Otolaryngology- Head and Neck Surgery Volume 121 Number 2 Research ForummMonday P79 tional advantage of a closed system, thereby improving physi- cian and patient safety. In comparison, the conventional CO 2 laser must be coupled to a microscope, is cumbersome, and is an open system with certain safety concerns. It has a much longer tissue dwell time, making patient cooperatio n and movement much more important. Spot size cannot be precisely predetermined. Conclusions: The introduction of new technology requires an in-depth understanding of the technological advantages of such a technology. This is particularly true if there is variation from an existing technology that is widely used and accepted by practitioners. Understanding flash scanner CO20toScan technology will greatly help to understand its advantages for office-based laser-assisted myringotomy in children. Poster 8 Comparative Ototoxicity of MiKasome vs. Conventional Amikacin in a Repeated Dosing Study EDWARD DODSON MD (presenter); ALBERT T LASH MA; RANDALL J WARREN MS; BRIAN MARSHALL DVM; MICHAEL PODELL DVM; Columbus OH; Columbus OH; Cincinnati OH; Columbus OH; Columbus OH Problem Addressed: This study determines the no-effect- level (NOEL) and maximum tolerated dose (MTD) for oto- toxicity comparing MiKasome| (liposomal encapsulated amikacin) with the conventional formulation of amikacin, a known ototoxic, aminoglycoside antibiotic. Click ABR is uti- lized to compare auditory function in rats administered 14 repeated daily doses of MiKasome versus amikacin, which is used as a positive control. Methods/Measures: Experimental dose groups of 10 rats each were administered 14 daily repeated doses of one of the following test or control articles--(1) MiKasome (IV): 100, 175, 200, 250, or 300 mg/kg; (2) conventional amikacin (SQ): 175 mg/kg; (3) empty lip0somes (IV): 250 mg/kg; or (4) D5W (IV): 250 mg/kg. Click ABR was obtained prior to treatment, at the conclusion of treatment, and after a 14-day posttreat- ment washout/recovery period. Results: ABR results indicated that MiKasome produced no observed ototoxic effects in rats administered doses of either t00 or 175 mg/kg IV, mixed results at doses of either 200 or 250 mg/kg IV, and increased ABR threshold at 300 mg/kg IV. All rats in the positive control group administered 175 mg amikacin/kg SQ showed increases in ABR threshold. ABR results of all rats given either empty liposomes or D5W were unaffected by treatment. Conclusions: Liposomal encapsulated amikacin does not produce sensorineural hearing loss, which is observable with an equivalent dosing regimen of conventional amikacin. The NOEL for MiKasome administered IV for 14 days was deter- mined to be 175 mg/kg; the MTD was determined to be 250 mg/kg. The MTD for amikacin administered SQ for 14 days was estimated to be less than 175 mg/kg. Clinical Significance: Ototoxicity of the conventional for- mulation of amikacin results in high-frequency heating loss associated with extensive loss of outer hair cells near the basal end of the cochlea. The absence of ototoxicity in this study with MiKasome treatment versus the presence of uni- form ototoxicity produced by conventional amikacin, utilized in equivalent dosing regimens, suggests a similar sparing effect from ototoxicity may be applicable to human beings. Poster 9 Effectiveness of Methotrexate for Long-Standing Immune- Mediated Cochleovestibular Disorders MARK W GRIMM MD; LAWTON H SALLEY JR MD (presenter); CHRISTOPHER M WISE MD; ROBERT F SPENCER PHD; ARISTIDES SISMANIS MD FACS; Richmond VA Problem Addressed: Corticosteroids are the principle treat- ment regimen for patients with immune-mediated cochleo- vestibular disorders (IMCVD). Long-term therapy with these agents, however, is associated with serious complications. The purpose of this study is to report the effectiveness of metho- trexate (MTX), an immunosuppressant successfully used in rheumatoid arthritis, in managing patients with long-standing symptoms (>1 year) prior to treatment. Methods/Measures: Thirty-eight patients diagnosed with IMCVD have been treated with low-dose oral MTX at our institution. Of these, 30 had symptoms of greater than 1 year duration. The possibility of spontaneous resolution of symp- toms was therefore minimal. These cases were reviewed retro- spectively for changes in clinical symptoms (vertigo, hearing loss, tinnitus, and aural fullness) and audiometric tests and the evaluation of any side effects of the long-term MTX therapy, Results: The mean duration of symptoms was 7 years (range 16 months to 30 years). The mean duration of treat- ment was 12 months (range 3-56 months). Vertigo, heating loss, aural fullness, and tinnitus improved in 64%, 50%, 78%, and 27%, respectively. With further stratification of this group by alteration of symptoms (1-5 years, 6-10 years, >10 years), a trend of continued efficacy was seen. Adverse reactions dur- ing the course of MTX treatment were limited and reversible. Conclusions: The results of this study suggest that low- dose oral MTX is an effective and safe long-term treatment modality for patients with IMCVD. Clinical Significance: Methotrexate should be considered for the long-term management of patients with IMCVD, espe- cially when prolonged treatment is necessary and where the continued use of corticosteroids may be contraindicated. Poster 10 Timing and Use of Antioxidants for Prevention and Rescue of Noise-lnduced Hearing Loss PETER A WEISSKOPF MD (presenter); RICHARD D KOPKE MD; CHRISTOPHER CHARON MD; RON JACKSON PHD; DERINWESTER PHD; MICHAEL E HOFFEN MD; DAVID LAMBERT MD; JOHN L BOONE MD; San Diego CA Problem: Noise-induced hearing loss is a critical problem rn Z O