To evaluate mastoid pneumatisation and facial canal dimensions.

In this retrospective study, 169 multidetector computed tomography scans of temporal bone were reviewed. Facial canal dimensions were evaluated at the labyrinthine, tympanic and mastoid segments using axial and coronal multidetector computed tomography scans of temporal bone. Mastoid pneumatisation and facial canal dehiscence were evaluated. Facial canal dehiscence was measured if it was found to be present.

This study showed that facial canal dimensions decreased in pneumatised mastoids. Facial canal dimensions in females were smaller than in males. Facial canal dehiscence was detected in 5.9 per cent and 6.5 per cent of the patients on the right and left sides, respectively. No correlations were found between facial canal dehiscence and mastoid pneumatisation. The length of dehiscence was 1.92 ± 0.44 mm (range, 0.86–2.51 mm) on the left side. In older subjects, left facial canal dehiscence was detected more, and the length of the dehiscence increased.

This study concluded that during surgery, facial canal dehiscence should be kept in mind in order to avoid complications.

To inform on the incidence of high jugular bulb and dehiscent high jugular bulb, and the symptoms related to these vascular anomalies.

A retrospective analysis was performed of temporal bone computed tomography scans of 3285 patients who attended our clinic with various symptoms. The medical records of patients with high jugular bulb and dehiscent high jugular bulb were analysed, and the clinical findings reviewed. Patients with dehiscent high jugular bulb were evaluated for hearing loss with pure tone audiometry.

High jugular bulb was evident in 730 patients (22 per cent) (510 right-sided, 220 left-sided; p < 0.01). Twenty-six high jugular bulb patients had dehiscent high jugular bulb. Ten of these 26 patients had vertigo, 15 had tinnitus and 1 had hearing disturbance. Ten dehiscent high jugular bulb patients had undergone pure tone audiometry: seven patients had conductive hearing loss, two had sensorineural hearing loss and one had mixed hearing loss.

The incidences of high jugular bulb and dehiscent high jugular bulb were 22 per cent and 3.5 per cent, respectively. Tinnitus was the most common symptom of all patients. Dehiscent high jugular bulb was associated with various degrees of hearing loss, but not hearing disturbance.

We report a rare case of posterior semicircular canal dehiscence caused by a jugular diverticulum, and we describe its surgical treatment using a dehiscence resurfacing manoeuvre.

The clinical findings, surgical procedure and outcomes are presented.

A 66-year-old man presented with disequilibrium, sound-induced vertigo, a reduced ocular vestibular evoked myogenic potential threshold, and pressure-induced vertical and torsional nystagmus. Computed tomography revealed a right posterior semicircular canal dehiscence caused by a diverticulum of the jugular bulb. The defect in the posterior semicircular canal was localised and resurfaced with bone paté, temporalis muscle fascia and conchal cartilage, under direct visualisation. Post-operatively, the patient's symptoms disappeared and his ocular vestibular evoked myogenic potential threshold normalised.

This case illustrates that posterior semicircular canal dehiscence can be surgically managed by resurfacing the defect site via a transmastoid approach.

To report the coexistence of multiple tegmen defects, forming a ‘honeycomb’ pattern, together with dehiscence of the superior semicircular canal.

We describe three cases in which the above findings were noted, and we review the relevant literature.

Superior semicircular canal dehiscence is defined as the absence of portions of bone over the canal along the floor of the middle fossa. Most published articles describe the defect as an isolated finding which is either unilateral or bilateral. Studies on temporal bones show either a defect over the superior semicircular canal or isolated defects over the tegmen. We describe three cases in which we found multiple tegmen defects, giving a characteristic honeycomb appearance, coexisting with dehiscence over the superior semicircular canal. This finding, which supports the theory of a developmental defect as the origin of the condition, has not previously been reported. A literature review is presented, with discussion of the aetiology and management of superior semicircular canal dehiscence.