Abstracts

Rationale: Cyclin-dependent kinase-like 5 (CDKL5) gene mutation causes early-onset epileptic encephalopathy.  Some studies have described various clinical and EEG features early in life but there is limited description of the EEG background.  We described the EEG findings in children with CDKL5 deficiency disorder (CDD) during the first year of life. Methods: We reviewed EEG data of 7 children with CDD who had EEG evaluations at Cleveland Clinic between birth and 12 months and described the EEG findings before age 6 months and after. Results: Seven of 29 children with CDD had EEG evaluations during infancy at the Cleveland Clinic. Epilepsy began at age 0.5 month to 8 months (mean age 2.68 months). All patients had seizures recorded during the EEGs. Two patients had initial EEG recorded before age 6 months.  Interictal EEG showed normal posterior background rhythm (PRD) 4-5 Hz when awake and symmetric sleep spindles. Interictal epileptiform discharges (IEDs) were sporadic and multifocal located bilaterally in the right and left temporal parietal regions but also centrally located in one patient. Both patients had infantile spasms, one had myoclonic seizures at the end of the spasms and another had occasional tonic seizures at the onset of the spasms. In 5 of 7 children, initial EEG was done after age 6 months. Of which 3 had classical hypsarrhythmia and infantile spasms. Two patients had a 5-6Hz PDR, symmetric sleep spindles and high voltage delta in the posterior head regions during sleep. Sporadic IEDs were seen in both patients with a predominance in the temporo-parietal occipital regions right and/or left temporal IED. One patient had two focal seizure types arising from the right temporo-parietal region (1) with right eye tonic deviation -> autonomic seizure -> spasm and (2) hypomotor seizure -> dyskinesic seizure -> spasms. The other patient had intermittent generalized slowing and asymmetric tonic seizures -> spasms. Conclusions: Infants with CDD had two main EEG patterns:  (1) epileptic spasms with persistence of a normal awake and sleep background and sporadic IED and (2) epileptic spasms with classic hypsarrhythmia. Older infants had focal delta slowing and generalized slowing that interrupted the normal awake and sleep background. All patients had epileptic spasms with or without other seizure types. Funding: None