Hypoplastic vestibular aqueduct in congenital temporal bone anomalies - implications for subtype diagnosis of Meniere's disease

Katherine L Reinshagen; Robert H Unger; Laura V Romo; David Bächinger; Rehab N Khalid; Andreas H Eckhard; Amy F Juliano

doi:10.3174/ajnr.A9489

Hypoplastic vestibular aqueduct in congenital temporal bone anomalies - implications for subtype diagnosis of Meniere's disease

AJNR Am J Neuroradiol. 2026 Jun 22:ajnr.A9489. doi: 10.3174/ajnr.A9489. Online ahead of print.

Authors

Katherine L Reinshagen¹, Robert H Unger¹, Laura V Romo¹, David Bächinger¹, Rehab N Khalid¹, Andreas H Eckhard¹, Amy F Juliano²

Affiliations

¹ From the Department of Radiology (K.L.R., L.V.R., A.F.J.), Massachusetts Eye and Ear, Radiology(R.H.U.,R.N.K.),Massachusetts General Hospital, Department of Otolaryngology-Headand Neck Surgery, Massachusetts Eye and Ear, Harvard, Medical School, Boston, MA, USA and Department of Otorhinolaryngology (D.B.), Headand Neck Surgery (A.H.E.), University HospitalZürich, University Zürich, Frauenklinikstrasse 24, 8091, Zürich, Switzerland.
² From the Department of Radiology (K.L.R., L.V.R., A.F.J.), Massachusetts Eye and Ear, Radiology(R.H.U.,R.N.K.),Massachusetts General Hospital, Department of Otolaryngology-Headand Neck Surgery, Massachusetts Eye and Ear, Harvard, Medical School, Boston, MA, USA and Department of Otorhinolaryngology (D.B.), Headand Neck Surgery (A.H.E.), University HospitalZürich, University Zürich, Frauenklinikstrasse 24, 8091, Zürich, Switzerland. amy_juliano@meei.harvard.edu.

PMID: 42331620
DOI: 10.3174/ajnr.A9489

Abstract

Background and purpose: As the endolymphatic (ES) undergoes normal postnatal maturation, the surrounding vestibular aqueduct (VA) undergoes a corresponding change in morphology, quantified by its angular trajectory (ATVA). In adult temporal bones with Meniere's disease (MD), a fetal orientation ATVA (≥140°) indicates underlying ES hypoplasia and defines the so called hypoplastic disease endotype (MD-hp). However, ES hypoplasia has also been described histologically in other inner ear syndromes and congenital conditions, independent of MD. We aimed to investigate whether ATVA ≥140° occurs in mature temporal bones beyond its established association with the MD-hp endotype.

Materials and methods: Retrospective retrieval of CT scans performed on patients over age 12 years at Massachusetts Eye and Ear between January 2016 and December 2024 was conducted, with search terms encompassing diseases previously described to be associated with temporal bone anomalies. CT studies that did not allow adequate assessment of the VA were excluded. Two neuroradiologists blinded to clinical information independently performed ATVA measurements, with consensus interpretation rendered for disagreements in ATVA categories (adult, intermediate, or fetal orientation).

Results: 103 patients with congenital temporal bone anomalies were identified. 98 patients (190 ears) met inclusion criteria. Fetal VA orientation (ATVA ≥140°) was identified in 8 ears from 6 patients. Intermediate VA orientation (ATVA 121°-139°) was identified in 19 ears from 15 patients. Among 8 patients with branchio-oto-renal (BOR) syndrome, 2 patients had bilateral fetal orientation ATVA and 2 patients had mixed fetal/intermediate orientation ATVA. Among 11 patients with trisomy 21, 5 demonstrated unilateral abnormal ATVA. Higher than 120° ATVA values were also observed in CHARGE syndrome, Apert syndrome, and Chiari I malformation. Review of clinical records did not show a diagnosis of MD within our cohort.

Conclusions: Fetal and intermediate ATVA orientations were observed in several congenital temporal bone anomalies without documented MD. These findings further support that abnormal ATVA reflects altered VA/ES developmental morphology and is not exclusive to the MD-hp endotype. Accordingly, fetal orientation ATVA should be interpreted within the broader clinical and radiologic context, particularly in the presence of additional congenital abnormalities.