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Large Vessel Vasculitis for the ABIM

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Large Vessel Vasculitis for the American Board of Internal Medicine Exam
Large Vessel Vasculitis
Large vessel vasculitis involves inflammation of large arteries, primarily the aorta and its major branches. The two main types are Giant Cell Arteritis (GCA) and Takayasu Arteritis (TA), each with distinct clinical features, epidemiology, and pathophysiology.
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Giant Cell Arteritis (GCA)
  • Definition:
    • Also known as temporal arteritis, GCA is an inflammatory vasculitis affecting the aorta and its major branches, especially the cranial arteries (temporal arteries).
    • Commonly seen in older adults, GCA is closely associated with polymyalgia rheumatica (PMR).
Large vessel vasculitis vessels
  • Epidemiology:
    • Primarily affects individuals over 50 years old, with a higher prevalence in females and individuals of Northern European descent.
  • Pathophysiology:
    • GCA is characterized by granulomatous inflammation, with multinucleated giant cells often found in the affected arterial walls.
    • Immune cell infiltration leads to vessel wall thickening and narrowing, which can result in ischemia, particularly in the head and neck region.
  • Clinical Presentation:
    • Constitutional Symptoms: Fever, fatigue, weight loss, and malaise.
    • Temporal Headache: Severe, localized headache often over the temple, associated with scalp tenderness.
    • Jaw Claudication: Pain in the jaw while chewing due to ischemia of the masseter muscles.
    • Visual Symptoms: Transient vision loss, often progressing to permanent blindness if untreated, due to ischemia of the optic nerve from occlusive arteritis.
    • Polymyalgia Rheumatica (PMR): Up to 50% of GCA patients present with PMR, characterized by pain and stiffness in the shoulders and hips.
  • Diagnosis:
    • Elevated ESR and CRP: Almost universally elevated in GCA, indicative of systemic inflammation.
    • Temporal Artery Biopsy: Gold standard for diagnosis, revealing inflammation with mononuclear cell infiltration, giant cells, and disruption of the internal elastic lamina.
    • Imaging: Doppler ultrasound can show a “halo sign” around the temporal artery. CT or MRI angiography may be used to assess aortic involvement.
  • Management:
    • Corticosteroids: High-dose prednisone is the mainstay of therapy (40-60 mg/day) to rapidly reduce inflammation and prevent vision loss.
    • Steroid Tapering: Once symptoms improve, corticosteroids are tapered slowly over months to years.
    • Tocilizumab: An IL-6 receptor antagonist approved as adjunctive therapy to corticosteroids for GCA, particularly in patients with relapsing disease.
    • Aspirin: Low-dose aspirin may be given to reduce the risk of ischemic complications such as stroke or vision loss.
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Takayasu Arteritis (TA)
  • Definition:
    • Takayasu arteritis is a chronic granulomatous vasculitis affecting the aorta and its major branches, often leading to vessel stenosis, occlusion, or aneurysms.
    • Also known as “pulseless disease” due to reduced or absent pulses in the upper extremities from arterial stenosis.
  • Epidemiology:
    • Primarily affects young women, especially of Asian or Latin American descent, typically presenting before age 40.
  • Pathophysiology:
    • Similar to GCA, TA involves granulomatous inflammation with giant cells, but affects different age groups and typically involves the aorta and its primary branches.
    • Chronic inflammation results in vascular remodeling, fibrosis, and segmental stenosis, leading to ischemic complications.
  • Clinical Presentation:
    • Constitutional Symptoms: Fever, fatigue, weight loss, and night sweats, which often precede vascular symptoms by months or years.
    • Vascular Symptoms:
    • Upper Limb Claudication: Reduced blood flow to the upper extremities causes pain and fatigue with activity.
    • Diminished Pulses and Bruits: Weak or absent pulses in the arms, often accompanied by bruits over affected vessels.
    • Blood Pressure Discrepancies: Marked difference in blood pressure between the arms, due to stenosis of the subclavian artery.
    • Hypertension: Common in TA due to renal artery stenosis, leading to renovascular hypertension.
    • Neurological and Cardiac Symptoms: Dizziness, syncope, angina, or heart failure may occur with aortic arch or coronary artery involvement.
  • Diagnosis:
    • Elevated ESR and CRP: Indicators of inflammation, but nonspecific.
    • Imaging:
    • MRI Angiography (MRA) and CT Angiography (CTA): Used to visualize stenosis, occlusion, and aneurysms in the aorta and its branches.
    • Conventional Angiography: Gold standard for detailed mapping of arterial lesions, though it is less commonly used with advancements in non-invasive imaging.
    • Biopsy: Rarely performed, as vascular lesions are often inaccessible.
  • Management:
    • Corticosteroids: First-line therapy with prednisone (1 mg/kg/day) to control active inflammation, often followed by a long, gradual taper.
    • Immunosuppressive Agents: Methotrexate, azathioprine, or mycophenolate mofetil may be added to corticosteroids to reduce relapse risk or for steroid-sparing effects.
    • Biologics: In cases resistant to conventional therapy, biologic agents like tocilizumab (IL-6 inhibitor) or TNF-alpha inhibitors can be considered.
    • Revascularization: Angioplasty or surgical bypass may be necessary for severe stenosis or symptomatic ischemia, particularly when medical management alone does not provide adequate blood flow.
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Differences Between GCA and TA
  • Age of Onset:
    • GCA typically affects patients >50 years, while TA commonly presents in patients <40 years.
  • Primary Involvement:
    • GCA predominantly affects cranial arteries and the aorta in older adults, while TA primarily involves the aorta and its main branches in younger individuals.
  • Diagnosis and Management:
    • Temporal artery biopsy is crucial for GCA, whereas imaging studies are central for TA.
    • Both conditions are managed primarily with corticosteroids, but biologic agents are increasingly used in refractory cases.
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Complications of Large Vessel Vasculitis
  • GCA:
    • Vision loss (irreversible if untreated), stroke, aortic aneurysm or dissection (due to large vessel involvement).
    • Prolonged corticosteroid use increases the risk of osteoporosis, diabetes, and infections.
  • TA:
    • Severe hypertension, ischemic heart disease, stroke, heart failure, aortic aneurysms, and dissection.
    • Arterial occlusion can lead to limb ischemia, which may require revascularization procedures.
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Key Points
  • Giant Cell Arteritis (GCA):
    • Common in patients >50 years old, especially with Northern European ancestry.
    • Presents with headache, jaw claudication, visual disturbances, and association with polymyalgia rheumatica.
    • Diagnosis confirmed by elevated ESR/CRP and temporal artery biopsy; corticosteroids are the primary treatment to prevent vision loss.
  • Takayasu Arteritis (TA):
    • Affects younger women, often of Asian or Latin American descent.
    • Symptoms include upper limb claudication, pulse deficits, blood pressure discrepancies, and hypertension.
    • Imaging with MRA or CTA is essential for diagnosis; managed with corticosteroids and immunosuppressive therapy for refractory cases.
  • Commonalities and Differences:
    • Both conditions involve granulomatous inflammation but differ in the affected age group and vessel involvement.
    • Corticosteroids are first-line treatment for both; tocilizumab is increasingly used for steroid-sparing in refractory cases.
  • Complications:
    • GCA: Vision loss, aortic aneurysms.
    • TA: Hypertension, limb ischemia, aortic aneurysms and dissections, requiring close monitoring and intervention as needed.

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