Nonconvulsive status epilepticus in epileptic encephalopathies in childhood

Rates of Status Epilepticus and Sudden Unexplained Death in Epilepsy in People With Genetic Developmental and Epileptic Encephalopathies

BACKGROUND AND OBJECTIVES

The genetic developmental and epileptic encephalopathies (DEEs) comprise a large group of severe epilepsy syndromes, with a wide phenotypic spectrum. Currently, the rates of convulsive status epilepticus (CSE), nonconvulsive status epilepticus (NCSE), and sudden unexplained death in epilepsy (SUDEP) in these diseases are not well understood. We aimed to describe the proportions of patients with frequently observed genetic DEEs who developed CSE, NCSE, mortality, and SUDEP. Understanding the risks of these serious presentations in each genetic DEE will enable earlier diagnosis and appropriate management.

METHODS

In this retrospective analysis of patients with a genetic DEE, we estimated the proportions with CSE, NCSE, and SUDEP and the overall and SUDEP-specific mortality rates for each genetic diagnosis. We included patients with a pathogenic variant in the genes SCN1A, SCN2A, SCN8A, SYNGAP1, NEXMIF, CHD2, PCDH19, STXBP1, GRIN2A, KCNT1, and KCNQ2 and with Angelman syndrome (AS).

RESULTS

The cohort comprised 510 individuals with a genetic DEE, in whom we observed CSE in 47% and NCSE in 19%. The highest proportion of CSE occurred in patients with SCN1A-associated DEEs, including 181/203 (89%; 95% CI 84-93) patients with Dravet syndrome and 8/15 (53%; 95% CI 27-79) non-Dravet SCN1A-DEEs. CSE was also notable in patients with pathogenic variants in KCNT1 (6/10; 60%; 95% CI 26-88) and SCN2A (8/15; 53%; 95% CI 27-79). NCSE was common in patients with non-Dravet SCN1A-DEEs (8/15; 53%; 95% CI 27-79) and was notable in patients with CHD2-DEEs (6/14; 43%; 95% CI 18-71) and AS (6/19; 32%; 95% CI 13-57). There were 42/510 (8%) deaths among the cohort, producing a mortality rate of 6.1 per 1,000 person-years (95% CI 4.4-8.3). Cases of SUDEP accounted for 19/42 (48%) deaths. Four genes were associated with SUDEP: SCN1A, SCN2A, SCN8A, and STXBP1. The estimated SUDEP rate was 2.8 per 1,000 person-years (95% CI 1.6-4.3).

DISCUSSION

We showed that proportions of patients with CSE, NCSE, and SUDEP differ for commonly encountered genetic DEEs. The estimates for each genetic DEE studied will inform early diagnosis and management of status epilepticus and SUDEP and inform disease-specific counseling for patients and families in this high-risk group of conditions.

Brain pathology in focal status epilepticus: evidence from experimental models

Status Epilepticus (SE) is often a neurological emergency characterized by abnormally sustained, longer than habitual seizures. The new ILAE classification reports that SE "…can have long-term consequences including neuronal death, neuronal injury…depending on the type and duration of seizures". While it is accepted that generalized convulsive SE exerts detrimental effects on the brain, it is not clear if other forms of SE, such as focal non-convulsive SE, leads to brain pathology and contributes to long-term deficits in patients. With the available clinical and experimental data, it is hard to discriminate the specific action of the underlying SE etiologies from that exerted by epileptiform activity. This information is highly relevant in the clinic for better treatment stratification, which may include both medical and surgical intervention for seizure control. Here we review experimental studies of focal SE, with an emphasis on focal non-convulsive SE. We present a repertoire of brain pathologies observed in the most commonly used animal models and attempt to establish a link between experimental findings and human condition(s). The extensive literature on focal SE animal models suggest that the current approaches have significant limitations in terms of translatability of the findings to the clinic. We highlight the need for a more stringent description of SE features and brain pathology in experimental studies in animal models, to improve the accuracy in predicting clinical translation.

Nonconvulsive status epilepticus manifesting as rapidly progressive dementia and infarction in the splenium of the corpus callosum: A case report

RATIONALE

Nonconvulsive status epilepticus (NCSE) is a heterogeneous disease with multiple subtypes. NCSE poses great diagnostic and therapeutic challenges due to the lack of typical symptoms. Here, we report a case of NCSE manifesting as rapidly progressive dementia (RPD) and infarction in the splenium of the corpus callosum. Additionally, the relevant literature was reviewed.

PATIENT CONCERNS

A 63-year-old man presented with RPD. Electroencephalogram (EEG) revealed NCSE, and brain magnetic resonance imaging (MRI) showed an isolated infarction in the splenium of the corpus callosum. Mini-mental state examination showed moderate cognitive impairment (14/30 points).

DIAGNOSIS

A diagnosis of NCSE with RPD and infarction in the splenium of the corpus callosum was made.

INTERVENTIONS

The patient was treated with intravenous diazepam (10 mg), oral levetiracetam (1.0g twice daily), oral sodium valproate (0.2g twice daily), and intramuscular phenobarbital sodium (0.2g once daily).

OUTCOMES

After the treatment, the symptoms were improved. The patient could answer questions. Repeated EEG showed that the background a rhythm was slightly overdeveloped, and no clinical or electrical seizures were observed. After discharge, the patient was treated with oral levetiracetam (1.0g twice daily) and oral sodium valproate (0.2g twice daily) for 6 months. At the last follow-up, the patient had clear consciousness, sensitive response, and fluent answering ability. Repeated mini-mental state examination showed that his cognitive function was significantly improved (28/30 points); nevertheless, the lesion in the splenium of corpus callosum remained unchanged on MRI.

LESSONS

NCSE manifesting as RPD and infarction in the splenium of the corpus callosum is extremely rare. Epileptic events and focal infarction are usually overlooked in patients with dementia, and the diagnostic value of MRI and EEG should be highlighted.