LXX The Effects of Anesthetics upon the Ear II. Procaine Hydrochloride

Rahm, Walter E.; Strother, William F.; Gulick, W. L.; Crump, J. F.

doi:10.1177/000348946006900402

Cited by 24 publications

(9 citation statements)

References 4 publications

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“…Antibiotics (20 -28), antiseptics, arachidonic acid metabolites (29), local anesthetics (30,31), toxins (32 -38) and albumin (19,(39)(40)(41), when placed in the round window niche, can either be recovered in perilymph or observed to cause inner ear changes, such as hair cell damage. Morphologic demonstration that passage of substances from the middle to the inner ear can occur through the membrane has been provided by reports of passage of cationic ferritin (Figs.…”

Section: Permeabilitymentioning

confidence: 99%

Clinical Aspects of Round Window Membrane Permeability Under Normal and Pathological Conditions

Goycoolea

2001

Acta Oto-Laryngologica

199

168

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Current research and an overall review of 25 years of round window membrane studies are presented. The approach, rationale and concepts that have evolved from these studies are described. Ultrastructural studies of the round window membrane of humans, monkeys, felines and rodents have disclosed three basic layers: an outer epithelium, a middle core of connective tissue and an inner epithelium. Interspecies variations are mainly in terms of thickness, being thinnest in rodents and thickest in humans. Morphologic evidence suggests that the layers of the round window participate in resorption and secretion of substances to and from the inner ear, and that the membrane could play a role in the defense system of the ear. Different substances, including antibiotics and tracers, when placed in the middle ear side traverse the membrane. Tracers placed in perilymph become incorporated into the membrane by the inner epithelial cells. Permeability is selective and factors affecting permeability include size, concentration, electrical charge, thickness of the membrane and tacilitating agents. Passage of substances through the membrane is by different pathways, the nature of which is seemingly decided at the outer epithelium of the membrane. Round window membrane studies have provided increased knowledge of the anatomy and function of this structure, as well as new insights into pathology and pathogenesis. The concepts that have evolved from these studies are potentially useful for understanding middle and inner ear interactions, and for eventual drug delivery (based on permeability) to the inner ear.

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Section: Permeabilitymentioning

confidence: 99%

Clinical Aspects of Round Window Membrane Permeability Under Normal and Pathological Conditions

Goycoolea

2001

Acta Oto-Laryngologica

199

168

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“…A number of diffusion studies have indicated the permeability of the round window membrane to such sub¬ stances as isotopes,4·5 antibiotics,6-' anesthetics, [8][9] proteins,1011 and tox¬ ins.12 Since the thickness of the round window membrane may affect its ability to act as a barrier between the middle and inner ear, a study deter¬ mining the thickness of the normal round window membrane is essential.…”

mentioning

confidence: 99%

Thickness of the Human Round Window Membrane in Different Forms of Otitis Media

Sahni¹,

Paparella²,

Schachern³

et al. 1987

Archives of Otolaryngology - Head and Neck Surgery

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\s=b\The thickness and morphologic characteristics of the round window membrane were evaluated in temporal bones from normal subjects as well as those with serous otitis media, purulent otitis media, and chronic otitis media. Temporal bones were studied in chronological order in six age ranges to determine the possibility of age-related differences. No significant difference in the mean thickness of the round window membrane was observed in terms of age groups in normal temporal bones or temporal bones from patients with otitis media; however, a significant difference in the mean thickness was observed in the various forms of otitis media compared with the normal round window membrane in all age groups. The membrane was thickest in patients with chronic otitis media when compared with that in normal subjects or those with serous or purulent otitis media. The epithelial layer (including the subepithelial space) and the fibrous layer were measured individually to determine in which layer the change in mean thickness occurred. These measurements showed an involvement of all layers of the round window membrane in those groups with otitis media, with maximal involvement of the combined epithelial layer and subepithelial space. (Arch Otolaryngol Head Neck Surg 1987;113:630-634) The physiologic role of the round window membrane as a phase dif¬ ferential in permitting labyrinthine fluid to move under the influence of the stapes is widely accepted.13 It is the process of diffusion through the round window membrane, however, that has attracted the attention of

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“…A previous study 8 shows that long term exposure of the middle ear cavity does not significantly change the cochlear potential. After the stability of the response was assured, tetracaine hydrochloride (2 per cent) was applied to the round window membrane by means of a small nylon tube affixed to a hypodermic needle on a 1 cc syringe.…”

Section: Methodsmentioning

confidence: 82%

XXXI The Effects of Anesthetics upon the Ear

Rahm¹,

Strother²,

Gulick³

et al. 1961

Ann Otol Rhinol Laryngol

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In earlier papers 7,8 it was pointed out that the use of topical anesthetics is considered by many surgeons to be a suitable method for anesthetizing structures of the ear during surgery. The favorable conditions accompanying the use of topical anesthesia have been dis cussed by Pitkin 5 and Goodman and Gillman. 3 Among the favorable conditions which they discuss, the fact that the action of topical anesthetics is reversible and is followed by complete recovery is especially critical. It is clear that any topical anesthetic which ad versely affects the sensitive structures of the cochlea is totally unsuited for otological surgery. Whereas Goodman and Gillman 3 specifically point out that the action of local anesthetic drugs is followed by complete recovery of nerve function with no evident structural dam age to nerve fibers or adjacent cells, data obtained in this laboratory indicate that a number of topical anesthetics produce very serious disruptions of the normal functioning of the cochlea when these drugs are applied to middle ear structures. The major effect noted involves a reduction in the magnitude of the electrical response of the cochlea. These losses have very serious implications for hearing.The manner in which the cochlea transduces acoustical energy so as to stimulate the auditory nerve has been a source of speculation for many years. However, many auditory theorists have come to believe that the electrical response of the cochlea directly triggers the auditory nerve. 1 · 2 · 4 · 0 · 10 According to the electrical hypothesis of audi tory nerve stimulation, any reduction in the magnitude of the cochlear response cannot help but have deleterious effects upon hearing. Ex perimental evidence is now available to show that the magnitude

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LXX The Effects of Anesthetics upon the Ear II. Procaine Hydrochloride

Cited by 24 publications

References 4 publications

Clinical Aspects of Round Window Membrane Permeability Under Normal and Pathological Conditions

Clinical Aspects of Round Window Membrane Permeability Under Normal and Pathological Conditions

Thickness of the Human Round Window Membrane in Different Forms of Otitis Media

XXXI The Effects of Anesthetics upon the Ear

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