gms | German Medical Science

Purpose: To prospectively measure and characterize neurocognitive functioning early after the beginning of radiation therapy (RT) depending on radiation dose in patients with and without brain tumors.

Materials and Methods: Eighty-two patients (median age 58.0 years, age range, 26-79 yr) were studied before and immediately after the beginning of RT. Sixty-four patients received RT to the brain (CNS-RT group), and eighteen patients treated with non-CNS-RT served as control group. The neuropsychological evaluation included examination of verbal learning and memory, visuoperception, nonverbal memory, attention, and speed of information processing. Only standardised neuropsychological instruments (all with published normative data) were used. Each session lasted about 1 hour. Premorbid intellectual functioning, emotional distress, KPS, brain lesion location, gender, handedness, and education were controlled.

Results: Patients with CNS-RT demonstrated attention (20-41th percentile) and verbal memory scores (32-48th percentile) below the average at baseline. Scores reflecting verbal memory were significantly different between the CNS-RT and control groups both at baseline (39th percentile vs 58th percentile) and immediately after the beginning of irradiation (29th percentile vs 52th percentile). Even after controlling for baseline level functioning and interference score, patients with brain tumors showed a significant poorer performance on verbal working memory (-5, +13, +16 percentile), verbal learning (-12, -2, +2 percentile), and verbal recognition (-16, -8, 0 percentile), and a smaller practice effect on tonic alertness (improvement in variability of reaction time: +4, +16, +26 percentile) as compared to patients without brain tumors and controls. Radiation dose-related deficits were seen for working memory performance in patients with brain tumors (for details see figure 1 [Fig. 1]).

Conclusion: Our data show no major impairment of cognitive functioning immediately after prophylactic cranial irradiation. Patients with intracranial tumors show a general deterioration with a dose-dependent impairment in supra-span working memory. Therefore, cranial RT in conjunction with peritumoral edema is the most likely cause for cognitive effects immediately after the beginning of RT in humans.