7 research outputs found
Clinical and imaging biomarkers of audiovestibular function in infratentorial superficial siderosis
Disabling hearing loss is known to affect over 400 million people worldwide while the
lifetime prevalence of dizziness can be as high as 40%. Rare causes for hearing and
balance impairment are often understudied. Infratentorial (classical) superficial
siderosis (iSS) is a rare but sometimes disabling complex neurological condition
most often associated with hearing and balance impairment, and myelopathy.
Olfactory loss has been reported but not yet systematically studied. iSS results from
a chronic low-grade and low volume bleeding into the cerebrospinal fluid and the
deposition of iron-degradation products (predominantly haemosiderin) in the subpial
layers of the central nervous system, with predilection for the cerebellum and the
vestibulocochlear nerves. Magnetic resonance imaging (MRI) allows haemosiderin to
be visualised in-vivo and is the mainstream diagnostic modality. Due to the assumed
rarity of iSS (prevalence of 0.03-0.14%), our research opportunities are limited. Few
dedicated studies describe iSS-related audiovestibular (AV) findings, often limited to
case-series, with mixed findings. There is currently no robust evidence that the
radiological haemosiderin appearances correlate with the objective clinical tests.
This project focuses on phenotyping the AV function in iSS and identifies
predominantly retrocochlear hearing loss with features suggestive of central auditory
dysfunction, and mixed vestibular (predominantly cerebellar) dysfunction. This work
introduces and validates an imaging rating scale aiming to capture the anatomical
extent of haemosiderin deposits visualised on MRI in a standardised and
reproducible way. The scale demonstrates excellent reliability and good validity, with
the scores correlating with hearing thresholds. This project estimates the prevalence
of MRI-defined iSS in a large UK Biobank sample, similar to other rare neurootological disorders. Using patient/self-report measures, this work captures markedly
low health-states of individuals with iSS and identifies possible iSS-specific auditory
characteristics. Finally, the work identifies high prevalence of olfactory dysfunction in
individuals with iSS