Abstracts

Rationale: Surgery represents an effective treatment for drug-resistant focal epilepsy in selected patients. In paediatric series, focal extra-temporal epilepsies represent about 20% of all epilepsy surgery candidates, whereas multilobar resections and hemispherectomy about 16% and 13% respectively. Although the extra-temporal epilepsies are a heterogeneous population, previous studies have reported an overall 54-66% seizure-free rate; however, results on seizure and cognitive outcomes among paediatric epilepsy centres, are still limited Selection criteria and procedures, along with measures of postsurgical outcome, might noticeably differ among centres and determining factors that could predict surgical outcome in this specific population, is key for improving the surgical treatment of epilepsy in children. Our aim in this study was to characterise the paediatric population who underwent surgical procedures for extra-temporal epilepsy in a single national tertiary-care centre and to identify possible determinants for favourable post-operative clinical and cognitive outcomes. Methods: A retrospective cohort study has been carried out, evaluating all children with extra-temporal focal epilepsy who underwent surgical resection at Great Ormond Street Hospital between 1997 and 2008. Exclusion criteria were a multilobar resection or functional hemispherectomy. Data on epilepsy history and pre-surgical neurophysiology, neuroimaging and neuropsychology workup have been collected and related to post-surgical seizure and cognitive outcomes. Results: Preliminary results are currently available for fifty-one out of about one hundred eligible candidates. Twenty-five (49%) were males, with a mean age at surgery of 6.8±1.2 years underwent focal extratemporal resection. Frontal resection was performed in 72.5%, parietal in 17.5% and occipital in 10%. Surgical procedures were performed on the left hemisphere in 47.4%. Intracranial monitoring was performed in twenty-four (47.1%) cases. Focal cortical dysplasia was the predominant aetiology, found in 51.2%, Tuberous Sclerosis in 12.2% and tumours in 9.8%. An early follow-up assessment was achieved at 13.6±2.0 months after surgery and 23/51 (45.1%) subjects were seizure-free (Engel class Ia), whereas 10/51 (19.6%) did not show any valuable post-surgical improvement (Engel class IV). Of sixteen children (31.4%) who had a longer follow-up (67.4±6.5 months), outcome in eleven had been maintained. Conclusions: Our preliminary data are concordant with previous reports in the literature suggesting surgical resection improves the epilepsy burden in a large percentage of drug-resistant children with a focal extra-temporal focus. Further analysis will help in determining if factors within the pre-surgical work-up may optimise the prediction of seizure-free outcome in this population.