Objectives: The aim of this study is to describe the incidence and characteristics of pain, sensory abnormalities, abnormal body sweating, and pathologic gustatory sweating in pain patients with persistent post-sympathectomy pain.
Methods: A retrospective chart review of a series of consecutive pain patients with persistent post-sympathectomy pain was performed. Inclusion criteria were: (1) sympathectomy performed for the indication of neuropathic pain, and (2) persistent pain after the procedure. Demographic data, patterns of pain before and after sympathectomy, patients' pain drawings, and incidence of pain had been collected concurrently at the time of referral. Additional data regarding sensory findings, surgical details of the sympathectomy, sweat patterns, and incidence of abnormal body sweating and pathologic gustatory sweating were extracted from the patients' charts or obtained in follow-up appointments.
Results: Seventeen adults (13 females and 4 males) with a mean age of 37 years (range 25-52) at the time of sympathectomy met the inclusion criteria. Five of the 17 patients experienced temporary pain relief for an average of 4 months (range 2-12 months), 3/17 retained the same pain as before the surgery, 1 patient was cured of her original pain but experienced a new debilitating pain, and 8/17 patients continued to have the same or worse pain in addition to a new or expanded pain. Pathologic gustatory sweating was present in 7/11 patients asked, and abnormal sweating (known as compensatory hyperhidrosis) in 11/13 patients asked.
Discussion: The present study does not allow for conclusions about the effectiveness of surgical sympathectomy for neuropathic pain. However, our findings indicate that if the pain persists after the procedure, the complications may be quite serious and at times worse than the problem for which the surgery was originally performed.
Surgical sympathectomy (SS) is most commonly performed for the treatment of palmar hyperhidrosis 1-7; however, it is also considered appropriate treatment of neuropathic pain attributable to involvement of the sympathetic nervous system. 4,8,9 A recent systematic literature review of the late complications following SS revealed that 25% of patients submitted to SS for treatment of neuropathic pain developed a new neuropathic pain syndrome, 18% an abnormal sweating pattern known as compensatory hyperhidrosis (CH), and 5% abnormal gustatory sweating (GS). 10
Neuropathic pain arises from injury or dysfunction of the peripheral or central nervous system. 11 Pain attributable to sympathetic nervous system involvement is known as sympathetically maintained pain (SMP). 12 CH is defined as sweating that arises primarily in non-denervated areas and occurs following cervico-dorsal SS. 13 It is currently considered compensatory based on the belief that it is a thermoregulatory reflex mediated by the remaining sweat glands that still possess sympathetic innervation. The mechanism of this paradoxical problem13 remains unresolved. Physiological GS is a normal phenomenon occurring in individuals who sweat in the upper lip and nape of neck while eating spicy (ie, capsaicin-containing) foods 14; however, pathologic GS can occur with preganglionic or postganglionic sympathetic nerve damage as well as sympathetic fiber damage within peripheral trigeminal branches following SS. 15 Pathologic GS primarily (but not exclusively) involves the side of the face ipsilateral to SS during ingestion of spicy or non-spicy foods.
While there is considerable documentation of late complications following SS for treatment of hyperhidrosis, 10 the evidence concerning the late complications of SS when the indication is neuropathic pain is inadequate. Specifically, evidence regarding the effectiveness of SS for the treatment of neuropathic pain is poor or absent. In his 1997 review of clinical trials for treatments of peripheral neuropathic pain and complex regional pain syndromes, Kingery found that all sympathectomy studies were outcome series and that no controlled trials were available. 16 He remarked that the long-term pain relief reported after sympathectomy in the non-controlled literature was contradictory to the results of controlled trials showing limited success of regional and systemic adrenergic blockade in Complex Regional Syndrom (CRPS).
The aim of the current study is to provide information about patterns and characteristics of pain and sensory abnormalities, and to outline the onset, incidence, localization, and severity of CH and GS in patients with persistent post-sympathectomy pain, seen in our clinic between 1994 and 2001. We also report CH following lumbar SS, a complication thought previously to occur only following cervico-dorsal SS.