Medical Student Nova Southeastern University College of Allopathic Medicine Asheville, North Carolina, United States
Introduction: Post-operative pneumocephalus is a commonly described and typically benign radiological finding after neurosurgical procedures. In chronic subdural hematoma (cSDH) patients, pneumocephalus has been examined as a risk factor for recurrence. However, the literature addressing potential associations between pneumocephalus and cSDH is limited and conflicting, especially when examining factors such as pneumocephalus volume and clinical symptomatology.
Methods: To evaluate the role of pneumocephalus in cSDH outcomes, a systematic review of the literature was completed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Prospective or retrospective studies on adult cSDH patients with clinical details on pneumocephalus and cSDH outcomes were included. Meta-analyses and studies not available in English or with pediatric patients, less than 5 patients, or insufficient information were excluded. Patient demographics and outcomes related to cSDH and pneumocephalus were extracted. The studies were not meta-analyzed due to methodological heterogeneity.
Results: Of 444 identified studies, 62 underwent full text screening. 36 studies (n=5,885 patients) were included. Mean patient age was 69.8 years old. 70.4% of patients were male. 19 studies found higher pneumocephalus rates or volumes in patients that also had greater cSDH recurrence. The minimum pneumocephalus volume related to increased cSDH recurrence ranged from 4 cm3 to 15 cm3. Three studies demonstrated complete resolution of intracranial air without apparent symptoms. Two studies found asymptomatic pneumocephalus to occur more frequently in elderly patients. 21 studies found that less intracranial air was related to cSDH outcomes including lower reoperation rates, post-operative seizures, length of stay, and short-term Markwalder scores.
Conclusion : While many studies demonstrated an association between pneumocephalus and worse outcomes in cSDH patients, there is not a consensus on the mechanism or on a causal role, especially given the lack of uniform pneumocephalus data. Less intracranial air was found to be associated with lower rates of cSDH recurrence.
