Abstracts

Rationale: The aim of this study was to characterize the clinical phenotypes and associated etiologies of patients (pts) with an electroencephalography (EEG) pattern of spike-wave activation in sleep (SWAS).


Methods: We performed a retrospective electronic medical record review of pts with documented potentiation of epileptiform discharges during sleep between 2021 and 2024 at Children's Nebraska. Pts with a spike-wave index (SWI) of ≥ 50% during non-REM sleep (NREM) were included in this study. The SWI was calculated as the percentage of one-second bins with ≥ one spike over a 10-minute period during NREM sleep on routine or long-term video EEGs.


Results: Out of 42 pts with an EEG report of SWAS, 32 had a SWI of ≥ 50%, and 16 had a SWI ≥ 85%. Neurocognitive assessments documenting behavioral/cognitive changes were available only in 14 out of 32 pts (14/32, 44%). Assessment of these changes was difficult in the remaining 18 pts due to severe baseline intellectual disabilities. Behavioral/cognitive decline associated with SWAS was confirmed in 7 pts (7/32, 22%). Seizure burden varied widely within the group with 24 out of 32 pts (24/32, 75%) experiencing seizures every few months in a year, 3 out of 32 pts (3/32, 9%) experiencing seizures monthly, 1 pt (1/32, 3%) experiencing weekly seizures, and 4 pts (4/32, 13%) experiencing daily seizures. Structural abnormalities were the most common etiology, 16 pts (16/32, 47%), followed by genetic, 2 pts (2/32, 6%). The cause was unknown in 14 pts (14/32, 41%). Structural abnormalities included malformation of cortical development (N= 5), hemorrhage (N=4), stroke (N=3), schizencephaly (N=1), congenital hydrocephalus (N =1), neonatal hypoxic-ischemic encephalopathy (N=1), and secondary global damage by infection (N=1). Pts with a structural etiology (N=16) had an earlier age of seizure onset (1.8 years vs 7.5 years p < 0.001), higher SWI (89% vs 76%, p = 0.013), and were tried on a higher number of antiseizure medications (4.6 vs 2.6, p = 0.007) compared to the rest (N=16). SWAS secondary to structural abnormalities tended to be refractory to medications (18% vs 50%, p= 0.137). The most commonly used medication was clobazam (N=19) followed by valproic acid (N=17). High-dose steroids were used in 9 pts. The success rate of VPA was the highest (29.4%, 5/17) followed by CLB (21.4%, 4/19). Steroids had the lowest success rate (11.1%, 1/8) in our cohort. One pt with SWAS secondary to a neonatal stroke underwent successful resective surgery with improvement in behavioral/cognitive status.

Conclusions: Our cohort of pts with SWAS had a highly variable clinical spectrum and were associated with heterogenous etiologies. Developmental regression was often difficult to recognize and was documented only in 22% of our pts. Given the discrepancies in the timely diagnosis of this syndrome and the inherent heterogeneity in the clinical presentation of these pts, conventional criteria for escalating interventions (medical and surgical) may lead to delays in offering definitive treatment. We recommend aggressive medical therapy in pts with non-lesional SWAS, and early presurgical work-up in patients with SWAS secondary to a structural etiology.


Funding: None