For severe cubital tunnel syndrome, patients with absent sensory nerve action potential tend to have more severe nerve damage than those without. Thus, it is speculated that such patients generally have a poor prognosis. How absent sensory nerve action potential affects surgical outcomes remains uncertain owing to a scarcity of reports and conflicting results. This retrospective study recruited one hundred and fourteen cases (88 patients with absent sensory nerve action potential and 26 patients with present sensory nerve action potential) undergoing either subcutaneous transposition or in situ decompression. The minimum follow-up was set at 2 years. Primary outcome measures of overall hand function included their McGowan grade, modified Bishop score, and Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH) score. For patients with absent sensory nerve action potential, 71 cases (80.7%) achieved at least one McGowan grade improvement, 76 hands (86.4%) got good or excellent results according to the Bishop score, and the average DASH score improved 49.5 points preoperatively to 13.1 points postoperatively. When compared with the present sensory nerve action potential group, they showed higher postoperative McGowan grades and DASH scores, but there was no statistical difference between the modified Bishop scores of the two groups. Following in situ decompression or subcutaneous transposition, great improvement in hand function was achieved for severe cubital tunnel syndrome patients with absent sensory nerve action potential. The functional outcomes after surgery for severe cubital tunnel syndrome are worse in patients with absent sensory nerve action potential than those without. This study was approved by the Ethical Committee of Huashan Hospital, Fudan University, China (approval No. 2017142).
Keywords: absent sensory nerve action potential; cubital tunnel syndrome; disease severity; electrodiagnostic testing; in situ decompression; nerve regeneration; neural regeneration; peripheral nerve compression; prognostic factors; subcutaneous transposition; surgical outcomes.