Abstracts

This is a Late-Breaking abstract.

Rationale: There is low interrater reliability of diagnosis of hypsarrhythmia (Hyp), partly due to lack of clearly defined EEG features. Moreover, there are no data whether presence (+Hyp) or absence of Hyp (-Hyp) has any prognostic value related to epileptic spasms (ES). We propose practical and objective criteria for the diagnosis of Hyp. We applied these criteria to evaluate the prognostic value of +Hyp vs -Hyp.

Methods: A total of 42 patients (pts) were diagnosed (dx’d) with ES at Rainbow Babies and Children’s Hospital during 2014-2022. Video-EEG (VEEG) was obtained pre- vigabatrin therapy (VGNT) (used as first-line), and 2 to 8 weeks (w) (median 4) post-VGNT. All pts were scheduled for a follow up (F/U) VEEG at 2 w of VGNT. After applying exclusion criteria, 2 board-certified epileptologists reviewed EEG data of 34 pts. EEG inclusion criteria was presence of awake state and non-REM sleep. Pts with Tuberous sclerosis was excluded. At ES presentation, (+Hyp) or (-Hyp) was dx’d using the proposed criteria (Figure). Seizure (SZ)-freedom with/without ASM was assessed during an average F/U period of 39.2 months (m) (2-104). Categorical data were analyzed using percentage, Chi square, and Fisher’s exacts. IBM SPSS version 26 was used for statistical analysis.

Results: A total of 18 (53%) males and 16 (47%) females were treated with VGN, and with subsequent ACTH (9/34: 26%). ES was dx’d at average age of 9.6 m (2-36) (Table). _x000D_ +Hyp vs. -Hyp: 20/34 (59%) had Hyp, while 14/34 (41%) did not. The primary reason for not meeting Hyp dx was due to amplitude < 300 uV in 13/14 (93%) pts. _x000D_ Etiology: The major cause (75%) of ES with Hyp was genetic with normal brain MRI (8/20) and idiopathic (7/20), while the major cause of ES without Hyp was cortical structural abnormality (13/14: 93%: p< 0.01)._x000D_ ES + other SZ type: 4/14 (29 %) without Hyp had an additional SZ type (simple motor) at ES dx. None of them had ES resolution or SZ-freedom at last follow up. All patients with Hyp had no additional SZ type. _x000D_ ES resolution and SZ freedom: More pts with Hyp had ES resolution than those without Hyp (13/20:65% vs. 4/14:28.6%, p< 0.05 ). Moreover, there was a higher chance of SZ-freedom in pts with Hyp (8/20:40% vs. 1/14:7.1%, p< 0.05). All pts with idiopathic cause (7) had Hyp and attained complete resolution of Hyp and ES after VGNT, and 5/7 (71%) were SZ-free. All 3 pts with Trisomy 21 in the study had Hyp, and attained ES resolution and became SZ-free(p < 0.05). Thus, all pts with idiopathic cause and Trisomy 21 as a cause of ES and Hyp, achieved resolution of Hyp and ES after VGNT.