Objectification and Differential Diagnosis of Vascular Pulsatile Tinnitus by Transcanal Sound Recording and Spectrotemporal Analysis: A Preliminary Study

Abstract

Objective: Although frequently classified as "objective tinnitus," in most cases vascular pulsatile tinnitus (VPT) is not equal to objective tinnitus because it is not easy to objectively document VPT. The present study was conducted to develop a novel transcanal sound recording and spectrotemporal analysis method for the objective and differential diagnosis of VPT.

Study design: A case series with a control group.

Setting: Tertiary referral center.

Patients: Six VPT subjects with radiological abnormalities and six normal controls.

Interventions and main outcome measure: The method was tested based on recordings obtained from the ipsilateral external auditory canal (EAC) using an insert microphone with the subject's head in four different positions. The recorded signals were first analyzed in the time domain, and short-time Fourier transform was performed to analyze the data in the time-frequency domain.

Results: From the temporal analysis, the ear canal signals recorded from the VPT subjects exhibited large peak amplitudes and periodic structures, whereas the signals recorded from the control subjects had smaller peak amplitudes and weaker periodicity. From the STA represented by two-dimensional spectrograms and three-dimensional waterfall diagrams, all of the VPT subjects demonstrated pulse-synchronous acoustic characteristics that were representative of their respective presumptive vascular pathologies, whereas the control subjects did not display such characteristics.

Conclusion: The present diagnostic approach may provide additional information regarding the origins of VPT cases as well as an efficient and objective diagnostic method. Furthermore, this approach may aid in the determination of appropriate imaging modalities, treatment planning, and evaluation of treatment outcomes.