Sonographic evaluation of the abductor pollicis brevis muscle reflects muscle strength recovery after carpal tunnel release

• Published in: Journal of medical ultrasonics (2001) Vol. 49; no. 2; pp. 279 - 287
• Main Authors: Ohno, Katsunori, Fujino, Keitaro, Fujiwara, Kenta, Yokota, Atsushi, Neo, Masashi
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.04.2022; Springer; Springer Nature B.V
• Subjects: Analysis; Carpal tunnel syndrome; Carpal Tunnel Syndrome - diagnostic imaging; Carpal Tunnel Syndrome - surgery; Evaluation; Fingers & toes; Grip strength; Hand Strength - physiology; Humans; Imaging; Medical research; Medicine; Medicine & Public Health; Medicine, Experimental; Muscle Strength; Muscle, Skeletal - diagnostic imaging; Muscle, Skeletal - physiology; Original Article–Orthopedics; Patient satisfaction; Questionnaires; Radiology; Recovery; Surgery; Thickness measurement; Thumb - surgery; Ultrasound; Wrist; United States > US; Japan; Carpal tunnel syndrome; Muscle strength; Ultrasound; Abductor pollicis brevis; Thenar muscle
• ISSN: 1346-4523; 1613-2254
• DOI: 10.1007/s10396-022-01195-6

Purpose This study aimed to examine the associations between sonographic measurements of the abductor pollicis brevis (APB), grip and pinch strength, and distal motor latency (DML) in patients with carpal tunnel syndrome (CTS) before and after surgery. Methods We prospectively studied patients (46 hands) who underwent 1 year of postoperative follow-up after endoscopic carpal tunnel release. The patients underwent ultrasound (US) scans, grip and pinch strength assessment, a nerve conduction study, and patient-reported outcome measures (Carpal Tunnel Syndrome Instrument and Michigan Hand Outcomes Questionnaire) before and 1 year after surgery. The standardized response mean was calculated to compare the sensitivity of clinical changes in these measurements. Results US measurements (thickness of the APB and the cross-sectional area of the APB) and muscle strength (grip strength, key pinch, and tip pinch) were greater, and DML was reduced after surgery compared with those before surgery (all P  < 0.05). Patient-reported outcome measures also showed clinical improvement 1 year after surgery ( P  < 0.05). US measurements of the APB were significantly correlated with grip and pinch strength (all P  < 0.05), but not with DML, before surgery and 1 year after surgery. The standardized response mean showed a large responsiveness for US measurements of the APB and patient-reported outcome measures. Conclusion US evaluation of the APB after CTS can complement the evaluation of grip and pinch strength in the clinical setting. Postoperative recovery of the APB leads to improved motor dysfunction in CTS. Therefore, US measurement of the APB could be a useful tool for evaluating motor function.