Diagnosis of horizontal semicircular canal benign paroxysmal positional vertigo

Objective To analyse the video-oculographic findings of positional tests in patients with horizontal semicircular canal paroxysmal positional vertigo (HSC BPPV). Methods Forty six patients were enrolled in this prospective study. The diagnosis was base history of brief episodes of vertigo and the presence of positional nystagmus as confirmed by video-oculographic examination during Dix-Hallpike and roll testing, and the exclusion of other disorders. Results Of 441 patients with BPPV diagnosed in our center, 46(10.43%) had HSC involvement. Of them, 38 (82.61%) patients had unilateral lesions, 5(10.87%) were associated with ipsilateral PSC BPPV, 3 (6.52%) patients had bilateral lesions. Thirty-five patients were confirmed both in Dix-Hallpike test and roll test, 11 were confirmed only in roll test. Geotropic nystagmus was seen in 25 patients in Dix-Hallpike test and roll test, while apogeotropic nystagmus in 13 patients. The direction of nystagmus could not be ascertained clinically in 3 patients and the direction of nystagmus was the same during right and left positional test in 5 patients. Seventeen patients were provoked nystagmus in unilateral maneuver and 29 patients in bilateral maneuver. Conclusion Patients of HSC BPPV with horizontal direction-changing positional nystagmus and geotropic nystagmus are more common. Always, nystagmus was provoked by bilateral maneuver, but was more serious on the lesion side. HSC BPPV can coexist with ipsilateral PSC BPPV. The roll test is more sensitive to horizontal semicircular canal benign paroxysmal positional vertigo.