Subependymal nodules, giant cell astrocytomas and the tuberous sclerosis complex: a population-based study.

OBJECTIVES: (1) In a population-based study of tuberous sclerosis (TSC), to identify the number of patients presenting with symptomatic giant cell astrocytomas (GCAs); (2) within a subset of this population, to identify the number who would be diagnosed with GCAs on predetermined radiological criteria. METHODS: Patients with TSC in Wessex (a geographical region of England) were identified, and their medical history determined. A subset 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 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 people were identified with TSC. Ten of these had a history of treatment for a symptomatic GCA. Forty-one of the remainder had a cranial MRI. Thirty-nine of these had subependymal nodules, of whom 24 (59%) had at least one (maximum 11) that showed enhancement with gadolinium. In seven (17%), the lesion was >1 cm, and all of these lesions showed gadolinium enhancement. CONCLUSIONS: In this study, the proportion of patients 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% gadolinium enhancement and 17% >1 cm in size). Screening for GCAs (performing scans on asymptomatic patients 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.

The relation of infantile spasms, tubers, and intelligence in tuberous sclerosis complex.

BACKGROUND: The aetiology of the learning difficulty in tuberous sclerosis is debated. It may be related to the amount of tubers in the brain or caused by the infantile spasms that occur in early life. AIMS: To examine the relative contributions to final intelligence (IQ) made by both cerebral tubers and infantile spasms. METHODS: As part of an epidemiological study of tuberous sclerosis in the south of England, patients were recruited who were able to undergo magnetic resonance imaging (MRI) without the need for an anaesthetic. Epilepsy history was determined by interview and review of clinical records. IQ was assessed using either Wechsler intelligence scales or Raven's matrices. RESULTS: A total of 41 patients consented to have an MRI scan. IQ scores were normally distributed about a mean of 91. Twenty six patients had a positive history of epilepsy, and 11 had suffered from infantile spasms. There was a significant relation between the number of tubers and IQ. Infantile spasm status partly confounded the relation between tubers and IQ, but did not render the relation statistically insignificant. The relation between infantile spasms and learning difficulty remained strong even when controlling for the number of tubers.