Dix-Hallpike test

The Dix-Hallpike test (or Nylen-Barany test) is a diagnostic maneuver used to identify benign paroxysmal positional vertigo (BPPV).

The Dix-Hallpike test is performed with the patient sitting upright with the legs extended. Their head is then rotated 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 closest 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, such as the DizzyFIX, are available to assist in the performance of the Dix-Hallpike Maneuver for patients with a diagnosis of BPPV.

There are several key characteristics of a positive test

 * 1) Latency of onset (usually 5-10 seconds)
 * 2) Torsional (rotational) nystagmus. If no torsional nystagmus occurs but there is upbeating or downbeating nystagmus, a CNS dysfunction is indicated.
 * 3) Upbeating or downbeating nystagmus. Upbeating nystagmus indicates that the vertigo is present in the posterior semicircular canal of the tested side.  Downbeating nystagmus indicates that the vertigo is in the anterior semicircular canal of the tested side.
 * 4) Fatigable nystagmus. Multiple repetition of the test will result in less and less nystagmus.
 * 5) Reversal. Upon sitting after a positive maneuver the direction of nystagmus should reverse for a brief period of time.

To complete the test, the patient is brought back to the seated position, and the eyes are examined again to see if reversal occurs. If the test is negative it makes benign positional vertigo a less likely diagnosis and CNS involvement should be considered. Note that the nystagmus may come in paroxysms and may be delayed by several seconds after the maneuver is performed.