Inspection time in patients with intracranial tumours before and after neurosurgery

Abstract

Introduction: Many patients with brain tumours experience dysfunction in several cognitive domains. Given the limited survival times of the majority of patients with brain tumours, maintenance or improvement of quality of life is as important as increasing survival time. Impaired cognition has a negative impact on quality of life and as such, cognitive function is becoming an increasingly important endpoint in clinical trials in neuro-oncology. However, measuring cognition in patients with brain tumours is problematic for a number of reasons. Most intracranial tumours are initially treated with surgery and studies of neurosurgical morbidity often evaluate physical as opposed to cognitive domains, yet the latter can have a greater negative impact on the patient’s quality of life. This thesis therefore details cognition in brain tumour patients at the time of presentation (pre-operatively) and examines the effects of surgical intervention on cognitive function. Of particular interest is the potential utility of inspection time, a computer-based measure of the brain’s information processing efficiency, as a measure of brain slowing as a result of the tumour and as an indicator of response to surgical intervention. Methods: The study is based on a cohort of 118 newly-presenting patients with a supratentorial brain tumour who were to have surgery (biopsy or resection). Each patient was administered a comprehensive battery of cognitive tests prior to surgery (baseline). The battery comprised inspection time testing, other standardised cognitive measures and assessment of mood, quality of life and functional status. Post-operatively, each patient repeated the inspection time test in addition to a selected number of the other tests administered at baseline. For comparison, a group of patients admitted for elective spinal surgery (n = 85) were also tested pre- and post-operatively. A group of healthy volunteers provided a second control group by being tested twice (n = 80). Results: The brain tumour cohort were significantly impaired by comparison with both control groups at baseline (pre-operatively) on the majority of the cognitive measures, including inspection time. Baseline inspection time scores were significantly related to some scores on the EORTC Quality of Life Questionnaire in the brain tumour group, but not in the spinal surgery group. There was no significant difference between the brain tumour and spinal surgery groups in term of the levels of pre-operative anxiety and depression. The brain tumour cohort showed significantly greater relative deterioration on inspection time following surgery by comparison with both control groups. The brain tumour cohort also deteriorated significantly on several other measures postoperatively by comparison with the healthy control group. Detailed analyses were carried out to determine the differential effects of tumour type, location, and type of surgery (biopsy or resection) on inspection time and other functions in the brain tumour group. Conclusions: Tumour-related cognitive impairment appears to be common in a heterogeneous group of brain tumour patients with a variety of different tumours located throughout the brain. Surgical intervention has a negative impact on function in brain tumour patients, although this deterioration may be transient. General slowing of visual information processing appears to be common to brain tumour patients and the inspection time task provides a feasible and useful method of assessment in brain tumour patients. The task is sensitive to tumour-related brain slowing and can provide a reliable assessment of response to surgery. Given the task’s advantages over more commonly-used cognitive measures, it could be usefully incorporated into cognitive tests batteries in neuro-oncology.