Middle Ear Pressure Assessment to Detect the Stapedius Reflex: A Prospective Observational Feasibility Study

To evaluate the feasibility of detecting stapedius reflex (SR) through direct middle ear pressure monitoring during contralateral acoustic stimulation.

Prospective, observational, single-centre feasibility study.

Tertiary referral centre; intraoperative setting during tympanotomy procedures.

Eleven adult patients (≥18 y) with unilateral sudden sensorineural hearing loss undergoing transtympanic dexamethasone instillation, with an elicitable SR through contralateral stimulation, were included in this study. Patients with SR thresholds >100 dB HL were excluded.

A pressure transducer was inserted intraoperatively into the middle ear. A tympanometer device on the contralateral side apply acoustic stimulation and monitored the SR on that side. Stimulation was ECG-synchronized, and filtering was applied to the pressure signal to enhance detection.

Detection of SR-related pressure changes using the pressure transducer, compared with tympanometry-based detection.

Out of 32 stimulus combinations, 24 elicited confirmed stapedius reflexes, while 8 did not. Among the 24 reflex-positive cases, the pressure-based method correctly identified reflex-related pressure changes in 20 instances, yielding a detection accuracy of 83.3% for confirmed reflexes. In the remaining 4 reflex-positive cases, the system failed to detect a response. In all 8 cases where no reflex was elicited, the system also did not detect any pressure changes, indicating no false positives.

Middle ear pressure monitoring is a feasible method for detecting SR. This approach demonstrates feasibility under intraoperative conditions and may, with further development and validation, support future objective reflex assessment in cochlear implant users.