In a patient with ischemic stroke, which vessel occlusions should involve neurointerventional radiology (neuro IR)?

Neurointerventional Radiology Involvement in Ischemic Stroke

Neuro IR should be involved for large vessel occlusions (LVO) of the internal carotid artery (ICA), middle cerebral artery M1 segment, and proximal M2 segment, particularly when patients have an NIHSS score ≥6. 1

Primary Indications for Neuro IR Consultation

Definite Large Vessel Occlusions Requiring Thrombectomy

• Internal carotid artery (ICA) occlusions - both intracranial and extracranial locations warrant neuro IR involvement, as mechanical thrombectomy and stenting achieve significantly higher recanalization rates (69-87%) compared to thrombolysis alone (38-48%) 2

• Middle cerebral artery M1 segment occlusions - these are the most common LVO requiring endovascular therapy, representing 33% of all large vessel occlusions 3

• Proximal M2 segment occlusions - mechanical thrombectomy is recommended for carefully selected patients within 6 hours of symptom onset 1

• Tandem occlusions (combined ICA-MCA lesions) - these represent 10.5% of LVOs and require coordinated endovascular management 3

Posterior Circulation Occlusions

• Basilar artery occlusions - intra-arterial thrombolysis is an option even in extended time windows (up to 6-12 hours or potentially up to 24 hours), given the devastating natural history without treatment 4, 5

• Vertebral artery occlusions - thrombectomy may be reasonable for carefully selected patients within 6 hours 1

• Posterior cerebral artery occlusions - consider for carefully selected patients within 6 hours 1

Time-Based Decision Algorithm

Within 6 Hours of Symptom Onset

• Immediate neuro IR consultation for any patient with confirmed LVO (ICA, M1, proximal M2) and NIHSS ≥6, regardless of IV thrombolysis eligibility 1

• Vascular imaging with CTA or MRA must be performed during initial evaluation to identify vessel occlusion location 5

• Do not delay catheter angiography to observe response to IV thrombolysis - both therapies should proceed in parallel 1

Extended Time Window (6-24 Hours)

• 6-16 hours: Neuro IR involvement is recommended for anterior circulation LVO if patients meet DAWN or DEFUSE-3 criteria (demonstrating mismatch between ischemic core and clinical deficits or hypoperfusion area) 1

• 16-24 hours: Neuro IR involvement is reasonable for anterior circulation LVO if patients meet DAWN criteria specifically 1

• Advanced imaging (CTP or DW-MRI with perfusion) is required to identify salvageable tissue in this window 5, 1

Vessel-Specific Considerations

Distal Vessel Occlusions

• M2 distal and M3 segments - thrombectomy may be reasonable in carefully selected cases, though high-quality evidence is limited 5

• Anterior cerebral artery occlusions - consider thrombectomy within 6 hours for carefully selected patients 1

• M2 occlusions represent 27% of all LVOs, making them a significant consideration 3

Carotid "T" Occlusions

• These terminal ICA occlusions extending into both M1 and A1 segments have particularly poor outcomes with IV thrombolysis alone (only 6% complete recanalization) 5

• Mechanical thrombectomy is strongly indicated for these cases 6

Critical Implementation Requirements

Neuro IR involvement requires:

• Immediate access to cerebral angiography 24/7 4

• Experienced interventionalists credentialed for endovascular stroke procedures 1

• Comprehensive stroke center capabilities with multidisciplinary team including stroke neurologists, neurointerventionalists, and anesthesiologists 5

Common Pitfalls to Avoid

• Do not withhold neuro IR consultation based solely on time from symptom onset - extended window criteria may still apply 1

• Do not delay mechanical thrombectomy to assess clinical response to IV thrombolysis - every 30-minute delay decreases good functional outcomes by 8-14% 5, 4

• Do not exclude patients with large ischemic cores from consideration without advanced imaging assessment in the extended window 7

• Leave vascular access sheath in place if cerebral vessel occlusion is identified during a cardiovascular procedure, to facilitate immediate thrombectomy access 5

• Recognize that LVO prevalence is approximately 18-19% among all acute ischemic stroke patients, making systematic screening with vascular imaging essential 3