Treatment of intracranial aneurysms

What is an intracranial aneurysm?

The term intracranial aneurysm is used to describe a dilation or weak point in the walls of arterial blood vessels. Such a weakness in the vessel wall leads to an increased risk of tears in the blood vessels (ruptures), which can result in bleeding in the surrounding tissue. Intracranial aneurysms often remain asymptomatic and therefore undiscovered, or are noticed only by chance during an examination carried out for other reasons, such as a vascular MRI or a CAT scan. However, they occasionally provoke atypical complaints, such as headaches or nausea. Further symptoms, such as ophthalmoplegia, or eye movement disorders, which cause double vision, depend on the size and the exact position of the aneurysm.

Aneurysms appear on vessels at the base of the brain, especially where the arteries divide. Vessel divisions lead to localised changes in flow conditions that encourage the formation of an aneurysm.

What are the consequences and dangers
If an aneurysm at risk of rupturing is not discovered and treated, it can burst and trigger a dangerous brain haemorrhage, a so-called haemorrhagic stroke. Such haemorrhages constitute a life-threatening emergency with serious consequences, or can even lead to death. However, both burst aneurysms and aneurysms discovered by chance can be treated to guard against a (further) haemorrhage.
In the acute emergency of an aneurysmal subarachnoid haemorrhage, sudden headaches usually occur, which are experienced by patients as more severe than any they have ever experienced in their lives. Frequently, and especially in the event of severe, bigger aneurysmal subarachnoid haemorrhages, headaches do not present as the only symptom. Neck stiffness, nausea and vomiting, sleepiness to the extent of loss of consciousness and coma, as well as symptoms of a stroke with paralysis, dysaesthesia and speech loss, can be caused by the rupture of an aneurysm.
An immediate diagnosis of the localisation and extent of the haemorrhage is decisive for the further progression of the disease and the prognosis after the haemorrhage event.
These days, this can be done quickly and safely thanks to the development of diagnostic imaging technologies (CAT scans, MRIs).
What are the risk factors?
An aneurysm occurs in cerebral arteries with pathologically altered wall construction. With each heartbeat, the blood from inside exerts high pressure on the vessel walls. Through this, the pathologically altered vessel section can become a weak point, which ultimately gives in and forms an aneurysm. The cause for these processes cannot always be determined exactly. Along with increased risk due to heredity, high blood pressure and smoking constitute the most important risk factors and, in contrast to heredity, are also the easiest to influence.
What are the treatment options?
The priority treatment objective for all aneurysmal subarachnoid haemorrhages is to seal off the source of the haemorrhage as quickly and fully as possible to prevent a further haemorrhage, which is often more dangerous than the first.
A proportion of the unruptured aneurysms that are discovered by chance also requires treatment to prevent a rupture that could worsen the prognosis significantly. This is, however, certainly neither necessary nor sensible for every one of these aneurysms. An experienced neurovascular unit should be contacted for appropriate advice.
Possible types of treatment include clipping or even catheter-based (endovascular) treatments with platinum coils – sometimes combined with intracranial stents – or treatment with special flow diverters.
Small metal clips (in various shapes) are placed on the base of the aneurysm neck, to separate the aneurysm from the course of the vessel.
Unlike clipping, it is not necessary to open the cranial vault if endovascular techniques are used. Instead, small platinum coils are introduced into the aneurysm through the femoral artery in the groin with the help of long, very thin plastic tubes, so-called microcatheters. In this treatment, the aneurysm is filled up with coils, thus preventing the aneurysm from rupturing.
In the case of complex types of aneurysm, a metal vascular support (stent) is inserted into the vessel, in addition to the coils, to prevent the coils from “falling out” of the aneurysm into the vessel. This procedure is referred to as stent-assisted coiling.
Flow diverters constitute another, relatively new, treatment option. These are very closely woven, braided stents, which are so dense they are able to reroute the blood flow. If a flow diverter is positioned in the section of the vessel where the aneurysm is located, it redirects the blood flow so that the inflow into the aneurysm is considerably reduced. In the long term, the blood in the aneurysm will thrombose through this change in the flow conditions and, in many cases, also completely shrivel up. As with the introduction of coils, this treatment leads to the aneurysm being sealed off. With this method, the risk of an aneurysm rupture with a subsequent cerebral haemorrhage is also minimised. This technique is frequently used for very irregular types of aneurysm, as in these cases stent-assisted coiling is not possible.
Summary
Intracranial aneurysms constitute a serious disease that must be controlled medically, and treated, if necessary. There are various treatment options available today that make it possible to treat virtually all types of aneurysm. Early operative or endovascular care of the aneurysm, as well as extensive rehabilitative treatment of neurological and neuropsychological symptoms can improve the prognosis of this disease considerably.
The treatment methods deployed are determined by the treating doctor, taking into consideration the diagnosis and assessing the chances and risks of the type of treatment concerned, in consultation with the patient. A neurovascular unit providing the latest treatment methods, carried out by experienced doctors, should be contacted for advice.
 
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