gms | German Medical Science

Objective: Intraventricular air entrapment (acute ventricular pneumocephalus) is a rare but potentially life-threatening complication of cranial surgery in the sitting position. Since its incidence and relevance are unknown, we assessed factors associated with its occurrence.

Method: In a retrospective chart review of 308 patients, acute ventricular pneumocephalus was defined as an emergency state associated with neurologic deterioration and requiring external ventriculostomy. The occurrence of pneumocephalus was correlated with patient-related and surgical variables. Multiple regression and binomial regression models were used to determine predictive factors for acute ventricular pneumocephalus.

Results: Acute ventricular pneumocephalus requiring external ventriculostomy was observed in 13/308 cases (4.2%). The mean ventricular air volume associated with neurological deterioration was 48.9 cm³ (95% CI: 28.7-69.0) compared to 7.4 cm³ (95% CI: 5.4-9.4; p<0.001) in asymptomatic patients. Intraoperative exposure of a ventricle increased the likelihood of acute ventricular pneumocephalus almost 50-fold (OR=49.0; 95% CI: 4.7-505.5; p=0.001). Preoperative presence of dilated ventricles was equally associated with acute ventricular pneumocephalus (OR 7.2; 95% CI: 1.3-41.4; p=0.03). Female patients had a tendency to develop less ventricular pneumocephalus (B=-4.37 for female patients, 95% CI: -8.04, -0.71; p=0.02). Subdural air volume correlated with age (B=0.3, CI: 0.08, 0.468; p=0.005), lesion localization (B=-2.49, 95% CI: -4.67, 0.31; p=0.025) and operation time (B=0.05, p=.022, 95% CI: 0.01, 0.09). The mean ventricular air on the 3rd day after surgery constituted 28.84% of the initial postoperative pneumocephalus, while subdural pneumocephalus declined to an average of 47.3% in the first 48 hours.

Conclusions: Entrapment of intracranial and particularly ventricular air after posterior fossa surgery occurred frequently in surgeries in the sitting position. However it only requires urgent ventriculostomy in 4% of cases. Intraventricular surgery and preoperative hydrocephalus were the most powerful predictors of acute ventricular pneumocephalus. Therefore these patients should warrant particularly diligent postoperative observation. Half of the intraventricular air is resorbed spontaneously without additional measures on the second postoperative day, indicating that a wait-and-see-attitude may be a safe alternative in patients without significant neurological impairment.