Development of HIGH-INTENSITY FOCUSED ULTRASOUND(HIFU) Therapy in Inferior Turbinate Hypertrophy.

Objectives Inferior turbinate (IT) hypertrophy is the main cause of chronic nasal obstruction. We developed a high-intensity focused ultrasound (HIFU) ablation device to treat patients with IT hypertrophy. Methods First, computed tomography (CT) images of patients without any evidence of sinonasal disease were evaluated to measure and compared the IT, medial mucosal thickness (MT), and space between the nasal septum and IT according to clinical characteristics such as septal deviation. A HIFU prototype was developed based on human anatomical studies. The experimental study was performed in five pigs; the cross-sectional areas of the nasal cavity airway and histological changes at 1 and 4 weeks postoperatively were evaluated to compare the efficacy of HIFU turbinoplasty with that of radiofrequency turbinoplasty and control. Results The mean medial MT of the anterior, middle, and posterior portions of the IT were 4.66±1.14, 4.23±0.97, and 6.17±1.29 mm, respectively. The mean medial IT spaces was 2.65±0.79 mm. The diameter and focal depth of the prototype were 4 mm and 3 mm. HIFU showed no postoperative complications including bleeding or scar formation. After HIFU treatment, the cross-sectional area of the nasal airway increased by 196.62(7.8%) mm3 and 193.74(8.3%) mm3 at 1 week and 4 weeks, compared with the increase of 87.20(3.1%) mm3 and 213.81(9.0%) mm3, respectively, after radiofrequency therapy. Qualitative histologic analysis after radiofrequency turbinoplasty showed epithelial layer disruption at 1 week and increased fibrosis along with decreased glandular structure at 4 weeks. The HIFU group had an intact epithelial layer at 1 week postoperatively. However, significant differences were observed at 4 weeks, including increased fibrosis, and decreased glandular structure. Conclusion The efficacy and safety of HIFU turbinoplasty had been observed in an animal study. Our results warrant the need for further human clinical trials.