====== Venous Sinus Stenosis Diagnosis ======

[[Venous sinus stenosis]] (VSS) is a narrowing of the major [[dural venous sinus]]es, typically the transverse and/or [[sigmoid sinus]]es, often associated with [[idiopathic intracranial hypertension]] (IIH). Diagnosis is based on clinical features and confirmatory imaging and pressure studies.

===== 1. Clinical Suspicion =====
  * Headache (daily, pressure-like)
  * Pulsatile tinnitus
  * Visual disturbances (transient obscurations, diplopia, papilledema)
  * Elevated intracranial pressure (ICP) signs

===== 2. Neuroimaging =====

==== MRI + MR Venography (MRV) ====
  * First-line, non-invasive
  * Findings:
    * Transverse/sigmoid sinus narrowing
    * Collateral venous channels
    * Optic nerve sheath distension
    * Posterior globe flattening

==== CT Venography (CTV) ====
  * High-resolution anatomical detail
  * Useful at bone-venous interfaces (e.g., transverse-sigmoid junction)

==== Digital Subtraction Angiography (DSA) + Manometry ====
  * Gold standard
  * Allows dynamic assessment of:
    * Sinus anatomy
    * **Trans-stenotic pressure gradient**
      * A gradient ≥ 4 mmHg = hemodynamically significant stenosis

===== 3. Key Diagnostic Criterion =====
  * **Functional stenosis** requires:
    * Anatomical narrowing on imaging **AND**
    * Elevated trans-stenotic gradient on manometry

===== 4. Differential Diagnosis =====
  * Arachnoid granulations (benign filling defects)
  * Sinus hypoplasia (anatomic variant)
  * Cerebral venous thrombosis
  * Secondary sinus collapse due to raised ICP

===== 5. Summary Table =====

^ Modality             ^ Findings                                               ^ Role                          ^
| MRI/MRV              | Sinus narrowing, optic sheath distension               | First-line screening          |
| CT Venography        | Confirms anatomy, good bone detail                     | Complementary study           |
| DSA + Manometry      | Direct visualization, pressure gradient measurement    | Definitive diagnosis          |