Direction-fixed positional nystagmus following head-roll testing:how is it related with a vestibular pathology?

Objective:The goal of this study is to analyze the clinical view of patients with direction-fixed positional nystagmus(DFPN)following head-roll maneuver.Methods:Sixty patients with DFPN were reviewed retrospectively.Patients were categorized into 3 groups according to the direction of nystagmus based on rotation side.Associated problems were documented,and cumulative data were compared between groups.One-way analysis of variance(ANOVA test)was used for statistical analysis(P<0.05).Results:Thirty-three patients(55%)had stronger nystagmus beating towards the direction of head-roll(Group-A).Three patients developed geotropic LC-BPPV.Fourteen patients had inner ear disease.Sixteen patients(27%)had stronger nystagmus beating against the direction of head roll(Group-B).Nine patients had inner ear disease.None of the patients tested with head-shaking had change of direction of nystagmus.Eleven patients(18%)had DFPN with equal velocity during right or left head-roll maneuver(Group-C).Of those,nine patients had inner ear disease.None of the patients had change of direction of nystagmus.Comparison of the incidence of associated problems(migraine,vestibular neuronitis,Meniere’s disease etc.)in each group was not statistically significant(P˃0.05).Conclusion:Patients with DFPN should be followed for a possibility of vestibular pathology since vestibular problem was documented for more than half of the patients in the follow-up.On the other hand,DFPN could be related with a temporary reason(thermal,physical or drug effect etc.)in some patients who do not exhibit any associated disease.Head-shaking testing is recommended to expose the lateral canal BPPV.But the incidence is low.