Discussion

Introduction: Post-operative intracranial air, or pneumocephalus, is encountered in nearly all patients undergoing intracranial surgery. While it rarely requires invasive intervention, common neurosurgical teaching is to minimize post-operative pneumocephalus when possible. In Deep Brain Stimulation (DBS), despite a very small craniotomy via burr hole and minimal dural opening, a wide range of post-operative pneumocephalus volume can be seen on imaging. We aim to quantify the degree of pneumocephalus after DBS surgery and potential correlation to lead position error.

Methods: Patients undergoing DBS for a variety of movement disorders including Parkinson’s disease and essential tremor were selected from a three-year period. All patients underwent staged operation with stage one including intracranial lead placement and stage two (typically performed two weeks later) involving placement of internal pulse generator. All patients underwent helical computed tomography (CT) scan following stage one operation, and volume of pneumocephalus was calculated using standardized formula.

Results: A total of 76 patients were identified from a three-year period, with mean post-operative pneumocephalus volume of 18.9 ± 15.8 ml (range 0.01 - 89.8 ml). No patients required invasive intervention or treatment due to presence of pneumocephalus and no patients were symptomatic despite volume range.

Conclusion : A fundamental teaching in cranial neurosurgery is to limit the volume of pneumocephalus to the surgeon’s best ability. We demonstrate a wide variation in post-operative pneumocephalus after deep brain stimulation surgery in a cohort of patients undergoing bilateral procedure. While no patients were acutely symptomatic because of pneumocephalus, further work to demonstrate an effect of intracranial air on lead placement error is needed.