Mycotic Aneurysm

An aneurysm is a dilation abnormality in the focal arterial section of the brain. It is the local widening of the blood vessels. The classification of aneurysms is based on types, location and the affected vessels. Its diagnosis and pathology can also be affected by other factors.

Pre-existing aneurysms are subject to secondary infection. But aneurysmal deterioration of the arterial wall can possibly be the result of an infection. And this infection can be brought about by bacteremia or septic embolization, as in the case of mycotic aneurysm.

What is it?

This term was coined by Osler to define aneurysms related to bacterial endocarditis, which have an appearance of “fresh fungus vegetations”. This kind is usually caused by a fungi or bacteria growth within the arterial wall, which is normally a result of septic embolus. And when the vessel wall is digested, a false aneurysm forms. And this is very unstable and highly prone to rupture.

The aneurysm usually forms in the neck, abdomen, thigh and arm. And less than 3% of abdominal aortic aneurysms are mycotic in nature. This kind is very life threatening. The infection in the arterial wall can lead to sepsis or fatal bleeding if it ruptures.

What are the symptoms?

The symptoms only begin to manifest or show when it ruptures. And as the arterial walls dissect, the blood clots will be broken off. And these blood fragments will travel and will get stuck somewhere. And the area where the blood clots are lodged won’t receive enough blood, cutting the blood flow circulation.

Therefore, the symptoms are dependent on the size and location and of the areas where there’s blood deprivation, and whether it is bleeding or expanding. An expanding mycotic has the following symptoms: neck pain, abdominal pain, arm pain and thigh pain. These are localized because these are the frequent locations of the swelling of the vessels. The infection may also cause other illness like fever, weakness, nausea and fatigue.

What are the radiographic features of the aneurysm?

The following are the radiographic features: interruption of arterial wall calcification, saccular, eccentric morphology, often wild and multilobulated appearance, adjacent reactive lymphadenopathy, and adjacent soft tissue stranding.

How to treat?

There are two known surgical procedures to treat it:  extraanatomic and in situ reconstruction. Aside from these surgical procedures, the treatment also involves antibiotic therapy.

The extraanatomic operation involves multiple operations to repair the natural direction of blood flow, while in situ reconstruction only requires a single definitive operation. In recent years, in situ reconstruction has received more emphasis. But surgeons prefer the extraanatomic procedure in treating their older patients.

The surgical decision can be influenced by a lot of factors. There’s the location of the arterial infection, patient’s general condition and immunologic state, the type of the bacteria, etc. But overall, the surgeon will choose what is best for the patient in general.