Ablation of Teflon Granuloma with the Free-Electron Laser Emitting in the Eight- to Nine-Micron Range

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Abstract

In this study, we developed a rat model for Teflon granuloma and used this model to evaluate the removal of the granuloma at laser wavelengths at which Teflon has a maximal absorption. Twenty-four Teflon granulomas were created in 12 rats, and the gross and histologic effects from laser incision at four different wavelengths (8.25, 8.5, 8.75, and 10.6 Jim) were evaluated acutely and at 7 and 14 days postoperatively. Polytetrafluoroethylene, or Teflon, is a relatively inert substance that has been used over the past 4 decades for endoscopic injection into the thyroarytenoid muscle of the larynx for the purposes of laryngeal rehabilitation in cases of unilateral vocal fold paralysis or incomplete glottic closure. In certain cases in which formation of granulomatous reaction to the Teflon occurs, patients may have significant dysphonia or airway compromise. Once Teflon has infiltrated the surrounding tissue planes, it is exceedingly difficult to remove endoscopically. Endoscopic removal of this granuloma is usually attempted with the carbon dioxide (CO2) laser and has had limited success. Examination of the infrared absorption spectrum of polytetrafluoroethylene reveals strong absorption in the mid-infrared region in the 8- to 9-μm range, with minimal absorption at 10.6 μm. Therefore, this absorption spectrum predicts a more efficient vaporization of Teflon at wavelengths near 8.5 μm. Using the free-electron laser to generate 8.25-, 8.5-, and 8.75-μm laser light, we found Teflon granuloma ablation was far superior to CO2 laser ablation at 10.6 μm. The 8.25-, 8.5-, and 8.75-μm wavelengths selectively ablated Teflon granuloma with minimal to no collateral thermal injury to tissue. The differences in thermal effects observed while actually using the lasers were confirmed histologically.

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