Risk factors and significance of post-operative edema in Parkinson Disease patients submitted to deep brain stimulation. A ten-year case series

Background: Peri-electrode edema after deep brain stimulation (DBS) surgery for Parkinson Disease (PD) has been reported in up to 100% of cases. The clinical significance of this finding is unclear, with most papers suggesting a benign course. The risk factors are also poorly defined. We aimed at defining the incidence rate, the clinical significance and the predictive factors of peri-electrode edema in patients undergoing DBS for PD. Methods: We reviewed data of 119 patients treated with frameless stereotactic DBS for PD between 2012 and 2022 at our Institution. A mixed-technique targeting was adopted. Awake surgery was used in 64.7% cases; in most cases, microelectrode recording (MER) was adopted. The target was the subthalamic nucleus (STN) in 91.2% cases. Results: Ninety patients were included. Postoperative edema related to lead placement was noticed in 40% patients after a median time of 2 days since surgery; in 88.9% of these cases, it was limited to subcortical white matter. Symptomatic edema was registered only in one case (1.1%), confirming previous reports on the benign clinical course. The only independent predictive factor for edema onset was asleep surgery (p = 0.0451). Notably, the use of directional electrodes was not associated with an increased risk of edema at multivariable analysis. Clinical parameters including age, and timing of CT scanning, did not affect edema onset. Conclusions: We confirmed the very low rate of symptomatic edema in DBS for PD. When feasible, awake DBS using MER is the ideal technique to reduce the risk of radiologic postoperative edema.