Teaching Case

A 58-year-old female patient presented to outpatient department of our hospital with headache, pulsatile tinnitus and left-ear discharge.

Initially CT angiography of intra/extra-cranial circulation was advised. It revealed dehiscence of mastoid bone with resultant sigmoid sinus diverticulum formation. Filling of mastoid air cells was also noted suggestive of mastoiditis. Both transverse sinuses also appeared narrowed before continuation into sigmoid sinuses. MRI of brain and MR venography were advised which revealed empty sella and also confirmed the stenoses of both transverse sinuses. No other abnormality was seen.

Of all the patients presenting with tinnitus, which is an auditory perception of internal origin [1], about 10% present with pulsatile tinnitus. [2] Causes of pulsatile tinnitus can be divided into vascular and non-vascular causes. Vascular causes include dural arteriovenous fistula, AVM, aneurysm, internal carotid artery stenosis or dissection, congenital vascular variants, transverse sinus stenosis, or increased cardiac output. Non-vascular aetiologies of pulsatile tinnitus include neoplasms, osseous pathology, idiopathic intracranial hypertension (IIH), and systemic disorders. [2] A newly established cause of pulsatile tinnitus is sigmoid sinus dehiscence and diverticulum. A good correlation was noted between patients with bilateral transverse sinus stenosis and idiopathic intracranial hypertension when compared with patients with pulsatile tinnitus and idiopathic intracranial hypertension. [3] Idiopathic intracranial hypertension is primarily a disorder of young obese women characterised by symptoms and signs associated with raised intracranial pressure in the absence of a space-occupying lesion or other identifiable cause. [4] Although pathophysiology of idiopathic intracranial hypertension is poorly understood, venous causes are considered main causative factors. [2] Modified Dandy criteria for diagnosing idiopathic intracranial hypertension follows:
1. Signs of increased intracranial pressure.
2. Negative neurologic examination.
3. Absence of deformity, displacement, or obstruction of the ventricular system and normal neuro-diagnostic studies, except for evidence of increased CSF pressure. Abnormal neuroimaging except for empty sella, optic sheath with filled CSF spaces, and smooth-walled non-flow-related venous sinus stenosis or collapse should lead to another diagnosis.
4. Awake and alert patient.
5. No other cause of increased intracranial pressure.
For CSF opening pressure of 200 to 250 mmH2O, at least one of the following is required:
- Pulse synchronous tinnitus.
- VI nerve palsy.
- Grade II papilloedema.
- Echography for drusen negative and no other disc anomalies mimicking disc oedema.
- MRV with lateral sinus collapse/stenosis.
- Partially empty sella on coronal or sagittal views and optic nerve sheaths with filled-out CSF spaces next to the globe on T2-weighted axial scans.[5]

Treatment: NORDIC Study Group developed the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT); a multicenter, double-blind, randomised, placebo-controlled study of 165 patients with mild visual loss. All patients received a lifestyle modification program of weight reduction with a low-sodium diet. Additionally, patients were randomised to receive either acetazolamide or matching placebo. [6] Among the 165 participants with idiopathic intracranial hypertension, beneficial effects of acetazolamide were seen on all quality of life (QOL) scales evaluated. Positive acetazolamide-related effects on QOL appeared to be primarily mediated by improvements in visual field, neck pain, pulsatile tinnitus, and dizziness/vertigo that outweighed the side effects of acetazolamide. [7]

Further trials and treatments options like transverse/sigmoid sinus stenting are currently under investigation.

Written informed patient consent for publication has been obtained.