Iyer Vasudeva G
Neurodiagnostic Center of Louisville, 2505 Bush Ridge Drive, Louisville, KY, USA.
Clin Neurophysiol Pract. 2021 Oct 13;6:256-259. doi: 10.1016/j.cnp.2021.09.003. eCollection 2021.
Patients with congenital thenar hypoplasia (Cavanagh syndrome) may undergo surgical intervention with a mistaken diagnosis of severe carpal tunnel syndrome. Conversely, patients with Cavanagh syndrome can develop co-morbid median nerve entrapment at the carpal tunnel later in life and may go untreated. This study is aimed at evaluating the role of ultrasonography in confirming/ruling out median nerve entrapment at the carpal tunnel in patients with Cavanagh syndrome.
6 patients with Cavanagh syndrome were identified during a 10-year period from among patients referred for preoperative electrodiagnostic confirmation of carpal tunnel syndrome. All patients underwent ultrasound imaging as well as electrodiagnostic studies including motor conduction study of the median nerve with recording electrodes over the lumbrical muscles.
Age range of patients was 39-76. The right hand was affected in 5 and left hand in 1 patient. Electrodiagnostic studies (EDX) confirmed carpal tunnel syndrome in 4 of the 6 patients. In one patient the nerve conduction studies were non-diagnostic due to absence of compound muscle action potential (CMAP) over the thenar, and the 2nd lumbrical muscles and absent sensory nerve action potentials (SNAP). Ultrasound images confirmed entrapment of median nerve at the carpal tunnel in all 5 patients. The sixth patient was mistakenly diagnosed with severe carpal tunnel syndrome by the referring physician, based on the thenar atrophy; the median nerve was normal in both ultrasound and electrodiagnostic studies.
Ultrasound was useful for confirming/ruling out comorbid carpal tunnel syndrome in all 6 patients with Cavanagh syndrome.
Ultrasound complements electrodiagnostic study findings in patients with congenital thenar hypoplasia and comorbid carpal tunnel syndrome. It is even more valuable when EDX findings are non-diagnostic due to absent CMAP and SNAP.
先天性大鱼际肌发育不全（卡瓦纳综合征）患者可能会因被误诊为严重腕管综合征而接受手术干预。相反，卡瓦纳综合征患者在晚年可能会并发腕管处正中神经受压，且可能未得到治疗。本研究旨在评估超声在确诊/排除卡瓦纳综合征患者腕管处正中神经受压方面的作用。
在10年期间，从因术前电诊断确诊腕管综合征而转诊的患者中识别出6例卡瓦纳综合征患者。所有患者均接受了超声成像以及电诊断研究，包括通过在蚓状肌上放置记录电极对正中神经进行运动传导研究。
患者年龄范围为39至76岁。右手受累5例，左手受累1例。电诊断研究（EDX）证实6例患者中有4例患有腕管综合征。1例患者由于大鱼际肌和第二蚓状肌上无复合肌肉动作电位（CMAP）且无感觉神经动作电位（SNAP），神经传导研究无法做出诊断。超声图像证实所有5例患者的正中神经在腕管处受压。第六例患者被转诊医生基于大鱼际肌萎缩误诊为严重腕管综合征；超声和电诊断研究均显示正中神经正常。
超声有助于确诊/排除所有6例卡瓦纳综合征患者并发的腕管综合征。
超声可补充先天性大鱼际肌发育不全并发腕管综合征患者的电诊断研究结果。当由于无CMAP和SNAP而导致EDX结果无法做出诊断时，超声更具价值。
