Objective:

To compare the use of CASE and Modified Rankin score (mRS) scores for description of functional impairment and correlate with treatment responsiveness. 

Background:

Diagnosis of AE is challenging due to a heterogenous clinical spectrum and approach to diagnosis and treatment of seronegative AE is an area of need.

Design/Methods:

Cases of seropositive and seronegative autoimmune encephalitis, fulfilling Graus et al. (2016) diagnostic criteria, were identified within a 12-month period from two academic medical centers. Retrospective chart review for extraction of pre-defined clinical data was performed. CASE and mRS scores calculated by independent investigators (GM, AA) to permit comparison of inter-rater agreement.

Results:

20 cases of AE identified; 6 (30%) seropositive and 14 (70%) seronegative. Mean age 63 years (SD 14.9); 55% Female. 7 cases met criteria for definite limbic AE , 6 for probable seronegative AE, 7 for  possible seronegative AE. Most common clinical manifestations were seizures in probable AE (n=5, 45.5%; p=0.04), psychiatric changes in definite limbic AE (n=5, 55.6%; p=0.02). At nadir of initial hospitalization, median CASE scores were 7 (IQR 2), 6.5 (IQR 7) ,12 (IQR=11), median mRS scores were 3 (IQR 1), 3.5 (IQR 2), 4 (IQR 2) for definite limbic, probable and possible AE. 17 patients (85%) received first-line treatment (IV corticosteroids, IVIg) within first two weeks of hospitalization [median 3 days (IQR 9)]. At initial outpatient follow-up median CASE scores were 3.5 (IQR 1), 6 (IQR 5), 2 (IQR 2), and median mRS scores were 3 (IQR 2), 3 (IQR 3), 1 (IQR2). At first outpatient follow up 85.7% (n=12) demonstrated improvement in CASE scores as compared to 50% (n=7) in mRS scores. 

Conclusions:

Longitudinal assessment of CASE scores from nadir of initial presentation may provide a better estimation of functional impairment related to AE, and is incompletely captured by mRS scores for individuals with seropositive and seronegative AE.