SURGICAL REMOVAL OF PAINFUL POST-HERPETIC SKIN AND ANALYSIS OF CUTANEOUS INNERVATION - A CASE REPORT
Karin L. Petersen, Frank Rice, Fred Suess, Marlene Berro, Michael C. Rowbotham University of California, San Francisco Pain Clinical Research Research Center & University of California, San Francisco-Mount Zion Pain Management Center

Introduction
Surgical removal of the painful skin as a treatment for post-herpetic neuralgia (PHN) was described anecdotally in the 1940's and 1950's in several case series. As outcomes varied from complete relief to no benefit, the procedure eventually fell out of favor. After trying numerous treatments for PHN with only partial relief, a patient followed at the UCSF Pain Clinical Research Center and the UCSF-Mount Zion Pain Management Center had the painful skin removed and donated it for analysis of cutaneous innervation.

Case Report
This 64 year-old male developed acute herpes zoster in the right T7 distribution in 1992. Deep pain, shooting pain and allodynia persisted and were primarily located on the back below the shoulder blade. He was first evaluated at UCSF in 1995. Monotherapy with tricyclic antidepressants, antiepileptic drugs, sodium channel blockers, opioids, and lidocaine patches each produced partial pain relief. At the time of surgery, he had been on a stable regimen of gabapentin, methadone, nortriptyline and daily application of lidocaine patches for more than a year.

On the day prior to surgery the patient rated PHN pain severity as 90 on the 0-100 mm VAS. The size and location of the most painful area and the area of allodynia to brush stimulation were each marked on the skin. Allodynia severity produced by 3 foam brush strokes was rated on a 0-100 mm scale as 76. Thermal thresholds were measured with a 10.24 cm² computer controlled thermode (Medoc, Israel). A capsaicin response test was performed on a 9 cm² area within the most painful area. The sensory testing pre-surgery showed modest sensory loss in the affected skin and marked worsening of pain and allodynia with application of capsaicin cream (0.075 %).

At surgery 10/27/00, an elliptical piece of skin (11.5 cm x 26 cm) corresponding to the area of pain and allodynia was excised to the fascia from the posterior midline to the posterior axillary line. One 3 mm skin punch biopsy was performed in contralateral skin. Twenty four skin samples were taken immediately from the excised skin. Tissue samples were stained for the axonal marker PGP 9.5, the neuropeptide CGRP, the VR-1 receptor, and other markers.

Pain evaluations and sensory mapping have been performed biweekly post-surgery in the UCSF Pain Clinical Research Center. The patient reported complete pain relief in the first week after surgery. After two weeks, occasional episodes of deep pain occurred but no allodynia was present on examination. Currently, he reports a stable 60% reduction in

overall pain level without recurrence of allodynia. He no longer requires lidocaine patches and is slowly tapering off gabapentin.

Pictures of cutaneous innervation will be presented at the meeting.

Corresponding Author: Karin L. Petersen, M.D., Postdoctoral Fellow, UCSF Pain Clinical Research Center, 1701 Divisadero Street, Suite 480, San Francisco, CA 94115, USA