Transverse sinus stenosis is a condition involving the narrowing of specific veins within the brain’s venous drainage system. This narrowing can impede the normal flow of blood from the brain, potentially affecting brain health and circulation.
What is Transverse Sinus Stenosis?
Transverse sinus stenosis refers to a reduction in the diameter of the transverse sinuses, which are large veins located at the back of the head. These sinuses are part of the dural venous sinuses, a network responsible for draining deoxygenated blood and cerebrospinal fluid from the brain. The transverse sinuses collect blood from other sinuses, such as the superior sagittal and straight sinuses, eventually emptying into the sigmoid sinuses and then into the jugular bulbs to return blood to the heart.
When narrowing occurs in these sinuses, it obstructs the outflow of blood and cerebrospinal fluid from the brain. This can lead to increased pressure within the skull, known as intracranial hypertension. The condition can manifest in two primary forms: intrinsic stenosis, where the narrowing is caused by structures within the sinus itself, such as enlarged arachnoid granulations or fibrous septa, and extrinsic stenosis, where external compression from surrounding tissues or elevated intracranial pressure causes the sinus to collapse.
Arachnoid granulations are small protrusions of the arachnoid mater, a membrane covering the brain, into the dural venous sinuses; when unusually large, they can obstruct blood flow. Extrinsic compression can occur when the brain parenchyma expands and presses against the sinuses, often seen in conditions involving increased intracranial pressure. Both intrinsic and extrinsic mechanisms may contribute to the narrowing.
Identifying the Symptoms
A common symptom of transverse sinus stenosis is pulsatile tinnitus, described as a whooshing sound in the ear synchronized with the heartbeat. This sound arises from turbulent blood flow through the narrowed sinus, perceived by the inner ear. It can be an isolated symptom or occur alongside other manifestations of increased intracranial pressure.
Other symptoms often stem from the elevated pressure within the skull caused by impaired venous drainage. Headaches are frequently reported, with some patients experiencing pulsatile headaches. Vision changes can also occur, including blurry vision or temporary vision loss.
In more pronounced cases, a medical sign known as papilledema may be observed. Papilledema is the swelling of the optic disc, the part of the optic nerve visible at the back of the eye, and is directly linked to increased intracranial pressure. While papilledema is a finding observed by a medical professional during an examination, it is an indicator of the underlying pressure issues associated with transverse sinus stenosis.
Diagnosis and Management
Diagnosis typically begins with a physical examination and a neurological assessment. Imaging techniques are then used to visualize the brain’s venous drainage system. Magnetic Resonance Venography (MRV) and Computed Tomography Venography (CTV) are commonly employed non-invasive methods. These scans can reveal a reduction in vessel caliber.
When non-invasive imaging is inconclusive, catheter angiography with venous manometry is considered the gold standard for diagnosis. This invasive procedure involves inserting a catheter into a vein to directly visualize the sinuses and measure the pressure gradient across the narrowed segment. A pressure gradient exceeding 8 mmHg is generally considered abnormal and indicative of obstruction.
Management strategies for transverse sinus stenosis vary based on symptom severity and the underlying cause. For asymptomatic individuals, a watchful waiting approach may be appropriate. Medical management involves medications that reduce intracranial pressure, such as carbonic anhydrase inhibitors like acetazolamide, which decrease cerebrospinal fluid production. Diuretics and other headache medications may also be prescribed to alleviate symptoms.
If medical treatments are ineffective or if there is a risk to vision, interventional procedures may be considered. Venous sinus stenting is a minimally invasive option where a stent is placed within the narrowed sinus to open it and restore blood flow. This procedure can reduce intracranial pressure and improve symptoms such as headaches, pulsatile tinnitus, and papilledema. Treatment is always tailored to the individual’s specific symptoms and the overall clinical picture.