Intraglandular botulinum toxin in postoperative head and neck fistula: a retrospective analysis

Purpose: Orocervical (OCF) or pharyngocutaneous fistula (PCF) are one of the disastrous complications of head and neck cancer surgery. Conventional standards of management are predominantly conservative. Though a majority of such patients respond to conservative management, it nevertheless causes significant delay in wound healing. This study explores the role of intraglandular Botulinum toxin injection in shortening the time to fistula healing.

Methods: Retrospective case-control study at a tertiary care oncology center in South Asia from January 2021 to December 2023 on all consecutive patients of OCF/PCF. Patients with any history of head and neck radiation were excluded. The case group received intraglandular (parotid+/-submandibular gland) botulinum toxin injection and conservative management and the control group received only conservative management. The time taken for the fistula to heal was the primary outcome.

Results: 31 patients in case and 104 patients were in control group. The mean time from fistula diagnosis till injection was 5.8 ± 3.1 days and the mean fistula healing time in case group was 18.5 ± 7.15 days (Range:10-34 days). The mean total dose of botulinum toxin was 59.2 ± 22.4 MU (Range: 40 to 100 MU). For control group, the mean time taken for the fistula to heal was 26 ± 15 days (Range:15 to 75 days). The difference was statistically significant (p-0.008, 95% CI: -9.0 to -2.0). Adverse effects attributable to botulinum toxin injection were: pain at the injection site (n = 3) and xerostomia (n = 1). On multivariate analysis, intervention with intraglandular botulinum toxin emerged as an independent variable impacting the time taken for fistula closure.

Conclusion: This is the largest study to show the efficacy of intraglandular botulinum toxin injection in reducing the time taken for healing of postoperative salivary fistula with a tolerable adverse effect profile.