Can vaccine-proximate seizures in Dravet syndrome be prevented?

Background: One-third of children with Dravet syndrome present with seizures proximate to vaccination (VPS) . We aimed to establish whether prophylactic benzodiazepine use prevented further seizures following vaccination in children with Dravet syndrome.

Methods: Retrospective multicentre cohort study of children with Dravet syndrome and previous VPS managed at a Specialist Immunisation Clinic between 2013-2017. We obtained clinical history, vaccination management and outcomes from medical records. We compared the management of patients who did/did not experience further VPS within 14 days of vaccination.

Findings: 18 children with Dravet syndrome who had a previous VPS were identified. In 11/18 (58%) children, the VPS was their first seizure. 16/18 children had further vaccination encounter(s) (46 encounters, median 3 encounters/child). There were 12 recurrent VPS in 11/16 (69%) children, with one child having two further VPS; all 12 were afebrile seizures and 7 (58%) were afebrile status epilepticus. VPS recurrence did not differ by age at revaccination (range: 6-62 months) or revaccination setting (outpatient, day stay or inpatient). Prophylactic benzodiazepine (clobazam/clonazepam) was effective with use in 26/46 (57%) of vaccination encounters and it was associated with lower VPS recurrence (odds ratio OR 0.033 (95%CI 0.004-0.291),P <0.01).

Interpretation: Of children with Dravet syndrome who have an initial VPS, 2/3 will have recurrent VPS, most frequently comprising life-threatening episodes of afebrile status epilepticus. Prophylactic post-vaccination use of benzodiazepine lowered the likelihood of VPS recurrence 30 fold. Benzodiazepines in at-risk post-vaccination period should be routinely implemented into vaccination management in children with confirmed or suspected Dravet syndrome.