Open resection of hypothalamic hamartomas for intractable epilepsy revisited, using intraoperative MRI

Hypothalamic hamartomas (HHs) are rare non-neoplastic lesions which cause drug-resistant epilepsy with associated behavioural, psychiatric and endocrine issues. With the development of new minimally invasive techniques for the treatment of HH, there is a need to reappraise the effectiveness and safety of each approach. We review the outcomes of HH patients treated surgically, utilizing intraoperative magnetic resonance imaging (IOMRI), by a team of Alder Hey NHS Foundation Trust tumour and epilepsy neurosurgeons since 2011. Patient records of all HH cases operated on since 2011 were reviewed to confirm history of presentation and clinical outcomes. Ten patients have undergone surgery for HH under the dual care of Alder Hey tumour and epilepsy neurosurgeons during this period. Eight cases had a midline transcallosal, interforniceal approach with the remaining 2 having a transcallosal, transforaminal approach. All patients had an IOMRI scan, with 40% needing further tumour resection post-IOMRI. Forty percent had a total resection, 3 patients had near-total resection and 3 patients had subtotal resection (similar to 30% tumour residual on post-operative MRI). No new neurological complications developed post-operatively. Hypothalamic axis derangements were seen in 3 cases, including 1 diabetes insipidus with hypocortisolaemia, 1 hypodipsia and 1 transient hyperphagia. Eighty percent are seizure free; the remaining two patients have had significant improvements in seizure frequency. IOMR was used to tailor the ideal tumour resection volume safely based on anatomy of the lesion, which combined with the open transcallosal, interforniceal route performed by surgeons experienced in the approach resulted in excellent, safe and effective seizure control.