Spontaneous nystagmus in benign paroxysmal positional vertigo

Objective: The purpose of this study was to evaluate the presence and eventually to study the features of spontaneous nystagmus (Ny) in our patients with diagnosis of benign paroxysmal positional vertigo (BPPV). Patients and methods: We retrospectively reviewed the clinical records of patients who presented with vertigo spells and were managed at our tertiary care referral center. Patients with only idiopathic BPPV presenting with typical vertigo spells and positioning Ny characteristic of the disease were included in this study. To investigate the positioning Ny, we studied the patients in the sitting position, during the head shaking test, and during the Dix-Hallpike test and the McClure-Pagnini test (Ny provoked by rotation of the head in a supine patient). Ny responses in all patients were observed using infrared videoscopy. Results: We managed 412 patients affected by BPPV. Of the 412 patients, 292 (70.87%) were diagnosed to be having posterior canal-BPPV and 110(26.99%) patients had horizontal canal-BPPV (HC-BPPV). The remaining 10 patients (2.44%) were identified to have anterior canal-BPPV. Spontaneous Ny in sitting position was observed, by infrared videoscopy, only in the patients affected by HC-BPPV. Conclusion: Spontaneous Ny in BPPV can be observed with infrared videoscopy in patients affected by HC-BPPV. The origin of this Ny is most likely due to a natural inclination of horizontal semicircular canal with respect to the horizontal plane. This Ny stops after flexion of the head in neutral position, and for this reason, it should be considered as a seemingly spontaneous Ny. This Ny, in our experience, is observed in most HC-BPPV patients but does not indicate the need for a different management protocol or any different prognostic value of HC-BPPV. (C) 2011 Elsevier Inc. All rights reserved.