Post-Operative Radiological Evaluation of a Bilateral Hypoglossal Nerve Stimulation System

Introduction Nervus hypoglossus stimulation implants are a well-known second-line option for the treatment of obstructive sleep apnea (OSA). Similar to other implants, postoperative radiological positional evaluation serves as a quality control measure for the surgical procedure and as a reference point for future adjustments. Furthermore, the impact of artifacts on the visual assessment of the adjacent structures might be of clinical importance. This study aimed to evaluate postoperative positional implant control and CT-generated artifacts of a bilateral hypoglossal nerve stimulation device. Material and methods We retrospectively evaluated postoperative radiological imaging of 9 patients on the first day after implantation of a bilateral nervus hypoglossus stimulation device. A variety of radiological imaging procedures were utilized: 8 CT scans (in sagittal and axial planes) and 9 X-ray examinations were conducted. Eight patients (89%) received postoperative X-ray and CT scans, and one patient (11%) received postoperative X-ray control only. Radiological imaging was analysed regarding the position of the implant, anatomy, and artifacts. The age range of patients varied from 59 to 87 years (mean, 68.9 years; SD, 8.6 years). Preoperative Apnoe-Hypopnoea Index (AHI) varied from 16.5 to 64 (mean 40.1) and Body Mass Index (BMI) ranged from 25 to 34 kg/m2 (mean 29.2 kg/m2). Results Evaluation of X-ray images did not reveal artifacts that affected the diagnostic accuracy of postoperative position control. In contrast, CT images showed artifacts in the coronal, sagittal, and axial planes, making radiological assessment more difficult. We observed a high variation of device position without any effect on functionality. Paddle asymmetry was found in 78% of cases (7 out of 9). Conclusion Postoperative radiologic monitoring after implantation of a bilateral hypoglossal nerve stimulator is recommended. A high variation of device position could be found. The variability in implant position observed in our study group does not affect the implant's functionality. CT artifacts need to be considered.