Abstract
Pneumatic otoscopy to assess the mobility of the tympanic membrane (TM) is a highly recommended diagnostic method of otitis media (OM), a widespread middle ear infection characterized by the fluid accumulation in the middle ear. Nonetheless, limited depth perception and subjective interpretation of small TM displacements have challenged the appropriate and efficient examination of TM dynamics experienced during OM. In this paper, a pneumatic otoscope integrated with low coherence interferometry (LCI) was adapted with a controlled pressure-generating system to record the pneumatic response of the TM and to estimate middle ear pressure (MEP). Forty-two ears diagnosed as normal (n = 25), with OM (n = 10), or associated with an upper respiratory infection (URI) (n = 7) were imaged with a pneumatic LCI otoscope with an axial, transverse, and temporal resolution of 6 µm, 20 µm, and 1 msec, respectively. The TM displacement under pneumatic pressure transients (a duration of 0.5 sec with an intensity of ± 150 daPa) was measured to compute two metrics (compliance and amplitude ratio). These metrics were correlated with peak acoustic admittance and MEP from tympanometry and statistically compared via Welch's t-test. As a result, the compliance represents pneumatic TM mobility, and the amplitude ratio estimates MEP. The presence of a middle ear effusion (MEE) significantly decreased compliance (p<0.001). The amplitude ratio of the OM group was statistically less than that of the normal group (p<0.01), indicating positive MEP. Unlike tympanometry, pneumatic LCI otoscopy quantifies TM mobility as well as MEP regardless of MEE presence. With combined benefits of pneumatic otoscopy and tympanometry, pneumatic LCI otoscopy may provide new quantitative metrics for understanding TM dynamics and diagnosing OM.
Highlights
Otitis media (OM), a middle ear infection, is a ubiquitous disease in early childhood, where more than 80% of children in the United States experience at least one infection before the age of 3 [1,2,3]
One identifying feature of OM is the accumulation of fluid in the middle ear cavity, known as a middle ear effusion (MEE), which contributes to the reduced mobility of the tympanic membrane (TM) [4]
The pneumatic low coherence interferometry (LCI) data sets and tympanograms were acquired from 42 ears from 30 pediatric subjects
Summary
Otitis media (OM), a middle ear infection, is a ubiquitous disease in early childhood, where more than 80% of children in the United States experience at least one infection before the age of 3 [1,2,3]. One identifying feature of OM is the accumulation of fluid in the middle ear cavity, known as a middle ear effusion (MEE), which contributes to the reduced mobility of the tympanic membrane (TM) [4]. To determine the presence of a MEE, examining TM mobility with a pneumatic otoscope is strongly recommended by the American Academy of Pediatrics, the American Academy of Otolaryngology – Head and Neck Surgery Foundation, and the American Academy of Family Physicians [5,6,7], as the diagnostic accuracy based solely on the visible features of the TM, such as color, transparency, and opacity, varies widely [8]. A sensitivity of 94% in detecting MEEs was determined for pneumatic otoscopy, again validating an importance of evaluating TM mobility during a clinical examination [9]. Since pneumatic otoscopy has been identified as a key tool to establish a diagnosis of OM, there is a greater need for an enhanced pneumatic device that can quantify TM mobility to provide objective and valuable information to physicians for improved diagnosis and management of OM
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