Beyond mass effect: An age-stratified analysis of CSF circulation disturbance in symptomatic intracranial arachnoid cysts.

Introduction: Symptomatic intracranial arachnoid cysts (AC) are commonly regarded as space-occupying lesions in which morbidity is attributed to mass effect and cyst volume. However, age-dependent differences in presentation suggest that disturbed cerebrospinal fluid (CSF) dynamics may substantially influence outcome, particularly in pediatric patients. Research question: We investigated whether markers of impaired CSF circulation are associated with postoperative morbidity and revision burden in symptomatic AC and whether these associations differ between pediatric and adult patients. Material and methods: This retrospective single-center cohort study included 30 patients who underwent surgery for symptomatic intracranial AC over 15 years. Patients were stratified into pediatric (<18 years) and adult groups. Clinical presentation, radiological markers of CSF disturbance (hydrocephalus, aqueductal stenosis, head circumference percentile), surgical course, reoperation rate, and functional outcomes (modified Rankin Scale [mRS], Karnofsky Performance Status [KPS], Lansky Play-Performance Scale (LPPS)) were analyzed. Results: Pediatric patients more frequently exhibited hydrocephalus and aqueductal stenosis. Postoperative hydrocephalus was strongly associated with increased reoperation frequency and worse functional outcome. Surgical burden correlated with worse outcome scales. Cyst volume reduction did not consistently correlate with clinical improvement. Younger age, increased head circumference, and neurenteric histology predicted salvage CSF diversion. Discussion and conclusion: Disturbed CSF dynamics are closely associated with morbidity and revision burden, particularly in pediatric patients. These findings support an age-dependent framework in which pediatric AC may primarily represent CSF circulation disorders, underscoring the importance of early recognition and targeted management.