• intracranial stenosis is a significant stroke risk factor  [Bos, 2014]
  • it is a cause of ~10% of strokes
  • the annual risk of recurrent stroke in symptomatic IC stenosis is  4-18%
  • modern imaging modalities (TCD/TCCD, CTA, and MRA) allow non-invasive and easy diagnosis of intracranial stenoses [Degnan, 2011]
Intracranial stenosis

Etiopathogenesis

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Diagnostic evaluation

Examples of intracranial stenoses detected on TCCD, CTA, MRA and DSA

TCD/TCCD

  • detection of the stenosis itself (→ see here)
    • optimal for screening and follow-up
  • evaluation of the distal flow, including cerebral vasomotor reactivity (CVR)
  • detection of MES (microembolic signals)

CT/MR angiography

  • the optimal imaging method is CTA
  • non-contrast intracranial MRA may overestimate the stenosis grade
MCA stenosis on CTA

Stenosis of M1 section of MCA on CTA
MCA stenosis on MRA (M1 segment)

Digital subtractive angiography

  • currently replaced by CTA in most cases

Xe133-CT

  • enables to determine the cerebral blood flow (CBF)

Intravascular sonography (IVUS) [Zacharatos, 2010]

  • used in cardiology, now it is tested in carotid and intracranial territories  IVUS
  • clarifies the morphology of the stenosis (which can help in etiological diagnosis – atherosclerotic plaque vs. inflammation, etc.)

Optic coherent tomography (OCT)  Optical coherence tomography imaging demonstrated the atherosclerotic plaque (white arrowheads) with calcifications) (Yang, 2021)

  • OCT uses near-infrared light to image arterial anatomy with much higher resolution than IVUS (10 vs. 100 um)
  • used in cardiology, also tested in vascular neurology
    • assessment of plaque structure   (Yang, 2021)
    • assessment of stent position after the procedure and in the follow-up period
    • the potential for use during the stenting procedure is investigated
  • outperforms IVUS in the determination of plaque morphology (presence of thrombus, bleeding, fibrous cap rupture, etc.) and in differentiating other causes of stenosis

Management

Asymptomatic stenosis
  • antiplatelet therapy + aggressive treatment of vascular risk factors (see below)
  • endovascular intervention is not indicated
Symptomatic stenosis
  • the risk of recurrent stroke/TIA or vascular death in patients with IC stenosis is 10-12%/year [Chimowitz,2005]
    • older studies reported a risk of up to 22%/year with conservative treatment; despite that, the risk is ~2 times higher than in patients with extracranial stenosis
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Intracranial angioplasty procedure

  • after the procedure, maintain dual antiplatelet therapy (aspirin 100 mg + clopidogrel 75 mg)
  • duration of DAPT
    • coated stents:  6-12 months (Taxus, Pharos)
    • standard stent (Wingspan): at least 4 weeks
  • then switch to long-term monotherapy
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