Preventing hearing damage using topical dexamethasone during reversible cochlear ischemia: An animal model

Krzysztof Morawski, Fred F Telischi, Jorge Bohorquez, Kazimierz Niemczyk

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

HYPOTHESIS: Local application of dexamethasone to the round window (RW) niche prevents cochlear damage caused by local reversible ischemia. BACKGROUND: Cochlear ischemia induced by internal auditory artery (IAA) compression/ stretching is thought to cause postoperative sensory hearing loss after attempted hearing preservation removal of acoustic neuroma tumors. Dexamethasone administered to the RW niche traveling through the membrane to the cochlear fluids may prevent ischemic damage. MATERIALS AND METHODS: Ten young albino rabbits were used for this study. Ischemic episodes were induced by compressing the IAA. Laser Doppler cochlear blood flow was measured using a probe positioned at the RW niche. Transtympanic electrocochleography was measured at 4, 8, and 12 kHz. In 5 test ears, dexamethasone was administered topically at the RW for approximately 50 minutes before the IAA compressions, whereas in 5 control ears, saline was applied in the same way. Each ear underwent one 10-minute IAA compression with a 60-minute postischemic period of transtympanic electrocochleography monitoring. RESULTS: In both control- and dexamethasone-treated ears, ischemic episodes measured by Laser Doppler cochlear blood flow were comparable. Fifty minutes after IAA decompression, in dexamethasone-pretreated ears, cochlear microphonic and compound action potential amplitudes at all test frequencies were 10 to 15% less reduced than those in control ears. Compound action potential latencies in dexamethasone-pretreated ears resulted in shorter latency delay than in control ears. CONCLUSION: The RW seems to be an efficacious route for the administration of dexamethasone into the inner ear. Dexamethasone showed a protective effect on cochlear function after local ischemia. Transtympanic electrocochleography was found to be a sufficient and effective tool in monitoring hearing.

Original languageEnglish
Pages (from-to)851-857
Number of pages7
JournalOtology and Neurotology
Volume30
Issue number6
DOIs
StatePublished - Sep 1 2009

Fingerprint

Cochlea
Dexamethasone
Hearing
Ear
Ischemia
Animal Models
Evoked Response Audiometry
Arteries
Acoustic Neuroma
Action Potentials
Lasers
Inner Ear
Decompression
Hearing Loss
Rabbits
Membranes

Keywords

  • Cochlear blood flow
  • Cochlear ischemia
  • Cochlear potentials
  • Cochlear reperfusion
  • Dexamethasone
  • Electrocochleography

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Clinical Neurology
  • Sensory Systems

Cite this

Preventing hearing damage using topical dexamethasone during reversible cochlear ischemia : An animal model. / Morawski, Krzysztof; Telischi, Fred F; Bohorquez, Jorge; Niemczyk, Kazimierz.

In: Otology and Neurotology, Vol. 30, No. 6, 01.09.2009, p. 851-857.

Research output: Contribution to journalArticle

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abstract = "HYPOTHESIS: Local application of dexamethasone to the round window (RW) niche prevents cochlear damage caused by local reversible ischemia. BACKGROUND: Cochlear ischemia induced by internal auditory artery (IAA) compression/ stretching is thought to cause postoperative sensory hearing loss after attempted hearing preservation removal of acoustic neuroma tumors. Dexamethasone administered to the RW niche traveling through the membrane to the cochlear fluids may prevent ischemic damage. MATERIALS AND METHODS: Ten young albino rabbits were used for this study. Ischemic episodes were induced by compressing the IAA. Laser Doppler cochlear blood flow was measured using a probe positioned at the RW niche. Transtympanic electrocochleography was measured at 4, 8, and 12 kHz. In 5 test ears, dexamethasone was administered topically at the RW for approximately 50 minutes before the IAA compressions, whereas in 5 control ears, saline was applied in the same way. Each ear underwent one 10-minute IAA compression with a 60-minute postischemic period of transtympanic electrocochleography monitoring. RESULTS: In both control- and dexamethasone-treated ears, ischemic episodes measured by Laser Doppler cochlear blood flow were comparable. Fifty minutes after IAA decompression, in dexamethasone-pretreated ears, cochlear microphonic and compound action potential amplitudes at all test frequencies were 10 to 15{\%} less reduced than those in control ears. Compound action potential latencies in dexamethasone-pretreated ears resulted in shorter latency delay than in control ears. CONCLUSION: The RW seems to be an efficacious route for the administration of dexamethasone into the inner ear. Dexamethasone showed a protective effect on cochlear function after local ischemia. Transtympanic electrocochleography was found to be a sufficient and effective tool in monitoring hearing.",
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