Three-component analysis of benign paroxysmal positional nystagmus

Evaluation of the utricular and saccular function using oVEMPs and cVEMPs in BPPV patients

BACKGROUND

It is well-known that ocular vestibular evoked myogenic potentials (oVEMPs) predominantly reflect utricular function whilst cervical vestibular evoked myogenic potentials (cVEMPs) reflect saccular function. To date, there are no published reports on the systemic evaluation of utricular and saccular function in benign paroxysmal positional vertigo (BPPV), nor are there any reports on the differences in VEMPs between patients with recurrent and non-recurrent BPPV. The aim of this study was to evaluate the difference in cervical and ocular (c/o)VEMPs between patients with BPPV and normal controls, as well as between patients with recurrent and non-recurrent BPPV.

METHODS

Thirty patients with posterior canal BPPV and 30 healthy subjects (as normal controls) were prospectively enrolled. cVEMP and oVEMP testing using 500 Hz tone-burst stimuli were performed on all. VEMP tests were repeated 3 times on each subject to ensure reliability and reproducibility of responses. VEMPs were defined as present or absent. Abnormal VEMP was defined by lack of VEMP response.

RESULTS

In the control group, abnormal cVEMPs responses were detected in 6.67% and abnormal oVEMPs responses were detected in 3.34%. In BPPV patients (10 with recurrent BPPV, 20 with non-recurrent BPPV), abnormal cVEMPs responses were detected in 30% and abnormal oVEMPs responses were detected in 56.7%. More patients with BPPV showed abnormal responses in c/oVEMPs as compared to the control group (p < 0.05). oVEMPs was more often abnormal as compared to cVEMPs in BPPV patients (p < 0.05). There was no statistical difference between abnormal cVEMP responses in non-recurrent BPPV patients (25%) and recurrent BPPV patients (40%) (p > 0.05). Differences in abnormal oVEMP responses (non-recurrent BPPV, 40%; recurrent BPPV, 90%) were significant (p < 0.05).

CONCLUSION

An increased occurrence of abnormal c/oVEMP recordings appeared in BPPV patients, possibly as a result of degeneration of the otolith macula. oVEMPs were more often abnormal in BPPV patients as compared to cVEMPs, suggesting that utricular dysfunction may be more common than saccular dysfunction. Furthermore, oVEMP abnormalities in the recurrent BPPV group were significantly higher than those in the non-recurrent BPPV group. Assessment of c/oVEMPs in BPPV patients may therefore be of prognostic value in predicting likelihood of BPPV recurrence.

Nystagmus discordance with 2-dimensional videonystagmography in posterior semicircular canal benign paroxysmal positional vertigo

OBJECTIVE

The Dix-Hallpike test is a standard component of the videonystagmography test battery and can diagnose posterior semicircular canal benign paroxysmal positional vertigo. The purpose of this study is to determine the prevalence of discordant, equivocal, and concordant nystagmus tracings in active posterior semicircular canal benign paroxysmal positional vertigo when compared directly with the eye video.

STUDY DESIGN

Case series with chart review of patients diagnosed with posterior semicircular canal benign paroxysmal positional vertigo by 2-dimensional videonystagmography from August 1, 2007, to August 1, 2012.

SETTING

A tertiary vestibular test laboratory.

SUBJECTS AND METHODS

Ninety-six adults (4 had bilateral involvement) with posterior semicircular canal benign paroxysmal positional vertigo were included. A total of 100 videos with accompanying videonystagmography tracings were reviewed to determine nystagmus trajectory as well as globe position. Descriptive statistics were used to describe prevalence. Fisher exact test was used to compare proportions.

RESULTS

Sixty-two percent of cases involved benign paroxysmal positional vertigo of the right posterior semicircular canal, while 38% involved the left posterior semicircular canal. The prevalence of discordant, equivocal, and concordant tracings was 65% (65/100), 29% (29/100), and 6% (6/100). All tracing errors involved the horizontal channel. There was no association between tracing accuracy and the ear of involvement or globe position (P > .05).

CONCLUSIONS

Two-dimensional videonystagmography tracings are not reliable for identifying nystagmus trajectory in posterior semicircular canal benign paroxysmal positional vertigo.

Damaged utricular function clarified by oVEMP in patients with benign paroxysmal positional vertigo

CONCLUSION

Utricular dysfunction in patients with posterior canal benign paroxysmal positional vertigo (pBPPV) was supported by findings for ocular vestibular evoked myogenic potential (oVEMP).

OBJECTIVE

To evaluate the utricular and saccular function in patients with pBPPV.

METHODS

This study focused on 12 patients definitively diagnosed with pBPPV showing typical nystagmus by Dix-Hallpike maneuver and 12 controls. In these subjects, oVEMPs and cVEMPs to air-conducted 500 Hz tone burst (125 dB SPL) were measured. The patients also underwent caloric tests.

RESULTS

More of the patients with pBPPV showed abnormal responses in oVEMPs by stimulation on their affected side than the controls, while the results of cVEMPs showed no significant differences between pBPPV patients and controls. The abnormal results for oVEMPs on the affected side showed a higher percentage than those for cVEMPs and caloric tests in pBPPV patients. There was no significant association between any of the tests. These findings support the possibility that oVEMP reflects the specific abnormal condition in pBPPV, i.e. that the urticular function in pBPPV patients was highly damaged.

