Cognitive function of patients with nasopharyngeal carcinoma with and without temporal lobe radionecrosis

Background: Radiotherapy is the primary treatment for nasopharyngeal carcinoma, and temporal lobe necrosis is observed in about 7% of patients after radiotherapy. Although some studies reported that these patients demonstrated cognitive impairment after radiotherapy, it is still unclear if the cognitive deficits are related to the radiation exposure or the radiation-induced necrosis. Objective: To compare the cognitive function of patients with and without temporal lobe necrosis after radiotherapy for nasopharyngeal carcinoma. Methods: A comprehensive neuropsychological battery was administered to 53 patients with nasopharyngeal carcinoma who had completed their radiotherapy at least 1 year previously. As evidenced by magnetic resonance imaging, 31 patients developed necrosis after treatment. Thirty-one age- and education-matched individuals were recruited as normal control subjects. Results: Whereas the performance of patients without temporal lobe necrosis was similar to that of normal control subjects, patients with temporal lobe necrosis demonstrated significant impairment on tests of verbal (P<.001) and visual memory (range, P<.001 to P=.03), language (range, P<.001 to P=.01), motor ability (P=.02), planning (P=.02), cognitive ability (P=.007), and abstract thinking (range, P=.009 to P=.04). However, the performance of patients with necrosis on tests of general intelligence (range, P=.08 to P=.15), attention (range, P=.06 to P=.55), and visual abilities (range, P=.06 to P=.47) was not significantly different from that of normal control subjects and patients without necrosis. Conclusions: Radiotherapy for nasopharyngeal carcinoma seemed to have adverse but insignificant effects on the cognitive functions of the patients. However, for patients who developed temporal lobe necrosis after radiotherapy, memory, language, motor ability, and executive functions were significantly impaired, although their general intelligence remained relatively intact.