Benign infantile focal epilepsy with midline spikes and waves during sleep: a new epileptic syndrome or a variant of benign focal epilepsy?

Objective: To analyze the electroclinical features and evolution of seven infants with benign infantile focal epilepsy with midline spikes and waves during sleep (BIMSE).
Material and Methods: Seven patients were examined at our department between February 2003 and February 2009, with onset of seizures between six and 13 months of age (mean, 10.2 months; median, 11 months). Patients with cryptogenic and symptomatic focal epilepsies were excluded. Sex, age, familial history, type of seizures and AED treatment were noted and EEG monitoring, MRI and CT scanning, and developmental and psychomotor evolution were investigated.
Results: Patients included five males and two females. All patients suffered from seizures during wakefulness. Two of the patients (29%) did not have a recurrence. Five (71%) had sporadic seizures (ranging between two and five). One of the seven patients (14%) presented with seizures in clusters. During seizures, staring was observed in six (86%), motion arrest in five (71%), stiffening in five (71%), cyanosis in three (42%), automatisms in one (14%) and lateralizing signs in four (57%). Two patients (29%) had secondary generalisation. The duration of the seizures ranged between 30 seconds and five minutes. No status epilepticus was observed. The interictal EEG recording during sleep showed low-voltage unilateral or bilateral spikes located in the central and vertex regions, followed by slow waves in all patients. Outcome was excellent in all patients.
Conclusion: We believe that BIMSE is a new syndrome rather than an early presentation of benign epilepsy of childhood with centrotemporal spikes, Panayiotopoulos syndrome, or a late presentation of benign focal infantile seizures.