Cerebral thromboembolism, which may precipitate seizures, is a major complication of native mitral valve disease. The Framingham Study estimated up to an 18-fold increased risk of thromboembolism if atrial fibrillation occurred with mitral disease.8
The most common valve disease precipitating cerebral thromboembolism is mitral stenosis. Indeed, cerebral thromboembolism may be the presenting manifestation in more than 10% of patients with mitral stenosis.7
Mitral regurgitation is less likely to result in embolic events, although concomitant mitral stenosis increases the risk of complications from mitral regurgitations. 9
Mitral valve prolapse (MVP), often asymptomatic, occurs in 5-7% of the adult population, and therefore is commonly cited as a cause for many medical disorders, including epilepsy and stroke.10 Some patients with MVP and no other risk factors have recurrent cerebral ischemic events, suggesting a possible causal relationship.11 Because of the vague association between stroke risk and MVP, the need for antiplatelet prophylaxis remains controversial in asymptomatic MVP.
Mitral annular calcification predicts a doubled risk of embolic stroke, independent of other risk factors of atherosclerotic cardiovascular disease, including age, sex, systolic blood pressure, diabetes mellitus, and cigarette smoking. Atrial fibrillation is more common in the presence of mitral annular calcification, but the risk of stroke appears to be independent of atrial fibrillation.12
Aortic stenosis and insufficiency can result in diffuse cerebral hypoperfusion, but these are unusual causes of clinically symptomatic cerebral ischemic events, unless associated with another source of emboli (e.g., mitral valve disease, atrial fibrillation, endocarditis).
Anticoagulation, which increases the risk of stroke and subsequent seizures, is recommended for all patients with mechanical valves and for and higher-risk patients with bioprosthetic valves. Balloon valvuloplasty is used as an alternative treatment in patients for whom surgery is inappropriate. Despite systemic heparinization during the procedure, embolization from release of calcific material results in embolic strokes in about 1% of cases.13 Seizures also have been reported as a result of exuberant dosing of lidocaine during such procedures.14
Infective endocarditis can precipitate seizures in up to 11% of patients, due to embolization of septic material, formation of cerebral abscess, or rupture of mycotic aneurysms.15 Neurologic complications are more frequent with left-sided valvular disease, especially the mitral valve. Prosthetic valves are associated with larger and less adherent vegetations, which are especially prone to embolization. Patients with prosthetic valve endocarditis do not appear to have a greater cerebral risk than those with native valve disease, however.
Focal seizures usually result from localized infarction, hemorrhage, or abscess. Generalized seizures, on the other hand, are more often the result of associated metabolic factors, hypoxia, or medications. Beta-lactam (e.g., penicillin and imipenem) and quinolone (e.g., levofloxacin and ciprofloxacin) antibiotics are especially associated with seizures. Infections by highly virulent organisms such as Staphylococcus aureus increase the likelihood of neurologic events.
Signs of cerebral embolization are the presenting symptom in up to 23% of patients with endocarditis16 and occur soon after initiation of antibiotic therapy in up to 30%.15 Cerebral hemorrhage, however, is more likely in endocarditis patients treated with anticoagulants, as the intraluminal arterial walls undergo inflammatory destruction, increasing the chance of hemorrhage.
Adapted from: Boggs J. Cardiac disorders. In: Ettinger AB and Devinsky O, eds. . Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;39-47.
With permission from Elsevier (www.elsevier.com).