Survival Analysis of Occipital Nerve Stimulator Leads Placed under Fluoroscopic Guidance with and without Ultrasonography

Background: Electrical stimulation of the greater occipital nerves is performed to treat pain secondary tochronic daily headaches and occipital neuralgia. The use of fluoroscopy alone to guide the surgical placementof electrodes near the greater occipital nerves disregards the impact of tissue planes on lead stability andstimulation efficacy.Objective: We hypothesized that occipital neurostimulator (ONS) leads placed with ultrasonography combinedwith fluoroscopy would demonstrate increased survival rates and times when compared to ONS leads placedwith fluoroscopy alone.Study Design: A 2-arm retrospective chart review.Setting: A single academic medical center.Methods: This retrospective chart review analyzed the procedure notes and demographic data of patients whounderwent the permanent implant of an ONS lead between July 2012 and August 2015. Patient data includedthe diagnosis (reason for implant), smoking tobacco use, disability, and age. ONS lead data included the dateof permanent implant, the imaging modality used during permanent implant (fluoroscopy with or withoutultrasonography), and, if applicable, the date and reason for lead removal. A total of 21 patients (53 leads) wereincluded for the review. Chi-squared tests, Fishers exact tests, 2-sample t-tests, and Wilcoxon rank-sum testswere used to compare fluoroscopy against combined fluoroscopy and ultrasonography as implant methods withrespect to patient demographics. These tests were also used to evaluate the primary aim of this study, which wasto compare the survival rates and times of ONS leads placed with combined ultrasonography and fluoroscopyversus those placed with fluoroscopy alone. Survival analysis was used to assess the effect of implant method,adjusted for patient demographics (age, smoking tobacco use, and disability), on the risk of lead explant.Results: Data from 21 patients were collected, including a total of 53 ONS leads. There was no statisticallysignificant difference in the lead survival rate or time, disability, or patient age with respect to the implantmethod with or without ultrasonography. There was a statistically significant negative effect on the risk ofexplant with regards to lead removal in smoking patients compared to non-smoking patients (hazard ratio0.36). There was also a statistically significant difference in smoking tobacco use with respect to the implantmethod, such that a greater number of patients whose leads were placed with combined fluoroscopy andultrasonography had a history of smoking (P = 0.048).Limitations: This study is a retrospective chart review that had statistically significant differences in the patientgroups and a small sample size.Conclusion: This study assessed the survival rates and times of ONS leads placed with ultrasonography andfluoroscopy versus fluoroscopy alone. We did not observe an effect to suggest that the incremental addition ofultrasound guidance to fluoroscopy as the intraoperative imaging modality used during the permanent implantof ONS leads yields statistically significant differences in lead survival rate or time. Medical comorbidities,including age and smoking status, may play a role in determining the risk of surgical revision and should beconsidered in future studies.Key words: Neuromodulation, peripheral nerve stimulation, occipital nerve stimulation, occipital neuralgia,chronic daily headaches, ultrasonograph