Early clinico-radiological outcomes following neuroendoscopic cysto-cisternostomy for middle cranial fossa arachnoid cysts: a prospective cohort study with illustrative cases

Background: The dysmorphogenetic arachnoid cysts’ pathomechanism is most favoured, and about 50% occur as middle cranial fossa cysts (MCFAC). Still being rare, management options are yet evolving. We described the clinico-radiological features, management and early outcomes of participants with MCFAC in our service. Methods: This prospective cohort study involved 29 pediatric participants recruited (from electronic health records, using ICD G93.0 D016080 for arachnoid cysts) between 01/01/2023 and 31/06/2023, following informed consent according to the ethical approval. All participants had neuro-imaging confirmed MCFAC. Baseline and follow-up data were retrieved and analyzed using summary (mean, standard deviation) and inferential (ANOVA, t-test) statistics. Results: They were averagely aged 6.2 ± 4.48 years and were mostly males (89.7%). 24.1% were asymptomatic. The commonest symptoms (n = 38) were headaches (23.7%), developmental delays (15.8%), eye complaints (15.8%) and cephalomegaly (7.9%). They were predominantly left-sided (89.7%). Galassi (G) 3 lesions were less (24.1%), with G2 and G1 lesions evenly sharing the rest. The average cyst volume was 58.4 ± 80.83cm3; there were significant differences (F = 4.682; p = 0.018) between the average volumes for G1 (14.4 ± 22.42cm3), G2 (61.7 ± 89.92cm3) and G3 (122.5 ± 94.37cm3) lesions. 44.8% of the participants had rigid-endoscopic cysto-cisternotomy (all between the ICA and oculomotor nerve into the interpeduncular cistern, using ventriculostomy forceps); including all G3, 50% of G2 and no G1 (had serial clinico-radiological observation) lesion. The average pre- (117.42cm3) and post-operative (53.48cm3) cyst volumes showed significant (t = − 2.797, p = 0.021) reductions. Conclusion: Middle cranial fossa arachnoid cysts occur predominantly amongst males, in middle childhood and left-sided. The treatment-related patient series are largely symptomatic, unlike the largely asymptomatic, screening-related series. Higher Galassi grade lesions presented with progressively, significantly larger cyst volumes and higher likelihoods of surgery. The average post-operative cyst volume at follow-up averagely showed almost 60% reduction from the pre-operative. All participants reported clinical remission. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.