Tumour and surgery effects on cognitive functioning in high-grade glioma patients.

BACKGROUND: Many high-grade glioma (HGG) patients have cognitive impairments, which impact daily functioning. Cognitive impairments can be caused by tumour-, treatment-, and patient-related factors. The effect of the tumour and of surgical resection on cognition is, however, not well known. We investigated tumour and surgical effects on cognitive functioning in patients with HGG.
METHODS: At baseline, preceding surgery, 62 patients with HGG underwent neuropsychological testing concerning seven cognitive domains: verbal and working memory, attention, executive functioning, psychomotor function, information processing speed, and visuoconstructive abilities. Thirty-nine patients were included in follow-up testing after surgery, but before subsequent treatment. Tumour size and site, use of anti-epileptic drugs and corticosteroids, and extent of resection were recorded.
RESULTS: Compared to healthy controls, cognitive functioning of patients was significantly impaired in all domains. Prior to surgery 79 % (49 of 62) of patients had cognitive impairment in at least one domain. At median follow-up of 5 weeks after surgery, 59 % (23 of 39) of patients were cognitively impaired in at least one domain. At follow-up, 49 % showed improvement, while 23 % declined. Left hemisphere tumour localization was associated with worse verbal memory (P=0.004), and larger tumours in this hemisphere with poorer executive functioning (P < 0.001). Changes in cognitive performance at follow-up relative to baseline were not related to tumour characteristics or extent of resection.
CONCLUSIONS: Tumour-related cognitive deficits are present in a majority of HGG patients preceding surgery. Surgery does not result in cognitive deterioration in the short term in most patients.