Clinicopathological Features and Early Surgical Outcome of Posterior Cranial Fossa Tumours in Children at Kenyatta National Hospital

Abstract

Study Background: Posterior cranial fossa (PCF) tumours account for 54 – 70% of brain tumours in children. The pattern of presentation is variable and is dependent on the location of tumour within the PCF, however, a triad of early morning vomiting, headache and gait imbalance is common. Radiologically, these tumours have a variable pattern of appearance that is useful for surgical planning, predicting diagnosis and outcome. Surgery is key in the management of these tumours, either for CSF diversion or tumour removal. Broad Objective: To describe clinicopathologic features and early surgical outcome of children managed surgically for PCF tumours in KNH Methodology: Nine months observational prospective cohort study at Kenyatta National Hospital. Children aged 12 years and below managed surgically at KNH for PCF tumour. Informed consent was obtained from the next of kin. At admission, data collected included patient demographics, presenting signs and symptoms, radiological details, surgical intervention, and post-operative management. The follow up period was in hospital up to 1 month with an end point of death or discharge. The main outcome measures included, length of ICU stay, length of hospital stay and complication rate. Other outcomes included the patterns of clinical and radiologic presentation, the various histologic types, and change in GCS and KPS. Data management and results: Data was collected using predesigned data collection forms, then entered Stata version 16. Results: Twenty-eight children with PCF tumours were analysed. The mean age was 6.49 years and the male to female ratio was 1:1.33. All the children presented with cerebellar signs and

symptoms; features of raised ICP were seen in 96.4% with an average duration before diagnosis of 40 days (1.5 months); motor signs were seen in 75% with a mean duration of 54.1days (2.5 months) before diagnosis; cranial nerve dysfunction was present in 67.9%; 85.7% of the patients had hydrocephalus. 78.6% had a GCS of >13 and 75% had a KPS >60 at admission. All patients had imaging done with 60.71% having both CT and MRI. The vermis was the most common location of PFT on imaging. Medulloblastoma was the most common radiologic diagnosis and histopathological tumour type at fifty percent and 35.7% respectively. The level of agreement between histopathological diagnosis and radiological diagnosis was 97.4% (p<0.001) and Kappa statistic 0.68. Eighty five percent had CSF diversion with majority being VP shunting. It took a mean of 18 days between CSF diversion and definitive surgery. 75% had a craniotomy for exposure and 21% had craniotomy plus C1 laminectomy. Telovelar approach was used 42.9%, transvermian in 39.3% and transcortical in 17.9%. Extubation was done in 53.6% of patients post operatively in theatre. Those who had delayed extubation remained intubated for a mean of 11.5 days. All patients were managed in ICU. The overall mean length of ICU stay was on 10.6 days, patients with delayed extubation had a mean length of ICU stay 18.4 days with those extubated early having a mean ICU stay of 3.8 days. The mean overall length of hospital stay was 24 days. The complication rate was 32.1%. Hydrocephalus was the most common complication at 77.8% followed by wound complications at 22.2%. Young age, less than 4.7 years, duration of hospital stay, and ICU stay were the main risk factors associated with developing complications. The 30-day mortality was 10.7%.

Conclusion: This study shows that, more female patients present with PCF in this population. Cerebellar signs and symptoms are the most common pattern of clinical presentation. The symptom duration before diagnosis is long. The most common imaging location is the vermis with medulloblastoma being is the most common radiological and histological tumour type. Long stay in ICU and long admission duration are associated with increased complication occurrence.