Infectious intracranial aneurysm

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Infectious intracranial aneurysm
Other namesMycotic aneurysm
Specialty Infectious disease, neurosurgery

An infectious intracranial aneurysm (IIA, also called mycotic aneurysm) is a cerebral aneurysm that is caused by infection of the cerebral arterial wall.

Contents

Signs and symptoms

Many patients with unruptured IIA may have no symptoms. In patients who do have symptoms these are often related to rupture of the aneurysm and to its cause. [1] Rupture of an IIA results in subarachnoid hemorrhage, symptoms of which include headache, dizziness, seizures, altered mental status and focal neurological deficits.[ citation needed ]

In contrast to other cerebral aneurysms, large aneurysm size does not increase the chance of rupture. Small IIAs tend to have high rupture rates, while larger IIAs more commonly cause symptoms due to pressure on the surrounding brain tissue.[ citation needed ]

Cause

Most IIAs are caused by bacterial infection, most commonly Staphylococcus aureus and Streptococcus species. In most cases the infection originates from left-sided bacterial endocarditis. [1] Other common sources include cavernous sinus thrombosis, bacterial meningitis, poor dental hygiene and intravenous drug use. The use of the term infectious aneurysm by the above authors is incorrect. Refer to Holtzman RNN, Pile-Spellman JMD, Brust JCM, Hughes JEO, Dickinson PCT: Surgical Management of Intracranial Aneurysms Caussed by Infection, in: Schmidek HH and Roberts DW(eds): Schmidek & Sweet Operative Neurosurgical Techniques: Indications, Methods, and Results ed.5. Philadelphia: Elsevier Inc. 2006 Vol 1: Chap. 87, pp1223-1259

Diagnosis

Diagnosis of IIA is based on finding an intracranial aneurysm on vascular imaging in the presence of predisposing infectious conditions. [1] Positive bacterial cultures from blood or the infected aneurysm wall itself may confirm the diagnosis, however blood cultures are often negative. Other supporting findings include leukocytosis, an elevated erythrocyte sedimentation rate and elevated C-reactive protein in blood.[ citation needed ]

Terminology

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 communication, 1993: "The correct usage is 'infected'. The term 'infectious' died out as a usage in termed of infected in 1726." And Jost, DA, former senior lexicographer of The American Heritage Dictionary, Boston, personal communication, 1996: "Infectious aneurysm will be interpreted by most users of English as an aneurysm that can communicate infection").[ citation needed ]

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.[ citation needed ]

Treatment

Treatment depends on whether the aneurysm is ruptured and may involve a combination of antimicrobial drugs, surgery and/or endovascular treatment. [1]

Prognosis

Mortality of IIA is high, unruptured IIA are associated with a mortality reaching 30%, while ruptured IIA has a mortality of up to 80%. [1] IIAs caused by fungal infections have a worse prognosis than those caused by bacterial infection. [2]

Epidemiology

IIAs are uncommon, accounting for 2.6% to 6% of all intracranial aneurysms in autopsy studies. [2]

Related Research Articles

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Sepsis Life-threatening organ dysfunction triggered by infection

Sepsis is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is followed by suppression of the immune system. Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion. There may also be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection. The very young, old, and people with a weakened immune system may have no symptoms of a specific infection, and the body temperature may be low or normal instead of having a fever. Severe sepsis causes poor organ function or blood flow. The presence of low blood pressure, high blood lactate, or low urine output may suggest poor blood flow. Septic shock is low blood pressure due to sepsis that does not improve after fluid replacement.

Intracranial aneurysm Cerebrovascular disorder

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Cerebrovascular disease Condition that affects the arteries that supply the brain

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Subarachnoid hemorrhage Bleeding into the subarachnoid space

Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of consciousness, fever, and sometimes seizures. Neck stiffness or neck pain are also relatively common. In about a quarter of people a small bleed with resolving symptoms occurs within a month of a larger bleed.

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A subdural hematoma (SDH) is a type of bleeding in which a collection of blood—usually but not always associated with a traumatic brain injury—gathers between the inner layer of the dura mater and the arachnoid mater of the meninges surrounding the brain. It usually results from tears in bridging veins that cross the subdural space.

Aortic aneurysm Notable enlargement of the aorta (heart artery)

An aortic aneurysm is an enlargement (dilatation) of the aorta to greater than 1.5 times normal size. They usually cause no symptoms except when ruptured. Occasionally, there may be abdominal, back, or leg pain. The prevalence of AAA has been reported to range from 2 to 12% and is found in about 8% of men more than 65 years of age. The mortality rate attributable to AAA is about 15,000 per year in the United States and 6,000 to 8,000 per year in the United Kingdom and Ireland. Between 2001 and 2006, there were approximately 230,000 AAA surgical repairs performed on Medicare patients in the United States.

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A thunderclap headache is a headache that is severe and has a sudden onset. It is defined as a severe headache that takes seconds to minutes to reach maximum intensity. Although approximately 75% are attributed to "primary" headaches—headache disorder, non-specific headache, idiopathic thunderclap headache, or uncertain headache disorder—the remainder are secondary to other causes, which can include some extremely dangerous acute conditions, as well as infections and other conditions. Usually, further investigations are performed to identify the underlying cause.

Intraparenchymal hemorrhage Medical condition

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Cavernous sinus thrombosis Medical condition

Cavernous sinus thrombosis (CST) is the formation of a blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. This is a rare disorder and can be of two types–septic cavernous thrombosis and aseptic cavernous thrombosis. Most commonly the form is of septic cavernous sinus thrombosis. The cause is usually from a spreading infection in the nose, sinuses, ears, or teeth. Staphylococcus aureus and Streptococcus are often the associated bacteria.

An infected aneurysm is an aneurysm arising from bacterial infection of the arterial wall. It can be a common complication of the hematogenous spread of bacterial infection.

Endovascular coiling

Endovascular coiling is an endovascular treatment for intracranial aneurysms and bleeding throughout the body. The procedure reduces blood circulation to the aneurysm through the use of microsurgical detachable platinum wires, with the clinician inserting one or more into the aneurysm until it is determined that blood flow is no longer occurring within the space. It is one of two main treatments for cerebral aneurysms, the other being surgical clipping. Clipping is an alternative to stenting for bleeding.

References

  1. 1 2 3 4 5 Ducruet, AF; Hickman, ZL; Zacharia, BE; Narula, R; Grobelny, BT; Gorski, J; Connolly ES, Jr (January 2010). "Intracranial infectious aneurysms: a comprehensive review". Neurosurgical Review. 33 (1): 37–46. doi:10.1007/s10143-009-0233-1. PMID   19838745. S2CID   25105554.
  2. 1 2 Clare, CE; Barrow, DL (July 1992). "Infectious intracranial aneurysms". Neurosurgery Clinics of North America. 3 (3): 551–66. doi:10.1016/S1042-3680(18)30646-6. PMID   1633479.