Influence of Intracranial Air on Electrode Position and Clinical Outcomes following Deep Brain Stimulation for Parkinson's Disease

<b><i>Background:</i></b> The introduction of intracranial air during deep brain stimulation (DBS) surgery is believed to negatively impact targeting accuracy and clinical outcomes. <b><i>Objective:</i></b> To quantify the relationship between intracranial air (ICA) volumes, targeting accuracy, and clinical outcomes in patients undergoing subthalamic nucleus (STN) DBS for Parkinson's disease. <b><i>Methods:</i></b> ICA in 73 consecutive STN DBS cases (146 leads) was measured by high-resolution CT and correlated with proximal lead bowing, electrode displacement, targeting accuracy, and clinical outcomes at 6 and 12 months. <b><i>Results:</i></b> There was a statistically significant correlation of ICA volume (mean ± SEM: 21.3 ± 13.7 cm³) and proximal lead bowing (2.8 ± 1.4 mm, <i>r = </i>0.34, <i>p</i> = 0.01). There was no significant correlation of ICA with targeting error (2.0 ± 1.2 mm), distal contact deviation (1.2 ± 0.7 mm), motor Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part III improvement at 6 months (42.3 ± 4.5%) or 12 months (30.3 ± 7.7%), or dopaminergic medication reduction at 6 months (44.7± 4.2%) or 12 months (32.9 ± 5.9%). Comparison of top and bottom ICA quintile extremes also revealed no differences in these measures. <b><i>Conclusions:</i></b> Though the proximal DBS lead bends in association with ICA, movement of the distal contact, targeting error, and clinical outcomes are not affected by ICA. This unexpected finding is maintained at ICA quintile extremes.