Cubital tunnel syndrome presenting with carpal tunnel symptoms: clinical evidence for sensory ulnar-to-median nerve communication.

nterneural communications in the upper extremity have been described in various schemes. They have remained, however, the subject of diagnostic, anatomical, and neu-rophysiologic interest and have seldom related directly to clinical decision making. In this report, we describe the case of a patient who, despite typical clinical complaints of carpal tunnel syndrome , did not manifest any of the clinical signs of median nerve compression. She showed evidence of ulnar nerve compression at the elbow, and provocative testing of the cubital tunnel reproduced the " carpal tunnel " symptom-atology. Awareness of the presence of ulnar-to-median nerve communication led to the correct yet counterintui-tive decision to perform cubital tunnel release. The authors have obtained the patient's written informed consent for print and electronic publication of the case report. A right-hand–dominant woman in her mid-30s was referred for evaluation of numbness and tingling in the right hand that started 7 years before presentation. The symptoms mainly involved the thumb and index finger and had worsened over the previous few months. They often awakened her at night. She had tried several anti-inflammatory drugs but obtained no relief. Occasionally, she had similar symptoms in the left hand. She denied any prior history of trauma. Physical examination revealed full, painless range of motion of the wrist and all digits and no signs of tenosy-novitis or arthritis. The Tinel sign, the Phalen test, and the Durkan test were all negative over the median nerve at the wrist. Thenar and hypothenar muscles showed no atrophy and were of normal power. Examination of the right elbow revealed a positive Tinel sign over the ulnar nerve with radiation into the thumb and index fingers—reproducing the symptoms. The ulnar nerve was short and subluxing. The rest of the elbow examination was unrevealing. No signs of nerve entrap-ment were found on the contralateral side. Radiographic evaluation of the elbow and wrist revealed no bone or soft-tissue abnormalities. Electrodiagnostic studies revealed mild ulnar nerve neuropathy at the level of the elbow but were otherwise unremarkable. Specifically, motor nerve conduction studies showed normal median nerve parameters. The ulnar nerve showed normal distal latency and amplitude, but the velocity was delayed across the elbow. Sensory nerve conduction studies revealed normal distal latencies of all nerves but reduced ulnar nerve amplitude. F-wave studies of the median and ulnar nerves, and electromyographic studies of the brachioradialis, flexor carpi radialis, extensor digitorum communis, first dorsal interosseous, and …