Can Intraoperative Cricopharyngeus Muscle Characteristics Be Used to Predict Treatment Success in <scp>RCPD</scp> ?

OBJECTIVES: To investigate intraoperative findings as predictors for favorable outcomes following Botox injection in patients diagnosed with retrograde cricopharyngeus muscle dysfunction (RCPD). METHODS: A retrospective review was performed on patients who underwent 70-80 U botulinum toxin injection (BT) for treatment of RCPD by a single surgeon between 2018 and 2023. Patient characteristics, intraoperative findings of cricopharyngeus muscle (CPM), symptoms, treatment response, and side effects were identified during preoperative and 1-month postoperative follow-up. RESULTS: A total of 71 patients were included in the study. A majority of the patients were Caucasian (n = 59 [83.1%]), female (n = 37 [52.1%]), with a mean age of 29.2 years (SD = 8.3). Of those, 68% (n = 48) of patients had a complete response to the initial Botox injection at 1-month follow-up. Compared to the mild thickness CPM, the moderate thickness CPM was 7.2 times less likely to have a full response to treatment (odds ratio [OR]: 7.24, confidence interval [CI]: 1.13-46.37, p = 0.037). Similarly, compared to the mild thickness CPM, thick CPM was 38.5 times less likely to have a full response to treatment (OR: 38.5, CI: 4.4-336.5, p = 0.001). CONCLUSION: Moderate and thick CPMs were less likely to have resolution of symptoms after initial injection with 70-80 U of Botox injection. Further research is needed to establish recommendations regarding dosing for patients with RCPD, especially in those with moderate and thick CPMs.