Lateral canal BPPV with Pseudo-Spontaneous Nystagmus masquerading as vestibular neuritis in acute vertigo: A series of 273 cases

OBJECTIVE: To investigate the incidence of Lateral Semicircular Canal BPPV (LSC BPPV) with Pseudo-Spontaneous Nystagmus in patients preliminarily diagnosed for vestibular neuritis in the Emergency Department (ED). METHODS: Retrospective study of 273 patients with acute vertigo and persistent horizontal nystagmus in upright position (male 110, female 163, 14-93 years old) observed over four years. All the patients were checked for any nystagmus modification by performing the Head Pitch Test (HPT) in the upright position. RESULTS: The HPT modified the beating direction of the persistent horizontal nystagmus in 56 of the 273 examined patients. The positioning tests subsequently confirmed the diagnosis of LSC BPPV in all those 56 patients. There were 37 geotropic variants and 19 apogeotropic variants and all of them were successfully treated by performing liberatory manoeuvres in the course of the same session. CONCLUSION: Performing the HPT in the upright position helps to differentiate a direction fixed nystagmus from a direction changing one, and in so doing, to make the differential diagnosis between vestibular neuritis and LSC BPPV, achieving the goal of successfully treating LSC BPPV in the first session.