Effect of radiation therapy on cerebral cortical thickness in glioma patients: Treatment-induced thinning of the healthy cortex

Abstract

Background With overall survival of brain tumors improving, radiation induced brain injury is becoming an increasing issue. One of the effects of radiation therapy (RT) is thinning of the cerebral cortex, which could be one of the factors contributing to cognitive impairments after treatment. In healthy brain, cortex thickness varies between 1 and 4.5 mm. In this study, we assess the effect of RT on the thickness of the cerebral cortex and relate the changes to the local dose. Methods We identified 28 glioma patients with optimal scan quality. Clinical CTs and MRIs at baseline and 1 year post-RT were collected and coregistered. The scans were processed via an automated image processing pipeline, which enabled measuring changes of the cortical thickness, which were related to local dose. Results Three areas were identified where significant dose-dependent thinning occurred, with thinning rates of 5, 6, and 26 μm/Gy after 1 year, which corresponds to losses of 5.4%, 7.2%, and 21.6% per 30 Gy per year. The first area was largely located in the right inferior parietal, supramarginal, and superior parietal regions, the second in the right posterior cingulate and paracentral regions, and the third almost completely in the right lateral orbital frontal region. Conclusions We have identified three areas susceptible to dose-dependent cortical thinning after radiation therapy. Should future prospective studies conclude that irradiation of these areas lead to cognitive decline, they need to be spared in order to prevent this debilitating consequence of treatment.

Dose-dependent volume loss in subcortical deep grey matter structures after cranial radiotherapy

“…With the advent of high-resolution brain imaging, the interest in morphological changes after RT has increased. The cerebral cortex has been shown to be susceptible to radiation-induced thinning, especially in areas associated with cognitive functioning [3][4][5][6]. Thinning rates are found to be dosedependent, meaning that a higher dose leads to a further diminished cortex.…”

Height, weight, and cardiovascular effects of stimulants on children with brain tumors

“…Impaired attention, slow processing speed, and hypersomnia are known complications of childhood brain tumor and its treatment, particularly radiotherapy 2,4,15,16 . There are multiple ways by which RT influences cognitive function, including gray and white matter volume loss, 2,5,17 and disruption of astroglial connexins 18 . Stimulants are effective in improving attention and processing speed in children with brain tumors, 6 but because of higher disposition to dysautonomia and cardiovascular morbidity, 12,13 it is possible that brain tumor survivors may react differently to stimulant medications.…”

“…Latter may represent involvement of eloquent areas of brain by the tumor or disruption of brain connectivity. Younger age and radiation treatment (RT) are the most important risk factors for cognitive impairment in childhood brain tumor survivors, and may be related to loss of gray and white matter volume 1,2,4,5 …”

“…Pathophysiology of impaired attention in childhood brain tumor survivors is related to white matter volume, 2 and is different from pathophysiology of developmental attention deficit and hyperactivity disorder in children without brain tumors. Gray matter loss and endocrine dysfunction may also contribute to cognitive impairment after radiation to the brain 5,14 …”

“…Gray matter loss and endocrine dysfunction may also contribute to cognitive impairment after radiation to the brain. 5,14 In order to better educate parents and clinicians, our aim was to determine effect of stimulant medications on BP, heart rate, weight, and body mass index (BMI) on childhood brain tumor survivors, and study risk factors for adverse outcomes.…”