This test will reproduce vertigo and nystagmus characteristic of posterior canal BPPV.When performing the Dix–Hallpike test, people are lowered quickly to a supine position, with the neck extended by the person performing the maneuver. For some people, this maneuver may not be indicated, and a modification may be needed that also targets the posterior semicircular canal. Such people 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 person 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 away from the side being tested, and the eyes are examined for nystagmus. A positive test is indicated by the patient report of a reproduction of vertigo and clinician observation of 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.The roll test can determine whether the horizontal semicircular canal is involved. The roll test requires the person to be in a supine position with their head in 30° of cervical flexion. Then the examiner quickly rotates the head 90° to the left side, and checks for vertigo and nystagmus. This is followed by gently bringing the head back to the starting position.
Signs and symptoms
Symptoms:

Paroxysmal—appears suddenly, and in episodes of short duration: lasts only seconds to minutes
Positional—is induced by a change in position, even slight
Vertigo—a spinning dizziness, which must have a rotational component
Torsional nystagmus—a diagnostic symptom where the top of the eye rotates toward the affected ear in a beating or twitching fashion, which has a latency and can be fatigued (vertigo should lessen with deliberate repetition of the provoking maneuver): nystagmus should only last for 30 seconds to one minute
Pre-syncope—(feeling faint) or syncope (fainting) is unusual, but possible
Visual disturbance—due to associated nystagmus, making it difficult to read or see during an attack
Nausea—is often associated
Vomiting—is common, depending on the strength of vertigo itself and the causes for this illnessMany people will report a history of vertigo as a result of fast head movements. Many are also capable of describing the exact head movements that provoke their vertigo. Purely horizontal nystagmus and symptoms of vertigo lasting more than one minute can also indicate BPPV occurring in the horizontal semicircular canal. The spinning sensation experienced from BPPV is usually triggered by movement of the head, will have a sudden onset, and can last anywhere from a few seconds to several minutes. The most common movements people report triggering a spinning sensation are tilting their heads upward in order to look at something and when rolling over in bed.People with BPPV do not experience other neurological deficits such as numbness or weakness. If those symptoms are present, a more serious etiology, such as posterior circulation stroke or ischemia, must be considered.