Subjective visual horizontal in patients with posterior canal benign paroxysmal positional vertigo

Patients with posterior canal benign paroxysmal positional vertigo (p-BPPV) could have mild excitation in the vestibular system on the affected side.

p-BPPV is considered to be caused by small particles dislodged from the utricular macula. While subjective visual horizontal (SVH) mainly reflects utricular function, there is less documentation on SVH in patients with p-BPPV. The purpose of this study was to clarify whether p-BPPV could affect SVH.

Twenty-eight patients with unilateral idiopathic p-BPPV were enrolled. For comparison, 17 patients with vestibular neuritis and 45 patients with cerebello-pontine angle (CPA) tumor were also examined. For measurement of SVH, we used a device that has a red bar of light-emitting diodes (LEDs) in front of the patient. Subjects were asked to rotate the bar to the position that they felt was horizontal in a completely dark room.

Deviation of SVH toward the unaffected side down was seen in 82.1% (23/28) of patients with p-BPPV. Mean+/-SD deviation of SVH from the true horizontal to the unaffected side down was 0.49+/-1.21 degrees. Conversely, deviation of SVH was toward the affected side down in 88.2% of patients with vestibular neuritis and in 75.6% of patients with CPA tumor.