腕遠位部と手掌にポートを設けるdual-portal techniqueが登場し⁵⁾，OCTRでみられる有痛性の手掌瘢痕を生じないことから，1990年代に急速に普及した．しかし合併症リスク，高コスト，適応が手術歴のない特発性CTSに限定される¹¹⁾などの理由から，近年は否定的な風潮にあり，ECTRとOCTRを合併症率，患者満足度，術後疼痛などで比較したメタ解析でも，ECTRがOCTRに対して優位なのは術後疼痛の弱さのみと結論されている³⁷⁾．

　今回われわれは，ECTRにおける手根管の不全開放および尺骨神経掌枝の断端神経腫形成が，難治性の慢性疼痛症候群である複合性局所疼痛症候群（complex regional pain syndrome：CRPS）の発生に関与した1例を経験したので報告し，これらの合併症を考察する．

　This 64-year-old woman had undergone endoscopic carpal tunnel release（ECTR）for right carpal tunnel syndrome 16 months earlier. Thereafter, she reported persistent dysesthesia in the thumb and index finger, developed burning pain in the middle and ring finger, paleness, coldness, and edema of the hand, a decreased range in hand motion, and a painful subcutaneous nodule just distal to the portal in the forearm. Based on physical, radiological, and electrophysiological studies, the diagnosis was incomplete carpal tunnel release associated with complex regional pain syndrome（CRPS). At open revision surgery, the carpal tunnel was released completely and the nodule was removed. Symptoms other than hypesthesia in the middle and ring fingers improved. Pathologically, the nodule was an amputation neuroma. Her CRPS was attributed to ECTR complications；i.e., persistence of median nerve compression and the formation of an amputation neuroma in the palmar cutaneous branch of the ulnar nerve at the portal. Surgeons must be aware that ECTR, a less invasive technique, may result in serious complications including CRPS.