The double crush syndrome: a common occurrence in cyclists with ulnar nerve neuropathy-a case-control study.

ABSTRACT

OBJECTIVE: To evaluate the incidence of double crush syndrome in the upper limbs of cyclists with clinical diagnosis of ulnar nerve neuropathy. DESIGN: Case-control study. SETTING: Outpatient clinics and university setting. PARTICIPANTS: Consecutive sampling of 70 cyclists (140 upper limbs) with a mean age of 36 years (+/-11.3). Seventy-two upper limbs were excluded, leaving 40 upper limbs with a clinical diagnosis of ulnar nerve neuropathy [ULNN (+)] and 28 without symptoms of ulnar nerve neuropathy [ULNN (-)]. ASSESSMENT Cyclists were examined clinically for the presence of proximal dysfunction using the following testing (independent variables) (1) thoracic outlet syndrome provocation testing elevated arm stress test and modified Cyriax release test; (2) presence of an elevated first rib cervical rotation lateral flexion test; and (3) presence of proximal symptoms reports of neck pain and shoulder pain. MAIN OUTCOME MEASUREMENTS The upper limbs of cyclists were categorized into 2 groups (dependent variable)-ULNN (+) and ULNN (-)-based on history, symptoms, motor, sensory, and provocative clinical testing. RESULTS: A significantly greater number of upper limbs of cyclists with ULNN (+) presented with positive provocative testing for thoracic outlet syndrome (elevated arm stress test P = 0.005; modified Cyriax release test P = 0.002) than did the upper limbs of cyclists with ULNN (-). The likelihood for the presence of neck pain, shoulder pain, and an elevated first rib was 3, 5, and 12 times greater, respectively, in the ULNN (+) than the ULNN (-) group. CONCLUSION: A statistically significant greater number of the upper limbs of cyclists with clinical diagnosis of ulnar nerve neuropathy presented with proximal dysfunctions suggestive of double crush syndrome.