Advantages of CO2 OtoScan laser vs. conventional CO2 laser for office-based LAM

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OtolaryngologyHead and Neck Surgery August 1999

Research Forum--Monday

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Long-term Observation of Surface Structure of Synthetic Auditory Ossicle (Apaceram) KATSUICHIRO OHSAKI MD PHD (presenter); AKIRA SHIBATA PHD; KUNIO II MD PHD; QING YE MD; SHINSUKE YAMASHITA PHD; YASUHIKO YAMASHITA; Tokushima Japan; Tokushima Japan; Tokushirna Japan; Tokushima Japan; Hyogoken Japan; Tokushima Japan

Methods: A study was made to obtain information about the surface structure of thin Apaceram disks of dense hydroxyapatite (HA) implanted in the soft tissue of rats for 6, 14, and 20 months. Thin Apaceram disks were implanted subcutaneously into the interscapular regions of 12 rats. Apaceram surfaces were analyzed by laser-Raman spectrometry at the molecular level and observed by scanning electron microscope. Surfaces of Apaceram specimens were compared with untreated Apaceram used as a control. Results: Apaceram surfaces were observed by scanning electron microscopy at magnifications of • • and • Many small crater-like cavities observed in the smooth surface area at 6-month implantation decreased prominently after 20 months, whereas the untreated surface was smooth. Numerous crystal grains were observed on original particle surfaces of Apaceram after implantation for 20 months. The study monitored a Raman spectral signal of v 1 (wave number = 960 cm-l: the strongest peak) on the basis of vibration due to PO43of HA as an indicator of the Apaceram component. Half-peak breadths (HPBs) of v I signal, as an indicator of demineralization and renfineralization, were compared. (1) Mean HPB (4.148 _+0.065, n = 12) of Apaceram surface after 14 months was significantly narrower than (4.310 + 0.173, n = 10) after 6 months (P < 0.05). (2) Mean HPB (4.225 _+0.028, n = 13) after 20 months was significantly wider than (4.148 _+0.065, n = 12) after 14 months of implantation (P < 0.01). (3) Comparison of mean HPB between untreated Apaceram surface and 20 months of implantation showed no significant difference. Using scanning electron microscopy, although untreated particle surfaces appeared to differ from implanted particle surfaces at 20 months, both had basically the same composition because there was no significant difference in mean HPBs. Conclusions: Ions such as Ca2+ and PO43- were released from the Apaceram surface implanted in the subcutaneous tissue of rats. Remineralization might have progressed gradually on the surface of Apaceram when released ions were saturated in the interfacial region (body fluid phase) between the Apaceram disk and the tissue. (Supported by grant no. 10671594 from the Ministry of Education, Science, Sports and Culture of the Japanese Government.) Poster 6

Type III Tympanoplasty: Do You Really Need a Prosthesis? LCDR BRIAN J MCKINNON MD (presenter); LORENZ F LASSEN MD; Virginia Beach VA

Problem: The goals of modern ear surgery are to control infection and reconstruct the sound-conducting mechanism. The confines of managed care have forced us to reconsider the use of a prosthesis with its cost versus a "natural" type Ill tympanoplasty. The objective of this investigationwas to compare postoperative hearing results in type Ill tympanoplasty with and without prosthesis. Methods: A retrospective chart review comparing the results of prosthesis use (PORP/TORP) versus no prosthesis in type IlI tympanoplasty. Results: Greater improvement in hearing was achieved in primary reconstruction than in revision reconstruction. The use of a prosthesis versus no prosthesis in primary reconstruction following canal wall down mastoidectomy gave equivalent hearing results. If a prosthesis was used, the Applebaum and Wehrs prostheses achieved the best results. Conclusion: The investigation revealed that type IlI tympanoplasty with canal wall down mastoidectomy without interposition prosthesis gives a hearing results comparable with those of canal wall down mastoidectomy with an interposition prosthesis. If an interposition prosthesis is used, there appears to be some advantage to establishing continuity of ossicles rather than drum-to-stapes using an Applebaum or Wehrs prosthesis. Clinical Significance: This study indicates no advantage in using a prosthesis for type III tympanoplasty with canal wall down mastoidectomy reconstruction. This suggests a possible cost benefit in a potential single-stage procedure without the costs or risks of a prosthesis. (Supported by the Department of Otolaryngology-Head and Neck Surgery, Naval Medical Center, Portsmouth, VA.) Poster 7

Advantages of CO 20toScan Laser vs. Conventional CO 2 Laser for Office-Based LAM MILTON WANER MD (presenter); Little Rock AR

Objective: Intermediate duration middle ear ventilation as well as office-based placement of middle ear ventilation tubes using the CO 20toScan laser has become increasingly practiced. The CO 20toScan uses SurgiTouch flash scanner technology, which is less familiar to otolaryngologists and therefore confusion exists regarding the advantages of this laser technology over conventional CO2 lasers. Methods: An in-depth comparison of the laser characteristics including spot size and power settings, tissue dwell time, depth of injury, and safety of the system will be presented between the CO20toScan and conventional CO 2 lasers. The benefits in different patient populations and clinical situations will be assessed. Results: The CO 20toScan provides a closed system with a shorter tissue dwell time, 90% decrease in depth of injury, and greater precision of spot size. In general, a single firing (75%) is all that is needed to obtain a precisely sized hole. The coupling of the laser to a hand-held otoscope confers the addi-

OtolaryngologyHead and Neck Surgery Volume 121 Number 2

tional advantage of a closed system, thereby improving physician 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-effectlevel (NOEL) and maximum tolerated dose (MTD) for ototoxicity comparing MiKasome| (liposomal encapsulated amikacin) with the conventional formulation of amikacin, a known ototoxic, aminoglycoside antibiotic. Click ABR is utilized 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 posttreatment 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 determined 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-

Research F o r u m m M o n d a y

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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 uniform 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 ImmuneM e d i a t e d 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

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O Problem Addressed: Corticosteroids are the principle treatment regimen for patients with immune-mediated cochleovestibular 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 methotrexate (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 symptoms was therefore minimal. These cases were reviewed retrospectively 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 treatment 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 during the course of MTX treatment were limited and reversible. Conclusions: The results of this study suggest that lowdose 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, especially 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