Supplementary sensorimotor area seizures in children and adolescents.

Rationale: Some types of seizures in children may be difficult to recognize; the diagnosis of seizures arising near the mesial posterior frontal supplementary sensorimotor area (SSMA) may be especially challenging. Such seizures have been well described in adults, but few pediatric cases have been reported even though onset is typically in childhood.

Methods: We studied 11 children and adolescents with SSMA seizures diagnosed by prolonged video electroencephalography (EEG).

Results: Mean age at onset was 5.8 years, and diagnosis by video EEG was made at a mean age of 12 years. Children had at least borderline intelligence and few abnormal findings on neurologic examination. Seizures were typically brief, frequent, and predominantly nocturnal, with bilateral tonic posturing, gross proximal limb movements, and preserved consciousness. Magnetic resonance imaging showed normal findings or a superior or mesial posterior frontal tumor or cortical dysplasia. Routine EEG findings were usually normal, but prolonged EEG showed epileptiform discharges over the vertex. Seizure onset in the region of the SSMA was confirmed by subdural EEG in six patients who were studied for epilepsy surgery. Five patients had seizure-free outcome or worthwhile improvement after operation. Two nonoperated patients are seizure-free on antiepileptic medication, and three are undergoing surgical evaluation.

Conclusions: Diagnosis of SSMA seizures in children may be challenging because of unusual symptoms (bilateral tonic limb involvement with preserved consciousness) and frequently normal routine EEG findings. Video EEG may be necessary for diagnosis, and magnetic resonance imaging may reveal a focal lesion. Increased recognition of this seizure type in pediatric patients should lead to earlier diagnosis for optimal medical or surgical treatment.