Intractable Benign Paroxysmal Positioning Vertigo

To investigate the occurrence rate, prognosis, and inner ear abnormality in intractable benign paroxysmal positioning vertigo (BPPV).A prospective study.Tertiary referral university hospital.Intractable BPPV was defined in case of either a persistent nystagmus or a frequent relapse each lasting more than 1 year after the initial diagnosis.T2-weighted 3-dimensional fast imaging employing steady-state acquisition sequences of magnetic resonance imaging (MRI) were reconstructed 3-dimensionally for 13 intractable BPPV patients and 14 control volunteers.Transition and relapse of nystagmus were monitored. Semicircular canals were evaluated for a stenosis or filling defect (obturation).Eighteen patients (4 with posterior canal type, 2 with horizontal canal type with geotropic nystagmus, and 12 with apogeotropic nystagmus) fulfilled the above criteria for intractability among 495 BPPV patients. The occurrence rate of intractable BPPV was 3.6%. Also, the rate of nystagmus transition was significantly higher in patients with geotropic nystagmus and the posterior canal type (100%) compared with those with apogeotropic nystagmus (33.3%). Of the 13 intractable BPPV patients who underwent MRI, 11 (84.6%) had a total of 23 canals with abnormal appearance (29.5%), showing a significantly higher incidence compared with controls. There was no correlation between the affected canal diagnosed by MRI and the type of nystagmus.The low incidence of nystagmus transition in patients with apogeotropic nystagmus suggests a difference in pathophysiology between apogeotropic nystagmus and other types of BPPV. Stenosis and filling defect (obturation) of canals on MRI, which would indicate an innate narrowing and/or an otoconial jam of the semicircular canal, may account for the intractability of BPPV.