The Yield of Genetic and Metabolic Testing in Epileptic Spasms

Objectives: To identify the yield of genetic testing and metabolic work up in patients with Epileptic Spasms (ES).

Background: ES are a challenging type of seizures with huge implications. Identifying the etiology in a cost-effective manner helps in management, utilization of personalized therapeutics and prognostication.

Methods: Retrospective review of the medical records of patients with ES who were treated at King Fahad Specialist Hospital, in Saudi Arabia, between 2009 and 2020. Pediatric patients less than 16-year-old presenting with ES and diagnosed by video-EEG were included. Our centers approach in ES workup was to start with clinical assessment and neuroimaging. If the etiology is not identified, we performed a full metabolic workup, and if that came back negative, we started genetic work up guided by clinical context.

Results: We have identified (n=127) patients with ES during the study period. Among our patients, an assigned etiology was reached by clinical and imaging studies in 58 patients, while the remaining (n=69/54%) required further workup. Metabolic testing helped identify the etiology in 8.7% of patients tested, while genetic testing identified the etiology in 66% of patients tested, with varying yield of each test. WES provided the highest testing yield, as 63% of WES tests provided a final diagnosis.

Conclusions: Metabolic workup has a low yield in identifying ES etiology. Genetic workup, on the other hand, had a high yield in identifying the etiology of ES when initial clinical assessment and neuroimaging were non-contributory. WES, in our cohort, was the most cost-effective genetic test.