MYOCLONIC EPILEPSY IN INFANCY (MEI)

	Mandatory	Alerts	Exclusionary
Seizures	Myoclonic seizures	Afebrile generalised tonic-clonic or clonic seizure at epilepsy onset	Absence seizures Atonic seizures Epileptic spasms Focal impaired awareness seizure Focal clonic (hemiclonic) seizure Myoclonic-absence seizure Tonic seizure
EEG	Normal background	Lack of generalised spike-wave in sleep Photoparoxysmal response at low flash frequency (suggests CLN2)	Myoclonic event captured on EEG without ictal EEG pattern Hypsarrhythmia Generalized slow (<2.5Hz) spike-wave
Age at onset			Myoclonic seizures begin ≤4 months or ≥ 3 years
Development at onset		Moderate or greater impairment Speech impairment by onset of epilepsy
Neurological exam		Abnormal, clinically significant	Dysmorphism Other congenital anomaly (suggests chromosomal cause)
Imaging			Structural cause for the epilepsy or significant abnormality
Other tests			Low CSF glucose or pathogenic variant in SLC2A1
Course of illness			Neurocognitive regression
Are MRI or ictal EEG required for diagnosis? A normal MRI is required for diagnosis An ictal EEG is not required for diagnosis but is strongly recommended if interictal sleep EEG does not show generalised spike-wave, to confirm that the myoclonus is epileptic.
Syndrome without laboratory confirmation: in resource-limited regions, this syndrome cannot be diagnosed without EEG showing generalized spike-wave discharges in sleep

NOTE Alert criteria are absent in the vast majority of patients with the syndrome, but rarely can be seen. Their presence should result in caution in diagnosing the syndrome and consideration of other conditions