Caloric Analysis of Patients with Benign Paroxysmal Positional Vertigo

Abstract

Original Article INTRODUCTIONPositional vertigo following sudden head motion in patients with benign paroxysmal positional vertigo (BPPV) is assumed to be due to freely floating otoconia inside the semicircular canals or those adhering to the cupula which make labyrinth sensitive to gravitational forces [1] . The majority of patients have quick relief of symptoms after repositioning maneuvers, although underlying pathology is obscure. Origin of these deposits is claimed to be due to degeneration of utricular neuroepithelium. Functional studies are needed to exclusively detect possible organic pathology of the utricule. Innervation of utricule is provided by superior vestibular nerve which also collects impulses from lateral and superior semicircular canals. The inferior vestibular nerve is connected to the posterior semicircular canal and the saccule.Caloric testing was first studied by the Nobel Prize winner Robert Barany in 1906, and later it was introduced to the otologic practice by Fitzgerald and Hallpike [2] in 1942. Videonystagmograpy (VNG) with caloric stimulation has been widely used in the analysis of severity of vestibular disorders. It reflects the degree to which the vestibular system is responsive and how symmetric the responses are between left and right. Caloric irrigation through the ear canal selectively stimulates the lateral canal [3] . However, studies indicate the contribution of other semicircular canals to the final response. Gacek et al. [4] have found severe dysfunction after caloric stimulation in seven patients who had singular neurectomy. Sensitivity of caloric stimulation to detect the vestibular pathology is subject to discussion [5] . Some problems may remain undiagnosed unless they cause severe vestibular dysfunction. The aim of this study is to analyze the incidence of caloric hypo-excitability, to investigate the role of symptom duration, and to compare the caloric responses in patients with lateral canal (LC-BPPV) and posterior canal (PC-BPPV). MATERIALS and METHODS MATERIALS and METHODS:A prospective study was conducted in 65 patients with BPPV (20 LC and 45 PC) who were subjected to caloric testing. Average slow-phase velocity and nystagmus duration were analyzed. RESULTS:Caloric hypo-excitability was 20.4%. It was more evident in patients with apogeotropic-type LC-BPPV. The comparison of average slowphase velocity of the nystagmus and nystagmus duration between selected types of BPPV for pathologic, non-pathologic, and the control ears after warm and cold stimulation was not statistically significant (p>0.05). No correlation was found between caloric results and symptom duration (p>0.05). CONCLUSION:Some patients presented caloric hypo-excitability. Reliability of caloric testing to differentiate the ear with normal and abnormal vestibular function in different types of BPPV was low. No difference was found in the analysis of the impact of symptom duration. Caloric testing is not an ideal tool to study BPPV.

Hearing as an Independent Predictor of Postural Balance in 1075 Patients Evaluated for Dizziness

“…Caloric testing is the most commonly used vestibular test to exclusively assess one side, and it provides quantification of unilateral vestibular disease by stimulating the horizontal semicircular canal. 14,30,31 The study also has possible limitations. Since the study included patients examined for dizziness of suspected vestibular origin, generalizability of the results to the general population is not determined.…”

A possible objective test to detect benign paroxysmal positional vertigo. The role of the caloric and video-head impulse tests in the diagnosis

“…This fact is interesting because it is thought that caloric irrigation selectively investigates the function of the horizontal semicircular canals ( Korres, 2004 ). Although, another investigation detected no statistically significant difference between the normal and involved ears of BPPV patients and the control group's results ( Yetişer, 2017 ). Hence, the caloric test was not confirmed to be an ideal approach to diagnose BPPV.…”

The clinical significance of direction-fixed mono-positional apogeotropic horizontal nystagmus

“…Our observations seem to suggest the possibility of a very particular and not so common type of lithiasis of the semicircular canal in which the debris are “trapped” close to the ampulla, and unable to move into the narrow tract of the canal. This situation would be associated with a normal caloric test, but a reduction of caloric response cannot be ex ante excluded 14 , 15 .…”