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Peri-ictal EEG in infants with PRRT2-related self-limited infantile epilepsy
Nicola Fearn1,2, Emma Macdonald-Laurs1,2,3, Laura Moylan1
1Department of Neurology, The Royal Children's Hospital, Parkville, Victoria, Australia.
Insights
PRRT2 gene variants cause infantile epilepsy with characteristic EEG abnormalities around seizures. These findings aid diagnosis and guide treatment with antiseizure medications.
Area of Science:
- Neuroscience
- Genetics
- Epilepsy Research
Background:
- Pathogenic variants in the *PRRT2* gene are a known cause of self-limited (familial) infantile epilepsy (SeLIE).
- SeLIE typically presents with focal seizures in infancy and is responsive to sodium channel blockers.
- Interictal electroencephalogram (EEG) findings in SeLIE are usually normal, complicating diagnosis.
Purpose of the Study:
- To describe the EEG characteristics in a cohort of infants with *PRRT2*-related SeLIE.
- To identify potential diagnostic markers for *PRRT2*-related SeLIE based on EEG findings.
- To correlate EEG abnormalities with clinical presentation and treatment response.
Main Methods:
- A cohort of infants diagnosed with *PRRT2*-related SeLIE between July 2020 and November 2021 was retrospectively reviewed.
- Clinical data and aetiologic investigation results were extracted from electronic medical records.
- All available EEG recordings were independently reviewed by two epileptologists.
Main Results:
- Ten infants with *PRRT2*-related SeLIE presented with focal seizures at a median age of 5 months.
- Seven of eight infants with EEG performed within 24 hours of a seizure showed focal epileptiform discharges, predominantly in temporo-occipital regions.
- Eight infants initially treated with levetiracetam were switched to oxcarbazepine, which was effective in two infants.
Conclusions:
- Posterior polymorphic focal epileptiform discharges on peri-ictal EEG are a significant finding in *PRRT2*-related SeLIE.
- These EEG abnormalities, especially with a relevant family history, strongly suggest *PRRT2*-related SeLIE.
- Identifying these EEG patterns has important implications for diagnosis and guiding treatment strategies, including the use of oxcarbazepine.
Objective:
Pathogenic PRRT2 variants cause self-limited (familial) infantile epilepsy (SeLIE), which is responsive to sodium channel blocking antiseizure medications. The interictal EEG is typically normal. We describe a cohort of infants with PRRT2-related SeLIE with striking peri-ictal EEG abnormalities.
Methods:
We included all infants diagnosed with PRRT2-related SeLIE during July 2020 to November 2021 at the Royal Children's Hospital, Melbourne. Clinical features and results of aetiologic investigations were collected from electronic medical records. All EEGs were reviewed independently by two epileptologists.
Results:
Ten infants presented with focal seizures at a median age of 5 months (range: 3-6 months). Eight had a family history of epilepsy, paroxysmal kinesigenic dyskinesia (PKD) or hemiplegic migraine. Seven of the eight infants with an EEG performed within 24 h of the most recent seizure had epileptiform discharges. Their EEGs showed focal sharp waves, spikes, polyspikes or fast activity independently over the left and right temporo-occipital regions. Conversely, the two infants with last known seizure greater than 24 h prior to their EEG had no epileptiform discharges. Oxcarbazepine was commenced in two infants and was effective. Eight infants were initially treated with levetiracetam, and all were subsequently switched to oxcarbazepine due to ongoing seizures or side effects.
Significance:
Posterior polymorphic focal epileptiform discharges on a peri-ictal EEG recording are a feature of PRRT2-related SeLIE. This finding, particularly in the presence of a family history of infantile epilepsy, PKD or hemiplegic migraine, suggests a diagnosis of PRRT2-related SeLIE and has important treatment implications.
