Pulsatile tinnitus usually originates from vascular structures, causing an arterial or venous bruit. We report a new cause of pulsatile tinnitus: a focal defect of the mastoid bone shell in the region of the transverse-sigmoid junction, with a normal transverse-sigmoid sinus.

Three patients complained of unilateral, pulsatile tinnitus present for many years. They were identified as having a focal defect of the mastoid bone shell in the region of the transverse-sigmoid junction. The patients underwent transmastoid reconstruction of the mastoid bone shell overlying the transverse-sigmoid sinus.

All three patients reported immediate resolution of their symptoms, and were asymptomatic at final follow up.

A focal defect of the mastoid bone shell overlying the transverse-sigmoid sinus, with no abnormality of the sinus itself, may be a new cause of pulsatile tinnitus. Surgical reconstruction of the mastoid bone shell overlying the transverse-sigmoid sinus can provide lasting symptom relief for patients with pulsatile tinnitus and computed tomographic evidence of the defect.

We present an extremely rare case of severe intracranial hypertension secondary to sigmoid sinus compression by a group A streptococcal epidural abscess.

Case report and review of the world literature.

A five-year-old boy was treated for acute otitis media and group A streptococcal bacteraemia, but subsequently developed severe intracranial hypertension. Computed tomography revealed that, although the sigmoid sinuses were not thrombosed, the patient had a dominant right sigmoid sinus that was almost completely compressed by a small epidural abscess. After surgical decompression of the epidural abscess, with aggressive debridement of the granulation tissue from the sigmoid sinus wall, the patient awoke from general anaesthesia with complete resolution of his symptoms and signs of intracranial hypertension. He suffered no sequelae over the subsequent six months' follow up.

This is the first reported case of intracranial hypertension due to an epidural abscess causing sigmoid sinus compression without thrombosis. This case illustrates the fact that, even in the absence of thrombosis of the sigmoid sinus, a small epidural abscess may require urgent surgical treatment.