Cortical pattern of reduced perfusion in hearing loss revealed by ASL‐MRI

Abstract

Age‐related hearing loss (HL) can be related to brain dysfunction or structural damage and may result in cerebral metabolic/perfusion abnormalities. Arterial spin labeling (ASL) magnetic resonance imaging (MRI) allows investigating noninvasively brain perfusion changes. Pseudocontinuous ASL and T1‐weighted MRI (at 3 T) and neuropsychological testing (Montreal Cognitive Assessment) were performed in 31 HL (age range = 47–77 years, mean age ± SD = 63.4 ± 8.4 years, pure‐tone average [PTA] HL > 50 dB) and 28 normal hearing (NH; age range = 48–78 years, mean age ± SD = 59.7 ± 7.4 years) subjects. Cerebral blood flow (CBF) and gray matter volume (GMV) were analyzed in the cortical volume to assess perfusion and structural group differences. Two HL subjects showing cognitive impairment were excluded from group comparisons. No significant differences in either global or local atrophy were detected between groups but the HL group exhibited significant regional effects of reduced perfusion within the bilateral primary auditory cortex, with maximal CBF difference (−17.2%) in the right lateral Heschl's gyrus. For the whole sample of HL and NH subjects (n = 59 = 31 HL + 28 NH), the regional CBF was correlated positively to the regional GMV (p = 0.020). In HL subjects (n = 31), the regional CBF was correlated negatively to the audiogram steepness (frequency range: 2–4 kHz, right ear: p = 0.022, left ear: p = 0.015). The observed cortical pattern of perfusion reduction suggests that neuronal metabolism can be related to HL before the recognition of brain structural damage. This also illustrates the potential of ASL‐MRI to contribute early functional markers of reduced central processing associated with HL.

A Proposed Hypothesis on Dementia: Inflammation, Small Vessel Disease, and Hypoperfusion Is the Sequence That Links All Harmful Lifestyles to Cognitive Impairment

“… Windsor and Ruckenstein (2018) , in fact suggested that anti-inflammatory therapies may reduce sensorineural hearing loss. In addition, a study by Ponticorvo et al (2019) showed that there was reduced cerebral perfusion in patients with hearing loss detectable prior to brain structural damage. This is not to deny that the disconnection from the auditory environment that hearing deficit implies may also play a role in inducing cognitive deficit, since those using hearing aids reduce their risk for cognitive decline ( Amieva et al, 2018 ; Maharani et al, 2018 ), but hearing deficit may fit into the hypothesis presented here better than suspected.…”

Hearing Loss and Cognitive Impairment: Epidemiology, Common Pathophysiological Findings, and Treatment Considerations

“…This The arterial spin labelling magnetic resonance imaging, instead, analyses cerebral perfusion in vivo and allows non-invasive investigation of brain perfusion changes. This technique revealed that perfusion within the bilateral primary auditory cortex in patients with hearing impairment is reduced, especially in the right lateral Heschl's gyrus, a critical area for auditory processing and which is also involved in many other cognitive skills [44].…”

Neuropsychological profile of hearing-impaired patients and the effect of hearing aid on cognitive functions: an exploratory study

“…Usually, HL seems to speed up cognitive decline through the combination of social and sensory isolation and through an increased cognitive load 13 . Indeed, peripheral HL decreases local cerebral blood flow in primary auditory cortex 14 and it is associated with decreased volumes in the auditory cortex, temporal lobe and whole brain, and also with a functional reorganization of the auditory cortical networks, consistent with more demanding listening and a reduction of cognitive reserve 13 . Furthermore, a reduction of perfusion in primary auditory cortex has been found by ASL-MRI in patients affected by HL in the early stages, suggesting that there is a relationship between HL and cortical activation/metabolism, even if no atrophy was found 14 .…”