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Talas DÜ, Beger O, Vayisoğlu Y, Hamzaoğlu V, Özalp H, Çakır S, Dağtekin A, Bağdatoğlu C. Cochleo-facial corridor to the vestibule and fundus of the internal auditory canal through oval window: a minimal invasive and cochlea sparing approach. Eur Arch Otorhinolaryngol 2021; 279:627-637. [PMID: 33595698 DOI: 10.1007/s00405-021-06680-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/04/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE This cadaveric work aimed to test the effectiveness of a modified surgical corridor (ExpTSA: expanded transcanal supracochlear approach) developed for anatomic cochlear preservation in selected vestibular schwannoma patients necessitating to perform cochlear implantation for appropriate cases to achieve the best outcome. METHODS The ears of 10 cadavers (at mean age 75.70 ± 13.75 years, range 45-92 years) were dissected from the external auditory canal (EAC) to the internal auditory canal by ExpTSA under the guidance of a microscope and endoscope. All stages of the surgical process were recorded step by step and evaluated morphometrically. RESULTS The vestibular base was successfully reached in all ears without damaging the cochlear morphology and facial nerve. The vestibular base was 23.33 ± 2.02 mm away from the entrance (external orifice) and 10.26 ± 1.33 mm from the exit (internal orifice) of EAC. The oval window and vestibular base were measured to be 2.94 ± 1.05 mm and 5.87 ± 1.24 mm deep from the facial nerve, respectively. The normal areas of the oval window, the exit and entrance of EAC were found as 2.90 ± 0.81 mm2, 42.52 ± 13.66 mm2, and 110.73 ± 25.32 mm2, respectively. After ExpTSA procedure, the areas of the oval window (11.04 ± 2.83 mm2), the exit (122.45 ± 20.41 mm2) and entrance (167.49 ± 30.94 mm2) of EAC were expanded approximately 280%, 188%, and 50%, respectively. CONCLUSION The ExpTSA may be performed for accessing to the vestibule and fundus of IAC for tumor removal of intravestibular schwannoma patients (with or without fundus involvement) with unserviceable hearing, preserving the cochlear morphology.
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Affiliation(s)
- Derya Ümit Talas
- Department of Otorhinolaryngology, Faculty of Medicine, Mersin University, Ciftlikkoy Campus, 33343, Mersin, Turkey.
| | - Orhan Beger
- Department of Anatomy, Faculty of Medicine, Gaziantep University, Gaziantep, Turkey
| | - Yusuf Vayisoğlu
- Department of Otorhinolaryngology, Faculty of Medicine, Mersin University, Ciftlikkoy Campus, 33343, Mersin, Turkey
| | - Vural Hamzaoğlu
- Department of Neurosurgery, Faculty of Medicine, Mersin University, Mersin, Turkey
| | - Hakan Özalp
- Department of Neurosurgery, Faculty of Medicine, Mersin University, Mersin, Turkey
| | - Salim Çakır
- Faculty of Medicine, Mersin University, Mersin, Turkey
| | - Ahmet Dağtekin
- Department of Neurosurgery, Faculty of Medicine, Mersin University, Mersin, Turkey
| | - Celal Bağdatoğlu
- Department of Neurosurgery, Faculty of Medicine, Mersin University, Mersin, Turkey
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Abstract
Modern research on ototoxicity goes back to the 1940s, when streptomycin was introduced into clinical practice. Today, aminoglycoside antibiotics and platinum-based chemotherapy, mainly cisplatin, are the most important drugs that damage the inner ear and cause hearing loss. The mode of drug administration as well as drug characteristics influence the likelihood that adequate monitoring of drug pharmacokinetics can be performed. It is not possible to predict the individual risk of treatment with an ototoxic drug, but identification of high-risk treatment protocols is important. There are many studies ongoing with the aim of discovering and developing drugs to treat different types of inner ear disorders. The mechanisms of ototoxicity and subsequent loss of hearing function have been mapped in various experimental models and have provided us with useful information for developing protective treatment. When an ototoxic lesion is established, restoration of hearing function becomes more difficult. For both aminoglycoside antibiotics and cisplatin, a large number of otoprotectors have been suggested. Systemic co-administration of an otoprotector would be the easiest approach to avoid ototoxicity in patients but it may negatively affect the intended pharmacotherapeutic aim of the ototoxic drug. New pharmacological formulations are being developed for local otoprotective treatment. This short review focuses on results from clinical reports on otoprotection in patients treated with aminoglycoside antibiotics and cisplatin. So far there is limited evidence for the safe management of otoprotection in patients. Further high-quality studies are needed to provide reliable data on the safety and effectiveness of pharmacological interventions to reduce drug-induced hearing loss.
