Epileptogenicity in Tuberous Sclerosis Complex: an ultra-high field MRI study of tuber microstructure

Tuberous sclerosis complex (TSC) is a genetically determined, multi-system neurocutaneous disorder characterised by development of hamartomas in multiple organ systems. It is one of the commonest causes of drug-resistant epilepsy in childhood. Major controversies in the field of epilepsy surgery for TSC revolve around uncertainties about the pathological substrates and mechanisms of seizure generation in TSC. Specific questions include: 1) What is the microstructural differences between tuber and peri-tuber tissues? 2) What is the relative contribution of tuber and peri-tuber tissues and the underlying genetic mutation (the so called “mTORopathy”)? 3) How best to localise seizure foci in these TSC patients, leading to more precise and minimally invasive epilepsy surgeries? Limited resolution of current clinical MRI system in part contributes to these ongoing clinical and research controversies.

My talk will first provide a brief overview from our TSC epilepsy surgery experience at the Royal Children’s Hospital, demonstrating compelling clinical and electrophysiological evidences that seizures are arise from the dysmorphic neurons resided in the centre of these tubers. The aim of our current research initiative is to draw concurrent ultra-high field MRI imaging, histopathology and genetic evidences, supporting these clinical findings. The talk will focus on reporting our progress made with ex vivo MRI imaging analysis of surgically resected tubers at 16.4 Tesla. Specifically, fibre-specific modelling based on high angular resolution diffusion-weighted imaging was use to examine tuber cortical cytoarchitecture and intratuberal white matter connectivity. Methodological challenges faced so far will also be discussed.