Abstracts

Clinical and experimental evidence suggest that hyperthermia decreases seizure threshold and experimental data demonstrate that cooling of the cortex changes its electrical behavior and may stop seizures. Cooling of the human brain has typically been performed under sedation or general anesthesia with or without the brain exposed. In this setting, application of cold saline stops after-discharges induced by electrical stimulation and intra-operative focal cooling of the cortex stops spontaneous interictal epileptiform discharges. Hence, adequate cooling of the cortex may have therapeutic potential for epilepsy, but a feasible and safe approach is necessary. Non-invasive whole-head cooling without sedation is an appealing choice, but its feasibility and safety have not been established.
Ten normal volunteers (5 females; 21-47 years old) underwent two cooling sessions (30 and 60 minutes) three days apart. The subjects were comfortably seated in a reclining chair and covered with blankets to keep the body warm during cooling. Cooling was performed using a head-neck cooling system (CoolSystems Inc.) consisting of a head/neck liner and conditioning unit. Intestinal temperature, as an indicator of central core temperature, was measured using a capsular probe (HQT Inc.), and external temperature was measured from multiple sites on the head (scalp, ears, face and mouth) and elsewhere (forearm, abdomen and leg). Pulse and O[sub]2 [/sub]saturation were monitored continuously.
Thirty minutes of cooling produced a mean scalp temperature reduction of 12.4[deg]C and a mean ear temperature reduction of 1.09[deg]C. At the end of cooling, the mean core temperature was decreased by 0.06[deg]C. At the end of 60 minutes of cooling, scalp temperature fell an average of 12.2[deg]C, and ear temperature 1.67[deg]C. The mean core temperature was decreased by 0.12[deg]C. The difference between the beginning and end of cooling was statistically significant for scalp temperature (p[lt] 0.0001) and tympanic temperature (right p[lt]0.0001, left p[lt]0.0003), but not for core temperature (p=0.2166). During both cooling sessions, temperature from the arm, abdomen, and leg remained unchanged, as did pulse and O[sub]2[/sub] saturation. There were no changes in subjects[rsquo] physical examination after cooling, and the subjects reported no complaints that necessitated interruption of cooling.
Whole-head cooling in normal volunteers for 60 minutes (using CoolSystems[apos] head-neck cooling system) proved feasible and safe, suggesting that it can easily be applied to the patients with medically refractory epilepsy who are not surgical candidates. Further study in patients is necessary to optimize the procedure for attaining a possible therapeutic effect.
[Supported by: The NINDS protocol # 02-N-0025.]