High-Resolution Three-Dimensional Magnetic Resonance Imaging of the Vestibular Labyrinth in Patients with Atypical and Intractable Benign Positional Vertigo

Abstract

Benign paroxysmal positional vertigo (BPPV) is a most common cause of dizziness and usually a self-limited disease, although a small percentage of patients suffer from a permanent form and do not respond to any treatment. This persistent form of BPPV is thought to have a different underlying pathophysiology than the generally accepted canalolithiasis theory. We investigated 5 patients who did not respond to physical treatment, presented with an atypical concomitant nystagmus or both with high-resolution three-dimensional magnetic resonance imaging of the inner ear. This method provides an excellent imaging of the inner ear fluid spaces. In all 5 patients, we found structural changes such as fractures or filling defects in the semicircular canals which we did not find in control groups. One patient clinically presented with the symptoms of a ‘heavy cupula’. Whereas crosssections through the ampullary region and the adjoining utricle showed no abnormalities, there were significant structural changes in the semicircular canals, which are able to provide an explanation for the symptoms of a heavy cupula.

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“…However, when 5 or 6 maneuvers are ineffective and once typical features of the nystagmus are observed, these patients should be assessed by a specific neuro-radiological study to rule out CNS conditions [9] . After CNS involvement has been ruled out, the persistence of positional vertigo symptoms should lead us to consider morpho-structural alterations of the labyrinth as well as metabolic and functional labyrinth conditions that facilitate the formation and maintenance of canaliths [8,12,13] .…”

“…Studies based on this technique have shown that patients with persistent BPPV had a higher incidence of abnormal MRI images (stenosis and canal filling defects) than normal controls [11][12][13] . These anomalies might correspond to really ductal narrowness or to plugs of otoconial debris [11,12] . Preliminary reports about these labyrinth abnormalities led us to consider the use of steroids because of their anti-inflammatory effect since glucocorticoid receptors are prevalent throughout the inner ear, including the vestibular structures (such as maculae of the utricle and saccule, otoconial membrane, the semicircular canal cristae, semicircular canal duct epithelium, and extramacular epithelium of the saccule) [15,18] .…”

“…Schratzenstaller et al [12] studied 5 patients suffering from persistent BPPV with high-resolution three-dimensional magnetic resonance imaging (MRI) of the inner ear. They found structural changes, such as filling defects in the semicircular canals, in these patients that were not present in control groups.…”

“…Other authors also found a high incidence of similar abnormal MRI images in patients with intractable BPPV [11,13] . These filling defects may indicate a narrowing and/or an otoconial jam of the semicircular canal, and it may suggest that an inflammatory process of the membranous labyrinth could explain the failure of the repositioning maneuvers [11][12][13] .…”

“…In particular, the use of three-dimensional high-resolution MRI protocols enables us to see the internal structure of the cochlea, vestibule, and semicircular canals. Studies based on this technique have shown that patients with persistent BPPV had a higher incidence of abnormal MRI images (stenosis and canal filling defects) than normal controls [11][12][13] . These anomalies might correspond to really ductal narrowness or to plugs of otoconial debris [11,12] .…”