Utility of Vertebrobasilar Insufficiency Testing (VBIT) as a Component of Videonystagmography

Norman J. Chan, MD, Taha A. Mur, MS, Kaitlin E. Palmer, MS, Bruce Zhang, MS, Paige M. Pastalove, AuD, Elizabeth Meenan, AuD, and Pamela Roehm, MD, PhD.

1 Department of Otolaryngology, Temple University School of Medicine, Philadelphia, PA

INTRODUCTION ABSTRACT

Any screening test is only useful if it has a high sensitivity and low false negative rate. VBIT is an inadequate screening test by that measure. MRA is considered the definite test for vertebrobasilar insufficiency. Using MRA as the confirmatory test, the results of this study indicate that VBIT may be no better than a coin toss in helping to determine if a patient should undergo further costly radiologic imaging. Our result is consistent with the findings of other studies that suggest VBIT sensitivity is less than 60%.1 Another reason to question the use of VBIT as a screening modality is the possibility that the cervical rotation maneuvers used for VBIT could induce a cerebrovascular accident, even though the risk is probably low. When applied to all patients undergoing VNG, VBIT testing does not appear to add additional data to contribute to diagnosis and can possibly result in significant patient morbidity or mortality. For these reasons, VBIT probably should not be used as a criterion for further radiologic testing for vertebrobasilar insufficiency. Limitations of this study include its retrospective nature and the small sample size of patients who had both VBIT and MRA. Further prospective studies involving a larger number of vertigo patients who all have MRAs of the head and neck within a short time after VBIT will provide a more definitive answer to the utility of VBIT as a screening test for vertebrobasilar insufficiency.

128 patients had VBIT performed as a component of their VNG.

Average patient age = 55 years (range = 19 to 89 years).

90 female patients (70.3%) 38 male patients (29.7%) Racial distribution was as follows: 35 Caucasian patients (27.3%) 56 black patients (43.8%) 28 Hispanic patients (21.9%) 3 Asian patients (2.3%) 6 patients of other backgrounds (4.7%).

23 patients had magnetic resonance angiography (MRA) of the posterior circulation within 1 year of the VBIT

72 had magnetic resonance imaging (MRI) of the brain within 1 year of the VBIT

When using MRA as the definitive test for vertebrobasilar insufficiency, the sensitivity of VBIT was 50%, specificity was 47.62%, positive predictive value was 8.33%, and negative predictive value was 90.91%.

2 patients had MRA showing abnormality of the posterior circulation

When MRI was used as the comparative test, VBIT’s sensitivity was 25.00%, specificity was 61.76%, positivity predictive value was 3.70% and negative predictive value was 93.33%.

4 patient had MRI showing abnormality of the posterior circulation

Institutional review board approval was obtained Retrospective chart review All adult patients (> 18 years old) evaluated for

vertigo at one of the Temple University Department of Otolaryngology – Head and Neck Surgery outpatient clinics who also had VBIT performed as a part of videonystagmography (VNG) between January 1, 2011 to February 1, 2014 was conducted

Demographic data, VNG and VBIT results, and results of magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) of the head and neck were extracted from each chart.

MRI and MRA results were only considered relevant and included in the statistical analysis if the imaging study was performed within one year before or after the date of the patient’s VBIT.

An MRI study was considered abnormal if an infarction was visualized in a portion of brainstem or cerebellum.

An MRA study was considered abnormal if stenosis, dissection or other abnormality of the vertebral or basilar arteries, or their branches were detected.

The sensitivity, specificity, positive predictive value and negative predictive value of VBIT were calculated using MRI or MRA as the confirmatory diagnostic modalities.

Vertebrobasilar insufficiency testing (VBIT) is commonly used by physical therapists to determine if cervical spine manipulation is contraindicated.1 Audiologists often include VBIT as a part of vestibular testing in patients with vertigo. In either case, the purpose of VBIT is to determine the adequacy of blood flow to the brain.1 The maneuver used in VBIT is either a combined extension rotation of the cervical spine or rotation alone.1,2 The head rotation is thought to result in compression of the vertebral artery contralateral to the direction of head rotation.1 VBIT is considered positive if the maneuver elicits any of the symptoms associated with decreased blood supply to the hindbrain including dizziness, vertigo, drop attacks, diplopia, dysarthria, dysphagia, ataxia, nausea, numbness and nystagmus.1

