Focal Cerebral Arteriopathy Severity Score Validation and Temporal Dynamics in Korean Pediatric Stroke: Distinguishing Inflammatory Arteriopathy From Unilateral Moyamoya Disease.

BACKGROUND

Focal cerebral arteriopathy-inflammatory type (FCA-i) is a leading cause of pediatric arterial ischemic stroke, but diagnostic challenges persist, particularly in East Asian populations where moyamoya disease (MMD) prevalence is high. The focal cerebral arteriopathy severity score quantifies arteriopathy severity but has not been validated in East Asian cohorts. We aimed to validate the focal cerebral arteriopathy severity score in Korean pediatric patients with FCA-i and compare temporal progression patterns with unilateral MMD.

METHODS

We conducted a retrospective cohort study of children with arterial ischemic stroke presenting to Seoul National University Hospital between January 2002 and December 2024. Patients were classified according to the Childhood Arterial Ischemic Stroke Standardized Classification and Diagnostic Evaluation criteria. The focal cerebral arteriopathy severity score was applied to serial magnetic resonance angiograms at baseline, peak severity, and final follow-up.

RESULTS

Among 216 children with arterial ischemic stroke, 132 patients (61.1%) demonstrated arteriopathy, including 49 with FCA-i (median age, 8.6 [interquartile range (IQR), 6.4-11.3] years; 55% male), 60 with MMD (median age, 5.7 [IQR, 3.1-9.2] years; 43% male), and 13 with arterial dissection (median age, 7.0 [IQR, 3.1-10.4] years; 62% male). In FCA-i patients, the severity score correlated significantly with baseline infarct burden (ρ=0.42; P=0.0069) and exhibited characteristic monophasic evolution with early peak at 2 months followed by gradual recovery reaching lowest values at 11 months. Patients with unilateral MMD demonstrated consistently higher severity scores at all timepoints compared with FCA-i (baseline: 6.0 versus 2.0; final: 8.0 versus 3.0; P<0.001) without radiographic recovery. A baseline severity score ≥8.0 predicted contralateral progression in unilateral MMD with an area under the curve of 0.962 (sensitivity, 0.83; specificity, 0.91).

CONCLUSIONS

The focal cerebral arteriopathy severity score demonstrates validity as a dynamic biomarker for monitoring FCA-i in Korean pediatric patients, exhibiting characteristic monophasic recovery patterns that distinguish it from progressive unilateral MMD.