Trigger Wrist

Abstract

Trigger wrist is a relatively rare disease compared to trigger finger, which is the most common disorder found in hands. Patients with trigger wrist usually complain about the following symptoms: snapping and clicking or triggering around carpal tunnel with or without mild to moderate median neuropathy. There are a total of five cases of trigger wrist: three cases of anomalous muscle belly of flexor digitorum superficialis and two cases of fibroma around flexor tendon sheath within carpal tunnel. This study reports on two of those cases: one with anomalous muscle and the other with fibroma of flexor tendon sheath. Accurate examination and proper diagnosis are mandatory to obviate improper and time-wasting treatment for patients with trigger wrist.

Keywords: Mass; Tenosynovitis; Triggering; Wrist.

Fig. 1. Trigger wrist by abnormal flexor digitorum superficialis (FDS) muscle. (A) Plain lateral radiography shows no abnormal soft tissue shadow. (B) Computed tomography shows soft tissue mass shadow between FDS at the wrist level. Abnormal FDS muscle (arrow).(C) Intraoperative photograph showing an anomalous FDS muscle belly of index finger within the carpal tunnel. (D) Surgical excision of the anomalous FDS muscle belly, allowing its tendon to move freely within the carpal tunnel and operative specimen measuring 1.5 cm × 1 cm, showing normal striated muscle.

Fig. 2. Trigger wrist by fibroma of flexor tendon sheath. (A) Coronal T2-weighted image of wrist magnetic resonance imaging showing soft tissue mass wrapping around flexor tendons from carpal tunnel to mid palmar area. (B) Soft tissue mass inside the carpal tunnel in axial image. (C) Intraoperatively, pale brown colored oval mass was identified between flexor digitorum profundus tendons and moderate synovial hypertrophy of tendon sheath. (D) Hypertrophy of fibrotic tissue was confirmed by pathology (H&E, ×200 high power field).