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Abstract
Ototoxicity diagnosis and management has historically been approached using a variety of methods. However, in recent years a consensus on useful and practical approaches has been developed through clinical guidelines of the American Speech Language Hearing Association, the American Academy of Audiology, and multiple clinical trials published in peer-reviewed literature. Some of the guidelines and approaches are used to detect and monitor ototoxicity, while others are used to grade adverse events. Some of the audiologic measures are primary, while others are adjunct measures and may be tailored to the specific needs of the patient or clinical trial. For some types of monitoring, such as drug-induced tinnitus or dizziness, validated paper survey instruments can be both sensitive and easy for fragile patients. This review addresses the characteristics of some of the most common clinical ototoxins and the most common methods for detecting and monitoring ototoxicity in clinical practice and clinical trials.
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Affiliation(s)
- Kathleen C M Campbell
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, PO Box 9626, Springfield, IL, 62704-9626, USA.
| | - Colleen G Le Prell
- Callier Center for Communication Disorders, University of Texas at Dallas, 1966 Inwood Road, Dallas, TX, 75235, USA
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Fox DJ, Cooper MD, Speil CA, Roberts MH, Yanik SC, Meech RP, Hargrove TL, Verhulst SJ, Rybak LP, Campbell KCM. d-Methionine reduces tobramycin-induced ototoxicity without antimicrobial interference in animal models. J Cyst Fibros 2015; 15:518-30. [PMID: 26166286 DOI: 10.1016/j.jcf.2015.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/19/2015] [Accepted: 06/19/2015] [Indexed: 12/21/2022]
Abstract
BACKGROUND Tobramycin is a critical cystic fibrosis treatment however it causes ototoxicity. This study tested d-methionine protection from tobramycin-induced ototoxicity and potential antimicrobial interference. METHODS Auditory brainstem responses (ABRs) and outer hair cell (OHC) quantifications measured protection in guinea pigs treated with tobramycin and a range of d-methionine doses. In vitro antimicrobial interference studies tested inhibition and post antibiotic effect assays. In vivo antimicrobial interference studies tested normal and neutropenic Escherichia coli murine survival and intraperitoneal lavage bacterial counts. RESULTS d-Methionine conferred significant ABR threshold shift reductions. OHC protection was less robust but significant at 20kHz in the 420mg/kg/day group. In vitro studies did not detect d-methionine-induced antimicrobial interference. In vivo studies did not detect d-methionine-induced interference in normal or neutropenic mice. CONCLUSIONS d-Methionine protects from tobramycin-induced ototoxicity without antimicrobial interference. The study results suggest d-met as a potential otoprotectant from clinical tobramycin use in cystic fibrosis patients.
