Peripheral Vertigo: Likelihood Ratios

Introduction: Remember that vertigo describes a spinning sensation. "Dizziness" as a symptom can refer to many different things, e.g. presyncope. There are two major categories within vertigo: central and peripheral lesions.

Peripheral causes of vertigo involve dysfunction of the vestibular apparatus or nerve.

This includes many specific causes, including:

Benign Paroxysmal Positional Vertigo (BPPV)

Vestibular Neuritis

Meniere's Disease

See the UpToDate article: http://www.utdol.com/online/content/topic.do?topicKey=genneuro/7125

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Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Patients with dizziness	40%	Am J Med 1999 Nov;107(5):468-78. PMID 10569302
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The likelihood ratios of findings for Peripheral Vertigo are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Head Impulse Test	+ 0 -	7	0.7
from UpToDate: "The head thrust test is performed by instructing the patient to keep his or her eyes on a distant target while wearing his usual prescription eyeglasses. The head is then turned quickly and unpredictably by the examiner, about 15º; the starting position should be about 10º from the primary position in the orbit. This is sometimes called the head impulse test. The normal response is that the eyes remain on the target. The abnormal response is that the eyes are dragged off of the target by the head turn (in one direction), followed by a saccade back to the target after the head turn; this response indicates a deficient VOR on the side of the head turn, implying a peripheral vestibular lesion (inner ear or vestibular nerve) on that side." Study: Am J Otol. 1997 Mar;18(2):207-13. PMID 9093678

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Matutinal Vertigo	+ 0 -	1.6	0.7
this is vertigo upon awakening in the morning for a peripheral lesion Study: JAMA. 1994;271(5):385-388. http://jama.ama-assn.org/cgi/reprint/271/5/385
[ + ] Dix-Hallpike Maneuver		Sensitivity = 78%
for Benign Paroxysmal Positional Vertigo (BPPV) specificity not assessed Study: JAMA. 1994;271:385-388. http://jama.ama-assn.org/content/vol271/issue5/index.dtl