Deep Brain Stimulation in Hemimegalencephaly with Medically Intractable Epilepsy: A Case Report
Delini Sivakumar1, Nada Ahmed1, Andrea Hakimi1
1Neurology, Prisma Health Upstate
Objective:
To highlight a unique case of medically intractable epilepsy secondary to hemimegalencephaly responsive to deep brain stimulation (DBS).
Background:
Hemimegalencephaly is a rare congenital disorder with overgrowth of a partial or entire cerebral hemisphere. This is seen in approximately 0.2% of childhood epilepsy and often leads to refractory seizures. In medically intractable cases, a hemispherectomy is considered to remove the epileptogenic focus.
Results:
A 22-year-old right handed male presented with medically intractable focal epilepsy secondary to right hemimegalencephaly. He developed convulsive seizures with gustatory auras at 9 years old. He had a normal birth history, but delayed cognitive impairment. Initial MRI brain was read as normal, however his pediatric neurologist noted right hemimegalencephaly and he was trialed on anti-seizure medications (ASM). This included levetiracetam, oxcarbazepine, valproic acid, clobazam, and lacosamide with initial response; however, efficacy waned over time. He later had focal seizures with impaired awareness and generalized tonic-clonic seizures. He was admitted to the epilepsy monitoring unit and a focal epilepsy with right fronto-central focus was observed. Repeat MRI brain and PET scan in 2018 revealed a right hemimegalencephaly that on further review traced back to imaging from 2009. Genetic testing was unrevealing. Seizures remained medically intractable and a vagus nerve stimulation (VNS) device was implanted with failed seizure control. He subsequently underwent DBS with bilateral lead placements in the anterior nucleus of the thalamus (ANT). In combination with ASMs, he reported a 60-70% seizure reduction.
Conclusions:
Hemimegalencephaly can occur in isolation or in association with syndromes such as tuberous sclerosis, Klippel-Trenaunay, or neurofibromatosis. While there is no cure, the goal is to reduce seizures with ASMs or hemispherectomy in refractive pediatric cases. Given the absence of motor deficits, hemispherectomy was not considered. This is a novel case of DBS being utilized in the management of hemimegalencephaly.