抄録
Introduction: In positional vertigo, spontaneous reversal of the initial positional nystagmus (the secondary phase nystagmus) is clinically rare without head position changes. We present herein a case of positional vertigo with the secondary phase nystagmus monitored and video-recorded using an infrared CCD camera.
Patient: A 65-year-old woman visited our otorhinolaryngological clinic with rotatory positional vertigo. At the initial visit, upbeat-torsional (counterclockwise) nystagmus induced by the head positional test was observed for>70s, with a latency of 2s; furthermore, the reversal of nystagmus was not observed when the head was moved back to the sitting position. Three days later, downbeat-torsional (clockwise) nystagmus induced by the head positional test was observed for 19s with a latency of 3s, and it was followed by reversal of initial positional nystagmus for 75s without head position changes.
Conclusion: The duration of positional nystagmus was>70s, and the reversal of nystagmus was not observed when the head was moved back to the sitting position. Therefore, we speculated that positional vertigo presumably involved canalolithiasis within the short-arm of the posterior canal. Further, we speculated that the secondary phase nystagmus was presumably due to the coexistence of long-arm type anterior canalolithiasis and short-arm type posterior canalolithiasis.
