Background: Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome, often requiring carpal tunnel release surgery. Anatomical anomalies within the carpal tunnel, such as the palmaris profundus (PP) tendon, may contribute to symptomatology or complicate surgical management. The PP is a rare vestigial muscle, with a reported cadaveric incidence of 0.125 per cent. It may share a fascial sheath with the median nerve and increase local volume within the carpal tunnel, thereby contributing to CTS. This review provides the first systematic synthesis of published cases of CTS associated with the PP. Methods: A systematic literature search was conducted across MEDLINE, Embase, PubMed and Cochrane Library on March 22, 2025. Studies were included if the PP was associated with CTS and if they were published in English. Two independent reviewers screened titles, abstracts and full texts, with data extracted on patient demographics, diagnostic methods, surgical approach, intraoperative findings and outcomes. Results: Eighteen studies, reporting on 21 patients, met the inclusion criteria. The mean age was 59.0 years with 76.2 per cent of cases involving the right hand. The PP was most often found arising from the flexor digitorum superficialis fascia and inserting into the palmar aponeurosis. Open carpal tunnel release and PP resection was the predominant surgical intervention (95.2%), with symptom resolution in 85.7 per cent of cases. A bifid median nerve was observed in 33.3 per cent of patients. Preoperative imaging rarely identified the anomaly. Conclusion: The PP is a rare but clinically relevant anatomical variant that may cause or contribute to CTS. Surgical vigilance and resection when encountered are strongly recommended to improve outcomes and reduce recurrence.
Kumar et al. (2026) studied this question.