Epineurotomy for leprous, high ulnar neuropathy: defining a safe corridor based on the epineural vascular anatomy.

Abstract

Leprous neuropathy is treatable but still a source of disability worldwide. Multidrug therapy (MDT) and oral steroids are the main stay of treatment. Ulnar nerve, at the elbow, is commonly involved. Nerve decompression may be required in selected cases by an epineurotomy (internal neurolysis). The preferred surface of ulnar nerve for performing this procedure to minimize iatrogenic vascular compromise is a matter of debate. We describe the epineural vessel arrangement on the medial and lateral surface of ulnar nerve around the medial epicondyle while performing epineurotomy for leprous neuropathy. We enrolled patients of symptomatic leprous ulnar neuropathy of less than oneyear duration on MDT that did not respond to steroids, for surgical decompression. Ten patients underwent epineurotomy of ulnar nerves (N = 11) around medial epicondyle. The epineural vessels were classified as per Sunderland's classification of arteriae nervorum. The number of epineural vessels was assessed on the medial and lateral surface of the ulnar nerve adjoining the medial epicondyle. The epineurotomy incision was placed over the surface of ulnar nerve having relatively less vessels. The mean number of epineural vessels on the medial surface was 9.72 (range; 7-14) and on the lateral surface were 4.72 (range; 3-6). The average number of vessels per cm2 of the medial and lateral surface of the nerve was 0.94 and 0.48, respectively. The most common type of epineural vessel was type 3 on both medial and lateral surface of the nerve. Lateral epineurotomy was performed in all 11 cases. All the patients had relief from neuropathic pain. The mean VAS score improved from 3.20 ± 0.89 to 0.50 ± 0.34 at 2years follow-up (p = 0.02). The mean motor score improved from 9.31 ± 4.12 to 15.42 ± 3.10 and sensory score improved from 40.0 ± 30.70 to 85 ± 9.90 at two years follow-up (p < 0.01). Lateral surface (facing the medial epicondyle) of ulnar nerve has a lesser density of epineural vessels in comparison to its medial (subcutaneous) surface. This anatomical understanding may be helpful in minimizing the iatrogenic vascular compromise of ulnar nerve while performing its epineurotomy around the medial epicondyle for leprous neuropathy. The findings may be extrapolated to other clinical indications of epineurotomy of ulnar nerve, for example, in cubital tunnel syndrome, traumatic ulnar neuroma in continuity, and benign ulnar nerve tumors.