The condition is diagnosed by the person's history, and by performing the Dix–Hallpike test or the roll test, or both. The Dix–Hallpike test is a common test performed by examiners to determine whether the posterior semicircular canal is involved. It involves a reorientation of the head to align the posterior semicircular canal (at its entrance to the ampulla) with the direction of gravity. This test will reproduce<unk>  and nystagmus characteristic of posterior canal<unk> . 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<unk> , 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<unk>  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<unk>  and nystagmus. This is followed by gently bringing the head back to the starting position. The examiner then quickly rotates the head 90° to the right side and checks again for<unk>  and nystagmus. In this roll test, the person may experience<unk>  and nystagmus on both sides, but rotating toward the affected side will trigger a more intense<unk> . Similarly, when the head is rotated toward the affected side, the nystagmus will beat toward the ground and be more intense. As mentioned above, both the Dix–Hallpike and roll test provoke the signs and symptoms in subjects suffering from archetypal<unk> . The signs and symptoms people with<unk>  experience are typically a short-lived<unk>  and observed nystagmus. In some people, although rarely,<unk>  can persist for years. Assessment of<unk>  is best done by a medical health professional skilled in the management of dizziness disorders, commonly a physiotherapist, audiologist, or other physician. The nystagmus associated with<unk>  has several important characteristics that differentiate it from other types of nystagmus. * Latency of onset: there is a 5–10 second delay prior to onset of nystagmus * Nystagmus lasts for 5–60 seconds *<unk> : the nystagmus occurs only in certain positions * Repeated stimulation, including via Dix–Hallpike maneuvers, cause the nystagmus to fatigue or disappear temporarily * Rotatory/torsional component is present, or (in the case of lateral canal involvement) the nystagmus beats in either a geotropic (toward the ground) or ageotropic (away from the ground) fashion * Visual fixation suppresses nystagmus due to<unk>  Although rare, CNS disorders can sometimes present as<unk> . A practitioner should be aware that if a person whose symptoms are consistent with<unk> , but does not show improvement or resolution after undergoing different particle repositioning maneuvers — detailed in the Treatment section below — need to have a detailed neurological assessment and imaging performed to help identify the pathological condition. Differential diagnosis<unk> , a distinct process sometimes confused with the broader term, dizziness, accounts for about six million clinic visits in the United States every year; between 17 and 42% of these people are eventually diagnosed with<unk> . Other causes of<unk>  include: * Motion sickness/motion intolerance: a disjunction between visual stimulation, vestibular stimulation, and/or proprioception * Visual exposure to nearby moving objects (examples of optokinetic stimuli include passing cars and falling snow) * Other diseases: (labyrinthitis, Ménière's disease, and migraine, etc.)
Benign paroxysmal positional vertigo
Stroke
Migraine-associated vertigo
Ménière's disease
Benign paroxysmal vertigo of childhood
Labyrinthitis
Alternobaric vertigo
Flicker vertigo