Neurostimulation in severe carpal tunnel release: A more precise technique for opponensplasty decision-making

OBJECTIVES: In this study, we aimed to investigate the relationship between intraoperative thenar muscle neurostimulation responses and postoperative thumb function recovery in patients with severe carpal tunnel syndrome (CTS). PATIENTS AND METHODS: Between January 2019 and December 2021, a total of 21 severe CTS cases in 20 patients (7 males, 13 females; mean age: 56.3±19.3 years; range, 52 to 76 years) based on clinical and electrophysiological findings were retrospectively analyzed. The median nerve motor branch (MNMB) was stimulated intraoperatively with a nerve stimulator. The patients were divided into two groups according to contraction response on abductor pollicis brevis (APB) muscle: Group C (contractile, n=13) and Group NR (non-responsive, n=7) with and without muscular contraction. The Levine Functional Severity Scale (LFSS) was used to measure the functional status of CTS patients. The Manual Muscle Testing (MMT) was used to assess muscle strength. Clinical outcomes were compared between the groups at one year of follow-up. RESULTS: The mean total preoperative LFSS score was significantly higher in Group NR than in Group C (p=0.010). The mean postoperative MMT score was significantly higher in Group C than in Group NR (p<0.001). There was no positive result in pick-up, button fastening, and needle pinch tests in Group NR (p<0.001). However, there were significant improvements in postoperative LFSS scores in Group C (p<0.05), while the scores remained unchanged in Group NR (p>0.05). CONCLUSION: Direct stimulation of the median nerve motor branch and observation of contraction response on APB muscle can be used to predict clinical recovery and facilitates making the decision for opponensplasty in severe CTS.