Effect of localized magnetic-induction hyperthermia on the brain. Temperature versus intracranial pressure

Normal brain and brain tumor temperatures were studied for their effects on intracranial pressure (ICP) in 13 patients who received 37 localized thermochemotherapy treatments for recurrent primary or metastatic brain tumors. Two transient neurologic complications occurred in patients with an elevated initial ICP value; thus, the authors concluded that an initial ICP value of 30 cm H2O or greater may contraindicate brain hyperthermia. It appears that noninvasive brain hyperthermia by magnetic-loop induction can cause an initial rise in ICP value, although a protective mechanism(s) that tends to lower ICP occurs over time, and also at a normal brain temperature of approximately 42.0 degrees C. Possible mechanisms of ICP reduction include direct heating of the hypothalamus with a reduction in pCO2 and the development of tachypnea and hyperpnea with a reduction in pCO2. Hyperthermia applied to the brain should be undertaken only with adequate monitoring of ICP; in addition, extreme caution should be taken in patients with an elevated initial ICP value and in those patients in whom adaptation to elevated pressure does not occur.