Objectives:In a population based study of tuberous sclerosis (TSC), we sought firstly to identify the number of patients who have presented with symptomatic giant cell astrocytomas (GCAs) and secondly, within a subset of this population, to identify the number who would be diagnosed with GCAs on predetermined radiological criteria.
Methods: Individuals with TSC in Wessex (a geographical region of England) were identified and their medical history determined. A subset of individuals were invited to have a cranial MRI if they did not have a history of a symptomatic GCA and if they were likely to tolerate having cranial imaging without a general anaesthetic. Scans were performed according to a standard protocol on a single scanner and were reported blindly by a neuroradiologist.
Results: 179 individuals were identified with TSC. Ten of the 179 individuals had a history of treatment for a symptomatic GCA. 41 individuals had a cranial MRI. Thirty-nine had subependymal nodules of whom 24 (59%) had at least one (maximum 11) which enhanced with gadolinium. In seven individuals (17%) the lesion was greater than 1cm and all of these lesions enhanced.
Conclusions: In this study, the proportion of those with TSC who had a history of symptomatic GCA was 5.6%. In the subset without such a history, who underwent imaging, the number diagnosed as having a GCA on radiological criteria was much higher (59% enhanced and 17% were greater than 1cm in size). Screening for giant cell astrocytomas (performing scans on asymptomatic individuals with TSC) would, therefore, identify large numbers of patients who had not presented with symptoms. This finding leads us to recommend that screening should not be undertaken.