Uncommon epileptic syndromes in children

Josefina de la Jara, Carla Vásquez-Hernández, Elías Ramírez-Rojo and Juan Moya-Vilches.  Uncommon epileptic syndromes in children: a review. Seizure: European Journal of Epilepsy, Copyright © 2021 

Highlights

• Lesser-known epileptic syndromes in children represent a diagnostic challenge.

• Refractory seizures and developmental deficits can be part of the clinical picture.

• Diagnosis of these syndromes is essential for timely workup and intervention.

• Genetic workup is useful for prognosis and can guide treatment in particular cases.

Abstract

Epileptic syndromes are well-defined conditions comprising particular clinical features [seizure types, age of onset, response to treatment] and characteristic electroencephalographic changes, while their etiology and subsequent prognosis may vary. The recognition of these syndromes is fundamental for pediatric neurology practice, representing an essential learning topic in this field. Nevertheless, many epileptic syndromes are still quite unfamiliar to students, residents and even neurologists, because of their low incidence and their minimal representation in the literature. This narrative review discusses the concept of epileptic syndromes and revisits seven lesser-known or uncommon syndromes in order to summarize their core clinical features, which can become important clues for daily neurological practice, namely epilepsy of infancy with migrating focal seizures, myoclonic epilepsy of infancy, self-limited infantile epilepsy, myoclonic encephalopathy in nonprogressive disorders, Jeavons syndrome, and epilepsy with myoclonic absences. 

From the manuscript:

Conclusions and final thoughts

For decades, the categorization of epileptic syndromes has been a difficult task. The most constant feature present in all classification systems is differentiation by age at onset, which may be helpful to bear in mind when seeking the correct diagnosis in paediatric patients with suspected epilepsy (even though a high percentage of cases will not meet the criteria for a well-defined syndrome). 

Most of the ‘uncommon’ syndromes described in the present review have an onset during infancy; while West and Dravet syndromes have been extensively investigated and represent ‘must-learn’ topics in academic fields, the remaining syndromes are either clinically rare or are rarely mentioned in relevant literature. On the other hand, while most epileptic syndromes presenting in childhood are well known by general paediatric neurologists, EMA [epilepsy with myoclonic absences] and JS [Jeavons syndrome] (both presenting during infancy) merit a directed approach, as publications related to EMA are scarce, and JS has yet to be formally recognised as a syndrome. 

There are many compelling reasons to discuss these types of underdog syndromes. Myoclonic status epilepticus in nonprogressive encephalopathies, EMA, and EIFMS [epilepsy of infancy with migrating focal seizures] are true developmental and epileptic encephalopathies, in which early diagnosis and opportune treatment are essential for improving outcomes, even in patients with previous DDs. JS does not constitute an encephalopathy itself, but refractoriness and cognitive impairment are common features, prompting the need for an adequate therapeutic plan that considers non-pharmacological tools (such as blue lenses). Finally, many of these syndromes seem to have a genetic aetiology to some extent; therefore, a comprehensive workup should consider epilepsy gene panels or other studies guided by clinical suspicion. A positive finding may help to clarify prognosis, determine the relevance of genetic counselling, and guide treatment choices in some cases. 

The aforementioned reasons are the basis for the purpose of this review: to compile a summary of these lesser-known syndromes in a single document that might be of benefit to medical students, future neurologists, and scholars. Discussion regarding the categorization of these ‘uncommon’ syndromes as legitimate syndromes is still needed; however, that type of debate goes beyond the scope of this review, as it has even proven difficult to accomplish, even for panels of experts. 

While some specific aspects of each syndrome may not have been covered in detail, we hope that the present manuscript comprises a general depiction of these ‘uncommon’ syndromes, providing a starting point for further exploration.