Drs. Jacob and Mathai Reply
To the Editor:
We are writing in response to the letter from Dr. A. Colin McDougall on our article entitled "Diagnostic Efficacy of Cutaneous Nerve Biopsy in Primary Neuritic Leprosy."
We agree that nerve biopsy should be performed by experienced persons. The technique of biopsy of a cutaneous nerve is simple because the course of these nerves can be traced under the skin at specific sites. It may be noted that the cutaneous nerves chosen for biopsy were the radial cutaneous nerve at the wrist, the cutaneous branch of the common peroneal nerve above and medial to the medial malleolus, and the sural nerve at the ankle as it winds behind the lateral malleolus. Any other cutaneous nerve which was biopsied was palpable in close proximity to an area of sensory loss. All cutaneous nerve biopsies in our scries were performed by dermatologists or dermatology trainees with not less than 3 months of training in minor surgical procedures.
Concern has been expressed that permanent loss of sensation will result when a full 1-cm segment of a cutaneous nerve is removed. The cutaneous nerves chosen for diagnostic purposes were from the sites of established neurological deficits. This was mentioned in the section on Materials and Methods. Thus, there is no need to fear worsening of sensory function after biopsy.
The possible danger of performing a sliver biopsy from the trunk of a peripheral nerve was also pointed out by Dr. McDougall. Sliver biopsy of the ulnar nerve above the elbow was performed by competent surgeons on two patients who presented with total (sensory-motor) neurological deficit indicative of damage to the nerve at that site. The size of the nerves in both patients was normal. It may be argued that even though there was existing neurological deficit, if the nerve pathology was due to a reversible condition, the removal of a segment of nerve could prevent restoration of function. Each time a biopsy on a nerve trunk was done, it was done as a calculated risk. We feel it is justifiable to do this and that the clinician must take this risk so that early diagnosis can be made and treatment started on patients who have treatable disease.
- Mary Jacob, M.B.B.S., M.N.A.M.S.
Associate Professor
- Rachel Mathai, M.B.B.S., D.D., F.R.C.P.(G)
Professor
Department of Dermatology
Christian Medical College Hospital
Vellore 632004, India