Quantitative sensory testing, neurophysiological and psychological examination in patients with complex regional pain syndrome and hemisensory deficits

Based on bed-side neurological testing, it has recently been shown that 33% of chronic complex regional pain syndrome (CRPS) type I patients exhibit s ensory impairments, which extend past the painful area of the affected limb in a hemisensory distribution (Pain, 80 (1999) 95). In the present study, the clinically observed changes in touch and temperature sensations on the side of the body ipsilateral to the affected limb were investigated quantit atively. Neurophysiological and psychological examinations were conducted t o detect changes in the peripheral and central nervous system as well as ps ychopathological abnormalities. In 40 patients with CRPS, a bed-side neurological examination was performed . Quantitative sensory testing was conducted at five locations on each side of the body. The evaluation of touch thresholds was performed using von Fr ey filaments (n = 40). To measure cool, warm and heat pain thresholds quant itatively, a thermal stimulator using a Peltier-element was used (n = 28). With respect to clinical findings, the initiating trauma and severity of ab normalities on nerve conduction testing, three patients were diagnosed as h aving a reliable CRPS II (causalgia) and five patients a possible CRPS II. Thirty-two patients were diagnosed as having a CRPS I. On clinical examination, 15 patients revealed generalized sensory deficits on the side of the body ipsilateral to the affected limb (hemisensory defic it, n = 12; sensory impairment in the upper quadrant of the body, n = 3). P atients with these generalized sensory deficits had a significantly longer illness duration (P < 0.05) and a significantly higher percentage of mechan ical allodynia/hyperalgesia than patients with spatially restricted sensory deficits (n = 25) (P < 0.05). In patients with generalized sensory impairm ent, thresholds for touch, warm and cold sensations, and for heat pain were significantly increased at all five locations tested ipsilaterally compare d with the contralateral body side, except for the cool threshold on the ch est and the heat pain threshold distally on the affected limb. In patients with sensory deficits limited to the affected limb, the touch threshold was significantly higher only in the distal part of the affected limb when com pared with the contralateral limb. In these patients, thermal testing revea led almost no differences in cool, warm and heat pain thresholds when compa ring both sides. Repeated thermal testing conducted in five patients with g eneralized sensory impairment reproduced the significant differences betwee n both sides for cool, warm and heat pain thresholds. However, the correlat ion between the results obtained in the first and second examinations was p oor. Neurophysiological recordings revealed pathological results in 46% for nerv e conduction studies, 24% for somatosensory evoked potentials and 39% for s ympathetic skin response. For all methods applied, there was no statistical ly significant difference in the incidence of pathological results between patients with generalized and patients with spatially restricted sensory ab normalities. Psychological examination using the structured clinical interv iew on DSM-IV (SKID) demonstrated a high frequency of affective, and anxiet y disorders, however, without significant differences between both groups. We conclude that hemisensory impairment in patients with CRPS Type I is pro bably related to functional disturbances in processing of noxious events in the thalamus and may be a clinical correlate of subcortical brain plastici ty in chronic pain. Copyright (C) 2001 International Association for the St udy of Pain. Published by Elsevier Science B.V. All rights reserved.