Characteristic analysis of positional nystagmus in patients with vestibular migraine / 第二军医大学学报

ABSTRACT

Objective To analyze the characteristics of positional nystagmus in patients with vestibular migraine (VM) and to discuss its possible mechanism. Methods We retrospectively analyzed the types, intensities, and time of positional nystagmus recorded by video nystagmography during Dix-Hallpike and Roll-test in 14 patients with acute episode of VM and 16 patients with benign paroxysmal positional vertigo (HSC-BPPV). Results A mixture of geotropic, apogeotropic and downbeat components with a variable combination of each component and various types of positional nystagmus were identified in VM. There was no significant difference in the latencies or the duration of positional nystagmus between VM group and HSC-BPPV group (P>0. 05). The peak slow-phase velocities (SPVmax) in horizontal component of positional nystagmus was (11.4 ± 2.3) °/s in VM group, which was significantly lower than that in the HSC-BPPV group ([56.8±9.4] °/s, P = 0.001). Compared with HSC-BPPV group, the time needed for reaching the SPVmax (tm) was significantly longer in VM group ([18.1±2.0] vs [5.9±1.1] s, P<0. 001), and the rate of velocity change was significantly slower in VM group ([0.54 ± 0.14] vs [7. 21 ±1. 79] °/s2, P<0.001). The asymmetry ratio of the stronger to softer SPVmax in HSC-BPPV group was significantly higher than that in the VM group (P = 0. 02). Conclusion Abnormal central integration mechanism in VM may lead to discordant transmission of semicircular canal rotation information, resulting in mixed nystagmus components and flat nystagmus that appeared at multiple positional maneuver.