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Affiliation(s)
- Daniel J Fox
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA; Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA; Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL, USA.
| | - Morris D Cooper
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Cristian A Speil
- Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Melissa H Roberts
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Susan C Yanik
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Robert P Meech
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Tim L Hargrove
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Steven J Verhulst
- Statistics and Research Consulting, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Leonard P Rybak
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Kathleen C M Campbell
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA; Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA
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Karasawa T, Steyger PS. Intracellular mechanisms of aminoglycoside-induced cytotoxicity. Integr Biol (Camb) 2011; 3:879-86. [PMID: 21799993 DOI: 10.1039/c1ib00034a] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since introduction into clinical practice over 60 years ago, aminoglycoside antibiotics remain important drugs in the treatment of bacterial infections, cystic fibrosis and tuberculosis. However, the ototoxic and nephrotoxic properties of these drugs are still a major clinical problem. Recent advances in molecular biology and biochemistry have begun to uncover the intracellular actions of aminoglycosides that lead to cytotoxicity. In this review, we discuss intracellular binding targets of aminoglycosides, highlighting specific aminoglycoside-binding proteins (HSP73, calreticulin and CLIMP-63) and their potential for triggering caspases and Bcl-2 signalling cascades that are involved in aminoglycoside-induced cytotoxicity. We also discuss potential strategies to reduce aminoglycoside cytotoxicity, which are necessary for greater bactericidal efficacy during aminoglycoside pharmacotherapy.
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Affiliation(s)
- Takatoshi Karasawa
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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Gleich O, Strutz J, Schmid K. [Endolymph homeostasis and Menière's disease: fundamentals, pathological changes, aminoglycosides]. HNO 2008; 56:1243-52. [PMID: 19020845 DOI: 10.1007/s00106-008-1841-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Although low dose intratympanal gentamicin has empirically been very effective in treating Menière's disease, the mechanisms of elimination or amelioration of vertigo are still insufficiently understood. Most animal studies investigating the effect of aminoglycosides used high doses that damage or kill hair cells and many other cell types of the inner ear. Additional studies are needed to investigate the effects of low dose gentamicin to elucidate the mechanisms affecting vertigo. In this article it will be explained how disturbances of endolymph homeostasis lead to endolymphatic hydrops and finally to leakage of K(+) from the endolymph into the perilymphatic space. This can lead to a non-physiological activation of vestibular nerve fibres thus causing vertigo.
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Affiliation(s)
- O Gleich
- HNO-Klinik, Universität Regensburg, Regensburg, Germany.
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Karasawa T, Wang Q, Fu Y, Cohen DM, Steyger PS. TRPV4 enhances the cellular uptake of aminoglycoside antibiotics. J Cell Sci 2008; 121:2871-9. [PMID: 18682499 DOI: 10.1242/jcs.023705] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The cochlea and kidney are susceptible to aminoglycoside-induced toxicity. The non-selective cation channel TRPV4 is expressed in kidney distal tubule cells, and hair cells and the stria vascularis in the inner ear. To determine whether TRPV4 is involved in aminoglycoside trafficking, we generated a murine proximal-tubule cell line (KPT2) and a distal-tubule cell line (KDT3). TRPV4 expression was confirmed in KDT3 cells but not in KPT2 cells. Removal of extracellular Ca(2+) significantly enhanced gentamicin-Texas-Red (GTTR) uptake by KDT3, indicative of permeation through non-selective cation channels. To determine whether TRPV4 is permeable to GTTR, stable cell lines were generated that express TRPV4 in KPT2 (KPT2-TRPV4). KPT2-TRPV4 cells took up more GTTR than control cell lines (KPT2-pBabe) in the absence of extracellular Ca(2+). TRPV4-dependent GTTR uptake was abolished by a point mutation within the crucial pore region of the channel, suggesting that GTTR permeates the TRPV4 channel. In an endolymph-like extracellular environment, clearance of GTTR was attenuated from KPT2-TRPV4 cells in a TRPV4-dependent fashion. We propose that TRPV4 has a role in aminoglycoside uptake and retention in the cochlea.
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Affiliation(s)
- Takatoshi Karasawa
- Oregon Hearing Research Center, Oregon Health and Science University, 3181 Sam Jackson Park Road, Portland, OR 97239, USA
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