Characteristics of Mid-Frequency Sensorineural Hearing Loss Progression

Area of Science:

• Audiology and Neurotology
• Hearing Science

Background:

• Mid-frequency sensorineural hearing loss (MFSNHL), also known as "cookie bite hearing loss," is an uncommon audiometric finding.
• The long-term progression and outcomes of MFSNHL are not well-characterized.

Purpose of the Study:

• To characterize the progression of MFSNHL over time.
• To determine the clinical significance of hearing threshold changes in patients with MFSNHL.

Main Methods:

• Retrospective chart review of 37 patients diagnosed with MFSNHL between 2012 and 2017.
• MFSNHL defined by audiometry showing a 1, 2, and 4 kHz average threshold >10 dB greater than the average threshold at 500 Hz and 8 kHz.
• Analysis of audiometric data, including serial audiograms for 23 patients with a median follow-up of 4 years.

Main Results:

• The average age at presentation was 11.8 years, with an average mid-frequency threshold of 47 dB.
• Across all frequencies, the average threshold on the initial audiogram was 37 dB, compared to 39 dB on the final audiogram.
• Only 5 out of 23 patients with serial audiograms showed threshold changes of 10 dB or more, and only one experienced clinical worsening.

Conclusions:

• MFSNHL is generally a stable hearing condition with minimal progression observed over a median follow-up of 4 years.
• The vast majority of patients (96%) with MFSNHL do not experience clinically significant worsening of their hearing.
• Further prospective studies with longer follow-up are needed to fully understand the long-term trajectory of MFSNHL.