Neurological damage after radial artery harvesting in coronary surgery: a direct measure.

BACKGROUND The incidence of neurological complications in the forearm after radial artery harvesting varies in the literature, ranging from 2% to more than 50%. Also, the areas affected and the type of neurological complications differ a lot. Peripheral nerve injuries may be divided into three types: neuroapraxia (conduction block that recovers within 3 months), axonotmesis (recovers 1 ml/day) and neurotmesis (needs surgery for recovering). We decided to perform a neuroelectrophysiological study, before and after surgery, in peripheral nerves of the forearm to find out the real incidence and the type of lesion after radial artery harvesting. METHODS Fifteen consecutive patients whose RA was going to be harvested were selected. Emergency patients, patients with severe liver or renal dysfunction were excluded. A complete neuroelectrophysiological study was performed in the median, ulnar and radial nerve. The amplitude was measured to check mielina status, whereas with the latency and nerve velocity conduction (NVC) we checked the axonal integrity. An electromyogram was also performed in the forearm muscles. A neurological clinical exploration was also performed. All these tests were performed before surgery and two weeks and two months after surgery. RESULTS Median nerve: A significant decrease in the amplitude that improved over time was registered. This decrease was observed in the motor and sensitive part of the nerve. No changes were observed regarding latency or NVC. Ulnar nerve: A decrease in the amplitude of the sensitive part of the nerve was observed (11.7-9.2-10.4 microV; P=0.006). No changes were observed regarding latency or NVC. Radial nerve: A statistical trend decrease observed regarding NVC of the sensitive part of the nerve branch was found (50.9 m/s vs. 47.1 m/s vs. 47.2 m/s; P=0.10). The electromyogram found no alterations. Clinically, three patients presented sensitive disorders in the median nerve territory and one of these also complained of sensitive disorders in the radial territory. Another patient referred dysesthesias in the ulnar nerve territory. All patients with the exception of one were asymptomatic two months after surgery. CONCLUSIONS Although only a few patients refer symptoms, most patients suffer changes in the peripheral nerves of the forearm (especially in the sensitive part) after RA harvesting. In our study the median nerve and the sensitive part of the ulnar and radial nerve were affected. These changes were temporary, affecting mainly the axon. All these data suggest neuroapraxia as the main peripheral nerve type lesion. We think that physicians and patients must be aware of this.