J Korean Neurosurg Soc.  2019 Jan;62(1):90-95. 10.3340/jkns.2018.0111.

Anomalous Muscles of the Wrist Encountered During Endoscopic Carpal Tunnel Surgery

• Park SH

• KMID: 2434350
• DOI: http://doi.org/10.3340/jkns.2018.0111

Abstract

OBJECTIVE
Anomalous muscles of the wrist are infrequently encountered during carpal tunnel surgery. Anatomic variants of the palmaris longus (PL), flexor digitorum superficialis, lumbricalis and abductor digiti minimi (ADM) have been reported but are usually clinically insignificant. Anomalies of the wrist muscles, encountered during endoscopic carpal tunnel surgery have rarely been described. I conducted this study to evaluate muscular anomalies of the volar aspect of the wrist, encountered during endoscopic carpal tunnel surgery.
METHODS
I studied a consecutive series of 1235 hands in 809 patients with carpal tunnel syndrome who underwent single-portal endoscopic carpal tunnel release (ECTR) from 2002 to 2014. Nine hundred seventy-three hands in 644 patients who had minimal 6-month postoperative follow-up were included in the study. The postoperative surgical outcome was assessed at least 6 months after surgery.
RESULTS
In eight patients, anomalous muscles were found under the antebrachial fascia at the proximal wrist crease and superficial to the ulnar bursa, passing superficial to the transverse carpal ligament . Those anomalous muscles were presumed to be variants of the PL or accessory ADM muscle, necessitating splitting and retraction to enter the carpal tunnel during the ECTR procedure. Other muscle anomalies were not seen within the carpal tunnel on the endoscopic view. The surgical outcome for all eight wrists was successful at the 6-month postoperative follow-up.
CONCLUSION
Carpal tunnel surgeons, especially those using an endoscope should be familiar with unusual findings of anomalous muscles of the wrist because early recognition of those muscles can contribute to avoiding unnecessary surgical exploration and unsuccessful surgical outcomes.

Keyword

Carpal tunnel syndrome; Endoscopy; Variants

MeSH Terms

Carpal Tunnel Syndrome
Endoscopes
Endoscopy
Fascia
Follow-Up Studies
Hand
Humans
Ligaments
Muscles*
Surgeons
Wrist*

Figure

• 

  Fig. 1. Operative findings of the right wrist with an anomalous muscle in a 51-year-old man with carpal tunnel syndrome. A : Exposure of the anomalous muscle through a transverse incision of the antebrachial fascia. B : More exposure of the anomalous muscle in an oblique direction after retraction of the incised antebrachial fascia. C : Exposure of the underlying ulnar bursa surrounding the flexor tendons after retraction of the anomalous muscle. D : The undersurface of the transverse carpal ligament without any abnormal structures in the carpal tunnel on the endoscopic view.

Reference

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