Hemiconvulsion-hemiplegia-epilepsy syndrome
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Hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome is an uncommon outcome of prolonged focal status epilepticus in childhood. The prolonged focal motor seizure usually occurs during the course of febrile illness and is followed by hemiplegia ipsilateral to the side of convulsions. This is accompanied by radiologic evidence of acute cytotoxic edema in the affected hemisphere followed by chronic atrophy. Intractable epilepsy may develop at a time remote from the initial presentation. The clinical features of HHE syndrome were first described more than 5 decades ago but its pathophysiology remains poorly understood and the long-term cognitive outcomes are unclear. Early recognition of the syndrome may help provide patients and families with an accurate prognosis regarding the subsequent development of epilepsy.

A 21-month-old boy, former 25-week premature infant, with a history of bilateral grade III/IV intraventricular hemorrhages and hydrocephalus with a ventriculoperitoneal shunt, presented with a likely prolonged period of right-sided jerking. There was no prior history of seizures and his motor and language development was age-appropriate. His parents stated that he was in his usual state of health and acting normally on the day prior to the presentation but he did have a tactile fever. He was last seen normal at midnight when he was checked on by his parents. His mother found him 6 hours later with right face, arm, and leg jerking but he had no impaired consciousness or eye deviation. During transport he had continuous right-sided jerking but was conscious and moving the left side normally.

He was febrile upon arrival to the emergency room and he initially received IV lorazepam and IV valproic acid with no effect. At that point he developed gaze deviation to the right and mental status deterioration. He received IV fosphenytoin, was intubated, and was admitted to the intensive care unit. The right-sided face, arm, and leg jerking continued so a pentobarbital infusion was started. The total duration of the seizure was approximately 10 hours. The patient remained in a pentobarbital coma for 48 hours before it was weaned and levetiracetam was started as a maintenance antiepileptic medication. On hospital day 5 his mental status improved but he was noted to have a right facial droop, right visual field deficit, right hemiparesis, right hyperreflexia, and no spontaneous speech.

Following a resolution of burst suppression the EEG became severely suppressed over the entire left hemisphere. MRI brain was done on hospital day 5 showed restricted diffusion with apparent diffusion coefficient correlation throughout the left hemisphere (figure, A). This progressed over the next month to more pervasive signal abnormalities and volume loss of the entire left hemisphere that was likely consistent with diffuse cortical necrosis (figure, B). Routine electrolytes and CSF analysis at the time of presentation were within normal limits. At the last follow-up (16 months posthospitalization) the patient remained seizure-free on levetiracetam.

HHE syndrome is a rare but serious disorder in the pediatric population. It can greatly impact the quality of life for patients and their families.HHE syndrome should be preventable by continued advances related to the rapid resolution of seizures. The severe impairments associated with HHE syndrome makes it imperative that continued research into the pathophysiology and treatment of the disorder is performed. It would be reasonable to pursue research related to preventing cytotoxic damage acutely with the use of NMDA antagonists or aggressive, early treatment of cerebral edema.

Source: https://www.neurology.org/sites/default/files/aanrf_cns_cases.pdf