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.
A specific antibody and epitope binding that shows the highest affinity and is pathogenic occurs between GPA antibodies and the anti-GBM epitope region, designated EA, which is residues 17-31 of the alpha 3 subunit of non-collagenous domain of type IV collagen. T cells are also implicated, though it is generally considered a type II hypersensitivity reaction. Diagnosis
The diagnosis of GPS is often difficult, as numerous other diseases can cause the various manifestations of the condition and the condition itself is rare. The most accurate means of achieving the diagnosis is testing the affected tissues by means of a biopsy, especially the kidney, as it is the best-studied organ for obtaining a sample for the presence of anti-GBM antibodies. On top of the anti-GBM antibodies implicated in the disease, about one in three of those affected also has cytoplasmic antineutrophilic antibodies in their bloodstream, which often predates the anti-GBM antibodies by about a few months or even years. The later the disease is diagnosed, the worse the outcome is for the affected person.In addition, if there is substantial suspicion of the disease, seralogic testing for ELISA assay is usually done by looking for alpha3 NC1 domain area of collagen IV in order to avoid false positives. Treatment
The major mainstay of treatment for GPS is plasmapheresis, a procedure in which the affected persons blood is sent through a centrifuge and the various components separated based on weight. The plasma contains the anti-GBM antibodies that attack the affected persons lungs and kidneys, and is filtered out.