John Libbey Eurotext

Koolen-de Vries syndrome associated with continuous spike-wave in sleep Volume 24, issue 5, October 2022

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Authors
1 Research Institute of the McGill University Medical Centre, Montreal, Quebec, Canada
2 Department of Neurology, Texas Children’s Hospital, Houston, Texas, USA
3 Department of Pediatric Neurology, Baylor University, Houston, Texas, USA
4 Department of Neurology, The Children’s Hospital at Westmead, Sydney, NSW, Australia
5 Child Neurology and Psychiatry, Salesi Pediatric Hospital, United Hospitals of Ancona, Ancona, Italy
6 Department of Neurology and Neurosurgery, Montreal Children’s Hospital, McGill University Health Centre, Montreal, Quebec, Canada
7 Division of Neurology, Department of Pediatrics, Montreal Children’s Hospital, McGill University Health Centre, Montreal, Quebec, Canada
Correspondence:
Kenneth Myers
Montreal Children’s Hospital, McGill University Health Centre Glen Site, 1001 Boulevard Décarie, Montreal, PQ, H4A 3J1, Canada

Koolen-de Vries syndrome (KdVS) is a genetic condition caused by 17q21.31 microdeletions or pathogenic variants in KANSL1. Affected patients most commonly exhibit some or all of the following: neonatal hypotonia, developmental impairment, facial dysmorphic features, and congenital malformations. Epilepsy occurs in approximately half, often with phenotypes on the epilepsy-aphasia spectrum. We describe six children with KdVS found to have continuous spike-wave in sleep (CSWS) on EEG, four of whom were diagnosed with epileptic encephalopathy with CSWS and two with Landau-Kleffner syndrome. When compared with other children with CSWS on EEG, patients with KdVS may present at slightly later ages and with a longer interval between seizure diagnosis and identification of CSWS. There is no clear best treatment for children with CSWS, but two patients in our cohort were trialed on a variation of the ketogenic diet, and both reported clinical improvement. In one of the patients, the response was dramatic, and CSWS recurred when weaning of the ketogenic diet was attempted. Based on our findings, an EEG capturing a prolonged period of sleep should be arranged in any child with KdVS presenting with developmental regression or plateau, particularly if they have a preceding history of seizures.