A Novel Inner Ear Manifestation In Alagille Syndrome: Fistula Between The Jugular Bulb And Lateral Canal Ampulla

XXIII. World Congress of Otorhinolaryngology Head and Neck Surgery, İstanbul, Türkiye, 9 - 13 Eylül 2026, ss.1265, (Özet Bildiri)

BACKGROUND & AIM

Alagille syndrome (ALGS) is a rare autosomal-dominant disorder that frequently involves the inner ear, most commonly

affecting the posterior semicircular canal. Multiple studies in the literature emphasize that the lateral semicircular canal is

typically spared. This report challenges this established paradigm by presenting a unique case demonstrating the first

suspected fistula between the jugular bulb and the lateral semicircular canal ampulla in ALGS.

MATERIAL & METHODS

A 12-year-old male diagnosed with ALGS presented to the otolaryngology clinic with bilateral hearing loss, predominantly on

the left side, without vertigo or tinnitus. His medical history included surgery for cholestatic liver disease and peripheral

pulmonary stenosis. Clinical evaluation comprised otomicroscopy, pure-tone audiometry, tympanometry, video head impulse

test (vHIT), and temporal bone high-resolution computed tomography (HRCT) to assess anatomical and functional

audiovestibular correlations. Otomicroscopy revealed right-sided adhesive otitis media and a left-sided Sade 2 pars tensa

retraction without ossicular erosion.

RESULTS

High-resolution computed tomography uniquely demonstrated a suspected left-sided fistula formation between the jugular

bulb and the lateral semicircular canal ampulla, alongside bilateral posterior semicircular canal aplasia. Audiologically, pure-

tone audiometry showed bilateral conductive hearing loss; this was mild on the right side and mild-to-moderate on the left

side, characterized by a sudden drop in the lower frequencies. In the left ear, despite the theoretically large third-window

effect expected from the fistula, supranormal bone conduction thresholds were absent. This expected audiological finding was

effectively masked by the concurrent left-sided retraction pocket, which increased tympano-ossicular stiffness and dampened

the altered inner ear hydrodynamics. Furthermore, this middle ear pathology prevented the proper execution of vestibular

evoked myogenic potential (VEMP) testing. Video head impulse test (vHIT) correlated with the anatomical anomalies, revealing

decreased gains and overt saccades in the bilateral posterior canals.

CONCLUSIONS

This case significantly expands the known inner ear manifestations of ALGS by presenting the first suspected lateral canal

ampulla-jugular bulb fistula, proving that the lateral canal can indeed be involved. Additionally, it highlights an important

secondary biomechanical interaction where concurrent middle ear pathologies can physically mask classic third-window

audiological findings.

KEYWORDS

Alagille syndrome, Jugular bulb, Semicircular canal fistula ,Third-window phenomenon, Inner ear malformations