# Functional Changes in the Glymphatic System in Children With Sensorineural Hearing Loss: A Study of Diffusion Tensor Imaging

## TL;DR

This study shows that children with hearing loss, especially those over 3 years old, may have impaired brain waste clearance systems, as seen through advanced imaging techniques.

## Contribution

The study introduces the use of DTI-ALPS and FW mapping to assess glymphatic function in children with sensorineural hearing loss.

## Key findings

- Children with SNHL had significantly lower ALPS indices in both brain hemispheres compared to healthy controls.
- Older children with SNHL showed higher free-water volume in white matter, linked to reduced glymphatic function.
- The left-hemisphere ALPS index was significantly lower in younger SNHL children compared to healthy peers.

## Abstract

Diffusion tensor imaging‐analysis along the perivascular space (DTI‐ALPS) indicators and free‐water (FW) mapping derived from diffusion tensor imaging (DTI) data have been proposed as noninvasive markers of glymphatic system (GS) function. This study aimed to investigate GS function in children with sensorineural hearing loss (SNHL) with particular focus on the sensitive period of auditory development.

This study enrolled 53 children with SNHL (SNHL group) and 42 age‐ and sex‐matched healthy children (healthy control [HC] group). Based on the age of 36 months, we separated the study participants into two groups: Group A (0–36 months; A‐SNHL group, n = 32; A‐HC group, n = 21) and group B (36–180 months; B‐SNHL group, n = 21; B‐HC group, n = 21). We collected their DTI image data and calculated the ALPS index for the left and right hemispheres and the fractional volume of free water in white matter (FW‐WM) and analyzed the differences between the groups. The DTI‐ALPS has several limitations, the most prominent one being the influence of microstructure. However, it has many advantages and high clinical value.

Compared to the HC group, the ALPS index for both hemispheres in the SNHL group was significantly lower (L: p < 0.001; R: p < 0.001), and group B exhibited the same results (L: p < 0.001; R: p < 0.001). In group A, the left‐hemisphere ALPS index of the A‐SNHL group was significantly lower than that of the A‐HC group (L: p = 0.002; R: p = 0.067). The FW imaging analysis indicated that the FW‐WM in the B‐SNHL group was significantly higher than that of the B‐HC group, and it exhibited a negative correlation with the left‐hemisphere ALPS index (r = −0.515, p = 0.017).

Children with SNHL (especially those over 3 years old) might exhibit compromised cerebral glymphatic function, possibly attributable to clearance dysfunction and interstitial fluid (ISF) retention. Despite the recognized limitation of DTI‐ALPS, its integration with FW mapping may enhance the noninvasive indirect evaluation of glymphatic function.