Description, Causes and Risk Factors:
An aneurysm caused by the growth of fungi or bacteria within the vascular wall, usually following impaction of a septic embolus.
Initially used to describe arterial infection caused by septic emboli from infective endocarditis, the term "mycotic aneurysm'' presently means (1) infectious erosive arteritis with false aneurysm caused by infection of the aortic wall but without preexisting aneurysm or (2) manifest infection in a preexisting aneurysm, which can be caused by all microorganisms, not only by fungi.
A mycotic aneurysm comes from irreversible damage to the walls of the artery due to an infection. Mycotic aneurysms come from an irreversible dilation of the artery that makes it two to two-and-a-half larger than normal.
A mycotic aneurysm as said is due to destruction of the vessel wall from a bacterial infection. It is a serious condition and despite the name, which means fungal toxin, the majority of mycotic aneurysms are caused by bacteria. It may be a false or true aneurysm, the latter meaning it involves all layers or the former when only a portion of the arterial wall is effected.
Staphylococcus pneumoniae is not commonly associated with mycotic aneurysms and is very rarely reported as a cause of vertebral osteomyelitis. S. aureus (30%) and Salmonella species (50%) are the predominant organisms in mycotic aneurysms in the post-antibiotic era, with S. aureus also being the major organism seen in vertebral osteomyelitis. The most common site of mycotic aneurysms is the femoral artery (38%), followed by the abdominal aorta (31%).
Mycotic can be present anywhere in the human body. They may appear in patients with endocarditis, which is an inflammation of the thin membrane lining of the heart. Typically, a mycotic aneurysm occurs where the blood vessel branches off. During treatment for endocarditis, the aneurysms may increase, decrease, remain the same size, or disappear. It may also appear in multiples or be solitary.
What is so alarming about a mycotic is how dangerous they can be. After a blood vessel begins to swell, if the bulge becomes large enough, it will burst. The bulging causes the wall of an artery to weaken. Regardless of location, it may cause localized pain and symptoms of infection such as fever.
A mycotic aneurysm can happen at any age. Mycotic cerebral aneurysm is a rare but serious complication of infective inflammation of the heart. In this case, usually the patient receives a warning sign of an excruciating headache.
If an aneurysm bursts, warning signs include: the worst headache of your life, vomiting, blurred or doubled vision, stiff neck, nausea, sensitivity to light, and loss of sensation in the extremities. Do not shrug off the symptoms until it is too late, especially if you have any of the risk factors.
The diagnosis of mycotic aneurysms can be very difficult. Fever and leukocytosis are usually the first findings in 70% of cases,with a palpable aneurysm or back pain constituting the third part of a classic triad of symptoms.The source of infection should be thoroughly investigated, and if warranted, CT of the chest and abdomen should be done.CT provides earlier diagnosis and is considered the "gold standard" for diagnosis of this disease.The CT scan may show irregular peripheral enhancement of the aortic wall, consistent with periaortic inflammation and effusion. Angiography provides the anatomic details of the lesion and adjacent vessels but will not show the periaortic extension that CT can demonstrate.Transesophageal echocardiography may also assist in the early diagnosis of mycotic aneurysms. Because of the close proximity of the esophagus to the aorta, it provides detailed views of the descending aorta. Color Doppler echocardiography can demonstrate the flow from the aorta into the abscess cavity.
The management of mycotic aneurysms requires eradication of the source of infection and maintenance of distal arterial flow.
Bactericidal antibiotics should be started immediately once the diagnosis has been made. Start with a broad-spectrum antibiotic covering both gram-positive and gram-negative bacteria until cultures from the aortic tissue and blood have been obtained. Adjustments in antibiotic selection can be made following sensitivity results.
Antibiotics should be continued postoperatively for a minimum of 6 to 8 weeks. In some cases, depending on the method of arterial reconstruction, oral antibiotics may be required for a lifetime.
Surgery is almost always indicated, since mortality for untreated patients is greater than 90%. Fortunately, surgery is available to treat aneurysms before they rupture. The good news about brain aneurysms is that surgery is usually able to restore health if done within 24 hours of the rupture. More importantly, there are ways to help prevent a brain aneurysm.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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