ACETYLCHOLINE SWEAT TEST - AN EFFECTIVE WAY TO SELECT PATIENTS FOR LUMBAR SYMPATHECTOMY

Although lumbar sympathectomy can benefit patients with critical limb ischaemia, many derive no benefit from the procedure. The poor predict ion of outcome may be related to pre-existing damage to the sympatheti c fibres. We assessed sympathetic nerve function with the acetylcholin e sweatspot test before and after lumber sympathectomy in 31 patients with critical limb ischaemia. Of 9 patients with normal sympathetic fu nction or minor denervation preoperatively (sweatspot score greater th an or equal to 8), 8 showed improvement in pain and/or healing of isch aemic lesions after sympathectomy. The procedure did not achieve dener vation in the patient without improvement, as shown by persisting symp athetic activity postoperatively. By contrast, among the 22 patients w ith lower sweatspot scores, indicating severe or complete sympathetic denervation, only 1 showed improvement (partial) after lumbar sympathe ctomy. 9 patients underwent oximetry before and after the operation; i n this subgroup there was a positive correlation between preoperative sweatspot score and the change in tissue partial pressure of oxygen (r (2)=0.35). Preoperative assessment of sympathetic nerve function by me ans of a sensitive, quantitative test of autonomic integrity can predi ct the outcome of the procedure with high sensitivity and specificity. A postoperative test allows verification of sympathetic denervation. We recommend use of this simple test in selecting patients for lumbar sympathectomy.