Neurointerventional Procedures

Neurointervention Toolkit - Gadgets & Gizmos

• Access Sheaths & Needles: For initial vascular entry (e.g., Seldinger technique).
• Catheters:
  • Guiding Catheters (5-9F): Provide support, pathway for other devices.
  • Microcatheters (1.5-3F): Navigate distal, tortuous vessels; deliver coils, liquids. Diameters often 0.010-0.027 inches.
• Guidewires & Microwires:
  • Guidewires (0.035-0.038 inch): Steer catheters.
  • Microwires (0.008-0.014 inch): Navigate microcatheters.
• Embolic Devices & Stents:
  • Detachable Coils: Platinum, for aneurysm occlusion.
  • Liquid Embolics: Onyx, n-BCA (glue) for AVMs, dAVFs.
  • Stent-Retrievers: For mechanical thrombectomy (e.g., Solitaire, Trevo).
  • Flow Diverters: For large/giant wide-necked aneurysms (e.g., Pipeline).
• Balloons: Angioplasty, temporary vessel occlusion, compliant/non-compliant types.

⭐ The Penumbra system is an example of an aspiration catheter used for mechanical thrombectomy in acute ischemic stroke, often in conjunction with stent retrievers.

Brain Angio Basics - Mapping the Pipes

• Digital Subtraction Angiography (DSA): Gold standard for cerebrovascular imaging. Principle: digital subtraction of bone/soft tissue.
• Access: Common femoral artery (Seldinger technique) standard; radial artery alternative.
• Catheters: Guiding catheters for support, microcatheters for superselective navigation.
• Contrast: Non-ionic, low-osmolar or iso-osmolar iodinated agents.
• Phases: Arterial, capillary, venous phases visualized.
• Key Anatomy:
  • ICA Segments (C1-C7): Cervical, Petrous, Lacerum, Cavernous, Clinoidal, Ophthalmic, Communicating.
  • Circle of Willis (CoW): Junction of ACA, ACoA, ICA, PCoA, PCA.
    • Anterior Circulation: ICA, ACA, MCA.
    • Posterior Circulation: Vertebral, Basilar, PCA.

⭐ The Circle of Willis is complete in only 20-25% of individuals; a hypoplastic posterior communicating artery (PCoA) is the most common variant.

Clot Busters & Fixers - Stroke & Aneurysms

• Ischemic Stroke (Clot Busters): 📌 TIME IS BRAIN
  • Mechanical Thrombectomy (MT):
    • Indication: Large Vessel Occlusion (LVO) - ICA, M1/M2, Basilar.
    • Window: Within 6 hours; up to 24 hours for select patients (DAWN/DEFUSE-3 criteria).
    • Devices: Stent retrievers (e.g., Solitaire), Aspiration catheters (e.g., Penumbra).
    • Goal: TICI score 2b/3 (reperfusion).
  • Intra-arterial (IA) Thrombolysis:
    • Agent: Alteplase (rtPA).
    • Window: Extended up to 6 hours if IV tPA failed/contraindicated. Less common with MT.
• Cerebral Aneurysms (Fixers):
  • Endovascular Coiling:
    • For ruptured/unruptured saccular aneurysms.
    • Platinum coils induce thrombosis.
    • Adjuncts: Stent-assisted, balloon-assisted for wide necks.
  • Flow Diverters (e.g., Pipeline):
    • For large/giant, wide-necked, or fusiform aneurysms.
    • Promotes aneurysm thrombosis by altering flow.

⭐ Mechanical thrombectomy for LVO stroke can be performed up to 24 hours from onset in eligible patients (DAWN/DEFUSE-3 trials), dramatically improving outcomes.

Vessel Repair Shop - AVMs, DAVFs & Stenosis

• Arteriovenous Malformations (AVMs):
  • Congenital; direct artery-to-vein shunt, no capillary bed.
  • Presentation: Hemorrhage, seizures, focal deficits.
  • Treatment: Embolization (glue, coils), surgery, radiosurgery.
  • Grading: Spetzler-Martin (size, eloquence, venous drainage).
• Dural Arteriovenous Fistulas (DAVFs):
  • Acquired; dural artery to venous sinus/cortical vein.
  • Symptoms: Pulsatile tinnitus, headache; hemorrhage if cortical venous reflux.
  • Classification: Cognard, Borden (venous drainage dictates risk).

  ⭐ Cortical venous reflux (e.g., Cognard type IIb and above) in DAVFs dramatically ↑ hemorrhage risk, mandating prompt intervention.

• Arterial Stenosis (Intracranial & Extracranial):
  • Mainly atherosclerotic.
  • Goal: Stroke prevention.
  • Treatment:
    • Medical therapy (antiplatelets, statins).
    • Percutaneous Transluminal Angioplasty & Stenting (PTAS).
      • Symptomatic intracranial: Consider for >70% stenosis if medical therapy fails.
      • Symptomatic carotid: >50-70% stenosis (NASCET criteria).

High‑Yield Points - ⚡ Biggest Takeaways

• Endovascular coiling is primary for most intracranial aneurysms, especially posterior circulation.
• Mechanical thrombectomy is crucial for large vessel occlusion in acute ischemic stroke (AIS).
• Embolization (glue/particles) treats AVMs, dural AVFs, and hypervascular tumors pre-operatively.
• Carotid artery stenting is an alternative for select symptomatic carotid stenosis.
• DSA remains gold standard for evaluating cerebrovascular pathology and guiding interventions.
• Vertebroplasty/kyphoplasty manage pain in osteoporotic vertebral compression fractures.