Powell, HWR; (2007) Investigating brain structure and function in temporal lobe epilepsy. Doctoral thesis , UCL (University College London).

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Abstract

Background Anterior temporal lobe resection (ATLR) is increasingly used in the treatment of patients with refractory temporal lobe epilepsy (TLE). Complications of surgery include a decline in language and memory abilities, and visual field defects. The principal aim of this thesis was to use magnetic resonance imaging (MRI) techniques to improve the planning of effective surgical treatment for patients with TLE by using functional MRI to localise areas in the brain involved in language and memory function, and MR-tractography to investigate the structural connections of these areas and those involved in visual function. Methods Ten control subjects underwent tractography to study the connections of the medial temporal lobe (MTL). Two patients underwent tractography pre- and post-operatively to look at the trajectory of the optic radiation. For the memory studies we scanned 10 control subjects and 15 presurgical patients with refractory TLE. For the combined language fMRI and tractography study, 10 control subjects and 14 patients with hippocampal sclerosis underwent both fMRI and tractography. All scans were performed on a 1.5T GE Signa Horizon scanner. Findings The connections of the MTL were identified in a group of control subjects. The optic radiation was mapped preoperatively and shown to be disrupted following ATLR in a patient with a visual field defect. A material-specific lateralisation of memory encoding activation was demonstrated in control subjects with reduced ipsilateral activation in patients with TLE. Increased ipsilateral hippocampal activation correlated with better preoperative memory function and with greater postoperative memory decline. fMRI and tractography were combined to study the structural connections of functional language areas in controls and TLE patients, demonstrating reduced left sided and increased right hemisphere connections in left TLE patients, findings that reflected the pattern of functional activation.

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