The phenotype of SCN8A developmental and epileptic encephalopathy

Elena Gardella, Carla Marini, Marina Trivisano, Mark P Fitzgerald, Michael Alber, Katherine B Howell, Francesca Darra, Sabrina Siliquini, Bigna K Bölsterli, Silva Masnada, Anna Pichiecchio, Katrine M Johannesen, Birgit Jepsen, Elena Fontana, Gaia Anibaldi, Silvia Russo, Francesca Cogliati, Martino Montomoli, Nicola Specchio, Guido RubboliPierangelo Veggiotti, Sandor Beniczky, Markus Wolff, Ingo Helbig, Federico Vigevano, Ingrid E Scheffer, Renzo Guerrini, Rikke S Møller

Research output: Contribution to journalArticlepeer-review


OBJECTIVE: To delineate the electroclinical features of SCN8A infantile developmental and epileptic encephalopathy (EIEE13, OMIM #614558).

METHODS: Twenty-two patients, aged 19 months to 22 years, underwent electroclinical assessment.

RESULTS: Sixteen of 22 patients had mildly delayed development since birth. Drug-resistant epilepsy started at a median age of 4 months, followed by developmental slowing, pyramidal/extrapyramidal signs (22/22), movement disorders (12/22), cortical blindness (17/22), sialorrhea, and severe gastrointestinal symptoms (15/22), worsening during early childhood and plateauing at age 5 to 9 years. Death occurred in 4 children, following extreme neurologic deterioration, at 22 months to 5.5 years. Nonconvulsive status epilepticus recurred in 14 of 22 patients. The most effective antiepileptic drugs were oxcarbazepine, carbamazepine, phenytoin, and benzodiazepines. EEG showed background deterioration, epileptiform abnormalities with a temporo-occipital predominance, and posterior delta/beta activity correlating with visual impairment. Video-EEG documented focal seizures (FS) (22/22), spasm-like episodes (8/22), cortical myoclonus (8/22), and myoclonic absences (1/22). FS typically clustered and were prolonged (<20 minutes) with (1) cyanosis, hypomotor, and vegetative semiology, sometimes unnoticed, followed by (2) tonic-vibratory and (3) (hemi)-clonic manifestations ± evolution to a bilateral tonic-clonic seizure. FS had posterior-temporal/occipital onset, slowly spreading and sometimes migrating between hemispheres. Brain MRI showed progressive parenchymal atrophy and restriction of the optic radiations.

CONCLUSIONS: SCN8A developmental and epileptic encephalopathy has strikingly consistent electroclinical features, suggesting a global progressive brain dysfunction primarily affecting the temporo-occipital regions. Both uncontrolled epilepsy and developmental compromise contribute to the profound impairment (increasing risk of death) during early childhood, but stabilization occurs in late childhood.

Original languageEnglish
Pages (from-to)e1112-e1124
Issue number12
Publication statusPublished - Sep 18 2018


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