Attending Physician Rutgers New Jersey Medical School East Orange, New Jersey, United States
Case Diagnosis: Vaughan-Jackson syndrome
Case Description: A 62-year-old male veteran with rheumatoid arthritis was referred for electrodiagnostic testing (EDX) to rule out ulnar neuropathy. He twisted his right wrist months prior and was unable to extend D5 several weeks after. Loss of D4 extension followed days later. XR showed erosions at the distal radio-ulnar joint.
Examination revealed a prominent dorsal wrist protrusion and atrophy of the hand intrinsics. Strength was normal except for mild D5 abduction weakness, trace D4 extension, and absent D5 extension. Light touch sensation was decreased at D5. Extensive EDX was normal except for increased polyphasic MUAPs with FDP testing.
Based on his rheumatoid arthritis, bony erosions, and relatively normal EDX, he was referred to plastic surgery with a provisional diagnosis of Vaughan-Jackson syndrome. MRI revealed EDM tendon attenuation and absent distal signal consistent with a tear. He will undergo Darrach’s procedure and reconstruction of the D4 and D5 extensor tendons.
Discussions: Multiple conditions can produce a hand posture resembling Vaughan-Jackson syndrome. The ulnar nerve innervates the medial two lumbricals, interossei, and the hypothenar muscles. Medial lumbrical dysfunction from ulnar lesions renders the MCP joints extended and the interphalangeal joints flexed when performing finger extension. A Benediction sign is also evident in proximal median nerve lesions when making a fist due to FDP dysfunction of D2 and D3. Posterior interosseous nerve compromise at the elbow from rheumatoid synovitis also impairs digital extension. Extensor tendon attrition in Vaughan-Jackson syndrome often progresses in an ulnar to radial direction, making early diagnosis critical.
Conclusions: Vaughan-Jackson syndrome is a pathological process by which distal radio-ulnar joint arthritis and ulnar head displacement through a perforated capsule causes progressive attrition of extensor tendons. Multiple neuropathies and musculoskeletal deformities can mimic this condition. A high index of suspicion is needed when evaluating new-onset finger weakness in a patient with RA.
