Double crush syndrome due to plating of humeral shaft fracture
A 62 year old woman sustained a closed fracture of right humeral shaft resulting from a car accident (OTA 12A3). We performed the open reduction and internal fixation through an anterolateral approach under general anesthesia and placed a 4.5 mm dynamic compression plate on the lateral aspect of the humerus. The placement of the implants was good except that the tip of the most proximal screw protruding approximately 1 cm through the medial cortex []. During in-hospital treatment, the patient recovered without complaining any discomfort of the right hand. 4 weeks postoperatively, however, she began to feel tingling over the thumb, index and middle fingers of the right hand, which was worse at night. The symptoms gradually progressed with thumb-index finger pinch weakness. When coming to our clinics 3 months postoperatively, she presented a sensory deficit of those fingers. Both Tinel's sign over carpal tunnel and Phalen's test were positive, as well as atrophy of the thenar muscles. She did not experience such symptoms prior to surgery to the humerus fracture. The neurophysiological study confirmed the clinical suspicion of CTS, with a prolonged distal latency and low amplitude of compound muscle action potential, so did the sensory nerve []. The neurophysiological finding of the proximal median nerve and ipsilateral ulnar nerve was normal. The criteria for electro-diagnosis of CTS included: Distal median motor latency >4.4 ms; difference between distal motor latency of median and ulnar nerve >1.1 ms; difference between distal sensory latency of median and ulnar nerve >0.2 ms. Although a transient improvement was observed with night splint treatment, the symptoms recurred after a few weeks. A carpal tunnel decompression was therefore recommended but the patient refused.\nAt 16 months postoperatively, the patient asked for removal of the implants. During the operation, we observed that the tip of the protruding screw twisted the median nerve with scar tissues. Extensive neurolysis around the median nerve was not performed, because we did not expect relief of symptoms of CTS after removal of the implants. At 2 weeks later, however, the patient experienced a significant relief of the tingling over fingers. At last review, 6 months after the implants removal, her sensations returned to near normal with full movement of the fingers. Although mild thenar atrophy was still present, the patient remained asymptomatic and denied additional carpal tunnel decompression surgery as she had no great difficulty in carrying out her daily activities.