Vertigo can be a challenging complaint to evaluate and treat. It can arise from a slew of vastly different pathophysiologies, with acuity ranging from minimally consequential to catastrophic. Differentiating the etiology of vertigo, therefore, is of ineffable importance. The Dix-Hallpike maneuver is a powerful tool in the physician armamentarium to distinguish one of the most common and benign iterations from some potentially devastating alternative diagnoses that physicians cannot miss. The maneuver, when properly employed, can identify a common, benign cause of vertigo, which can then be treated with bedside maneuvers, often providing instant relief to patients. 
The Dix-Hallpike maneuver aims to identify benign positional paroxysmal vertigo (or BPPV). This disease process is thought to be caused by free-floating debris (often in the form of a calcium carbonate stones, termed otoliths) in the semicircular canals of the inner ear. Three canals make up this system, each forming a loop filled with endolymph and lined with hair cells. During normal rotational movement of the head, the fluid endolymph remains relatively motionless while the canals and the hair cells move. The hair cells are mechanically pushed by the resistance of the endolymph, opening mechanically gated ion channels that trigger an action potential indicating rotational movement. Each of the three canals is oriented slightly differently, with the anterior and posterior canals in the vertical plane, set to detect movement in the sagittal and coronal planes, respectively, and the lateral canal 30 degrees off from the horizontal plane, detecting movement to the left or right in the horizontal plane.
Benign positional paroxysmal vertigo is typically thought to be caused by dislodgement of a piece of calcium carbonate from the otoconial membrane within one of the canals, physically displacing hair cells on movement and creating persistent action potentials until the response is fatigued, generally within 30 to 60 seconds. This results in the sensation of movement and nystagmus characteristic of vertigo in brief paroxysms with positional changes of the head. The posterior canal is affected 90% of the time in benign positional paroxysmal vertigo, and lateral canal pathology causes approximately 8% of cases. The Dix-Hallpike maneuver is the gold standard for diagnosing benign positional paroxysmal vertigo caused by a posterior canal otolith. The patient is positioned recumbent with the head back and toward the affected ear, causing the otolith to progress superiorly along the natural course of the canal. Typically, after a five to 20-second delay, this will cause vertigo and rotary or up-beating nystagmus, which will resolve within 60 seconds.
The Dix-Hallpike maneuver is indicated for patients with paroxysmal vertigo in whom benign positional paroxysmal vertigo is considered in the differential. These patients experience vertigo in brief episodes lasting less than one minute with changes of head position and return to total normalcy between episodes. Light-headedness or a sensation of nausea might last longer than one minute, but if the sensation of movement persists for more than one-minute alternative diagnoses must be considered. Dizziness is a common complaint, and serious causes must be considered and excluded first. Non-paroxysmal vertigo is more likely to be caused by a vestibular syndrome or central etiology, such as brainstem stroke. Distinguishing these causes requires thorough neurological examination (possibly including the HINTS exam), a detailed history, and possibly, imaging with CT scan and MRI as indicated. Any neurological deficit, especially truncal ataxia, should generate concern for a central cause and trigger further workup. If the history is consistent with benign positional paroxysmal vertigo, the Dix-Hallpike maneuver is the test of choice for diagnosis.
The Dix-Hallpike maneuver should be avoided in a patient with neck pathology, in whom the movements involved could be dangerous to the patient. Cervical instability, vascular problems like vertebrobasilar insufficiency and carotid sinus syncope, acute neck trauma and cervical disc prolapse are absolute contraindications. In patients without an absolute contraindication, one paper suggests briefly assessing neck rotation and extension before attempting the maneuver to see if these positions can be comfortably maintained for thirty seconds.
All that is required for this test is a bed that can recline to horizontal, but certain equipment can be helpful, if available. Frenzel goggles can be useful to magnify the movements of the eyes. A mat table can be useful for elevating the shoulders and keeping the patient closer to the ground and thus safer. Video ENG equipment can be used by advanced practitioners to better monitor eye movements during this maneuver.
This test can be accomplished by a single practitioner.
Position the patient appropriately and counsel them about what is about to happen, ready them for vertigo (and possibly nausea and vomiting) they will experience. Consider an antiemetic before implementing the test.
The patient begins sitting up, and their head is oriented 45 degrees toward the ear to be tested. The clinician then lies the patient down quickly with their head past the end of the bed and extends their neck 20 degrees below the horizontal, maintaining the initial rotation of the head. The clinician then watches the patient's eyes for torsional and up-beating nystagmus, which should start after a brief delay and persist for no more than one minute. This would indicate a positive test. If the test is negative but clinical suspicion remains high, the patient should be given a chance to recover for at least one minute, and then testing of the other ear can be undertaken. Lateral canal pathology may not be detected by this method, and a supine roll test may be done if this is suspected.
Nausea and vomiting are common during this maneuver; this can potentially be avoided by giving an antiemetic before testing.
The Dix-Hallpike maneuver is the gold standard for diagnosis of benign positional paroxysmal vertigo, so it is difficult to assess its sensitivity and specificity acutely. The exclusion of dangerous etiologies of vertigo should be the clinician's primary concern, requiring excellent history and physical examination skills. Once these etiologies have been ruled out, if benign positional paroxysmal vertigo is on the differential, the Dix-Hallpike maneuver can diagnose the problem. This can be readily transitioned into the Epley maneuver, in which the position of the otolith continues to be manipulated until it is out of the posterior canal, ending the sensation of vertigo with positional changes and curing the disease process. While there is a high rate of recurrence and this is not always effective, relieving the symptoms of our patients in this way is highly desirable, and patients can be given instructions on how to do this at home for recurrences.
When uncertainty exists as to the etiology of vertigo, specialty consultation is appropriate. Especially when a provider suspects a central etiology, emergent evaluation at a stroke center should be undertaken. Strong evidence exists for the use of the Epley maneuver for benign positional paroxysmal vertigo. A meta-analysis of the data performed by the Cochrane collaboration concluded that the Epley maneuver was effective for treating BPPV, but that there was a high likelihood of recurrence of symptoms. 
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