New feature of nystagmus and its application in benign pistional paroxysmal vertigo

The nystagmus caused by the anterior, posterior or multiple semicircular canals benign positional paroxysmal vertigo (BPPV) is usually very complex accompanied with rotation characteristics. However, most of the conventional features can only describe the horizontal and vertical eye movements. The objective of this study is to propose a new feature of the nystagmus to evaluate the rotary of eye movements and position the affected semicircular canals of BPPV. Our study included 50 patients. Firstly, using the image processing techniques, we compiled a program to extract the new feature: nystagmus torsion angle and also some conventional features from the Video-nystagmograph (VNG) to evaluate rotary and horizontal eye movements separately. These extracted features were further used to diagnose the position of the affected semicircular canals. Posterior semicircular canal BPPV (P-BPPV) were involved in 32 patients (64%), whereas the anterior semicircular canal BPPV (A-BPPV) and horizontal semicircular canal (H-BPPV) were involved in 2 (4%) and 14 (28%), respectively. Two patients (4%) had the Multiple-canal BPPV (M-BPPV). The result of the diagnoses shows that this proposed method can diagnose the BPPV accurately. Clinically, this new method may be used to provide helpful guidelines for physicians´ objective diagnosis.