Neurocognitive effects of therapeutic irradiation for base of skull tumors

Purpose: To determine whether radiation therapy delivered to the paranasal sinuses causes any long-term impairment in neurocognitive function as a res ult of incidental brain irradiation. Methods and Materials: Nineteen patients who received paranasal sinus irrad iation at least 20 months and up to 20 years before assessment were given a battery of neuropsychologic tests of cognitive function. Radiation was del ivered by a three-field (one anteroposterior and two lateral) technique. Th e median radiation dose was 60 Gy (range 50-68 Gy) in fractions of 1.8 to 2 Gy, The volume of irradiated brain was calculated from planning computed t omography slices or simulation films. The results of the neuropsychologic t ests were compared to normative control values. Results: Memory impairment was found in 80% of the patients, and one-third manifested difficulty with visual-motor speed, frontal lobe executive funct ions, and fine motor coordination. Two of the patients had frank brain necr osis with resultant dementia and blindness, and three had evidence of brain atrophy. Three of the fourteen patients without documented cerebral atroph y or necrosis were disabled from their normal activities. Three patients al so developed pituitary dysfunction, Neurocognitive symptoms were related to the total dose of radiation delivered but not to the volume of brain irrad iated, side of radiation boost, or chemotherapy treatment. The pattern of Z est findings was consistent with radiation injury to subcortical white matt er. Conclusions: Radiation therapy for paranasal sinus cancer may cause delayed neurocognitive side effects. Currently, however, the development of severe adverse effects appears to be decreasing because of improvements in the te chniques used to deliver radiation. Lowering the total dose and improving d ose distributions should further decrease the incidence of delayed brain in jury due to radiation. (C) 2000 Elsevier Science Inc.