Blood-flow measurements of injured peripheral nerves by laser Doppler flowmetry

The effects of injury on peripheral nerve blood flow were studied, using a Laserflo blood perfusion monitor. A total of 11 nerves were studied, five normal and six injured nerves in four patients. Two of the patients had lacerating brachial plexus injuries, and two other patients had compressive neuropathies of their ulnar nerves at the elbow. All of the readings were taken intraoperatively while the patients were undergoing exploration and repair under general anesthesia. Measurements of the damaged nerves were taken serially from the site of injury proximally and distally, by approximating a flexible metric ruler to the dorsal aspect of the nerve along the same axis. In the acutely lacerated injured nerves (3 to 7 days), the measurements were taken at 1, 5, 10, and 20 mm. The maximal amount of retraction in any of the nerves was 1 cm; thus, the overall architecture of the nerves was maintained. In the compressed nerves, measurements were taken at 1, 2 and 3 cm proximal and distal to the medial epicondyle. Measurement of normal undamaged nerves was performed at six different sites along the same axis of the nerve. The averaged results indicate that the normal blood flow ranged from 47 ml/100 g/min to 63 ml/100 g/min, with a mean of 56 ml/100 g/min. In the injured nerves, blood flow was most depressed at sites closest to the laceration, and increased consistently and progressively at sites distant from the injury in both directions.(ABSTRACT TRUNCATED AT 250 WORDS)