Conclusion: Contrast-enhanced magnetic resonance imaging (MRI) reveals variations in the endolymphatic morphology of the cystic lateral semicircular canal (CLSC) that correlate with inner ear function. This report is the first to suggest a relationship between the morphology and function of this common inner ear malformation in clinical cases.
Objectives: This study investigated the radiological and functional findings of a common inner ear malformation using computed tomography (CT), gadolinium contrast-enhanced magnetic resonance imaging (MRI), caloric testing, and cervical and ocular vestibular evoked myogenic potential (VEMP) testing.
Method: Four ears in three patients who were radiologically diagnosed with a CLSC and a normal cochlea on high-resolution CT and contrast-enhanced MRI were included. Semicircular canal and vestibular functions were analyzed using the caloric test and cervical and ocular VEMP testing.
Results: Unilateral and bilateral cystic canals were found in two and one patients, respectively. In the first patient, the malformed vestibule and cystic space were separate on imaging, and perilymph filled the cystic space. The functional test results were normal. In the second patient, endolymph filled both cystic spaces, and the functional responses were poor. In the third patient, endolymph filled the cystic space, and the ear did not respond during functional testing.
Keywords: Inner ear malformation; caloric test; endolymph; perilymph.