Autogenous vein graft repair of digital nerve defects in the finger: a retrospective clinical study

Twenty-two digital nerve repairs were performed in the finger using autogenous vein grafts. Eighty-two percent of the repairs were available for follow-up. Results of sensibility return were assessed using moving two-point discrimination, Semmes-Weinstein monofilaments, and vibratory testing. Two-point discrimination averaged 4.6 mm for 11 acute digital nerve repairs using vein conduits 1 to 3 cm in length. Delayed digital nerve repair with vein conduits yielded poor results. Semmes-Weinstein values demonstrated comparable levels of return of slowly adapting fiber/receptors to the quickly adapting fiber/receptors, as evidenced by moving two-point discrimination tests. Vibratory sensibility was present in all. A review of previous experiences with end-to-end digital neurorrhaphies and digital nerve grafting suggests that repair of 1- to 3-cm gaps in digital nerves with segments of autologous vein grafts appears to give comparable results to nerve grafting. Further laboratory and clinical research is necessary to better define the role of interpositional vein conduits for repair of peripheral nerves.     

An alternative to the classical nerve graft for the management of the short nerve gap

Reconstruction of a short nerve gap by a nerve graft produces donor-site scarring, loss of donor nerve function, and neuroma formation. This study compared the regeneration achieved after 1 year in 16 monkeys across a 3-cm upper arm ulnar nerve gap with a bioabsorbable polyglycolic acid nerve conduit with the regeneration achieved with a classical interfascicular interpositional sural nerve graft. The results demonstrated electrophysiologic and histologic evidence of neural regeneration across the gaps in all experimental groups. The bioabsorbable nerve conduit groups and the sural nerve graft group had mean fiber diameters, amplitudes, and conduction velocities each significantly less than those of normal control ulnar nerves. There was, however, no significant difference between any of the experimental groups. Electromyography demonstrated recovery of 19 of the 28 (68 percent) intrinsic muscles studied. These results demonstrate that the primate peripheral nerve can regenerate across short nerve gaps when guided by an appropriate nerve conduit, suggesting that a single-stage biodegradable polyglycolic acid conduit may be used as an alternative to a short interfascicular nerve graft.     

Coronary artery bypass graft surgery in Newfoundland and Labrador

BACKGROUND: Newfoundland and Labrador, like other health care jurisdictions, is faced with widening gaps between the demands for health care and a strained ability to supply the necessary resources. The authors carried out a study to determine the rates of appropriate and inappropriate coronary artery bypass grafting (CABG) in the province and the waiting times for this surgery. METHODS: This retrospective cohort study was performed in the tertiary care hospital that receives all referrals for coronary angiography and coronary artery revascularization for Newfoundland and Labrador. By reviewing the hospital records, the authors identified 2 groups of patients: those in whom critical coronary artery disease was diagnosed on the basis of coronary angiography and who were referred for CABG between Apr. 1, 1994, and Mar. 31, 1995, and those who actually underwent the procedure during that period. By applying specific criteria developed by the RAND Corporation, the authors determined the appropriateness and necessity of CABG in each case. They also compared waiting times for CABG with optimal waiting times; as determined by a consensus-based priority score. RESULTS: A total of 338 patients underwent CABG during the study period. The cases were characterized by multivessel disease and late-stage angina symptoms. Almost all of the patients had high appropriateness scores (7-9), and nearly 95% had high necessity scores (7-9). However, during the study period, the waiting list increased by about 20%, because a total of 391 patients were referred by the weekly cardiovascular surgery conference; the authors identified these and an additional 31 patients as having necessity scores of 7 or more. Only 7 (23%) of 31 patients for whom CABG was considered very urgent underwent surgery within the recommended 24 hours, and only 30 (24%) of the 122 patients for whom CABG was considered urgent underwent surgery within the recommended 72 hours. INTERPRETATION: These results provide evidence that the cardiac surgery program in Newfoundland and Labrador is performing CABG in patients for whom surgical revascularization is highly appropriate and necessary. Access to CABG is less than ideal, however, since the waiting list continues to expand, and many patients wait beyond the recommended time for surgery.     

Effects of nerve growth factor on nerve regeneration through a vein graft across a gap.

The limited availability of donor sites for nerve grafts and their inherent associated morbidity continue to stimulate research toward finding suitable alternatives. In the following study, the effect of direct administration of nerve growth factor (NGF) into a nerve conduit across a gap was tested in a rat sciatic nerve model. A 1-cm segment of the right sciatic nerve in Sprague-Dawley rats was resected, and the gap was then bridged using one of three methods: group I (NGF-treated group, n = 12), a vein graft filled with NGF (100 ng in 0.3-ml phosphate buffered saline); group II (control group, n = 12), a vein graft filled with phosphate buffered saline only; group III (standard nerve graft, n = 11), a resected segment of the sciatic nerve. All animals were evaluated at 3 and 5 weeks by behavioral testing and at 5 weeks by electrophysiologic testing. At 3 weeks, sensory testing showed that the latency to a noxious stimulus in group I animals (8.0 +/- 5.4 sec, mean +/- SD) was significantly lower than that of group II animals (13.2 +/- 6.5 sec), indicating that sensory recovery was superior in the animals receiving NGF. The mean latency of animals in group III was 12.9 +/- 6.5 sec, but the difference between the latencies of group I and group III did not reach statistical significance. At 5 weeks, there was no difference in sensory testing between groups. Motor function in groups I and III as measured by walk pattern analysis was superior to that of group II at 5 weeks (toe spread ratios 0.66 +/- 0.09, 0.48 +/- 0.07, and 0.69 +/- 0.09 for groups I, II, and III, respectively). Mean motor conduction velocities across the 1-cm gap were 8.6 +/- 4.7 m/sec, 2.5 +/- 0.7 m/sec, and 6.9 +/- 2.9 m/sec in groups I, II, and III respectively. The difference between groups I and III was not statistically significant, but the motor conduction velocity of group II was significantly slower than that of either group I or III (p < 0.002). The positive effects of NGF on regeneration of nerves across a gap seen in this study suggest that it may be useful for treating peripheral nerve injuries in combination with autogenous vein grafts.