Abstracts

Rationale: Parietal lobe epilepsy is relatively uncommon compared to epilepsy originating from other regions of the brain. There is a lack of literature describing the neuropsychological outcome for children undergoing epilepsy surgery involving the parietal lobe. This study was done to compare pre and post-operative evaluation of children to determine the neuropsychological outcome after parietal lobe epilepsy surgery.Methods: Subjects who had undergone epilepsy surgery involving only the parietal lobe were ascertained from the neurosurgical database (1997-2006) at the Hospital for Sick Children, Toronto, Canada. Subjects were eligible if follow-up data was available at least one year from time of surgery. Analysis included age of onset of epilepsy, age at surgery, EEG and ECOG findings, MRI findings, intra-operative description of location of lesion, pathology of lesion, seizure outcome and neuropsychological evaluation (pre-operative and 1-year post-operative). Results: 4 patients (2 males) met inclusion criteria and were evaluated. All were right handed and were left hemisphere dominant. Age of onset of seizure ranged from 3 to 14 years. Duration of seizures prior to surgery ranged from 6 months to 12 years. 3 subjects had resection of the cortex and pathology showed low grade astrocytoma (n=2) and porencephalic cyst. Among them, 2 remained seizure free and off AED (5.5 years post-op). One subject with a right hemisphere lesion had no neuropsychological deficit. A second subject with a left hemisphere lesion had constructional dyspraxia. Neither patient worsened cognitively after surgery. The third subject with a low grade astrocytoma in the left hemisphere had no improvement in seizure outcome (4 years post-op), had no specific neuropsychological deficit related to parietal lobe and did not worsen after surgery. The fourth subject, who was non-lesional but had extensive epileptogenic zone extending from anterior to posterior regions of the right parietal lobe underwent multiple subpial transections (MST) alone. Seizure control worsened (11 years post-op). Baseline assessment showed borderline performance IQ as a result of constructional dyspraxia; and significant problems with mathematics, with well below age and grade level for testing on mental arithmetic and written computation. However, performance IQ improved to low average after surgery.Conclusions: This case series of 4 pediatric patients who underwent parietal lobe surgery and who had pre and post-operative neuropsychological evaluation demonstrates reasonable long-term seizure control(50%). Although this is a small series, it is important to document that epilepsy surgery was well tolerated in these 4 children. The neuropsychological deficits were consistent with expected parietal lobe function and did not worsen despite one child having no improvement and one having increased seizures post-operatively. Surgery should be considered in children with intractable epilepsy originating from the parietal lobe.