Dix–Hallpike test
| Dix–Hallpike test | |
|---|---|
| Medical diagnostics | |
| ICD-9-CM | 95.46 |
The Dix–Hallpike test — or Nylen–Barany test — is a diagnostic maneuver used to identify benign paroxysmal positional vertigo (BPPV).
When performing the Dix-Hallpike test, patients are lowered quickly to a supine position, with the neck extended by the clinician performing the maneuver. A positive test is indicated by patient report of a reproduction of vertigo and clinician observation of nystagmus. For some patients, this maneuver may not be indicated, and a modification may be needed that also targets the posterior semicircular canal. Such patients include those who are too anxious about eliciting the uncomfortable symptoms of vertigo, and those who may not have the range of motion necessary to comfortably be in a supine position. The modification involves the patient moving from a seated position to side-lying without their head extending off the examination table, such as with Dix-Hallpike. The head is rotated 45 degrees to the side being tested, and the eyes are examined for nystagmus. Both the Dix-Hallpike and the side-lying testing position have yielded similar results, and as such the side-lying position can be used if the Dix-Hallpike cannot be performed easily.
If the test is negative, it makes benign positional vertigo a less likely diagnosis and central nervous system involvement should be considered.
Although there are alternative methods to administering the test, Cohen proposes advantages to the classic maneuver. The test can be easily administered by a single examiner, which prevents the need for external aid. Due to the position of the subject and the examiner, nystagmus, if present, can be observed directly by the examiner.
The negative predictive value of this test is not 100%. Some patients with a history of BPPV will not have a positive test result. The estimated sensitivity is 79%, along with an estimated specificity of 75%.
The test may need to be performed more than once as it is not always easy to demonstrate observable nystagmus that is typical of BPPV. The test results can also be affected by the speed the maneuver is done in and the plane the occiput is in.
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