Cerebral aneurysm are pathological local protrusions of the walls of the arterial vessels of the brain. With a tumor-like course, a cerebral aneurysm simulates a clinic of volumetric formation with damage to the optic, trigeminal and oculomotor nerves. With apoplexy, an aneurysm of the cerebral vessels manifests itself as symptoms of subarachnoid or intracerebral hemorrhage, which suddenly occur as a result of its rupture. Aneurysm of cerebral vessels is diagnosed on the basis of anamnesis, neurological examination, X-ray of the skull, examination of cerebrospinal fluid, CT, MRI and MRA of the brain. In the presence of indications, an aneurysm of cerebral vessels is subject to surgical treatment: endovascular occlusion or clipping.
I67.1 Brain aneurysm without rupture
According to some data, aneurysm of cerebral vessels is present in 5% of the population. However, it is often asymptomatic. An increase in aneurysmal expansion is accompanied by thinning of its walls and can lead to rupture of the aneurysm and hemorrhagic stroke. An aneurysm has a neck, a body and a dome. The neck, like the vessel wall, is characterized by a three-layer structure. The dome consists only of intimacy and is the weakest place in which the aneurysm of the cerebral vessels can rupture. The gap is most often observed in patients aged 30-50 years. According to statistics, it is a ruptured aneurysm that causes up to 85% of non-traumatic subarachnoid hemorrhages (SAH).
Congenital protrusion of cerebral vessels is a consequence of developmental abnormalities that lead to a violation of the normal anatomical structure of their walls. It is often combined with other congenital pathologies: polycystic kidney disease, aortic coarctation, connective tissue dysplasia, arteriovenous malformation of the brain, etc.
Acquired cerebral aneurysm can develop as a result of changes occurring in the vessel wall after a traumatic brain injury, against the background of hypertension, with atherosclerosis and hyalinosis of the vessels. In some cases, it is caused by the introduction of infectious emboli into the cerebral arteries. Such an aneurysm in modern neurology is called mycotic. Hemodynamic factors such as uneven blood flow and arterial hypertension contribute to the formation of pathology.
Aneurysm of the cerebral vessels is a consequence of changes in the structure of the vascular wall, which normally has 3 layers: the inner — intima, the muscular layer and the outer — adventitia. Degenerative changes, underdevelopment or damage to one or more layers of the vascular wall lead to thinning and loss of elasticity of the affected area of the vessel wall. As a result, in a weakened place under the pressure of the blood flow, the vascular wall protrudes, an aneurysm forms. Most often, the protrusion is localized in the places of branching of the arteries, because there the pressure exerted on the vessel wall is highest.
In its form, the aneurysm of the cerebral vessels is baggy and fusiform. Moreover, the first ones are much more common, in a ratio of about 50:1. In turn, the bag shape can be single- or multi-chamber. By localization, an aneurysm of the anterior cerebral artery, the middle cerebral artery, the internal carotid artery and the vertebrobasilar system are isolated. In 13% of cases, multiple aneurysms are observed, located on several arteries. There is also a classification by magnitude. According to it , aneurysms are isolated :
- miliary – up to 3 mm in size
- small — up to 10 mm
- average — 11-15 mm
- large — 16-25 mm
- giant — more than 25 mm.
According to its clinical manifestations, pathology may have a tumor-like or apoplexy course. With a tumor-like variant, the aneurysm of the cerebral vessels progressively increases and, reaching a significant size, begins to squeeze the anatomical formations of the brain located next to it, which leads to the appearance of appropriate clinical symptoms. The tumor-like form is characterized by the clinical picture of an intracranial tumor. It is most often detected in the area of the visual intersection (chiasm) and in the cavernous sinus.
The anomaly of the vessels of the chiasmal region is accompanied by impaired acuity and visual fields; with prolonged existence, it can lead to atrophy of the optic nerve. Aneurysm of the cerebral vessels located in the cavernous sinus may be accompanied by one of the three syndromes of the cavernous sinus, which are a combination of paresis of the III, IV and VI pairs of CN with damage to various branches of the trigeminal nerve. Paresis of the III, IV and VI pairs is clinically manifested by oculomotor disorders (weakening or inability to converge, development of strabismus); defeat of the trigeminal nerve — symptoms of trigeminal neuralgia. Long-term existing may be accompanied by the destruction of the skull bones, detected during radiography.
Often, the disease has an apoplexy course with the sudden appearance of clinical symptoms as a result of an aneurysm rupture. Only occasionally an aneurysm rupture is preceded by headaches in the frontal-orbital region.
