Clinical Utility of Laser-Doppler Vibrometer Measurements in Live Normal and Pathologic Human Ears

Abstract

The laser-Doppler vibrometer (LDV) is a research tool that can be used to quickly measure the soundinduced velocity of the tympanic membrane near the umbo (the inferior tip of the malleus) in live human subjects and patients. In this manuscript we demonstrate the LDV to be a sensitive and selective tool for the diagnosis and differentiation of various ossicular disorders in patients with intact tympanic membranes and aerated middle ears. Patients with partial or total ossicular interruption or malleus fixation are readily separated from normal-hearing subjects with the LDV. The combination of LDV measurements and air-bone gap can distinguish patients with fixed stapes from those with normal ears. LDV measurements can also help differentiate air-bone gaps produced by ossicular pathologies from those associated with pathologies of inner-ear sound conduction such as a superior semicircular canal dehiscence.The key audiological tool for defining conductive hearing loss is the air-bone gap, which is the difference between air-conducted and bone-conducted hearing levels. The pathology associated with such gaps may, in certain cases, be readily observable during otoscopic examination, for example, cerumen impaction, perforations of the tympanic membrane (TM), acute otitis media, chronic otitis media, etc. However, the diagnosis of the precise pathology causing a conductive hearing loss in patients with an intact TM is difficult, and conclusive diagnosis is often only made at the time of exploratory middle ear surgery.Although there are tools available for presurgical diagnosis of such disorders, they have imperfect selectivity and sensitivity. Tympanometry and acoustic-reflex testing, in conjunction with audiometry, are sensitive to different ossicular disorders (Jerger, 1975;Margolis & Shanks, 1985), for example (1) a normal tympanogram coupled with a lack of ipsilateral acoustic reflex and a significant air-bone gap that is either flat or upward sloping with increasing frequency is usually associated with stapes fixation. (2) A hypomobile tympanogram with a loss of reflex thresholds and a mild to moderate conductive loss is often associated with malleus fixation. (3) A hyper-mobile tympanogram with a loss of ipsilateral reflex and either a 50-dB flat or downward sloping conductive loss is usually associated with either a total or partial ossicular disarticulation.A major problem with the above scheme is that standard single-frequency (226 Hz) tympanometry is relatively insensitive to ossicular disorders and many ears with fixed or Address for correspondence: John Rosowski, Eaton-Peabody Lab, Massachusetts Eye & Ear Infirmary, 243 Charles Street, Boston, MA 02114. E-mail: John_Rosowski@meei.harvard.edu. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript interrupted ossicular chains are not reliably differentiated by this technique. The selectivity and sensitivity of tympanometry to ossicular disorders can be improved by measurements at multiple frequencies (Lily, 1984;...

Conductive Hearing Loss Caused by Third-Window Lesions of the Inner Ear

“…Vestibular evoked myogenic potential and OAE responses are typically absent in patients with true middle ear disease but may be present in third-window lesions (9)(10)(11)13,15). Measurement of umbo velocity by laser Doppler vibrometry can also help to differentiate lesions of the middle ear from the inner ear in patients with CHL (11,21,28). Vestibular manifestations comprising sound-induced or pressure-induced vertigo and eye movements may be evident in third-window lesions caused by canal dehiscences.…”

“…We have conducted a series of studies to investigate the mechanisms by which an air-bone gap arises in SCD, including theoretic model analyses (17,22), experimental measurements in a cadaveric human temporal bone preparation (21), experiments in a chinchilla model of SCD (17)(18)(19), and measurements of middle ear sound transmission in patients with SCD (11,17,21,28). These investigations have provided strong evidence to support the pathologic thirdwindow hypothesis in SCD.…”

Wave motion on the surface of the human tympanic membrane: Holographic measurement and modeling analysis

“…A technique that measures both the magnitude and phase angle of TM motion is laser Doppler vibrometry (LDV). LDV has been used repeatedly to measure the sound-induced motion at specific locations on the TM surface, such as the umbo, over a wide frequency range (0.1 to 20 kHz) (e.g., Decraemer et al 1989;Goode et al, 1993Goode et al, , 1994Goode et al, , 1996Gan et al, 2004;Rosowski et al, 2008). These results provide more quantitative views of a vibrating TM: The displacement magnitude of the TM at the umbo varies with frequency and peaks around 1 kHz while the phase angle of the displacement and stimulus sound pressure is near 0 up to about 1 kHz and then decreases with increasing frequency.…”

Investigation of middle ear anatomy and function with combined video otoscopy-phase sensitive OCT

“…However, since they require direct access to the middle ear bones, a surgical incision in the TM is needed for the examination. Both LDV and laser holography are usually combined with audiometry to enable a more complete assessment of the hearing sensitivity [11,12].…”