Emergence of lingual dystonia and strabismus in early-onset SCN8A self-limiting familial infantile epilepsy

Caterina Ancora, Juan Dario Ortigoza-Escobar, Margherita Aluffi Valletti, Francesca Furia, Jens Erik Klint Nielsen, Rikke S. Møller, Elena Gardella*

*Corresponding author for this work

Research output: Contribution to journalComment/debateResearchpeer-review


Pathogenic variants in SCN8A are associated with a broad phenotypic spectrum, including Self-Limiting Familial Infantile Epilepsy (SeLFIE), characterized by infancy-onset age-related seizures with normal development and cognition. Movement disorders, particularly paroxysmal kinesigenic dyskinesia typically arising after puberty, may represent another core symptom. We present the case of a 1-year-old girl with a familial disposition to self-limiting focal seizures from the maternal side and early-onset orofacial movement disorders associated with SCN8A-SeLFIE. Brain MRI was normal. Genetic testing revealed a maternally inherited SCN8A variant [c.4447G > A; p.(Glu1483Lys)]. After the introduction of valproic acid, she promptly achieved seizure control as well as complete remission of strabismus and a significant decrease in episodes of tongue deviation. Family history, genetic findings, and epilepsy phenotype are consistent with SCN8A-SeLFIE. Movement disorders are an important part of the SCN8A phenotypic spectrum, and this case highlights the novel early-onset orofacial movement disorders associated with this condition. The episodes of tongue deviation and protrusion suggest focal oromandibular (lingual) dystonia. Additionally, while infantile strabismus or esophoria is a common finding in healthy individuals, our case raises the possibility of an ictal origin of the strabismus. This study underscores the importance of recognizing and addressing movement disorders in SCN8A-SeLFIE patients, particularly the rare early-onset orofacial manifestations. It adds to the growing body of knowledge regarding the diverse clinical presentations of SCN8A-associated disorders and suggests potential avenues for clinical management and further research.

Original languageEnglish
JournalEpileptic Disorders
Issue number2
Pages (from-to)219-224
Publication statusPublished - Apr 2024


  • intermittent esotropia
  • lingual dyskinesia
  • movement disorders
  • paroxysmal strabismus
  • SCN8A
  • self-limiting familial infantile epilepsy

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