Increased pain sensitivity in alcohol withdrawal syndrome

Withdrawal from analgesic and addictive substances such as opioids or ethanol is associated with increased sensitivity to sensory stimulation in animal models. Here, we investigated perception of innocuous and noxious thermal or electric stimuli applied to the left hand or sternum in 30 male patients undergoing withdrawal from alcohol, 30 male abstained alcoholics and matched controls. The alcohol withdrawal scale and the Banger score were obtained to estimate the severity of withdrawal. In addition, the Beck depression inventory was used to estimate the influence of depressive symptoms on pain perception. The data presented provide substantial evidence that subjects undergoing alcohol withdrawal show increased heat pain sensitivity. Interestingly, this effect was observed both on the left hand and sternum. Pain thresholds and tolerances of electric stimuli did not differ between groups. However, in a subgroup analysis, a higher sensitivity for electrical pain thresholds and tolerances was observed in those patients that were identified to require pharmacological treatment for withdrawal according to disease severity. Furthermore, the perceived painful thermal and electrical sensation was substantially influenced by the affective state of patients. No differences were found between patients of the abstained group and control subjects for any pain parameter. In conclusion, we demonstrate withdrawal-induced hyperalgesia upon thermal stimulation in patients. Since the influence of affective symptoms on pain perception during withdrawal is remarkable, we assume that peripheral and central mechanisms might account for this finding, which should be assessed in detail in future studies.