Journal of Neurology, Neurosurgery, and Psychiatry 1987;50:1216-1220 Thermal sensitivity is not changed by acute pain or afferent stimulation

SUMMARY The effect of conditioning stimulation on thermal sensitivity and clinical pain was stud-ied in 40 patients and six healthy subjects. Thresholds regarding cold, warm and heat pain percep-tion did not differ significantly between the painful and non-painful skin areas in patients or between patients and healthy subjects before stimulation. The patients received either 100Hz TENS, 2 Hz TENS, 100 Hz vibration, or placebo. No significant changes in thermal sensitivity were observed during and after conditioning stimulation in any of the test groups, although 24/40 (60%) of the patients reported reduction of their clinical pain intensity. The results indicate that (a) thermal sensitivity is not influenced by the presence of clinical pain, (b) the effects of stimulation on thermal sensitivity (thresholds) and clinical pain are not closely related, (c) central inhibitory effects of TENS and vibration are crucial for their pain relieving capacity. Several studies have been performed to elucidate the pain reducing effect of transcutaneous electrical nerve stimulation (TENS) in experimentally induced pain in healthy volunteers as well as in pain patients. Few studies have actually compared the effect of afferen