Aneurysm

An aneurysm is a hereditary or acquired vascular malformation that can take different shapes. The size of an aneurysm can differ from few millimeters to several centimeters and it can affect various parts of the body, for example, the brain, carotid arteries or leg arteries. As bulge at the wall of a vessel, it can rupture and cause a bleeding entailing severe consequences.

Within this text passage, we would like to focus especially on the intracranial, cerebral aneurysm. Those aneurysms have a bad prognosis if they are not successfuly treated. More precisely, the bleeding resulting from the aneurysm has a bad prognosis. Simplified you can say that after the occurence of a bleeding half of the patients die before reaching a hospital. One third of the lucky patients reaching the hospital dies, one third survives with disabilities, and only the last third successfuly recovers from the aneurysm without any permanent damage.

Due to this reasons, it is very important to detect and treat aneurysms before they cause a cerebral bleeding, the so-called subarachnoid bleeding (SAB). This sort of bleeding protrudes into the subarachnoid space (the brain is completely surrounded by cerebrospinal fluid). It is also possible that the bleeding affects the cerebral tissue itself.

The subarachnoid bleeding secondarily leads to vascular spasms (constrictions or stenoses) that can cause apoplectic stroke. In addition, the subarachnoid space sticks togetherso that a normal circulation of the cerebrospinal fluid is not possible anymore. Consequently, the intracranial pressure rises (hydrocephalus).

Symptoms aneurysm

Symptoms caused by an aneurysm can be very different subject to its location and position. A cerebral aneurysm can cause an increasing feeling of pressure inside the head, hydrocephalus, headache, facial paralysis and apoplectic stroke.

Causes aneurysm

The aneurysm can be hereditary or acquired. The aneurysm of brain supplying arteries often emerges on basis of a hereditary weakness of the arterial wall. This weakness is detected in the course of life and is not caused by arteriosclerosis. In contrast to aneurysms of brain supplying arteries do aneurysms of the aorta or leg arteries have an acquired cause – arteriosclerosis. Both sorts of aneurysms differ substantially in their appearance.

Diagnostics aneurysm

An aneurysms located at a peripheral spot of the body sometimes can be detected by touching it as part of a clinical examination. More difficult is the detection of aneurysms not located at such an exposed spot. In this case, the diagnosis is confirmed by imaging examinations like ultrasound, CT, MRI or angiography. To decide and plan a treatment, it is necessary to carry out an intra-arterial angiography (often 3D angiography) which helps estimating the exact size and location of the aneurysm. With reference to the results of the angiography, physicians are able to decide which therapy would be most promising. An aneurysm is often detected by accident as a result of an imaging examination.

Therapy aneurysm

Within this text passage, we would like to focus on the therapy of cerebral aneurysms. If an aneurysm ruptures, it has to be treated immediately. In case of an earlier detection, it has to be decided if and how it has to be treated (closed).

We differentiate the following treatment options:

• neurosurgery (open surgery), the so-called clipping
• neuroradiological intervention (endovascular), the so-called coiling or coil embolization
• It is always an individual decision whether coiling or clipping is chosen.

Which method is selected, depends on different factors:

• age of the patient
• clinical condition of the patient
• location and size of the aneurysm
• shape of the aneurysm and condition of the affected vessel

Many aneurysms can be treated with coiling / coil embolization. Coils are small platinum spirals. They are placed in the aneurysm of an affected vessel to close it, inserted through a catheter in the femoral artery.

But there are aneurysms that should be closed neurosurgically. Given neurosurgery, the skull is opened and the aneurysm is separated from the affected vessel by a platinum clip using a special neurosurgical microscope.

The coiling techniques have become very complex. For the support of the coil placement, there are some additional procedures, for example:

• Stent placement / stent implantation / stenting
• Remodelling

In the first case, a stent is placed before inserting the coil in order to prevent the coil from falling back into the affected vessel and obstructing it (the result would be apoplectic stroke). During remodelling a small balloon is put right before the base of the aneurysm while the coil is placed. Falling back of the coil and obstructing the vessel should also be averted in this situation. Both interventions are performed if the the aneurysm has a broad base (so-called broad-based aneurysm).

With help of a multicentric, randomized study (ISAT) started in the 1990ies, it could be proven that the treatment with coils or clips is equal.

If the aneurysm has been coiled, the correct position of the coil can be examined by MRI. If it has been clipped, the clips produce to many artifacts so that the correct position can only by controlled by angiography. Coils as well as clips are MRI compatible.

Indication of the interventional / surgical treatment of an aneurysm

It has been discussed recently in different studies that detected aneurysms with a size less than 1 cm should not be treated but observed. This approach contradicts the clinical observation that a huge part of ruptured aneurysms of patients suffering from subarachnoid bleeding was less than 10 mm, often between 3 mm and 8 mm. Due to this reason, it should be carefully and critically evaluated in each individual case if the indication for an interventional / surgical treatment of an aneurysm is given.