Abstracts

Rationale: Electrical status epilepticus in slow wave sleep (ESES) is an EEG phenomenon characterized by nearly continuous activation of spike-wave discharges during non-REM sleep. The combination of specific clinical features plus the electrical findings of ESES make the diagnosis of either Landau-Kleffner (LKS) or Continuous Spike and Wave in Slow Wave Sleep (CSWS). Inhibitors of carbonic anhydrase have been found to have an anticonvulsant effect. Sulthiame has been shown to be useful in ESES but is not readily available in the US (Wirrell, Pediatr Neurol 2006; 35(3):204-8; Fejerman, Epilepsia 2012; 53(7):1156-61). Acetazolamide, which is a more easily obtainable carbonic anhydrase inhibitor, is helpful in the treatment of focal epilepsy and in catamenial epilepsy (Lim, Epilepsia 2001; 42(6):746-749). Children with ESES often are trialed on multiple medications and therapies in an attempt to improve Spike-Wave Index (SWI) as a measure of therapeutic efficacy. The reduction in SWI often correlates with clinical improvement in behavior and academic function. The goal of this case series was to examine the effects of acetazolamide on improvement in SWI in children with LKS and CSWS. Methods: This study was a single center retrospective review. Patients were screened using our electronic epilepsy database with the keywords of ESES, LKS, CSWS, and acetazolamide. Patients who had never received acetazolamide, did not have a diagnosis of LKS or CSWS, or who did not have EEGs before and after starting acetazolamide were excluded. Results: Of the 55 charts reviewed, 7 fulfilled inclusion criteria (6 male, 1 female). Of these children, 3 had LKS, 4 CSWS. The average age at initiation of acetazolamide was 9.1 years. Prior to acetazolamide treatment, the average number of therapies failed due to lack of efficacy was 7, which includes diazepam, high dose corticosteroids, IVIG, and ketogenic diet. None of the children were candidates for surgical intervention. All children had focal clinical seizures. At follow-up, six of seven children (86%) were on acetazolamide and average number of AEDs was 2 (range 1-3). The average SWI before initiation of acetazolamide was 70% (range 5%-100%) compared to 39% (range 0-90%) following acetazolamide therapy. Six children (86%) had improved SWI and 1 had worsening. The average change in the SWI in those who had improvement was 39%. Three children (43%) had SWI reduction from 85% or greater to less than 50%. Conclusions: Acetazolamide is a potential effective therapy for children with ESES. A limitation of this study is its retrospective nature. It is important to achieve reduction in SWI in children with ESES early so that further regression is halted and prior skills can be reattained. Acetazolamide is a well tolerated AED that can be used as an adjunct to other therapies. This study adds to the knowledge that acetazolamide can be used effectively and safely in children with ESES for reduction in SWI and improvement in clinical functioning.