Benign paroxysmal positional vertigo is classified into five subtypes according to the features of positional nystagmus: lateral canalolithiasis, lateral light cupula, lateral heavy cupula, posterior canalolithiasis and posterior heavy cupula.

The first aim of the study was to clarify whether the lateral canal type or posterior canal type was more common. The second aim of the study was to assess the aetiology of benign paroxysmal positional vertigo by investigating the onset time of each subtype.

The subjects were 512 consecutive patients with benign paroxysmal positional vertigo. The patients were prospectively aggregated, and interviews were used to evaluate onset time.

The lateral canal type (55.5 per cent) was more common than the posterior canal type (44.5 per cent). Time of awakening was the most common onset time in every subtype.

The incidence of lateral canal type is higher than that of posterior canal type. The aetiology of benign paroxysmal positional vertigo is closely related to sleep.

To estimate the incidence of tympanogenic labyrinthitis ossificans.

The records of patients treated with mastoidectomy for various tympanogenic aetiologies from January 2007 to December 2011 were retrospectively reviewed. Patients whose high-resolution computed tomography scans showed evidence of labyrinthine calcification of the temporal bone were enrolled. Patients with a history of head and neck cancer, meningitis, and otosclerosis, and patients with cochlear implants, were excluded from this study.

A total of 195 patients were enrolled in this study; 4 of the patients presented with calcification in the inner ear. Therefore, the incidence of tympanogenic labyrinthitis ossification was 2 per cent. The computed tomography findings revealed: (1) cochlear calcifications of the basal and middle turn in two patients; and (2) vestibular, superior semicircular canal, posterior semicircular canal and lateral semicircular canal calcification in one, four, three and two patients, respectively.

The incidence of tympanogenic labyrinthitis ossification in patients who had undergone a mastoidectomy was 2 per cent.

Superior semicircular canal dehiscence affects the auditory and vestibular systems due to a partial defect in the canal's bony wall. In most cases, sound- and pressure-induced vertigo are present, and are sometimes accompanied by pulse-synchronous tinnitus.

We describe a 50-year-old man with superior semicircular canal dehiscence whose only complaints were head rotation induced tinnitus and autophony. Head rotation in the plane of the right semicircular canal with an angular velocity exceeding 600°/second repeatedly induced a ‘cricket’ sound in the patient's right ear. High resolution temporal bone computed tomography changes, and an elevated umbo velocity, supported the diagnosis of superior semicircular canal dehiscence.

In addition to pulse-synchronous or continuous tinnitus, head rotation induced tinnitus can be the only presenting symptom of superior semicircular canal dehiscence without vestibular complaints. We suggest that, in our patient, the bony defect of the superior semicircular canal (‘third window’) might have enhanced the flow of inner ear fluid, possibly producing tinnitus.