Abstract
Background We describe a 42-year-old patient with reported “shaking” vision referred due to
concerns of possible vestibular system dysfunction. The patient has known history
of Usher syndrome type I, bilateral cochlear implants, and severe vision impairment.
Purpose This case describes an unusual nystagmus previously only reported in individuals
with central demyelinating disorders, significant light deprivation, or in congenital/early-onset
visual pathway impairment.
Research Design Case study.
Data Collection and Analysis Retrospective chart review of vestibular function.
Results Vestibular function was likely absent in this case. There was no evidence of vestibular
(jerk) nystagmus for sinusoidal harmonic acceleration stimuli or repeatable responses
for cervical vestibular evoked myogenic potentials. Significant pendular low-amplitude
high-frequency oscillations of approximately 6 Hz were present for horizontal and
vertical tracings throughout testing.
Conclusion Nystagmus may not always be associated with vestibular system impairment. In this
case, the patient's reported “shaking” vision was attributed to pendular low-amplitude
high-frequency nystagmus and hypothesized to relate to long-standing significant vision
impairment. This presentation is unusual in adults and has historically been associated
with individuals with significant central pathology or in those with long duration
light deprivation.
Keywords
vestibular system - pendular nystagmus - Usher syndrome
