Abstract
BACKGROUND: Benign Paroxysmal Positional Vertigo (BPPV) is a common vestibular disorder caused by displaced otolith debris in the inner ear. This study explored the order effect related to the sequence of performing different diagnostic positional maneuvers. METHODS: 3D simulations of the Supine Roll Test (SRT), Dix-Hallpike maneuver (DHM), and Deep head hanging tests, performed in the standardized prescribed way, were used to study various types of horizontal, posterior, and anterior canal BPPV. The simulations allowed visualization of the movement of the otolith debris and the resulting nystagmus patterns. The results of the sequence of tests and the starting side of the tests (from left or right) were observed. RESULTS: Simulations of the SRT on horizontal canal BPPV (hc-BPPV) showed different patterns of nystagmus: direction changing, direction fixed, and unilateral (only elicited in one position) nystagmus. These patterns depended on the position of the debris within the horizontal canal and the side from which the SRT began. Simulations of the DHM showed that the test procedure could displace debris in the horizontal canal. The SRT, however, caused no movement of debris in the vertical canals. The deep head hanging test could displace debris in all canals. CONCLUSION: An order effect can occur when performing diagnostic maneuvers for BPPV. The maneuvers can displace debris in the semicircular canals into new positions that may influence the findings in subsequent maneuvers and confound interpretation. A standardized testing protocol, starting with the SRT first, can decrease the order effect and simplify the interpretation of test results and in turn improve diagnostic accuracy and outcomes in the management of BPPV.