Intracranial atherosclerotic disease

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Intracranial atherosclerotic disease (ICAD) is the term applied to atherosclerosis of the large intracranial arteries and is a cause of ischemic stroke.

Epidemiology

ICAD is an important cause of stroke in certain racial groups particularly Asians, but also Hispanics and Black people. ICAD is identified in 46% of Chinese patients with stroke . In Caucasians however, ICAD is a uncommon cause of stroke.

Risk factors

The traditional risk factors for atherosclerosis apply to ICAD, particularly:

Clinical presentation

Asymptomatic ICAD is commonly diagnosed incidentally in brain imaging given the abundance of neuroimaging performed worldwide. When symptomatic, ICAD can present as either:

Pathology

See atherosclerosis article.

Radiographic features

CT angiography, MR angiography and DSA are the modalities which identify arterial stenoses and occlusion seen in ICAD.

DSA is the gold standard for assessment of stenosis severity however, compared with CTA and MRA, is less sensitive at the determination of plaque morphology. DSA, being an invasive test is associated with procedural risks including stroke and dissection. Intravascular US (IVUS) can be used in conjunction with DSA to assess plaque stability and composition, similar to its more accepted use in coronary artery disease.

Focal segments of arterial narrowing forming stenosis may demonstrate calcified or non-calcified atheroma and CTA and MRA can determine remodeling. Intraplaque hemorrhage can also be assessed.

Transcranial Doppler ultrasound (TCD) has been used successfully but requires on adequate bone windows.

Treatment and prognosis

The mainstay of treatment is antithrombotic therapy (anticoagulation and/or antiplatelet medications) along with routine medical management for the modification of risk factors.

Surgical treatments such as intracranial endarterectomy and extracranial to intracranial bypass procedures have been trialled but lost popularity with the emergence of endovascular techniques.

Endovascular treatment were first trialled with balloon angioplasty but now almost solely involves endovascular stenting which is currently accepted as the treatment of choice.

Differential diagnosis