The diagnostic accuracy and utility of vertebrobasilar insufficiency testing is currently being debated.1 As a screening test used to determine whether a patient should undergo further radiologic testing to evaluate the patency of the vertebrobasilar system or if a patient can safely proceed with further cervical spine manipulation by a physical therapist, VBIT should have a high sensitivity to minimize the number of false negative results.1 However, a systematic review by Hutting et al determined that the sensitivity of VBIT is low and ranges from 0 to 57%.1 VBIT also has a very variable positive predictive value ranging from 0 to 100%.1 VBIT maneuvers themselves involve manipulation of the cervical spine and could theoretically induce a stroke. Although some studies have shown that VBIT maneuvers can cause changes in blood flow in the vertebral arteries, there is little evidence to suggest that reduced blood flow directly results in symptoms typically associated with vertebrobasilar insufficiency.3,4 With questionable diagnostic utility and the potential for harm, it is uncertain if this test should be utilized. This study sought to evaluate the diagnostic utility of vertebrobasilar insufficiency testing in patients referred for evaluation of vertigo.

1. Hutting N, Verhagen AP, Vijverman V, Keesenberg MD, Dixon G, Scholten-Peeters GG. Diagnostic accuracy of premanipulative vertebrobasilar insufficiency tests: a systematic review. Man Ther. 2013 Jun;18(3):177-82.

2. Zaina C, Grant R, Johnson C, Dansie B, Taylor J, Spyropolous P. The effect of cervical rotation on blood flow in the contralateral vertebral artery. Man Ther. 2003 May;8(2):103-9.

3. Kerry R, Taylor AJ, Mitchell J, McCarthy C. Cervical arterial dysfunction and manual therapy: a critical literature review to inform professional practice. Man Ther. 2008 Aug;13(4):278-88.

4. Mitchell J, Keene D, Dyson C, Harvey L, Pruvey C, Phillips R. Is cervical spine rotation, as used in the standard vertebrobasilar insufficiency test, associated with a measureable change in intracranial vertebral artery blood flow? Man Ther. 2004 Nov;9(4):220-7.

METHODS

When applied to all patients undergoing VNG, VBIT testing does not add additional data to contribute to diagnosis, and should not be used as a criterion for further radiologic testing for vertebrobasilar insufficiency.

RESULTS

DISCUSSION

CONCLUSION

REFERENCES

Objective: To determine the utility of the addition of vertebrobasilar insufficiency testing (VBIT) as a component of videonystagmography (VNG) in the evaluation of patients with vertigo or imbalance. Study design: Retrospective chart review Setting: Tertiary referral center Patients: All patients aged 18 years and older who had a VBIT performed as a part of their VNG between January 1, 2011 to February 1, 2014. Intervention: None Main outcome measure: Sensitivity and specificity of VBIT in prediction of vertebrobasilar insufficiency compared with results on imaging. Results: One hundred and twenty-eight patients had a VBIT performed as a component of their VNG. Twenty-three patients had magnetic resonance angiography (MRA) of the posterior circulation within 1 year of the VBIT. Seventy-two had magnetic resonance imaging (MRI) of the brain within 1 year of the VBIT. When using MRA as the definitive test for vertebrobasilar insufficiency, the sensitivity of VBIT was 50%, specificity was 47.62%, positive predictive value was 8.33%, and negative predictive value was 90.91%. When MRI was used as the comparative test, VBIT’s sensitivity was 25.00%, specificity was 61.76%, positivity predictive value was 3.70% and negative predictive value was 93.33%. Conclusion: When applied to all patients undergoing VNG, VBIT testing does not add additional data to contribute to diagnosis, and should not be used as a criterion for further radiologic testing for vertebrobasilar insufficiency.

39 year old female with a history of migraine headaches who presented with a complaint of daily episodes of vertigo for 2 weeks that start spontaneously and can last up to 1 hour. She experienced nausea and right aural fullness but denied hearing loss, otalgia, otorrhea, or tinnitus. The dizziness is exacerbated by lying down. Physical examination was unremarkable with normal Weber and Rinne tuning fork tests. Patient experienced subjective dizziness on both sides with Dix-Hallpike testing. Audiogram and tympanogram were normal. There were central findings on VNG testing in addition to a positive VBIT. Patient had subsequent MRI brain without contrast and MRA of the head and neck that were negative for vertebrobasilar insufficiency. Patient was subsequently diagnosed and treated for migraine-associated vertigo.

Patient Case