14 Folia Medica 2012; 54(1): 14-21 Copyright © 2012 Medical University Plovdiv doi: 10.2478/v10153-012-0001-9 NEUROCOGNITIVE IMPAIRMENTS IN BRAIN TUMOR PATIENTS Ivo I. Kehayov, Borislav D. Kitov, Christo B. Zhelyazkov, Stefan D. Raykov, Atanas N. Davarski Department of Neurosurgery, Medical University, Plovdiv, Bulgaria ABSTRACT There is an increased scientific interest in cognitive impairments caused by brain tumors during the last decade. It has lead to the introduction and routine clinical usage of neu- ropsychological test batteries in brain tumor patients, thus making them an important clinical measure for the assessment of the efficacy of the different treatment regimens such as surgery, radiotherapy and chemotherapy. The effect of cognitive deficit on patients’ quality of life and survival has been unequivocally proven. These are among the most com- mon neurological symptoms associated with brain tumors. The improvement in cognitive function and delay in neurocognitive decline are acceptable endpoints in clinical trials. Cognition has been demonstrated to be an independent predictor of survival in patients with cerebral neoplasms. Key words: cognitive deficit, brain tumor, glioma, neurotoxicity, surgery INTRODUCTION Cognitive function (from Latin “cognoscere” – to know, to learn) is the process by which sensory input is elaborated, transformed, reduced, stored, recovered, and used. 1 Cognition is considered to bе а complex multifaceted system, composed of several interwoven mental domains: attention/concentration, visuospacial аnd constructional skills, sensory and perceptive function, lаnguаgе, memory, executive funсtiоns, and intellectual functioning. 2,3 Those are regarded to be determined by either localized or distributed substrate in the central nervous system. 4,5 The clinical psychopathological correlates of brain tumors have been thoroughly discussed over the past decades. 6 However, cognition is relatively underestimated in current literature. Therefore, this review aims to cast light on the latest achievements in the diagnosis and prognosis of cognitive dysfunc- tion before and after neurosurgical interventions. ETIOLOGY OF THE COGNITIVE DEFICIT IN BRAIN TUMOR PATIENTS Patients with brain tumors often experience cogni- tive dysfunction associated with the disease and its treatment, including surgery, radiotherapy (RT), and chemotherapy. As more effective therapies have prolonged survival for many patients, cognitive dys- function has been recognized as the most frequent complication among long-term survivors. 7 Visuo- construction, processing speed, and verbal memory measures may be the most important domains to as- sess when evaluating cognitive change in brain tumor clinical trials. 8 Executive functions, which are also commonly affected in the brain tumor population, influence the patient’s safety and abilities of daily living. 9 Cognitive difficulties often have an impact on quality of life and interfere with the patient’s ability to function at premorbid levels. 10,11 Cogni- tive deterioration, which may eventually progress to dementia, worsens patient’s quality of life and well-being. 12,13 Neurocognitive impairments in brain tumor patients are among the most common neurological symptoms which precede the time of diagnosis. Cognitive dysfunction results from the neoplastic process itself, secondarily from shift or compres- sion of intracranial structures, and associated brain edema. 14,15 Although tumor type or volume has not been found to predict cognitive performance, cogni- tive dysfunction is seen more frequently at diagnosis in rapid-growing tumors such as glioblastomas than in slow-growing ones such as low-grade gliomas. 16 Cognitive deficit can result from brain corti- cal lesions but due to the vast cortico-subcortical pathways, it may also occur after white matter injury, or even following damage to the cerebellar structures. 17 REVIEW Correspondence and reprint request to: I. Kehayov, Department of Neurosurgery, Medical University, Sofia E-mail: dr.kehayov@gmail.com; Mob.: +359 899 105 352 15A Vassil Aprilov St., Plovdiv 4002, Bulgaria Received 24 September 2012; Accepted for publication 10 October 2012