SUPINE ROLL TEST - (APOGEOTROPIC POSITIONAL NYSTAGMUS)

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Supine roll test (SRT) of the patient elicits an apogeotropic horizontal positional nystagmus on yawing the head maximally to the right as well as to the left, which is visibly stronger on the right. The side to which the SRT elicits the weaker horizontal apogeotropic positional nystagmus lateralizes the involved horizontal semicircular canal. In this case, the left horizontal semicircular canal is involved. The etiology could be either left short anterior (ampullary) arm horizontal semicircular canalolithiasis or left horizontal semicircular cupulolithiasis to the canal (Cup-C) or the utricular side (Cup-U). The short anterior ampullary arm horizontal semicircular canalolithiasis and cupulolithiasis are difficult to differentiate, but if the supine roll test elicits persistent apogeotropic nystagmus lasting more than 1 minute and there are no changes in the direction of nystagmus even after repetitive supine head roll tests, it is explicable by the horizontal canal cupulolithiasis.