Authors :
Presenting Author: Jacob Tiller, BS (Underway) – SLC6A1 Connect
Kevin McEntee, BSCS – Cornell Weill Medicine
Zachary Grinspan, MD, MS – Cornell Weill Medicine
Ashwin Mahesh, BA – Weill Cornell Medical College
Rationale:
Children with SLC6A1 neurodevelopmental disorder often have a distinctive EEG feature that may correlate with brief eye fluttering or inattention: paroxysmal bursts of rhythmic delta, sometimes with a notch or a spike-wave morphology. Reports from an ongoing clinical trial (NCT04937062) suggest these bursts decrease after treatment with glycerol phenylbutyrate. Quantifying these bursts would provide clinical researchers a biomarker of treatment response.Methods:
We collected EEGs from children with SLC6A1 variants enrolled in NCT04937062, before and after treatment with glycerol phenylbutyrate. We processed 18 channel pairs of electrodes in the “double banana” montage. We selected 412 seconds of EEG from a single patient, pre-treatment. An expert identified the abnormal bursts. Three spectral features were calculated at one second intervals: delta power from 2.5-4 Hz, autocorrelation with lags corresponding to 2.5 - 4 Hz, and spectral entropy from 0 - 30 Hz.
First, we used the following thresholds (selected ad hoc): delta power > 105,000 μV², autocorrelation > .410, and entropy < = 3.16. A one second segment of EEG was labeled abnormal when all three thresholds were met simultaneously in three or more channels. We applied these to the expert-reviewed EEG then found sensitivity and PPV with 1.5 sec windows on each side of events.