P2.110: Case Report: Management of Hemiconvulsion Hemiplegic Epilepsy Syndrome Utilizing Ketamine and Ketogenic Diet

Introduction: Status epilepticus (SE) is defined as the bodies inability to terminate seizure activity at time points, T1 and T2, by which neuronal injury, death, or alterations of neuronal networks has begun. First line medications are benzodiazepams, with second line being antiseizure drugs (ASD). Approximately 10-40% of cases of SE will progress to refractory SE (RSE) or supra-refractory SE (SRSE). A rare, and uncommon etiology of prolonged RSE or SRSE is a syndrome called Hemiconvulsion-Hemiplegia-Epilepsy (HHE).

Case Description: A 17-month-old female with a medical history of Phelan-McDermid 22q13 Deletion Syndrome and 20p13 Duplication Syndrome presented with new onset seizures, described as clonic activity of her right upper and lower extremity. She was notable to be febrile at 102.7°F, and hypoglycemia at 48 upon arrival. She received levetiracetam and fosphenytoin loads but was admitted to the PICU intubated due to hypoxemic respiratory failure and RSE. Her workup was negative for infection or autoimmune etiology. She was placed on a cEEG and required midazolam and ketamine drips to obtain both clinical and sub-clinical seizure cessation. Though shortly after weaning her drips, sub-clinical seizures reemerged. An MRI brain was obtained and notable for cytotoxic edema involving the entire left cerebral hemisphere (image). The combination of her MRI findings and clinical picture of hemiconvulsive SE, was consistent with HHE syndrome (HHES). Despite adding on various ASDs, her course continued to be complicated by both clinical and sub-clinical seizures. It was decided to restart a ketamine drip, and midazolam was exchanged to a pentobarbital drip. She was also started on a ketogenic diet around this time. With a combination of these measures, she reached burst suppression on cEEG. She was successfully weaned off all drips and her additional ASDs were optimized along with optimizing her ketogenic dietary formulation.

Discussion: HHES is based off clinical and radiographical findings that are not better explained by additional etiologies. HHES is defined as hours of prolonged, unilateral and clonic convulsions that are often unrecognized at first. HHES is divided into two groups, idiopathic and symptomatic. The etiology of HHES is unknown, but there is an assumed relationship between repetitive seizures, brain edema, brain atrophy, and chronic epilepsy. There is some thought that NMDA-type glutamate receptor antagonists, like ketamine, may help prevent further neurological injury. In fact, in one case series, 51% of the patients obtained SE cessation with the addition of ketamine. The ketogenic diet is well known and established for seizure control, though there are few reports of its utility in HHE.

Conclusion: In this unique case, through the utilization and optimization of ketamine and ketogenic diet, we were able to obtain seizure cessation, and advocate for earlier utilization of these measures in RSE/SRSE and HHES.