New insights in phenomenology and treatment of epilepsy in CDKL5 encephalopathy

Eight patients, seven girls and one boy, had CDKL5 gene mutation, duplication, or deletion. Epileptic spasms started at a mean age of 3.5 months (range = 4 weeks–8 months). In five cases, tonic seizures preceded spasms at a median age of 6 weeks. In one patient who started at 8 months, spasms had a component of terror on awakening, reminding sleep terror. In two patients, electroencephalogram polygraphy of a so-called tonic seizure revealed that the tonic phase was followed by an overlooked clonic phase and then by a cluster of spasms during which each spasm was preceded by a brief clonic jerk revealed by electromyography. This sequence is rather particular and can be an early diagnostic clue. Progressive transition from this seizure type to epileptic spasms in clusters seems to result from increasing expression of the CDKL5 gene, as the child grows older. Five patients responded to the combination of vigabatrin and zonisamide. •peculiar ictal sequence is identifiable on (video-EEG/polygraphy) and could be an early diagnostic clue•clusters of spasms are very early sign of encephalopathy appearing initially in the structure of this peculiar type of seizures.•the combination of vigabatrin and zonisamide is promising and should be given as soon as CDKL5 mutation is suspected