TRANSVERSE SINUS STENOSIS
Transverse sinus stenosis refers to the narrowing (stenosis) of the transverse sinus, a large venous channel in the brain responsible for draining blood from the brain toward the internal jugular vein. The transverse sinuses are part of the dural venous sinuses, which are specialized blood vessels within the dura mater (the outermost membrane surrounding the brain) that collect venous blood from the brain and direct it toward the jugular veins.
When there is stenosis (narrowing) of the transverse sinus, it can obstruct the normal flow of blood from the brain, potentially leading to increased intracranial pressure and other neurological symptoms. This condition is also referred to as transverse sinus thrombosis if the stenosis is caused by a clot.
ANATOMY
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The transverse sinus is located on each side of the brain and runs along the back of the skull. It collects venous blood from the brain's internal structures, such as the cerebellum, brainstem, and cerebral hemispheres, before draining it into the internal jugular vein.
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The sigmoid sinus is a continuation of the transverse sinus, leading directly into the internal jugular vein, and from there, blood is returned to the heart.
SYMPTOMS
The symptoms of transverse sinus stenosis are typically related to impaired venous drainage from the brain, which can cause increased intracranial pressure and reduced blood flow. Symptoms may include:
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Headache: A common symptom due to increased intracranial pressure. Headaches may be persistent, throbbing, and worse in the morning or when changing position (such as lying down)
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Tinnitus: Ringing or pulsatile sounds in the ears, often caused by increased pressure in the venous system or impaired venous drainage from the brain
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Visual Impairment: Blurred vision, transient visual loss, or even blind spots may occur due to pressure on the optic nerves or from papilledema.
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Neurological Symptoms:
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Symptoms such as dizziness, nausea, or vomiting due to increased intracranial pressure.
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In severe cases, neurological deficits like motor weakness, seizures, or cognitive changes may develop.
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Swelling of the Neck: In some cases, neck or facial swelling may occur due to impaired venous drainage.
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Cognitive Impairment: Patients with transverse sinus stenosis may experience difficulty concentrating, memory problems, or a general feeling of "brain fog."
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Seizures: In severe cases of venous congestion or increased intracranial pressure, seizures may occur due to reduced cerebral blood flow.
CAUSES
Transverse sinus stenosis can result from various conditions, including:
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Venous Thrombosis
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Transverse sinus thrombosis is a condition in which a blood clot forms within the transverse sinus, leading to stenosis or complete blockage. This can occur due to various factors, such as:
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Hypercoagulable states (conditions that increase blood clotting, like certain genetic disorders, cancer, or pregnancy).
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Infections (e.g., sinusitis or otitis media).
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Trauma or surgery in the head or neck region, particularly if there is damage to the venous system.
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Oral contraceptives, pregnancy, or hormone replacement therapy (all of which can increase the risk of clotting).
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External Compression:
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Tumors, cysts, or enlarged lymph nodes around the neck and base of the skull can compress the transverse sinus, leading to narrowing and reduced venous outflow.
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Atherosclerosis: Although less common in veins, atherosclerotic plaques can form in the venous system and contribute to stenosis of the transverse sinus.
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Idiopathic Intracranial Hypertension (IIH): Also known as pseudotumor cerebri, IIH is a condition characterized by elevated intracranial pressure without an identifiable cause. The high pressure can lead to narrowing or stenosis of the venous sinuses, including the transverse sinus.
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Congenital Anomalies: Some individuals may have an inherent narrowing of the transverse sinus due to structural or developmental abnormalities in the venous system.
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Fibromuscular Dysplasia: A rare condition that causes abnormal growth in the walls of blood vessels, including veins, which can lead to stenosis in the transverse sinus.
DIAGNOSIS
Diagnosing transverse sinus stenosis typically involves a combination of clinical examination, imaging, and sometimes diagnostic procedures:
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Imaging:
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Magnetic Resonance Imaging (MRI) with Magnetic Resonance Venography (MRV): This is the gold standard for diagnosing transverse sinus stenosis. MRV allows detailed imaging of the venous structures and can identify areas of narrowing or occlusion in the transverse sinus.
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CT Venography (CTV): This test can also be used to visualize venous sinuses, particularly if MRV is not available or contraindicated.
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Conventional Venography: This invasive test, which involves injecting contrast into the venous system and taking X-ray images, is rarely used today but may be helpful in certain situations.
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Lumbar Puncture (Spinal Tap): A lumbar puncture may be performed to measure opening pressure in the cerebrospinal fluid (CSF). Elevated opening pressure can indicate increased intracranial pressure, which might be secondary to impaired venous drainage from the brain.
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Fundoscopic Eye Exam​: The ophthalmologist may observe papilledema (swelling of the optic disc), which is indicative of increased intracranial pressure and can be seen in patients with transverse sinus stenosis.
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Ultrasound: In certain cases, Doppler ultrasound of the neck veins may help assess venous flow and detect stenosis or clot formation.
TREATMENT
The treatment for transverse sinus stenosis depends on the severity of the condition, the underlying cause, and the presence of complications such as increased intracranial pressure or venous thrombosis. Common treatments include:
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Anticoagulation:
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If the stenosis is due to venous thrombosis, anticoagulant therapy (e.g., heparin or warfarin) is typically used to prevent further clotting and manage the risk of embolism.
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Management of Idiopathic Intracranial Hypertension (IIH):
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If transverse sinus stenosis is associated with IIH (pseudotumor cerebri), treatment may include:
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Acetazolamide (a carbonic anhydrase inhibitor) to reduce cerebrospinal fluid (CSF) production and lower intracranial pressure.
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Weight loss for patients who are overweight or obese, as it has been shown to reduce intracranial pressure in IIH.
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Diuretics like furosemide to reduce fluid buildup.
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In severe cases, optic nerve sheath fenestration (a surgical procedure to relieve pressure on the optic nerve) or a lumbar peritoneal shunt may be needed.
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Endovascular Procedures:
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In cases of severe stenosis or thrombosis, endovascular procedures like angioplasty (dilating the narrowed sinus) or the placement of a stent to keep the vein open may be considered.
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Surgical Intervention:
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Surgical interventions may be required to address external compression, such as tumor removal, or to insert a stent in the stenosed transverse sinus
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STENTING
Transverse sinus stenting is a medical procedure used to treat venous sinus stenosis — a narrowing of the transverse sinus. It’s most commonly done in patients with Idiopathic Intracranial Hypertension (IIH)/Pseudotumor cerebri when high pressure in the brain is linked to this narrowing.
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It’s usually considered when:
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A person has Idiopathic Intracranial Hypertension (IIH).
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There is evidence of transverse sinus stenosis on imaging (MRI/MRV, CT venogram).
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Other treatments (like medication or weight loss) haven’t worked.
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A pressure gradient (> 4–10 mmHg) is found across the stenosis during venous manometry (a catheter-based pressure test).
How the Procedure Works
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Venous access is typically gained through the femoral vein (in the groin).
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A catheter is threaded up through the venous system into the transverse sinus.
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A stent (a mesh-like tube) is placed in the narrowed area to hold it open.
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This improves blood outflow and can reduce intracranial pressure.
PROGNOSIS
The prognosis for transverse sinus stenosis depends on the underlying cause and the promptness of treatment. If the condition is diagnosed early and treated effectively, especially in cases of venous thrombosis or IIH, the outcome can be favorable. However, untreated stenosis may lead to chronic increased intracranial pressure, permanent vision loss (due to papilledema), and in severe cases, stroke or cognitive decline.