Infectious intracranial aneurysm

The term mycotic aneurysm, initially attributed to Osler and used to describe bacterial intracranial aneurysms, is a misnomer. Most investigators currently agree that its use should be strictly limited to descriptions of aneurysms of fungal origin. Yet efforts to establish an accurate nomenclature have been generally unsuccessful. Therefore, we are resigned to the fact that the term mycotic aneurysm will remain in general parlance. At the same time, we prefer the use of a more specific and accurate heading, namely, infected intracranial aneurysm, to include the categories of intracranial bacterial aneurysm, fungal aneurysm, spirochetal aneurysm, infested or amebic aneurysm, viral aneurysm and phytotic aneurysm, according to the specific infecting organism or agent. The terms infectious aneurysm and infective aneurysm are flawed because they imply that the aneurysm itself is the infecting agent rather than being the end point of an infecting process. Until such a pathogenesis has been detected, it is the intention of the authors to avoid catachresis and the application of archaic language(Marcus S, The George Delacorte Professor of English and Comparative Literature, Columbia University, New York, personal communicationa, l993: " The correct usage is 'infected'. The term 'infectious' died out as a usage in termed of infected in l726." And Jost, DA, Former Senior Lexicographer of The American Heritage Dictionary, Boston, personal communication, l996:"Infectious aneurysm will be interpreted by most users of English as an aneurysm that can communicate infection").

The term infected intracranial aneurysm lacks the properties of complete definition because it refers to the initial process that affects the arterial wall and to aneurysms found to have bacteria in their walls at the time of excision(Table 87-1, Patient 3; see Case Report 9, Fig. 87-9), but not to the processes of focal dilatation or subsequent aneurysm formation and enlargement. It also accurately describes the congenital or berry aneurysm that has become secondarily infected. The terms septic aneurysm and septic embolism and septic arteritis are also commonly used. However, the word septic refers to infection involving the blood stream and is not really descriptive of the aneurysm themselves.