Altered auditory brainstem responses are post-acute sequela of SARS-CoV-2 (PASC), 2025, Christopher Niemczak et al

[Mij]

Abstract
The Post-acute Sequela of SARS-CoV-2 (PASC) syndrome, also known as Long-COVID, often presents with subjective symptoms such as brain fog and cognitive fatigue. Increased tinnitus, and decreased hearing in noise ability also occur with PASC, yet whether auditory manifestations of PASC are linked with the cognitive symptoms is not known.

Electrophysiology, specifically the Auditory Brainstem Response (ABR), provides objective measures of auditory processing. We hypothesized that ABR findings would be linked to PASC and with subjective feelings of cognitive fatigue.

Eighty-two individuals, 37 with PASC (mean age: 47.5, Female: 83%) and 45 healthy controls (mean age: 38.5, Female: 76%), were studied with an auditory test battery that included audiometry and ABR measures. Peripheral hearing thresholds did not differ between groups. The PASC group had a higher prevalence of tinnitus, anxiety, depression, and hearing handicap in addition to increased subjective cognitive fatigue. ABR latency findings showed a significantly greater increase in the wave V latency for PASC subjects when a fast (61.1 clicks/sec) compared to a slow click (21.1 clicks/sec) was used.

The increase in latency correlated with cognitive fatigue scores and predicted PASC status. The ABR V/I amplitude ratio was examined as a measure of central gain. Although these ratios were not significantly elevated in the full PASC group, to minimize the cofounding effect of age, the cohort was median split on age. Elevated V/I amplitude ratios were significant predictors of both predicted PASC group classification and cognitive fatigue scores in the younger PASC subjects compared to age-matched controls providing evidence of elevated central gain in younger individuals with PASC.

More frequent tinnitus also significantly predicted higher subjective cognitive fatigue scores.

Our findings suggest that PASC may alter the central auditory pathway and lead to slower conduction and elevated auditory neurophysiology responses at the midbrain, a pattern associated with the typical aging process.

This study marks a significant stride toward establishing an objective measure of subjective cognitive fatigue through assessment of the central auditory system.
LINK

 

[Mij]

I had this test done 2 years after ME onset but it was not an issue for me.

 

[Creekside]

It sounds like an interesting approach. I think ME alters neural function individualistically, so averaging out large numbers of responses would dilute abnormalities. Maybe the right mathematical processing could reveal something interesting ... or just reveal interesting random patterns that someone will make a big fuss about.

 

[Eleanor]

Data collection took place in 2021–2022 at a point in the pandemic when it became increasingly difficult to find individuals who had never had COVID-19; thus, we cannot rule out that the individuals in the control group have other characteristics that differentiate them from those who contracted the illness.

 

[Eleanor]

Our study aligns with other’s showing significant effects on wave latencies compared to controls, indicating potential brainstem dysfunction16,17,53. This supports the hypothesis that persistent brainstem dysfunction may contribute to PASC, given the brainstem’s vulnerability to SARS-CoV-2 infection and its role in regulating various physiological processes54. Subtle delays in neural transmission within the brainstem could have severe downstream consequences.

Ref 16 is https://www.cambridge.org/core/jour...aring-system/17853CF0327CD3181FF8A8121C8CB75C

Ref 17 is https://www.sciencedirect.com/science/article/pii/S0196070922000552?via=ihub

Ref 53 is https://ejo.springeropen.com/articles/10.1186/s43163-024-00612-6

Ref 54 is https://pubs.acs.org/doi/10.1021/acschemneuro.0c00793

 

[Yann04]

Our findings suggest that PASC may alter the central auditory pathway and lead to slower conduction and elevated auditory neurophysiology responses at the midbrain, a pattern associated with the typical aging process.

Is this a possible factor in sound intolerance. I really have no clue what this article is saying but this jumble of words sounds relevant.