Hemiconvulsion–hemiplegia syndrome in a patient with severe myoclonic epilepsy in infancy

Abstract

Summary We report a 2‐year‐old girl who had repeated febrile or afebrile seizures since infancy. Prolonged left/right hemiconvulsions and myoclonus of the eyelids/extremities with generalization to tonic–clonic seizures, were refractory to antiepileptic agents. At age 1 year and 4 months, she contracted rotavirus infection, and developed status epilepticus with persistent right hemiclonic seizures. Left unilateral brain edema with subsequent emergence of cortical laminar necrosis and white matter lesions, and progressive atrophy of the left cerebral hemisphere were noted during this period. She showed residual right hemiparesis and mild intellectual disability, and had generalized/eyelid myoclonia and hot water epilepsy after a 5‐month seizure‐free period. Analysis for SCN1A, the gene encoding the neuronal voltage‐gated Na+ channel α1 subunit revealed a nonsense mutation, R1892X. These indicate the potential risk in patients with severe myoclonic epilepsy in infancy (SMEI) to develop hemiconvulsion–hemiplegia (HH) syndrome. SCN1A mutations may need to be further explored in patients with HH syndrome without features of SMEI.

Dravet syndrome as epileptic encephalopathy: evidence from long-term course and neuropathology

“…It is of note that even on quantitative analysis, there was no neuropathological evidence of neuronal loss in the post-mortem adult cases with Dravet syndrome, showing that Dravet syndrome per se , and SCN1A mutation (one post-mortem adult case with Dravet syndrome), are not sufficient to cause hippocampal neuronal loss despite decades of drug-resistant seizures and recurrent episodes of status epilepticus. Rarely, significant clinical and imaging changes have been reported in Dravet syndrome following status epilepticus (Sakakibara et al ., 2009; Chipaux et al ., 2010; Tang et al ., 2011). There may be age-dependent vulnerability of the brain to injury induced by seizures (Haut et al ., 2004), but it is difficult to separate out effects of seizures on the brain from the effects of the disease process per se , and the effects of drugs and other factors.…”

Acute Encephalopathy in a Patient with Dravet Syndrome

“…They mentioned 2 children with residual severe neurological defi cits after prolonged status epilepticus triggered by acute febrile illness [7] . Only one case of hemiconvulsion-hemiplegia syndrome has been reported in a child who subsequently developed a characteristic feature of Dravet syndrome [8] . Chipaux et al reported an unusual pattern in 3 patients with Dravet syndrome who had refractory status epilepticus followed by severe cognitive and motor deterioration, and whose neuroimages showed anoxic-ischemic like lesions [1] .…”

Hemiconvulsion-hemiplegia-epilepsy syndrome: clinical course and neuroradiological features in a 20-month-old girl

“…However, repeated febrile and afebrile seizures since infancy have been reported 1. Seizures may be simple partial, partial with secondary generalisation or status epilepticus in nature 4.…”

“…Cerebral hemiatrophy is a consistent finding in all patients by cranial CT and/or MRI 2–6. Furthermore, vasospasms of cerebral vascular smooth muscle has been proposed as the mechanism of seizure by Yamazaki et al 2 Potential risk of HHE with severe myoclonic epilepsy in infancy has been proposed by Sakakibara et al 1…”