Stroke due to Other Mechanisms

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Management Algorithm: Stroke due to Other Mechanisms

• Dissection
• Cerebral Venous Sinus Thrombosis
• Hypercoagulability and Hematological Disorders
• Complicated Migraine
• Vasculitis
• Infection, Endocarditis
• Mitochondrial Cytopathy
• Genetic
• Non-Inflammatory Vasculopathy

Diagnostic Criteria

Clinical scenario or ischemic pattern on neuroimaging which is either not consistent with embolic, large vessel or lacunar etiology, or which suggests an alternative mechanism.

Differential Dx

• Embolic
• Large Vessel
• Lacunar

Dissection

• Sites of injury include intracranial or extracranial carotid or vertebral arteries
• Patients may present with or without ischemic infarction. Asymptomatic patients may be identified by oculosympathetic palsy sparing sudomotor fibers, hypoglossal palsy and periorbital headache (ICA) or severe neck pain (vertebral). Pseudoaneurysm formation should be suspected when lower cranial neuropathy develops late after carotid dissection
• A history of cervical trauma is absent in many cases
• T1 fat-suppression axial MRI of the neck may demonstrate subintimal hemorrhage even in the absence of lumenal stenosis
• Consider immediate anticoagulation and re-image at 6-month followup
• Consider stenting or surgery for symptomatic cases failing maximal medical therapy
• Consider possible collagen vascular disease ( e.g. Ehler's Danlos) when multivessel dissection or strong family history is present
• Consider renovascular imaging (e.g. MRA) if cerebrovascular imaging suggests fibromuscular dysplasia
• In the absence of collagen vascular disease, recurrent dissection is rare. Most patients return to full levels of activity after a suitable interval (3-12 months) without complications.

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Cerebral Venous Sinus Thrombosis

• sites of involvement include the sagittal sinuses, venous sinuses and internal jugular veins
• patients may present with headache, visual disturbance, elevated intracranial pressure, ischemic infarction, hemorrhagic infarction, seizures, encephalopathy
• patients with hypercoagulability, dehydration or craniofacial infection are at increased risk. Presence of CVST should prompt evaluation for these causes.
• Diagnosis is suggested by hyperdensity in torcula on non-contrast CT, and may be confirmed with contrast CT, CT venography, MR venography or Transfemoral angiography.
• Anticoagulation should be started immediately, even in the presence of hemorrhagic infarction. Patients who progress on heparin should be considered for transvenous thrombolysis.

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Hypercoagulability and hematological disorders

• Causes of hypercoagulability include malignancy (esp. mucin producing adenocarcinoma), pregnancy (or postpartum period), oral contraceptive use, inherited thrombophilias (esp. protein C, S, Factor V leiden, antithrombin III, prothrombin mutation), antiphospholipid antibodies, end stage renal disease (proteinuria), liver failure, disseminated intravascular coagulation (infection, malignancy, trauma), heparin-induced thrombocytopenia
• Causes of hyperviscosity include leukocytosis (blast crisis), thrombocytosis (ET), erythrocytosis (PV), cryoglobulinemia, Waldenstrom's, sickle cell anemia
• Consider hematology consult and, if appropriate, screening for occult malignancy. Since hypercoagulability of malignancy may be resistant to warfarin, consider LMW Heparins in this setting.
• Consider long term anticoagulation as determined by underlying cause
• Consider family screening if prothrombotic genetic polymorphism detected|

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Complicated Migraine, also known as Migrainous Stroke

• In contrast to classic migraine (headache accompanied by transient neurologic symptoms) or acephalgic migraine (transient neurologic symptoms in the absence of headache), complicated migraine is an older terminology used to denote ischemic stroke that occurs in the setting of migrainous symptoms, often in patients with a history of classic migraine.
• The relationship between the migraine and stroke is uncertain, and may be due to vasospasm, hypercoagulability or recurrent neuronal depolarizations (spreading depression). These patients still warrant a full evaluation for embolic sources, but may benefit from migraine prophylaxis which includes antiplatelet therapy and calcium-channel antagonists. Consider avoiding medications which may precipitate vasospasm (e.g., tryptans, ergotamines, amphetamines,stimulants, silfenadil) or migraine (oral estrogens).
• Consider genetic and mitochondrial evaluation in families with migraine and stroke or stroke-like episodes (See below)

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Non-infectious Vasculitis-Arteritis

Small-medium size arteries

• Granulomatous Angiitis of the CNS presents with headache and subacute mild to moderate encephalopathy, although patients may present with stroke as the initial symptom. TFA may show focal narrowing with abrupt vessel cutoffs and delayed venous phase if the vessels involved are of sufficient diameter to be identified (50 microns?). In other cases, brain biopsy with examination of meningeal vessels is necessary to identify the inflammatory component. Lumbar puncture reveals mild pleiocytosis and elevated total protein, with or without red blood cells. Signs or symptoms of systemic vasculitis are absent. Treatment includes supportive care and immunosuppression (prednisone, imuran, cyclophosphamide).
• Giant Cell arteritis ("Temporal Arteritis") occurs in patients over 60 and is associated with headache, jaw claudication, polymyalgia rheumatica, malaise, fever, weight loss, cranial neuropathies and often anemia. Patients may complain of indurated, tender temporal arteries It should be considered in any older patient with transient monocular blindness. When the diagnosis is strongly suspected, prednisone 60-80 mg should be started and a temporal artery biopsy obtained within 48-72 hours. There may be a role for ultrasound in the diagnostic evaluation of the temporal artery, and for bilateral biopsy to confirm the diagnosis.
• Systemic Lupus Erythematosis has CNS involvement in up to 75% of cases, mainly in the form of diffuse microangiopathic T2 hyperintensities on MR imaging. Behavioral disturbances, seizures and cranial neuropathies may occur, with stroke-like episodes, peripheral neuropathy, myelopathy and frank psychosis occurring less frequently. Cerebritis may occur without infarction, and may be detected with MR imaging. Treatment includes supportive care and immunosuppression (prednisone, imuran, cyclophosphamide).
• Other rarer causes include polyarteritis nodosa, Wegener's granulomatosis and Behcet's syndrome all of which have peripheral manifestations and less commonly involve the CNS.

