Described just over 20 years ago, superior semicircular canal dehiscence remains a relatively unknown and easily missed cause of dizziness and auditory symptoms.

This review focused on the origin, presenting symptoms and underlying pathophysiology of superior semicircular canal dehiscence, and the available treatment options.

The bony dehiscence acts as a ‘third window’, affecting inner-ear homeostasis, and resulting in hypersensitivity and a vestibular response to lower sound level stimuli. The third window effect explains the pressure- and sound-induced vertigo, oscillopsia, and nystagmus, as well as autophony, conductive hyperacusis and tinnitus. The origin of superior semicircular canal dehiscence is linked to the combination of a congenital or developmental factor, and a ‘second event’ like head trauma, rapid pressure changes or age-related factors. Computed tomography of the temporal bone and reduced vestibular-evoked myogenic potential thresholds can confirm the diagnosis. Despite only retrospective cohorts, surgery is considered a safe treatment option, targeting mainly vestibular but also auditory symptoms, with transmastoid approaches gaining popularity.

Disorders of balance often pose a diagnostic conundrum for clinicians, and a multitude of investigations have emerged over the years. Vestibular evoked myogenic potential testing is a diagnostic tool which can be used to assess vestibular function. Over recent years, extensive study has begun to establish a broader clinical role for vestibular evoked myogenic potential testing.

To provide an overview of vestibular evoked myogenic potential testing, and to present the evidence for its clinical application.

Structured literature search according to evidence-based medicine guidelines, performed between November 2008 and April 2009. No restrictions were applied to the dates searched.

The benefits of vestibular evoked myogenic potential testing have already been established as regards the diagnosis and monitoring of several clinical conditions. Researchers continue to delve deeper into potential new clinical applications, with early results suggesting promising future developments.

To assess vestibular evoked myogenic potentials in patients with fibromyalgia syndrome.

Twenty-four patients with fibromyalgia syndrome (two men and 22 women) and 21 female controls were included in the study. All patients underwent vestibular evoked myogenic potential testing.

Statistical comparison of fibromyalgia patients with control subjects showed a significant difference with respect to n23 latencies and interpeak latencies (p < 0.05). There was no significant difference in p13 latencies, nor in p13 amplitudes, n23 amplitudes or interpeak amplitudes (p > 0.05).

Although patients with fibromyalgia syndrome generally have subjective neurotological symptoms, clinical and laboratory assessments usually fail to detect any objective abnormality. However, it is possible to detect abnormalities on vestibular evoked myogenic potential testing in such patients, indicating dysfunction in the vestibulospinal pathway, possibly in the saccule. Elongation of the n23 latency and of the interpeak latency of waves p13–n23, during vestibular evoked myogenic potential testing, may be a useful, objective indicator demonstrating neurotological involvement in fibromyalgia syndrome patients. Future research investigating the mechanisms of this latency elongation may help increase understanding of the pathogenesis of fibromyalgia syndrome.

To report eight cases of inferior vestibular neuritis, in order to raise awareness of this new subtype of vestibular neuritis.

We retrospectively analysed 216 patients (104 males and 112 females; age range 10–64 years; mean age 38.4 years) with full clinical documentation who had attended our hospital's vertigo clinic between May 2007 and December 2008. All patients underwent systematic investigation, including hearing tests, radiology, caloric testing and vestibular evoked myogenic potential testing.

Of 216 patients with vestibular neuritis, eight cases were diagnosed as inferior vestibular neuritis, based on comprehensive analysis of test data. The clinical features of these eight patients were consistent with the characteristics of vestibular neuritis. The results of pure tone audiometry and caloric testing were normal, and the possibility of central lesions was excluded by cerebral computed tomography or magnetic resonance imaging on admission. Six cases had unilateral loss of vestibular evoked myogenic potentials, whereas two had a unilateral lower amplitude of vestibular evoked myogenic potentials.

Inferior vestibular neuritis is a novel subtype of vestibular neuritis, which involves the inferior vestibular nerve alone. Vestibular evoked myogenic potential testing is a useful aid to the diagnosis of inferior vestibular neuritis.