Deficits of thermal sensation in patients with unilateral cerebral lesions.

Using a quantitative psychophysical test, the thresholds for detection of heat and cold were determined at both wrists in 16 hemiparetic patients with unilateral cerebral lesions and 1 patient with a unilateral frontal lesion but no hemiparesis. These data were compared with normal values for the absolute thermal thresholds and the symmetry of thermal thresholds in 25 age-matched control subjects. Significant elevation of thermal thresholds was found in all patients with clinically detectable deficits of nociceptive or thermal sensations. Thresholds were also elevated in 3 of 10 hemiparetic patients with no clinical evidence of impairment of nociceptive or thermal sensations. Deficits were found in patients with superficial cortical lesions as well as in those with extensive lesions involving deep structures, including thalamus. In patients with superficial lesions, the elevation of thermal threshold was slight (less than 1 degree C) and there was often little or no sensory deficit to clinical testing. In patients with very high thermal thresholds (greater than 6 degrees C), the lesions involved deep structures and there were clinically obvious deficits of thermal and nociceptive sensations.