We report the use of Acetazolamide (AZM) in a cohort of children with the EEG pattern of electrical status epileptics in slow-wave sleep (ESES).

ESES is an EEG finding characterized by nearly continuous activation of epileptiform discharges during slow-wave sleep. This pattern is seen in epileptic encephalopathies, such as Landau-Kleffner syndrome (LKS) and continuous spike and wave in slow-wave sleep syndrome (CSWS).

Timely treatment is critical to preserve cognition but often challenging with relapse being common. Sulthiame has been used to treat ESES successfully but is unavailable in the United States. However, its mechanism of action is similar to AZM, a carbonic-anhydrase inhibitor with anti-epileptic properties.

We reviewed a total of ten patients with ESES. Eight patients were prescribed  AZM as a second-line medication for ESES, first being a benzodiazepine - diazepam or clobazam. Out of whom, six patients tolerated the medication well, while two discontinued due to side effects namely acidosis and encephalopathy. AZM was effective in four of the six patients (66%). All four patients not only showed cognitive and behavioral improvement, significant improvement on EEG was also noted. Spike-wave index (SWI) improved by > 50% in these patients.

The literature is limited on AZM use for ESES. We note that AZM has shown efficacy (66%) comparable to BZDs (60% in other studies), both clinically and electrographically. Since, it is better tolerated we support the consideration of an AZM trial as a second-line medication in patients who have failed or did not tolerate BZDs, prior to initiation of steroids.