Review Showcases Inconsistencies in MS Auditory, Vestibular Research
While studies show abnormalities, more evidence about MS's effects on both systems are needed, researchers said
Abnormalities in the auditory and vestibular systems, which control hearing and balance, are frequently reported among people with multiple sclerosis (MS), a new study found.
However, there is a substantial amount of variability in scientific studies that assess these abnormalities, making it difficult to draw an overarching conclusion about how these systems are typically affected.
“This systematic review clearly demonstrates that both peripheral and central audio-vestibular functions may be affected by [MS lesions] and by the MS inflammatory process. This suggests that a comprehensive audio-vestibular test battery should be incorporated in the assessment protocols of [people with] MS,” researchers wrote.
The review paper, “Effects of multiple sclerosis on the audio-vestibular system: a systematic review,” was recently published in BMJ Open.
In MS, inflammation in the central nervous system causes damage to nerve fibers, interfering with normal neurological signaling. Depending on which parts of the nervous system are affected, this can give rise to a wide range of disease symptoms.
Three scientists in the U.K. reviewed scientific studies published from 2000 to 2021 in order to assess how MS tends to affect the auditory and vestibular systems.
“Literature needs to be combined and summarised to better understand the potential effects of MS on the auditory and/or vestibular systems. If auditory and/or vestibular disorders in [people with] MS are better understood, early identification and early intervention could occur, resulting in improved quality of life,” the researchers wrote.
Their review included 35 studies: 14 assessed only the auditory system, 18 only the vestibular system, and three evaluated both.
Across the 17 studies that assessed the auditory system, over half a dozen different assessments were used to evaluate auditory involvement. For some specific assessments, there were generally consistent trends — in particular, 12 out of 13 studies that assessed auditory brainstem responses (ABR) showed significant abnormalities for people with MS. The researchers suggested that ABR should be included in auditory test batteries for MS.
For most other auditory assessments, however, the results were less clear, with some studies showing differences among MS patients, while others revealed no difference. The wide variation in study designs and assessment strategies made it impossible to draw reliable conclusions from the available data.
“The specific effects of MS on the auditory system, based on the results of auditory tests included in this systematic review, could not be established,” the scientists concluded.
Results for the vestibular system were generally more consistent. Nearly all the studies found vestibular abnormalities of some kind in MS patients, suggesting “that the vestibular system may be more affected by MS than the auditory system,” the researchers said.
Again however, there was substantial variation from study to study in terms of design and the tests used to assess vestibular impairment, making it difficult to draw generalized conclusions and underscoring a need for further, more uniform research, the scientists said.
“Although abnormal results in [people with] MS on both auditory and vestibular tests were identified, further studies are necessary to quantify this effect and obtain more robust evidence on the effects of MS on the auditory and vestibular systems,” they concluded.