Which test verifies the horizontal canal's function when assessing for BPPV?

The Roll test specifically assesses the horizontal canal's function in the context of Benign Paroxysmal Positional Vertigo (BPPV) by evaluating the response of the porcine and the cupula within the horizontal semicircular canals. During this test, the patient is positioned lying down, and the clinician rotates the patient's head to one side and then the other while observing for nystagmus (involuntary eye movements) and associated symptoms.

This is crucial because BPPV can occur due to dislodged otoconia that can affect different canals depending on the specific type of BPPV present. The Roll test helps to determine if the horizontal canal is involved, guiding appropriate treatment options.

Other tests mentioned in the options assess different canals or overall vestibular function. The Side lying test is less common for specifically assessing horizontal canal BPPV, while the Dix-Hallpike maneuver targets the anterior and posterior canals. Vestibular Rehabilitation maneuvers are utilized for treatment rather than specific diagnostic purposes regarding the horizontal canal. Thus, the Roll test is recognized as the correct test for evaluating function specifically related to the horizontal canal in BPPV.