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🌟 Venous sinus thrombosis

 🎯 Pathology

  • blood clots in the venous sinuses of the brain

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🧠 Dural venous sinuses

  • “pools” of “pockets” of venous blood found between the periosteal and meningeal layers of the dura that drain into the internal jugular veins

  • course of the dural venous sinuses:

    • superior sagittal sinus

      • sits on top of the falx cerebri

    • inferior sagittal sinus

      • sits at the bottom of the falx cerebri

    • straight sinus

      • continuation of the inferior sagittal sinuses

    • transverse sinus

      • joins the superior sagittal sinus at the confluence of the sinuses

    • sigmoid sinus

      • continuation of the transverse sinus that takes the course of an “S-shape”

      • continuous with the internal jugular vein

    • cavernous sinus

      • clinically relevant

      • blood is drained into the transverse and sigmoid sinuses via the petrosal sinuses

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💡 Causes

  • hypercoagulability states

    • hypercoagulability disorders: factor V Leiden, prothrombin gene mutation

    • malignancy

    • pregnancy

    • drugs: combined oral contraceptive pill (COCP), hormone replacement therapy (HRT)

    • infection

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🩺 Clinical features

  • sudden onset headache (most common symptom)

  • altered mental status

  • focal neurological deficit (depends on the area of the brain affected)

  • signs of raised intracranial pressure

 

Cavernous sinus thrombosis

  1. palsies of CN III, IV, V (ophthalmic branch) and VI as these nerves pass through the cavernous sinus

  2. infection is a common cause such as orbital cellulitis

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🕵️‍♂️ Investigations

  • initial

    • non-contrast CT

      • may show hyperdensity within the sinus as the thrombus is denser than blood

      • but sensitivity is low

  • best

    • MRI venography

      • the classic “empty delta sign” is seen with thrombosis of the sagittal sinus

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💆‍♂️ Management

  • manage risk factors

  • anticoagulation

    • initial: low molecular weight hepatin

    • long-term: warfarin

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🧲 High-yield tips 

  • “headache + hypercoagulability + altered mental status” - think venous sinus thrombosis

  • venous sinus thrombosis can lead to a subarachnoid haemorrhage as cortical veins can rupture and bleed into the subarachnoid space

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