Comparing results from vestibular caloric stimulation and vHIT from a specialised outpatient clinic.

BACKGROUND

Until recently, vestibular caloric stimulation was the only objective diagnostic method for isolating the function of the lateral semi-circular canals responsible for maintaining balance. Since 2014, the Video Head Impulse Test (vHIT) has been applied in the Czech Republic to investigate the function of all semi-circular canals. Studies conducted so far have shown that the results of these two methods do not often agree.

METHODS

The aim of this study was to compare the results of vestibular caloric stimulation and vHIT in a cohort of patients with peripheral vestibular syndrome at a specialized outpatient clinic. The study lasted from July 2016 to August 2017 and included patients with unilateral peripheral vestibular syndrome (n=32; 24 females and 8 males, mean age 49.4 years) and a positive result with either vestibular caloric stimulation or vHIT.

FINDINGS

90% of the patients had a positive vestibular caloric stimulation result, while the vHIT was positive only in 50% of the patients. Both methods were positive in 13 subjects, vestibular caloric stimulation was positive and vHIT was negative in 16 subjects and in 3 cases vestibular caloric stimulation was negative and vHIT was positive. Based on these numbers, both methods concur in 45% of the cases. In 13 patients, apart from lateral canal disorders, vHIT revealed disorders in one of the vertical canals - the front right in 4, the rear right in 2, the front left in 3 and the rear left in 4. When sorted into subgroups of the "TiTrATE" diagnostic algorithm based on the time course and triggering factor, vHIT was found to be positive for acute spontaneous vertigo in 62.5% of cases. vHIT was negative for 70% of chronic and spontaneous episodic complaints.

CONCLUSIONS

The diagnosis of peripheral vestibular disorders should take the pathophysiological basis of the disease into account, as this can differ in peripheral disorders. This could then explain the discrepancy between the results of the two methods. The time course of the disease can be a predictor of the vHIT outcome. Localizing the impaired function of particular semi-circular canals using vHIT can inform selective vestibular rehabilitation.