Vestibular function assessment using the video head impulse test and videonystagmoscopy in congenital nystagmus and vertigo: a long-term case report

Congenital nystagmus (CN) has long posed challenges for the study of vestibular function, particularly in the semicircular canals (SCCs). The authors recently reported for the first time the use of the video head impulse test (vHIT), including head impulse (HIMP) and the suppression head impulse (SHIMP) protocols, in a patient with pseudopendular CN and vertigo resulting from vestibular neuritis. Here, the authors describe the case of a new patient with jerk CN, vestibular migraine, and vertigo using vHIT and videonystagmoscopy. They report the following findings: (a) successful assessment of peripheral vestibular function in all SCCs; (b) confirmation of previously observed and newly detected selective dysfunction of the lateral SCCs, including deficient vestibulo-ocular reflex (VOR); (c) sparing of the vertical SCCs, allowing the diagnosis and treatment of posterior SCC benign paroxysmal positional vertigo (BPPV) reported for the first time in CN; (d) the utility of videonystagmoscopy in detecting vertical SCC BPPV in this patient; (e) the necessity of SHIMP to clarify severe lateral HIMP abnormalities for accurate interpretation; and (f) the interaction of the CN with a deficient VOR, fostering visuo-vestibular compensatory mechanisms through training. These findings support the value of vHIT and videonystagmoscopy, providing new perspectives for assessing and managing the most frequent vertigo syndromes in CN and vertigo.