Abstracts

Rationale: Neurofibromatosis type 2 (NF2) is an autosomal dominant neurocutaneous disease caused by mutations in the NF2 gene. Adults most commonly present with vestibular schwannomas, and children have a much more varied presentation, which may delay diagnosis. Epilepsy is rarely present and more often symptomatic of meningiomas as opposed to extensive focal cortical dysplasia (FCD)-like lesions seen on imaging. An ictal electroencephalogram (EEG) recording has never been published in NF2 with FCD. Methods: We present the case of a 7-year old female who developed focal seizures and status epilepticus. Ictal EEG was recorded. Serial magnetic resonance imaging (MRI) demonstrated a stable extensive cortical dysplasia centered around the left anterior temporal lobe. She had a previous history of recurrent unilateral oculomotor nerve. We performed whole exome sequencing (WES) in order to obtain an early diagnosis.  Results: The ictal EEG recording localized to the known FCD-like lesion. WES demonstrated a de novo pathogenic mutation causing a premature stop codon in the NF2 gene. Based on this genetic result, further dedicated MRI was performed, which identified a small enhancing left-sided vestibular schwannoma. Conclusions: We present the first case of focal epilepsy in NF2 electrographically localized to an FCD-like lesion. This case demonstrates the utility of early WES in a child with unexplained neurologic features, including FCD. The role of a NF2 mutation in the pathogenesis of FCD is unclear but is supported by other oncogene mutations in the MTOR pathway. Funding: None.