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

Abstract

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.

Asleep Deep Brain Stimulation Reduces Incidence of Intracranial Air during Electrode Implantation

“…This was set at 7 ml of air, since previous studies have shown that electrode placement with less than 1 mm vector deviation averaged this volume of pneumocephalus [14]. There is a significantly lower proportion where more than 7 mL of air is introduced in aDBS (Table 2), with a rate of 5.6% in aDBS compared to 34% in wkDBS (OR 0.1, p < 0.0001, Fisher exact test).…”

“…In DBS cases with more than 1 mm of vector error off the planned trajectory, the reported average volume of intracranial air is 15 mL, while cases with less than 1 mm of electrode deviation have an average of 7 mL of pneumocephalus [14]. In this study, we examined the incidence of pneumocephalus volumes > 7 mL between aDBS and wkDBS, and found that the odds of high-volume pneumocephalus in wkDBS was 10 times that of aDBS.…”

“…Among the factors affecting accuracy of electrode placement, considerable interest has been dedicated to brain shift secondary to accumulation of intracranial air introducing a stereotactic error during the implantation [14-20]. This brain shift generally occurs in a posterior direction [20] and can cause up to 4 mm shift in subcortical structures [16, 17, 20].…”

“…Of concern is the precept that anatomic placement of electrodes requires high fidelity between the preoperative imaging and intraoperative imaging in order to accurately place electrodes; brain shift, especially from intracranial air [14-20], may therefore differentially affect aDBS compared to wkDBS, since the former relies on image guidance based on preoperative and intraoperative fused images while the latter rely supplementarily on physiological localization. To address this, we examined a large series of both aDBS and wkDBS cases for the incidence and volume of introduced air during electrode placement, providing a direct comparison between the 2 techniques.…”

Bilateral Deep Brain Stimulation: The Placement of the Second Electrode Is Not Necessarily Less Accurate Than That of the First One

“…On the one hand, Azmi et al [16] described that in their series of 32 patients who underwent bilateral STN DBS, there was more deviation from the planned target, as well as more microelectrode recording tracks required for the second side of surgery. …”