Central nervous system complications of infective endocarditis.

The frequent association between central nervous system symptoms and infective endocarditis (IE) has been recognized for more than a century since it was first described by Sir William Osier. However, important changes in the natural history of infectious endocarditis have occurred in recent decades. The introduction of antimicrobial agents, the increase of age of onset, and a change in frequency of the most common infective agents are among some of the factors responsible for this change.In addition, at the same time that rheumatic heart disease has become less frequent, other underlying cardiac conditions have been recognized as important niduses of infection, namely, mitral valve prolapse, mitral annulus calcification and calcific aortic valve, and congenital cardiac wall and aortic valve defects. This pattern has been seen in large series of patients with IE and neurologic complications.New diagnostic and therapeutic invasive procedures, drug addiction, and the association between neoplastic disease and IE are increasingly recognized as underlying conditions associated with the development of IE. Finally, an increasing number of patients have undergone cardiac valve replacement, making it one of the most common underlying conditions that predisposes to IE. IE should be suspected in the presence of fever, cardiac murmur, and a neurologic deficit. However, the diagnosis can be particularly difficult because of the similarity with other conditions, the nonspecific character of the symptoms, and sometimes the long latency of valve infection. The diagnosis of IE requires a high index of suspicion supported by echocardiography and blood cultures for confirmation. On the other hand, head CT scan and MRI have improved the recognition of neurologic complications, particularly stroke, occurring in this condition. Despite the introduction of antimicrobial agents and the changing etiologic spectrum, the frequency of neurologic complications in IE has remained unchanged. Three large studies published in the last three decades reported an incidence of neurologic