Recovery of otolith function in patients with benign paroxysmal positional vertigo evaluated by sinusoidal off-vertical axis rotation

The vestibulo-ocular reflex (VOR) was studied via sinusoidal off-vertical axis rotation (OVAR) to evaluate otolith function in patients with benign paroxysmal positional vertigo (BPPV). Subjects were sinusoidally rotated with eyes open in complete darkness at frequencies of 0.4 and 0.8 Hz with a maximum angular velocity of 60 degrees /s in earth vertical axis rotation (EVAR) and OVAR. Ten patients with BPPV patients were investigated. We performed OVAR tests for all patients for the following different points and compared otolith function: (1) The point at which patients had typical nystagmus; we call this state 'Before', that is, before recovery. (2) The point when their nystagmus disappeared; we call this state 'After' that is, after nystagmus disappear. Results showed that VOR gain during OVAR at 0.8 Hz in a 30 degrees nose-up position in BPPV patients was significantly less than the gain during EVAR at the point Before. On the other hand, gain was not significantly different between EVAR and OVAR at the point After. VOR gain itself at 0.8 Hz nose-up OVAR showed a significant increase at the point After compared to Before. This increase of VOR gain might be caused by the recovery of the otolith function in patients with BPPV.

Head-tilting stabilometry in patients with benign paroxysmal positional vertigo

OBJECTIVE

One of the pathologic conditions underlying benign paroxysmal positional vertigo (BPPV) is degeneration of the otolith organs. In this study, we examined changes in the parameters of stabilometry under an upright condition and head-tilt conditions in patients with BPPV.

METHODS

We performed stabilometry on 21 patients with right BPPV, on 21 patients with left BPPV and on 21 controls. First, the subject stood barefoot in an upright position with both feet together on the platform with eyes closed. Next, tilting of the head about 30 degrees to the left was added. Then, tilting about 30 degrees to the right was performed.

RESULTS

In right BPPV patients, the total length of velocity vectors in the right or left direction on right or left head-tilt were significantly smaller than those in an upright position. The enveloped area and total length of velocity vectors in the right or left direction were significantly larger than those in controls. In left BPPV patients, there were no parameters that showed any significant difference.

CONCLUSIONS

In this study, lesions of right BPPV patients were coincidentally more severe than those in left BPPV patients, and velocity vectors with head-tilts were significantly smaller than in an upright position. Using the total length of the velocity vectors, head-tilting stabilometry has the potential to become a reliable otolith function examination method.

Evaluation of the otolith function using sinusoidal off-vertical axis rotation in patients with benign paroxysmal positional vertigo

The vestibulo-ocular reflex (VOR) was studied via sinusoidal off-vertical axis rotation (OVAR) to evaluate the otolith function in patients with benign paroxysmal positional vertigo (BPPV). Subjects were sinusoidally rotated with eyes open in complete darkness at frequencies of 0.4 and 0.8 Hz with a maximum angular velocity of 60 degrees s(-1) in earth-vertical axis rotation (EVAR) and OVAR. Twenty-three controls and 24 BPPV patients were investigated. Results showed that VOR gain during OVAR at 0.8 Hz in a 30 degrees nose-up position in BPPV patients was significantly less than the gain during EVAR, whereas the gain was not significantly different between EVAR and OVAR in the controls in each condition. In addition, to examine each type of BPPV, we also investigated whether there were any differences between the patients who suffered from dizziness and those who did not. VOR gain in OVAR of BPPV patients who were suffering from dizziness was significantly less than that of BPPV patients without dizziness. Not only cupulolithiasis or canalolithiasis, but also otolith dysfunction was considered to be the possible origin of BPPV. Because sinusoidal OVAR produced minimal nausea compared to constant velocity OVAR, the stimulation of 0.8 Hz nose-up in sinusoidal OVAR may be used to evaluate otolith function without discomfort for patients.

Pathological localization of so-called posterior canal BPPV

OBJECTIVE

Based on the hypothesis that the origin of nystagmus is from the posterior canal (PC), the nystagmus in the head hanging and sitting position should be mirror images. To clarify the anatomical origin of positioning nystagmus in BPPV patients, we analyzed the positioning nystagmus of benign paroxysmal positioning vertigo (BPPV) patients three-dimensionally.

METHODS

Twenty-six patients with BPPV participated in this study. The positioning nystagmus was recorded in complete darkness from the patient's left eye by means of an infrared CCD camera. We performed three-dimensional analysis of nystagmus using video image analysis system (VIAS). Subsequently, the rotation axis of the 3D eye movements of the positioning nystagmus was calculated.

RESULTS

Among the 26 patients tested, 20 patients demonstrated the axes of nystagmus in good or relatively good alignment to the PC axis. However, in 11 of these 20 patients there was poor alignment of the axis of nystagmus in the sitting position to the PC axis. In addition, six patients showed axes of nystagmus with poor alignment to the PC in the head hanging position. Among them, two patients exhibited axes of nystagmus in good alignment with the anterior canal, in spite of diagnosis of these patients as PC BPPV by experienced examiner based on the positioning nystagmus test.

CONCLUSION

These results demonstrated that only one-third of patients who were diagnosed as BPPV, could be diagnosed as true BPPV which originates from a PC pathology. Besides the possibility that the pathology may originate from the AC, it is still unclear which part of the inner ear may be the candidate site of origin of the pathology of BPPV in the other 15 patients.