Abstracts

Rationale: Selective amygdalohippocampectomy (SAH) is a recognised surgical treatment in adults, offering effective seizure control (seizure freedom in 70%) with good neuropsychological outcome. There are few studies in children and available data are conflicting. Comparisons are complicated by mixed pathology and differing surgical approaches and selection criteria. Small series of SAH in children with hippocampal sclerosis (HS) have shown rates of Engel I/II outcome between 56-83%. However, concerns have been raised about cognitive decline, particularly after left-sided procedures. We assessed seizure control and cognitive function after transsylvian (TS) SAH in children with suspected HS and congruent pre-operative investigations. Methods: In a retrospective case series of children undergoing TSSAH between March 2001 and October 2008, inclusion criteria were: epilepsy resistant to medical control, age <18 yrs, HS, congruent MR imaging and EEG, and a minimum of 1 year follow up. Extratemporal resections were excluded. We assessed pre- and post-surgery the number of anti-epileptic drugs (AEDs) and neuropsychological functioning. Seizure outcome was examined according to Engel at 1 and 2 years and most recent follow-up by an independent assessor. Results: After onset of partial seizures intractable to medical therapy at median 3.58 (range 1.5-11) years, 4 patients received right and 4 left sided TSSAH (all right-handed; 5 girls (1 left TSSAH)) at a median age of 14.2 (range 5.3-17.7) years; follow-up was 3.3 (1.0-6.8) years. All patients had a favourable seizure outcome. At most recent follow-up, all were classified as Engel I, subclassified as four Ia (50%; completely seizure free since surgery), three Ib (37.5%; auras only since surgery) and one Ic (12.5%; some seizures post surgery but seizure free >2yrs). This was improved in comparison to earlier assessment of outcome at 1 and 2 years, when all patients were Engel I or II. No patients were classified as Engel III or IV at any point during follow-up. Processing speed improved post-operatively (p<0.05). Full scale IQ assessment showed both improvement and decline. There were no significant changes from baseline to follow-up in general memory, learning or delayed recognition, although learning and delayed recognition were reduced in 3 of 4 fully assessed patients. Visual and verbal memory assessment similarly showed no significant changes, although one patient showed a consistent decline. There was no decline in verbal memory following left-sided resections. One patient with right-sided resection showed a paradoxical improvement in visual memory but modest decline in verbal memory. At 2 years, all patients had significantly reduced numbers of AEDs (Z=-1.86, p <0.05 one tailed). Conclusions: In carefully selected paediatric patients, TSSAH may offer similar or improved seizure outcome comparable to adult studies. Neuropsychological results showed no consistent, substantial decline post-surgery and processing speed improved. Larger series with longer follow-up are needed to further evaluate the potential benefits of TSSAH in children.