Small vessel vasculitis
There are several vasculitides that affect small vessels. Pauci-immune
Granulomatosis with polyangiitis. Systemic vasculitis of medium and small arteries, including venules and arterioles. Produces granulomatous inflammation of the respiratory tracts and necrotizing, pauci-immune glomerulonephritis. Most common cause of saddle nose deformity in USA (nose flattened due to destruction of nasal septum by granulomatous inflammation). Almost all patients with granulomatosis with polyangiitis have c-antineutrophil cytoplasmic antibody, but not vice versa. Current treatment of choice is cyclophosphamide. At least two out of four criteria yields sensitivity and specificity of 88 and 92%. Nasal or oral inflammation (oral ulcers or purulent/bloody nasal discharge, may be painful)
Abnormal chest X-ray with showing nodules, infiltrates, or cavities
Microscopic hematuria or red blood cell casts
Vessel biopsy shows granulomatous inflammation
Peak incidence: ages 40–60, males > femalesEosinophilic granulomatosis with polyangiitis (formerly known as Churg–Strauss syndrome). Affects medium and small vessels with vascular and extravascular granulomatosis. Classically involves arteries of lungs and skin, but may be generalized. At least four criteria yields sensitivity and specificity of 85 and 99.7%. Asthma (history of wheezing or presently wheezing)
Eosinophilia > 10% on complete blood count
Mononeuropathy or polyneuropathy
Migratory or transient pulmonary opacities on chest x-ray
Paranasal sinus abnormalities
Vessel biopsy showing eosinophils in extravascular areasMicroscopic polyarteritis/polyangiitis. Affects capillaries, venules, or arterioles. Thought to be part of a group that includes granulomatosis with polyangiitis since both are associated with antineutrophil cytoplasmic antibody and similar extrapulmonary manifestations. Patients do not usually have symptomatic or histologic respiratory involvement. Immune complex
Hypersensitivity vasculitis (allergic vasculitis). Usually due to a hypersensitivity reaction to a known drug.
Diffusion-weighted imaging may be used as it is able to identify the damage within a few minutes of symptomatic onset.Clinical features include paraparesis or quadriparesis (depending on the level of the injury) and impaired pain and temperature sensation. Complete motor paralysis below the level of the lesion due to interruption of the corticospinal tract, and loss of pain and temperature sensation at and below the level of the lesion. Proprioception and vibratory sensation is preserved, as it is in the dorsal side of the spinal cord. Causes
Due to the branches of the aorta that supply the anterior spinal artery, the most common causes are insufficiencies within the aorta. These include aortic aneurysms, dissections, direct trauma to the aorta, surgeries, and atherosclerosis. Acute disc herniation, cervical spondylosis, kyphoscoliosis, damage to the spinal column and neoplasia all could result in ischemia from anterior spinal artery occlusion leading to anterior cord syndrome. Other causes include vasculitis, polycythemia, sickle cell disease, decompression sickness, and collagen and elastin disorders. A thrombus in the  artery of Adamkiewicz can lead to an anterior spinal syndrome. This is the most feared, though rare complication of bronchial artery embolization done in massive hemoptysis. Anatomy
The anterior portion of the spinal cord is supplied by the anterior spinal artery. It begins at the foramen magnum where branches of the two vertebral arteries exit, merge, and descend along the anterior spinal cord. As the anterior spinal artery proceeds inferiorly, it receives branches originating mostly from the aorta. The largest aortic branch is the artery of Adamkiewicz.