Role of subjective visual vertical in patients with posterior canal benign paroxysmal positional vertigo as a prognostic marker after canalith repositioning maneuver

Objective:To study the potential role of subjective visual vertical(SVV)as a prognostic marker for canalith repositioning maneuver(CRM)in patients with posterior canal benign paroxysmal positional vertigo(PC-BPPV)for the Indian population.Methods:SVV was examined in 30 patients with PC-BPPV before and after canalith repositioning maneuver and after complete resolution of PC-BPPV.Study parameters included the mean of 10 angular tilt readings and direction of deviation,which were compared before and after CRM and following complete resolution of PC-BPPV.Results:The angle of SVV tilt was greater and deviated towards the affected ear before CRM in all patients,which decreased significantly shortly after CRM and continued to decrease after complete resolution of PC-BPPV(p<0.0001).Conclusions:SVV can be used to test utricular dysfunction in PC-BPPV.The angle of tilt improves in response to CRM,which may be used as a prognostic marker in patients with PC-BPPV receiving CRM.

The Value of Subjective Visual Vertical in Diagnosis of Vestibular Migraine

Objective To study the value of the subjective visual vertical(SVV)in the diagnosis of vestibular migraine(VM).Methods This study recruited 128 VM patients and 64 age-matched normal subjects.We detected the SVV during the interval between attacks in both groups,in sitting upright,and the head tilted at 45°to the left or right.We then examined the correlation between the SVV results with the vestibular evoked myogenic potential(VEMP)and canal paresis(CP).Results It was found there was a significant difference in SVV at the upright position between VM patients and normal controls(P=0.006)and no significant difference was found at the tilts of 45°to the left or right between the two groups.The SVV results at the upright position were significantly correlated with cervical VEMP(P=0.042)whereas not significantly correlated with CP and VEMP.There existed no significant difference in the conformity to the Müller effect(M effect)between the two groups.ROC analysis exhibited that the sensitivity,specificity of SVVs at the upright were 67.200%and 62.500%respectively.The diagnostic value of SVV at the upright position was significantly higher than that at tilts of 45°to the left and right(P=0.006).Nonetheless the diagnostic accuracy was relatively low.Conclusion Abnormality in SVV possibly stems from the lasting functional disorder of cerebellar or high-level cortical centers in VM patients or is linked to the vestibular compensation.The SVV is of low diagnostic value for VM and the value of SVV in VM warrants further study.

Implementation of a Subjective Visual Vertical and Horizontal Testing System Using Virtual Reality

Subjective visual vertical(SVV)and subjective visual horizontal(SVH)tests can be used to evaluate the perception of verticality and horizontality,respectively,and can aid the diagnosis of otolith dysfunction in clinical practice.In this study,SVV and SVH screen version tests are implemented using virtual reality(VR)equipment;the proposed test method promotes a more immersive feeling for the subject while using a simple equipment configuration and possessing excellent mobility.To verify the performance of the proposed VR-based SVV and SVH tests,a reliable comparison was made between the traditional screen-based SVV and SVH tests and the proposed method,based on 30 healthy subjects.The average results of our experimental tests on the VR-based binocular SVV and SVH equipment were−0.15◦±1.74 and 0.60◦±1.18,respectively.The proposed VR-based method satisfies the normal tolerance for horizontal or vertical lines,i.e.,a±3◦error,as defined in previous studies,and it can be used to replace existing test methods.