ABSTRACT
A more frequent consequence of brain radiation than radiation necrosis is brain atrophy. If substantial volumes of brain tissue are irradiated, most patients develop MRI-documented evidence of enlarged cerebral sulci and ventriculomegaly. In addition, MR scans may reveal hyperintensity, most marked in cerebral white matter around the ventricles on the T2weighted or fast fluid-attenuated inversion recovers (FLAIR) images; hypodensity is noted on the CT scan. These changes may worsen over time. Both atrophy and white matter abnormalities are usually clear-cut by 1 year following RT, but occasionally they may become obvious within 2 or 3 months after RT is completed. They can persist or progress thereafter. The symptoms are those of a ‘subcortical dementia’79 with memory loss, apathy and slowed cognitive responses. Some patients also have gait abnormalities suggesting gait apraxia, and urinary urgency followed by incontinence. The triad of gait difficulties, incontinence and dementia suggest the syndrome of normal pressure hydrocephalus.80 If the scan also suggests hydrocephalus, i.e. if ventricular dilatation is greater than cortical atrophy, the patient may respond at least temporarily to ventricular shunting. The gait disturbance and incontinence respond best to shunting, whereas the memory impairment usually does not respond. Cerebral atrophy is untreatable.
