Neurosurgical practice and its influence on postoperative paediatric cerebellar mutism syndrome-the Alder Hey experience

Abstract

Background: Postoperative cerebellar mutism syndrome (pCMS) is a recognised complication following posterior fossa tumour (PFT) resection in children, marked by delayed-onset mutism or reduced speech with neurocognitive and motor deficits. Injury to proximal efferent cerebellar pathways is implicated. This study evaluates the impact of modified surgical techniques and experience on pCMS incidence over 17 years at a single tertiary centre.

Methods: We retrospectively reviewed 176 PFT resections in 167 patients (age 0-18) from 2007 to 2023. Surgical modifications from 2016 aimed to reduce pCMS risk and included reduced CUSA use, avoidance of transvermian approaches, limited cerebellar retraction, and preoperative risk stratification via the Rotterdam pCMS score. pCMS was classified as grade 1 (mutism) or grade 2 (reduced speech).

Results: Overall pCMS incidence was 17.6% (31/176). Rates declined from 23.2% pre-2016 to 12.6% post-2016 (p = 0.10). Midline tumours had higher pCMS rates (24%) than hemispheric (10%, p = 0.01). Among midline tumours, pCMS dropped from 40% to 17% post-modification (p = 0.02). Medulloblastomas had the highest pCMS rate (31.7%), followed by ependymomas (25.8%) and pilocytic astrocytomas (11.5%) (p = 0.02). High Rotterdam risk scores correlated with higher pCMS rates (p = 5 × 10⁻⁷), but incidence in high-risk patients fell from 65% to 29% after 2016 (p = 0.03). High-volume surgeons had lower pCMS rates (15% vs. 24%), with a notable reduction post-2016 (10% vs. 23%, p = 0.08).

Conclusion: Our findings highlight that optimising surgical technique and experience, alongside tailored preoperative planning and intraoperative strategies, may reduce pCMS rates in paediatric PFT resections, particularly in high-risk groups, and supports the need for prospective multicentre studies to validate modifiable surgical risk factors.

Keywords: Cerebellar mutism syndrome (CMS); Paediatric; Posterior fossa syndrome (PFS); Posterior fossa tumour (PFT).