Clinicopathological associations in temporal lobe epilepsy patients utilising the current ILAE focal cortical...

This study utilised the revised 2011 ILAE classification of focal cortical dysplasia (FCD) (Blümcke et al., 2011) to examine pathology in a cohort of children and adults who underwent temporal lobe epilepsy (TLE) surgery, and to describe the electroclinical and imaging features associated with these pathologies.

The sample population were children (n=26) and adults (n=47) who underwent TLE surgery between 2002 and 2011 at our institutions. Neuropathology and MRI studies were re-reviewed by experts blinded to the original diagnosis. EEG and clinical data including current seizure outcome were determined by patient file review and/or patient contact. Pre-operative data, post-operative outcome and pathological diagnoses were compared.

The commonest pathology in the adult cohort was isolated hippocampal sclerosis (HS) (n=24, 51.1%) and in the paediatric cohort, isolated tumour (n=10, 38.5%). Overall, HS with associated FCD (FCD IIIA) was the third most common pathology (n=12, 16.4%). Temporal grey matter signal changes on MRI were associated with FCD IIIA (p=0.035). FCD IIIA had the poorest post-surgical seizure outcome compared to all other pathologies (p=0.026). A history of bilateral convulsive seizures was more common in adults (n=40, p<0.0005), and was associated with failure to achieve postoperative seizure freedom (p=0.045). Postoperatively, paediatric TLE had higher rates of seizure freedom (p=0.005) and more children had ceased medication (p<0.0005).

FCD IIIA is a comparatively common pathological subtype in TLE, with a poor post-surgical outcome. Pre-operative recognition of FCD IIIA may be feasible through grey matter signal change on MRI. Paediatric patients had a higher rate of seizure freedom than adults. Pre-operative bilateral convulsive seizures were associated with poor outcome after surgery.