Abstracts

Tuberous Sclerosis Complex (TSC) is an autosomal dominant condition in which the most significant neurological features of the disease are directly attributable to lesions of the cerebral cortex (tubers), which are known to distort both the internal and external cortical surface. The geometry of the cortical surface has a direct influence on the degree to which the surface is inter-connected, how fast a signal can travel across the surface, and how much of the grey matter can be affected by that signal. It is postulated that the area of the cortex is directly related to its intrinsic properties. Stereological estimates of the surface area may be determined from [italic]in-vivo[/italic] volumetric MRI data. The aim of this study was to measure cortical surface geometry from MRI data in a cohort of TSC brains and to correlate these measures with other quantitative radiological data (tuber count and volume) and clinical features (seizure control and cognitive status). Using a 3 Tesla MR scanner, 3D MPRAGE contiguous fine cut sequences were acquired for five TSC patients and five normal controls. A semi-automated, computer based stereological software programme (MEASURE) was used to estimate cortical surface area. When corrected for cortical volume, three of the five TSC patients had increased surface areas above the 95% confidence limit as determined by the normal control group. The mean and standard deviation of surface areas measured for the control group was 1595cm² (32.14), and for the TSC patient group was 1907.12cm² (305.92). It was found that increasing surface areas correlated with increasing tuber load, poorer seizure outcome and cognitive decline. The findings in this study of increased surface area to volume ratio in the more clinically affected brains of TSC suggests a process of arrested cortical development. It is envisaged that surface area measurements may act as a reliable surrogate of external cortical deformation caused by the pathological lesions of TSC. Further studies will be required to confirm the initial findings of this study. (Supported by Tuberous Sclerosis Alliance)