Introduction: Few case reports describe the development of a hematoma under oral anticoagulation as the cause of an atraumatic carpal tunnel syndrome.
Case report: A 76 years old woman presented an acute atraumatic carpal tunnel syndrome of her left hand under oral anticoagulation with rivaroxaban due to atrial fibrillation. 12 years ago, palmar plate osteosynthesis of a distal radius fracture had been performed on the affected wrist. Open decompression of the carpal canal was performed due to persistent severe pain under intense pain therapy and progressive neurological symptoms. The cause of the pain was a hematoma due to a rupture of the flexor pollicis longus and the second flexor digitorum profundus tendon with concomitant synovitis at the plate's distal rim. After decompression, pain relieved and neurological deficits improved rapidly.
Discussion: Ruptures of the flexor tendons occur in palmar plate osteosynthesis in up to 1.5% in the long term postoperative course. Very distal plate positions, like in this case, increase that risk. Under anticoagulation, the rupture induced a hematoma increasing local pressure resulting in an acute carpal tunnel syndrome. Acute nerve compression syndromes should be treated surgically without delay.
Conclusion: Therapy with anticoagulants may increase hematoma after tendon rupture, thus supporting the development of an atraumatic acute carpal tunnel syndrome and complicating the surgical therapy. Hardware removal after fracture healing should be advised in patients with Soong grade 2 plate positions especially those taking anticoagulants.
Keywords: Carpal tunnel syndrome; Oral anticoagulants; Palmar plate osteosynthesis; Tendon rupture.