Abstract Details

Title Long-term Clinical Outcome of Cryptogenic New-onset Refractory Status Epilepticus (C-NORSE) Patients

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S24 - Epilepsy Clinical Syndromes and Management (3:30 PM-3:42 PM)

Poster/Presentation
Number 001

Background

C-NORSE lacks comprehensive knowledge regarding its longitudinal clinical phenotypes and long-term treatment outcomes. We aimed to investigate the longitudinal clinical profiles for long-term outcomes and prognostic factors in C-NORSE patients.

Objective

To investigate the longitudinal clinical profiles and prognostic factors for cryptogenic New-Onset Refractory Status Epilepticus (NORSE).

Design/Methods

In a prospective cohort study for encephalitis, C-NORSE patients diagnosed based on the ILAE consensus definition between January 1, 2014, to March 31, 2023 were analyzed. The primary study outcomes included longitudinal clinical data during a 2-year follow-up (mRS, CASE score, seizure frequency, and the number of anti-seizure medications) and a 3-month follow-up MRI, featuring serial brain volumetric analyses for two years.

Results

Among 135 NORSE patients, 74 with C-NORSE (median age 32.7 [IQR 23.5-47.3], 36 [48.6%] male) were included. All patients received first-line immunotherapy (steroids or IVIG), with 83.8% (62/74) regaining mental functionality within a median duration of 30 days [IQR 14-56]. One year later, 37.1% (26/70) of individuals achieved favorable outcomes (mRS 0, 1, and 2), increasing to 50% (31/62) after two years. Unfavorable one-year prognosis correlated with hippocampal atrophy plus extra-limbic lesions observed at 3-month MRI (OR 1.295, 95% CI 1.086 to 1.544, P = .006) and prolonged unconsciousness exceeding 60 days (OR 1.426, 95% CI 1.101 to 1.847, P = .010). On longitudinal MRI brain volumetric analysis, significantly different rates of hippocampal atrophy were observed between the good and poor outcome groups (β = -44.2; 95% CI, -69.69 to -16.71; P = .002). Continuous immunotherapy appeared effective up to the 18^th week following NORSE onset, but its efficacy beyond that point remained uncertain.

Conclusions

This study elucidates the prognostic factors in C-NORSE. The presence of hippocampal atrophy and extra-limbic lesions on 3-month follow-up MRI were the poor prognostication factors. Continuous immunotherapy may benefit C-NORSE patients up to the 18^th week from onset.

Authors/Disclosures
Yoonhyuk Jang, MD, PhD PRESENTER	Mr. Jang has nothing to disclose.
Soo Hyun Ahn, MD (Seoul National University Hospital)	Dr. Ahn has nothing to disclose.
Su Yee Mon	No disclosure on file
Ji Hye You, NP (Seoul National University Hospital)	Ms. YOU has nothing to disclose.
Kyung Il Park	No disclosure on file
Han Sang Lee	No disclosure on file
Kon Chu (Seoul National University Hospital)	No disclosure on file
Sang Kun Lee, MD (Seoul national University Hospital)	Prof. Lee has nothing to disclose.
Soon-Tae Lee, MD, PhD (Department of Neurology, Seoul National University Hospital)	Prof. Lee has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Advanced Neural Technologies. Prof. Lee has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche/Genentech. Prof. Lee has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Celltrion. The institution of Prof. Lee has received research support from Roche. The institution of Prof. Lee has received research support from Celltrion. Prof. Lee has received intellectual property interests from a discovery or technology relating to health care.