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Paroxysmal tonic upgaze in a child with SCN8A‐related encephalopathy ∗
Author(s) -
Solazzi Roberta,
Castellotti Barbara,
Canafoglia Laura,
Messina Giuliana,
Magri Stefania,
Freri Elena,
Ragona Francesca,
Franceschetti Silvana,
Di Francesco Jacopo C.,
Gellera Cinzia,
Granata Tiziana
Publication year - 2021
Publication title -
epileptic disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.673
H-Index - 53
eISSN - 1950-6945
pISSN - 1294-9361
DOI - 10.1684/epd.2021.1305
Subject(s) - epilepsy , medicine , pediatrics , neurology , encephalopathy , phenotype , intellectual disability , electroencephalography , differential diagnosis , neuroscience , psychology , psychiatry , genetics , pathology , gene , biology
Pathogenic variants in the SCN8A gene have been associated with a broad phenotypic spectrum, ranging from benign familial infantile seizures to severe, early‐onset developmental and epileptic encephalopathy. This spectrum also includes an “intermediate phenotype” characterized by different degrees of cognitive disability, mild neurological impairment, and therapeutically manageable epilepsy. We report on a child harbouring a de novo , novel SCN8A deletion, whose clinical picture is consistent with an SCN8A ‐related “intermediate phenotype”. This patient's peculiar feature is the occurrence of paroxysmal tonic upgaze (PTU), a non‐epileptic disorder consisting of sustained conjugate upward deviation of the eyes, with neck flexion, and downbeat saccades. PTU has been described in otherwise healthy children, as well as in a few genetic syndromes, but has never been observed in SCN8A ‐related phenotypes. This report, therefore, adds a new symptom to the spectrum of movement disorders associated with SCN8A ‐related developmental and epileptic encephalopathy. In this short communication, we provide video‐EEG documentation of PTU and seizures, and discuss the challenging differential diagnosis between the two symptoms.