Inner ear pressure changes following square wave intracranial or ear canal pressure manipulation in the same guinea pig

Thalen, Elisabeth; Wit, H. P.; Segenhout, Hans M.; Albers, F. W. J.

doi:10.1007/s00405-001-0431-0

Cited by 12 publications

(8 citation statements)

References 19 publications

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“…The dependence on inner ear volume was explained by round window membrane position influencing aqueduct flow resistance (Wit et al 2003). The study also indicated that aqueduct flow resistance does not depend on flow direction, in contrast with evidence from earlier research (Densert et al 1981;Carlborg et al 1982;Thalen et al 2001Thalen et al , 2002.…”

Section: Introductioncontrasting

confidence: 93%

“…Because it was found that RC is not constant during inner ear pressure recovery after a change of inner ear pressure (Thalen et al 2002), we restricted our analysis to the first part of the recovery curves, immediately following a middle ear pressure step (at t 0 ). A horizontal line was fitted to the part of the measured p i curves preceding t 0 , to obtain a value for p 1 (see Fig.…”

Section: Feijen Et Al: Round Window and Aqueduct Flow 405mentioning

confidence: 99%

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Cochlear Aqueduct Flow Resistance Depends on Round Window Membrane Position in Guinea Pigs

Feijen¹,

Segenhout²,

Albers³

et al. 2004

JARO

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The resistance for fluid flow of the cochlear aqueduct was measured in guinea pigs for different positions of the round window membrane. These different positions were obtained by applying different constant pressures to the middle ear cavity. Fluid flow through the aqueduct was induced by small pressure steps superimposed on these constant pressures. It was found that the resistance for fluid flow through the aqueduct depended on the round window position but not on flow direction. The results can be explained by special fibrous structures that connect the round window with the entrance of the aqueduct. It was also found that the equilibrium inner ear pressure depends on middle ear pressure, indicating that the aqueduct does not connect the inner ear with a cavity with constant pressure.

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Section: Introductioncontrasting

confidence: 93%

Section: Feijen Et Al: Round Window and Aqueduct Flow 405mentioning

confidence: 99%

Cochlear Aqueduct Flow Resistance Depends on Round Window Membrane Position in Guinea Pigs

Feijen¹,

Segenhout²,

Albers³

et al. 2004

JARO

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show abstract

“…The frequencies of 2 and 4 Hz used in our experiments are notably below the helicotrema cutoff frequency in guinea pigs (Marquardt et al, 2007 ) and will be filtered out by the helicotrema, preventing BM excitation at these frequencies and damage to the cochlear sensory cells during the RW probe stimulation. The role of the cochlear aqueduct in pressure relief at frequencies 2−4 Hz, used to vibrate the RW in our experiments, should be small because the time constant for inner ear pressure relaxation due to the cochlear aqueduct is in the order of seconds (Thalen et al, 2002 ; Feijen et al, 2004 ). The potential influence of mass and viscosity of a relatively large volume of fluid placed on the RW in our experiments should also be small.…”

Section: Discussionmentioning

confidence: 99%

Drug distribution along the cochlea is strongly enhanced by low-frequency round window micro vibrations

2021

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The cochlea’s inaccessibility and complex nature provide significant challenges to delivering drugs and other agents uniformly, safely and efficiently, along the entire cochlear spiral. Large drug concentration gradients are formed along the cochlea when drugs are administered to the middle ear. This undermines the major goal of attaining therapeutic drug concentration windows along the whole cochlea. Here, utilizing a well-known physiological effect of salicylate, we demonstrate a proof of concept in which drug distribution along the entire cochlea is enhanced by applying round window membrane low-frequency micro vibrations with a probe that only partially covers the round window. We provide evidence of enhanced drug influx into the cochlea and cochlear apical drug distribution without breaching cochlear boundaries. It is further suggested that ossicular functionality is not required for the effective drug distribution we report. The novel method presented here of local drug delivery to the cochlea could be implemented when ossicular functionality is absent or impeded and can be incorporated in clinically approved auditory protheses for patients who suffer with conductive, sensorineural or mixed hearing loss.

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“…The assumptions (a), (b), and (c) of the pistonphone do not apply to the external auditory canal. Thalen et al (2002) measured the inner ear pressure in the scala tympani with a micropipette during square wave pressure manipulation of the intracranial compartment of a guinea pig, and subsequently, of the external ear canal in the same animal. As expected, the combination of the cochlear aqueduct and the inner ear behaves as a low-pass filtering system for intracranial pressure manipulation and as a complementary high-pass system for ear canal pressure manipulation.…”

Section: Rationalementioning

confidence: 99%

Transfer function for vital infrasound pressures between the carotid artery and the tympanic membrane

Kenji

Yamashita

2013

The Journal of the Acoustical Society of America

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While occupational injury is associated with numerous individual and work-related risk factors, including long working hours and short sleep duration, the complex mechanisms causing such injuries are not yet fully understood. The relationship between the infrasound pressures of the tympanic membrane [ear canal pressure (ECP)], detected using an earplug embedded with a low-frequency microphone, and the carotid artery [carotid artery pressure (CAP)], detected using a stethoscope fitted with the same microphone, can be quantitatively characterized using systems analysis. The transfer functions of 40 normal workers (19 to 57 years old) were characterized, involving the analysis of 446 data points. The ECP waveform exhibits a pulsatile character with a slow respiratory component, which is superimposed on a biphasic recording that is synchronous with the cardiac cycle. The respiratory ECP waveform correlates with the instantaneous heart rate. The results also revealed that various fatigue-related risk factors may affect the mean magnitudes of the measured pressures and the delay transfer functions between CAP and ECP in the study population; these factors include systolic blood pressure, salivary amylase activity, age, sleep duration, postural changes, chronic fatigue, and pulse rate.

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Inner ear pressure changes following square wave intracranial or ear canal pressure manipulation in the same guinea pig

Cited by 12 publications

References 19 publications

Cochlear Aqueduct Flow Resistance Depends on Round Window Membrane Position in Guinea Pigs

Cochlear Aqueduct Flow Resistance Depends on Round Window Membrane Position in Guinea Pigs

Drug distribution along the cochlea is strongly enhanced by low-frequency round window micro vibrations

Transfer function for vital infrasound pressures between the carotid artery and the tympanic membrane

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