出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/24 18:43:20」(JST)
| Dix–Hallpike test | |
|---|---|
| Diagnostics | |
| ICD-9-CM | 95.46 |
The Dix–Hallpike test[1] — or Nylen–Barany test — is a diagnostic maneuver used to identify benign paroxysmal positional vertigo (BPPV).[2]
The Dix–Hallpike test is performed with the patient sitting[3] upright on the examination table with the legs extended. The patient's head is then rotated to one side by approximately 45 degrees. The clinician helps the patient to lie down backwards quickly with the head held in approximately 20 degrees of extension. This extension may either be achieved by having the clinician supporting the head as it hangs off the table or by placing a pillow under their upper back. The patient's eyes are then observed for about 45 seconds as there is a characteristic 5–10 second period of latency prior to the onset of nystagmus. If rotational nystagmus occurs then the test is considered positive for benign positional vertigo. During a positive test, the fast phase of the rotatory nystagmus is toward the affected ear, which is the ear closer to the ground. The direction of the fast phase is defined by the rotation of the top of the eye, either clockwise or counter-clockwise. Home devices are available to assist in the performance of the Dix–Hallpike Maneuver for patients with a diagnosis of BPPV.[4]
There are several key characteristics of a positive test:
To complete the test, the patient is brought back to the seated position, and the eyes are examined again to see if reversal occurs. The nystagmus may come in paroxysms and may be delayed by several seconds after the maneuver is performed.
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.[5]
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.[6]
There are several disadvantages proposed by Cohen for the classic maneuver. Patients may be too tense, for fear of producing vertigo symptoms, which can prevent the necessary brisk passive movements for the test. A subject must have adequate cervical spine range of motion to allow neck extension, as well as trunk and hip range of motion to lie supine. From the previous point, the use of this maneuver can be limited by musculoskeletal and obesity issues in a subject.[5]
In rare cases a patient may be unable or unwilling to participate in the Dix–Hallpike test due to physical limitations. In these circumstances the side-lying test or other alternative tests may be used.[7]
Precautions
Absolute contraindications
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| リンク元 | 「ディックスホールパイクテスト」 |
| 関連記事 | 「maneuver」「D」 |
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