Large arteries

Takayasu's arteritis is a disorder of unknown etiology more prevalent in Asian women which affects the aorta and origins of the great vessels. Its propensity to involve the subclavian arteries has led to the eponym, "pulseless disease". TIA or cerebral infarction may occur due to low flow hemodynamics. There is no known treatment aside from cervical artery-to-artery bypass.

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Infectious Vasculitis-Arteritis

Tuberculosis and tertiary syphilis cause a pachymeningitis at the bas eof the brain, leading to occlusive arteriopathy often with associated lower cranial neuropathies. Lumbar puncture for CSF sampling is required for diagnosis, and peripheral manifestations may be lacking late in the disease course (anergy, negative serologies). Mucormycosis may cause stroke by direct vessel invasion or associated inflammatory vasculitis. Viral infections (CMV, VZV, HIV) may cause focal vasculitis and respond to directed antiviral therapy.

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Endocarditis

• Infective native valve endocarditis may be due to a variety of organisms including gram positive cocci, gram negative cocci, fungi. Organisms most likely to cause cerebral embolism include staph aureus, strep viridans and enterococci, and the fungi aspergillus and candida species. Mycotic aneurysm (infectious aneurysm) is more common with these virulent organisms and may be due to infected material embolized to the vaso vasorum or to more distal arterial branches with focal intimal invasion. The majority of mycotic aneurysms are located in the distal MCA and ACA territories and are unlikely to be seen with non-invasive imaging. Treatment of endocarditis consists of parenteral antibiotics without the use of anticoagulation, with diagnostic angiography only in selected patients. Angiography may be considered in patients with unexplained neurologic deficits or CT imaging suggestive of cerebritis. Prosthetic valve endocarditis is treated in essentially the same manner, although the risk of thromboembolism must be weighed against the risk of hemorrhagic CNS events, and patients may benefit from continued naticoagulation if they have no evidence of hemorrhage on brain imaging. For patients who develop hemodynamic compromise requiring valve replacement, there is an increased risk of CNS hemorrhage with cardiac surgery that must be weighed against the risk of recurrent emboli and cardiac morbidity. If surgery is to be performed, it may be best to oeprate early (within 3 days of stroke) or much later (>2 weeks) to minimize the risk of blood-brain barrier dysfunction at the time of surgery.
• Marantic (non-bacterial thrombotic) endocarditis occurs in patients with malignancy (often mucin-producing adenocarcinoma) or connective tissue disease (e.g., SLE) and often coexists with disseminated intravascular coagulation. Treatment is directed toward the underlying lesion, and antiplatelet or anticoagulant therapy may be helpful in preventing furhter emboli. In some patients with hypercoagulability of malignancy, warfarin may be less effective than the heparins.

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Mitochondrial Cytopathy

Mitochondrial encephalopathy with lactic acidosis and stroke-like episodes syndrome (MELAS) is a syndrome which often manifests in adolescence with abrupt onset of stroke-like episodes including alternating hemiparesis, hemianopsia, cortical blindness, focal or generalized seizures. Serum and CSF lactate is increased and is accompanied by CT or MR abnormalities. The presence of "ragged red" fibers on muscle biopsy confirms the diagnosis. Defetcs in mitochondrial DNA are the cause, and defects in Complex 1 have been associated with MELAS. Treatment is supportive and co-enzyme Q supplementation may be helpful.

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Genetic

• Except in the rare cases discussed below, stroke risk is not a monogenic disorder. The genes that increase predisposition to stroke likely reflect generalized systemic factors such as lipid and carbohydrate metabolism, vascular reactivity, coagulation and inflammation.
• Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare stroke syndrome documented in a number of small families. It is often associated with classic migraine and is a progressive ischemic disease without treatment which results in death within 10 years of onset. Some of the inherited thrombophilias (e.g., protein C or S deficiency, protrhombin mutation, factor V Leiden mutation) have been linked to single genes. While these can be the cause of cerebral ischemia, they more commonly present with venous thomboembolism.

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Non-inflammatory Vasculopathy

• Moya-Moya disease is characterized by its angiographic appearance, "something hazy like a puff of cigarette smoke drifting in the air", namely proliferation of small vessels at a site of focal narrowing in the supraclinoid ICA and proximal MCA and/or PCA stem. It is usually bilateral although can be asymmetric, and progresses to involve all the basal arteries. TIA or cerebral infarction may occur due to low flow hemodynamics. Hemorrhage due to small vessel rupture is a frequent complication. Treatment consists of hemodynamic management, and a variety of procedures designed to stimulate new vessel formation from the cortical surface (encephaloduroateriosynagniosis, omental onlay or extracranial to intracranial bypass).
• Conditions such as antiphospholipid antibody syndrome ("Sneddon's Syndrome"), vasospasm after occult subarachnoid hemorrhage, collagen vascular diseases (Ehler's-Danlos, fibromuscular dysplasia, Sjogren's), sympathomimetic use (cocaine, ephedrine, pseudoephedrine, OTC diet preparations, cold medicines, etc) may present with evidence of segmental arterial narrowing on cerebrovascular imaging and ishemic symptoms.

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