Journal Club: Sudden onset hearing loss - subgroup identification with isolated posterior semicircular dysfunction?

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Today's journal article

Tsuzuki N, Masuda K, Yamanobe Y, Mizuno K, Ozawa H, Wasano K. Idiopathic Sudden Sensorineural Hearing Loss Caused by Infarction of the Vestibulo-Cochlear Artery Can Be Detected by Testing Semicircular Canal Function and Audiometry: Proposal for Angiopathic Sudden Sensorineural Hearing Loss. 

Why I picked this article

Sudden-onset hearing loss is a type of sensorineural hearing loss in which people experience a sudden drop in hearing sensitivity within a few days. In approximately half cases, patients with sudden hearing loss recover hearing. Currently, the large majority of sudden-onset hearing loss remains "no known cause". The consequence is that without knowledge of the cause or the underlying pathology, there is no promising targeted therapeutic development to treat this condition. 

One of the suspected underlying pathological causes is a vascular pathology. For example, the loss of blood flow to the cochlea could temporarily shut down the hearing function. But there is no simple diagnostic method that can confirm that “this is the vascular subtype of sudden-onset SNHL”. 

This research asks whether isolated posterior semicircular canal dysfunction can serve as a clinical clue for vascular change. It focuses on the vestibulo‑cochlear artery. 

Some of the research findings

Participants and timeline:
  • n = 17 Idiopathic sudden onset sensorineural hearing loss patients
  • video head impulse testing (vHIT) to assess vestibular function was done within 28 days of onset of hearing loss.
  • Two groups were separately analysed: 
    • IPSCD group: 6/17 with isolated posterior canal dysfunction (IPSCD) on vHIT.
    • No‑IPSCD group: 11/17 without IPSCD.
Clinical associations were examined and compared in two groups: 
  • Coronary artery disease: higher in isolated posterior semicircular canal dysfunction (IPSCD) (odds ratio: infinite; p = 0.03).
  • Regular antithrombotic use: higher in IPSCD (odds ratio: infinite; p < 0.01).
  • Note: “infinite” odds ratios usually mean zero events in the comparison group; they signal a strong association but are unstable in small samples.
  • With audiograms, IPSCD ears showed profound, flat, or high‑frequency‑descending configurations—patterns consistent with a vascular mechanism affecting the VCA supply. 
  • The pattern (IPSCD on vHIT + vascular comorbidity/medication + audiogram shapes) is consistent with VCA involvement. The authors propose ISSNHL with IPSCD as a candidate vascular subgroup.
  • vHIT‑based screening for IPSCD in ISSNHL could enrich a vascular‑risk subgroup for interventional trials.

Haruna's takeaway

This literature piques my interest as I am very interested in the cochlear vasculature. I believe that some past literature suggested that the vestibular system, including the semicircular canal, is more resistant to vascular problems, because the vestibular system receives input from multiple vascular sources. Cochlea mainly only has one branch going from the common cochlear artery -> spiral modiolar artery, making it perhaps more susceptible. It would be really great if we could somehow take direct measurements of the cochlear blood flow in humans. 

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This is Haruna's 66/100 of the 100-day challenge to post a science blog article every day! I love inner ear biology & cochlear physiology.