The effect of delayed-release antibiotics on the rate of postoperative wound infection for implanted neuromodulatory devices.

Objective: Implanted neuromodulatory devices are important for the surgical management of pain, epilepsy, movement disorders, and spasticity. These devices are surgically implanted, but many must be periodically explanted and replaced as batteries deplete or devices fail. Replacement surgery risks further infections that require device explantation, incur large financial costs, and reduce patient quality of life. To reduce infection rates, a single surgeon began using vancomycin-impregnated absorbable calcium sulfate delayed-response beads with neuromodulatory device and intrathecal pump primary implantations and replacements. The infection rates when using vancomycin-impregnated beads were compared with previously published rates from the same surgeon.

Methods: Patients were identified who underwent primary placement or replacement of an implanted neuromodulatory control device (pumps, generators, and stimulators) with vancomycin-impregnated absorbable calcium sulfate beads between 2019 and 2022. Control data were obtained from patients who underwent surgery prior to the start of using antibiotic beads (2016-2019). Postoperative infection status as well as de-identified demographic and clinical data were extracted from electronic health records. Patients were stratified by use of antibiotic beads, device type, and whether they had an infection within 1 year requiring explantation. Statistical comparisons were made using independent t-tests, Fisher's exact test, and the chi-square test, with α set at 0.05. Effect size was calculated using Cohen's h statistic.

Results: A total of 665 surgeries were included for 611 patients who received antibiotic beads with device implantation, compared to 393 surgeries for 379 patients without antibiotic beads. The postoperative wound infection rate was 1.5% (n = 10 patients) versus 3.6% (n = 14 patients) for antibiotic beads versus controls (p = 0.03). When stratified by device type, a significant reduction in infection rate was found only with deep brain stimulation (DBS) generators (3.4% for controls vs 0.2% for beads, p = 0.002), which corresponds to a small to medium effect size (h = 0.27).

Conclusions: The use of vancomycin-impregnated absorbable calcium sulfate beads was associated with a reduced rate of postoperative infection rates with implantable devices, and specifically for DBS primary implantation and replacement surgeries.