Intracranial Air Correlates with Preoperative Cerebral Atrophy and Stereotactic Error during Bilateral STN DBS Surgery for Parkinson’s Disease

Objective: We examine the effect of intracranial air on stereotactic accuracy during bilateral deep brain stimulation (DBS) surgery for Parkinson’s disease (PD). We also assess factors that may predict an increased risk of intracranial air during these surgeries. Methods: 32 patients with PD underwent bilateral DBS surgery. The technique used for implantation of the leads has been standardized in over 800 subthalamic nucleus (STN) implantations. For lead implantation, the goal of the neurophysiological technique is identification of the STN and its borders with 3 microelectrode recording (MER) tracks. We examined the number of tracks and the degree of deviation from the planned target on each side. Total intracranial air (TIA) was then compared in these groups. We also examined the relationship between the TIA and length of surgery, ventricular volume and the degree of atrophy. Results: Side 2 in this series required more MER tracks. The TIA was larger in patients with more than 3 MER tracks on side 2 of surgery. There was more deviation from the target on side 2. In addition, the TIA in patients with >1 mm of vector deviation on side 2 was more than in those without. The TIA correlated with the number of tracks on side 2 as well as with the degree of the second euclidean deviation on side 2. There was a correlation of degree of atrophy with TIA. Conclusion: In bilateral STN DBS for PD, intracranial air may contribute to error in stereotactic accuracy especially on the second side. In addition, there is a correlation between the accumulated volume of intracranial air and the degree of cerebral atrophy.