The Role of Focal Epilepsy Features in Defining SCN1A Mutation-positive Dravet Syndrome as Generalized and Focal Epilepsy

Young Jun Ko; Il Han Yoo; Jiwon Lee; Jeehun Lee; Mi-Sun Yum; Tae-Sung Ko; Hunmin Kim; Hee Hwang; Soo Yeon Kim; Jong-Hee Chae; Ji-Eun Choi; Ki Joong Kim; Byung Chan Lim

doi:10.14581/jer.21019

The Role of Focal Epilepsy Features in Defining SCN1A Mutation-positive Dravet Syndrome as Generalized and Focal Epilepsy

J Epilepsy Res. 2021 Dec 31;11(2):127-135. doi: 10.14581/jer.21019. eCollection 2021 Dec.

Authors

Young Jun Ko¹, Il Han Yoo², Jiwon Lee³, Jeehun Lee³, Mi-Sun Yum⁴, Tae-Sung Ko⁴, Hunmin Kim¹, Hee Hwang¹, Soo Yeon Kim⁵, Jong-Hee Chae⁵, Ji-Eun Choi⁶, Ki Joong Kim⁵, Byung Chan Lim⁵

Affiliations

¹ Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Suwon.
² Department of Pediatrics, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon.
³ Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Korea.
⁴ Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
⁵ Department of Pediatrics, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
⁶ Department of Pediatrics, Seoul National University Boramae Hospital, Seoul, Korea.

Abstract

Background and purpose: This study was aimed to describe focal epilepsy features of SCN1A mutation-positive Dravet syndrome patients.

Methods: A total of 82 SCN1A mutation-positive patients were reviewed retrospectively (39 boys and 43 girls). Seizure type and electroencephalography (EEG) findings were investigated according to the stage, disease onset, and steady state (after age 2 years). Long-term video EEG data were used to classify the seizure type.

Results: Focal seizures at onset and the steady state were found in 54.9% (45/82) and 90% (63/70) of patients, respectively. Afebrile focal seizures were an initial seizure in about one fourth of the patients (22/82, 26.8%). Of 48 seizures captured during long-term video EEG monitoring of 30 patients, 19 seizures were classified as focal onset (39.6%). Of the 19 focal seizures, 12 were either focal motor or focal non-motor seizures, and seven were focal onset bilateral tonic-clonic seizure. Focal epileptiform discharges were more frequent than generalized epileptiform discharges at seizure onset and during the clinical course on conventional EEG (3.7% vs. 0%, 52.9% vs. 32.9%, respectively).

Conclusions: Our study provides a comprehensive description of focal epilepsy features of SCN1A mutation-positive Dravet syndrome patients. Recognizing these features as defining the clinical spectrum of Dravet syndrome may lead to earlier genetic diagnosis and tailored management.

Keywords: Dravet syndrome; Generalized epilepsy; Partial epilepsies; SCN1A.