Selective Bilateral Posterior Canal Dysfunction: A Case Series Investigation into the Clinical Trends and Associative Factors.

Background:  The video head impulse test measures high-frequency vestibulo-ocular function of all six semicircular canals. Isolated semicircular canal dysfunction has been correlated with several peripheral and central vestibular etiologies. Selective bilateral posterior canal dysfunction is a trend seen in the clinical setting but less commonly reported in the medical literature.

Purpose:  The purpose of this work is to explore the clinical profile of bilateral posterior canal dysfunction along with other presenting factors such as hearing loss, increased age, and associated nystagmus patterns.

Method:  A case series of three patients (age range: 67-74 years) is presented to illustrate the similarities and clinical associations between vestibular and balance history, medical history, and vestibular test results.

Results:  All three patient cases presented with below reference range posterior semicircular canal function on video head impulse testing. Two patients also presented with down-beating nystagmus, and two endorsed subjective hearing loss while the third presented with presbycusis.

Conclusion:  Selective bilateral posterior canal dysfunction in association with advanced age, presbycusis, and signs of down-beating nystagmus may be associated with vestibulocochlear degenerative processes. Yet, central disorders, technical and patient factors may present clinical challenges to elucidate the cause.