Abstract
Conclusions: Although combined utricular and canal paresis has been described previously, this is the first report of canal hyperactivity associated with utricular hypofunction. Unsteadiness and swaying were the most common symptoms, and patients with shorter duration of symptoms also had positional vertigo. We propose that this syndrome is a variant of utricular dysfunction and should be considered in the differential diagnosis of peripheral vestibular disorders. Objective: To describe a syndrome of instability associated with utricular dysfunction and hyperactive caloric responses. Methods: The study comprised 11 consecutive patients exhibiting abnormalities of the eccentric subjective visual vertical test (e-SVV) and high responses during the caloric test of the videonystagmography (VNG). We carried out a review of symptoms, physical examination, and vestibular tests. Results: There was no gender predilection or obvious etiology. The patients' main complaint included instability with linear symptoms (i.e., tilting, rocking, and swaying), with positional vertigo as a secondary symptom. Oculomotor testing, visual fixation index, and brain MRI were normal, excluding a central nervous system disorder. VNG was essentially normal except for hyperactive responses during the caloric testing in all patients. Abnormal e-SVV was found in 10 patients unilaterally and bilaterally in 1 patient. Abnormal oVEMP was found in seven of seven patients, further supporting a utricular site of lesion.
