Atonic variant of benign childhood epilepsy with centrotemporal spikes (atonic-BECTS): a distinct electro-clinical syndrome
To describe the clinical and electroencephalographic features, treatment strategies and outcome in a series of children with the atonic variant of benign childhood epilepsy with centrotemporal spikes (atonic-BECTS). Out of the 148 patients with BECTS reviewed from January 2005 to June 2010 in our Institute, there were seven (5%) with atonic-BECTS. All underwent video EEG, high-resolution magnetic resonance imaging (MRI), neuropsychological evaluation and language assessment. Their progress was followed. In addition to sodium valproate, three were treated with steroids, followed by intravenous immunoglobulin (IVIG) when the seizures relapsed while tapering or after stopping the steroids. All of the children had earlier onset (mean=2.4 years), increased frequency and increased duration of focal seizures compared to typical BECTS. Head drop and truncal sway due to axial or axiorhizomelic atonia occurring several times per day or week was the key manifestation. The atonic seizures worsened with carbamazepine in three, clonazepam in two and clobazam in one. When the atypical seizures commenced, some children developed one or more of the following problems: hyperactivity, attention deficit, clumsy gait, and mild cognitive or language dysfunction. Three children became seizure free, one on steroids and the other two on IVIG. BECTS in children with an early age of onset and frequent and prolonged seizures is more likely to evolve into atonic-BECTS. Carbamazepine and some benzodiazepines may worsen these seizures. Three children became seizure free with immunomodulatory therapy, one on steroids and the other two on IVIG, and had complete resolution of the transient motor and cognitive impairment. Atonic-BECTS needs to be differentiated from Lennox-Gastaut syndrome since it is potentially treatable and children recover with no sequel. Although all the children in this series continued to be on treatment with sodium valproate it is currently undetermined whether they would have required to do so if followed up for an extended period of time.