A Case of Labyrinthitis Occuring in Undiagnosed Congenital Nystagmus

Abstract

If direction-changing gaze-evoked nystagmus accompanies sudden hearing loss, central lesions should be considered as the cause. A 33-year-old female presented at our hospital with sudden hearing loss and dizziness. A series of vestibular function tests confirmed a visual fixation disorder with central causes; however, no specific findings were found on brain MRI. Subsequent smooth pursuit and optokinetic nystagmus tests confirmed bidirectional saccadic pursuit and reversed optokinetic nystagmus, suggesting congenital nystagmus. A history of abnormal eye tremors was rechecked, and labyrinthitis occurring in undiagnosed congenital nystagmus was diagnosed. The diagnosis can be challenging when vestibulocochlear disease occurs in patients with undiagnosed congenital nystagmus. In the absence of specific findings on MRI, vestibular function tests, including the optokinetic nystagmus and smooth pursuit tests, should be conducted. In particular, it is crucial to investigate the history of abnormal eye tremors.