Mesial temporal lobe seizures may activate thermoregulatory mechanisms in humans: An infrared study of facial temperature

Facial temperature T_f, an important link in cerebral thermoregulation and an ignored index of autonomic activity, was studied in three patients with mesial temporal epilepsy. Sets of infrared images were obtained automatically during seizures and also hourly, round-the-clock. For each patient, scan sets were sorted into: (1) ictal; (2) interictal with negligible motion; and (3) interictal with motion. Comparisons of mean, variance, and trend in each scan set among these groups showed considerable variability. However, significant trends in T_f occurred (P < 0.05) in two-thirds of seizures in one patient, three-fourths in another, and two-ninths in the third, consisting of steady decreases in T_f beginning at peak seizure intensity R_max and continuing into the postictus. Maximal ictal T_f was greater than interictal T_f (P < 0.05), but it negatively correlated with R_max in two subjects. The ictal changes in T_f, which may have a homeostatic role, suggest activation of thermoregulatory mechanisms during mesial temporal seizures.