P95 Surgical approach and morbidity of paediatric fourth ventricular tumours: analysis of a large institutional series

Objectives To characterise the surgical management of paediatric 4th ventricular tumours and their attendant neurological complications. Design Retrospective cohort study. Subjects Children referred to our institution with tumours of the 4th ventricle between 2008–2017 inclusive. Methods Clinical notes and imaging review. Two-tailed Fisher’s test used to determine differences between proportions. Results 95 patients were seen (53 males, mean 5.81y). The commonest presenting symptom was vomiting (63.3%). The commonest tumour type was medulloblastoma (54 cases)>pilocytic astrocytoma (20)>anaplastic ependymoma (12)>ATRT(4)>Teratoma (2), with 3 miscellaneous lesions. 55 pts presented with hydrocephalus. 27.4% of patients had an EVD (30.8% of these prior to tumour surgery), and 23.3% a VP shunt sited. The surgical approach was either via telovelar (50%) or transvermian (50%) routes; 29.5% were done in the sitting position. In the first 5y of the series, 7/31 cases used the telovelar approach, whilst in the latter 5y, this proportion was 30/51 (p=0.0015). New post-operative deficit was evident in 68% of cases (42.4% gait abnormality, 23.9% cranial neuropathy, 16.3% diplopia). There was no significant difference in the rates of cerebellar mutism syndrome between telovelar or transvermian approaches (p=0.62). There was 1 mortality within 30d of operation. Conclusions Resection of paediatric 4th ventricular tumours is increasingly performed by the telovelar route, and carries significant morbidity, although surgical mortality remains low.