Reevaluating Electroencephalography Monitoring in Koolen-de Vries Syndrome: A Case of Delayed Focal Impaired Consciousness Seizure Diagnosis

Koolen-de Vries syndrome (KdVS) is a rare multisystem genetic disorder due to deletions in the KANSL1 gene. The most common type of seizure documented in these patients is focal impaired consciousness seizure (FICS). These seizures present with difficult-to-distinguish characteristics, including autonomic symptoms, brief loss of consciousness, and post-ictal confusion. The ambiguity of this presentation can make it difficult to detect clinically. This case presents an eight-year-old male child with KdVS who presented to the clinic with complaints of increased outbursts, spatial disorientation, issues with mood and self-regulation, and episodes of "spacing out" as noted by his teacher. The initial diagnosis was dysautonomia and was conservatively managed. However, due to worsening neurocognitive outcomes, neurological referral and work-up were initiated to further elucidate the etiology of his symptoms. The patient's electroencephalography (EEG) findings showed frequent focal sharp waves consistent with FICS. He was then treated accordingly with diazepam and amantadine, which led to a significant improvement in neurological status. This case highlights the importance of the use of EEG in KdVS patients, as well as the implications of implementing guidelines recommending the low threshold required for use of EEG and full neurological work-up for patients with any alarm symptoms possibly indicative of FICS or other epileptiform activity.