Morphological and histological changes of rabbit vocal fold after steroid injection.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to investigate the morphological and histological change of vocal folds (VFs) after steroid injection in a rabbit model. STUDY DESIGN: Prospective animal study. SETTING: Tertiary academic medical center. SUBJECTS AND METHODS: Twenty-four New Zealand white rabbits were used in this study. We randomly classified rabbits into the 3 groups and triamcinolone acetonide suspension was injected to the right VF with different concentrations. Left VF was injected with the same volume of phosphate-buffered saline as control. Endoscopic evaluation was performed to measure morphological changes. The larynges were collected for histological analysis, and the VFs were stained with hematoxylin-eosin for assessing inflammatory response, glandular atrophy, and muscular atrophy and with Masson's trichrome for assessing collagen deposition. RESULTS: In morphological assessment, there were no differences in VF mass reduction, mucosal atrophy, and granulation formation between both VFs. Histological assessments showed no significant difference in inflammatory response, glandular atrophy, and collagen deposition between both VFs. However, there was a difference in muscular atrophy and epithelial layer thinning in steroid injected right VFs. Muscular atrophy had been completely recovered over time, but mild epithelial thinning was continued until 12 weeks. The longer exposure time and larger dose did not increase the intensity of muscular atrophy or epithelial thinning. CONCLUSION: We demonstrated that the VF steroid injection resulted in no significant changes in morphology and histology of rabbit VF. However, steroid injection may induce several VF histological changes and these results are needed to be considered when treating humans.

Local steroid injection via the cricothyroid membrane in patients with a vocal nodule.

OBJECTIVE: To analyze the usefulness and safety of a steroid injection into vocal nodules via the cricothyroid membrane. Local administration of steroid directly into the larynx has been reported in many laryngeal diseases with different methods. DESIGN: Prospective case series at an academic tertiary care hospital. PATIENTS: Eighty patients with vocal nodules were enrolled between December 2008 and May 2010. INTERVENTIONS: Triamcinolone acetonide was injected through the cricothyroid membrane with a transnasal flexible laryngoscope to patients in a sitting position. MAIN OUTCOME MEASURES: Vocal nodules were evaluated before and 2 and 4 weeks after the injection; improvement was assessed both objectively and subjectively. RESULTS: The nodules disappeared in 35 patients by the fourth week after the injection (44%), and 39 patients showed improvement (49%). Jitter, shimmer, maximum phonation time, and mean voice handicap index also improved significantly after the steroid injection (P < .05 for all). Six patients with voice-related occupations showed improvement at the second week (8%), but the nodules had recurred after 4 weeks. Four patients experienced mild vocal fold atrophy, and 2 patients showed a white plaque formation on the vocal fold that resolved spontaneously 1 to 2 months after the injection. CONCLUSIONS: A local steroid injection via the cricothyroid membrane is a useful and safe treatment option for vocal nodules. However, vocal nodules are caused mainly by excessive voice use; therefore, nodules can recur unless the voice use pattern changes. Further study of this treatment technique, including long-term follow-up, is needed.