The first symptom of a rupture is a sudden very intense headache. Initially, it may be local in nature, corresponding to the location of the aneurysm, then it becomes diffuse. Headache is accompanied by nausea and repeated vomiting. There are meningeal symptoms: hyperesthesia, rigidity of the occipital muscles, symptoms of Brudzinsky and Kernig. Then there is a loss of consciousness, which can last for a different period of time. There may be epileptiform seizures and mental disorders from slight confusion to psychosis. Subarachnoid hemorrhage, which occurs when an aneurysmal expansion is ruptured, is accompanied by a prolonged spasm of the arteries located near the aneurysm. In about 65% of cases, this vascular spasm leads to damage to the brain substance by the type of ischemic stroke.
In addition to subarachnoid hemorrhage, a ruptured cerebral aneurysm can cause hemorrhage into the substance or ventricles of the brain. Intracerebral hematoma is observed in 22% of rupture cases. In addition to general cerebral symptoms, it is manifested by increasing focal symptoms, depending on the localization of the hematoma. In 14% of cases, a ruptured aneurysm causes hemorrhage in the ventricles. This is the most severe variant of the development of the disease, often leading to a fatal outcome.
The focal symptoms that occur during rupture may be of a diverse nature and depend on the location of the aneurysm. When located in the area of carotid artery bifurcation, visual function disorders occur. The lesion of the anterior cerebral artery is accompanied by paresis of the lower extremities and mental disorders, the middle cerebral artery is accompanied by hemiparesis on the opposite side and speech disorders. An aneurysm localized in the vertebrobasilar system at rupture is characterized by dysphagia, dysarthria, nystagmus, ataxia, alternating syndromes, central facial nerve paresis and trigeminal nerve lesion. The protrusion of the cerebral vessels located in the cavernous sinus is located outside the dura mater and therefore its rupture is not accompanied by hemorrhage into the cranial cavity.
Quite often, the disease is characterized by an asymptomatic course and can be detected randomly when examining a patient due to a completely different pathology. With the development of clinical symptoms, diagnosis is carried out by a neurologist on the basis of anamnesis data, neurological examination of the patient, X-ray and tomographic examinations, examination of cerebrospinal fluid.
Neurological examination makes it possible to identify meningeal and focal symptoms, on the basis of which it is possible to make a topical diagnosis, i.e. to determine the location of the pathological process. Intsrumental diagnostics includes:
- Radiography. Skull x-ray helps to detect petrified aneurysms and destruction of the bones of the base of the skull. A more accurate diagnosis is provided by CT and MRI of the brain.
- Angiography. Cerebral angiography allows you to determine the location, shape and size of the aneurysm. Unlike X-ray angiography, magnetic resonance imaging (MRA) does not require the introduction of contrast agents and can be performed even in the acute period of rupture of a cerebral aneurysm. It gives a two-dimensional image of the cross-section of the vessels or their three-dimensional three-dimensional image.
- Lumbar puncture. In the absence of more informative diagnostic methods, a ruptured cerebral aneurysm can be diagnosed by performing a lumbar puncture. The detection of blood in the resulting cerebrospinal fluid indicates the presence of subarachnoid or intracerebral hemorrhage.
During the diagnosis, a tumor-like aneurysm of the cerebral vessels should be differentiated from a tumor, cyst and brain abscess. Apoplexy aneurysm of cerebral vessels requires differentiation from epileptic seizure, transient ischemic attack, ischemic stroke, meningitis.
Patients whose cerebral aneurysm is small in size should be constantly monitored by a neurologist or an operating neurosurgeon, since such an aneurysm is not an indication for surgical treatment, but needs to be monitored for its size and course. Conservative therapeutic measures are aimed at preventing an increase in the size of the aneurysm. They may include normalization of blood pressure or heart rate, correction of blood cholesterol levels, treatment of the consequences of TBI or existing infectious diseases.
Surgical treatment is aimed at preventing aneurysm rupture. Its main methods are aneurysm neck clipping and endovascular occlusion. Stereotactic electrocoagulation and artificial aneurysm thrombosis with coagulants can be used. For vascular malformations, radiosurgical or transcranial removal of AVMs is performed.
A ruptured cerebral aneurysm is an urgent condition and requires conservative treatment similar to the treatment of hemorrhagic stroke. According to the indications, surgical treatment is performed: removal of the hematoma, its endoscopic evacuation or stereotactic aspiration. If an aneurysm of the cerebral vessels is accompanied by hemorrhage into the ventricles, ventricular drainage is performed.
The prognosis of the disease depends on the place where the vascular protrusion is located, on its size, as well as on the presence of pathology leading to degenerative changes in the vascular wall or hemodynamic disorders. A non-increasing cerebral aneurysm can exist throughout the patient’s life without causing any clinical changes. In case of rupture, 30-50% of patients die, 25-35% have persistent disabling consequences. Repeated hemorrhage is observed in 20-25% of patients, the mortality after it reaches 70%.