Brain stem stroke is an acute violation of cerebral circulation of an ischemic or hemorrhagic nature, covering the brain stem. Pathology is characterized by polymorphism of symptoms, accompanied by motor, sensory disorders, impaired cranial nerve function, vestibulo-atactic syndrome. Extensive strokes with damage to vital centers due to high mortality have an extremely unfavorable prognosis. Pathological foci are detected by neuroimaging methods (CT and MRI of the brain, angiography). Treatment includes drug therapy, surgical correction, complex rehabilitation.
ICD 10
G46.3 Stroke syndrome in the brain stem (I60-I67+)
General information
Brain stem stroke is a common neurological disease, accounting for 18-20% of all acute disorders of cerebral circulation. At the same time, the ratio of ischemic and hemorrhagic types is 3:1. The probability of developing pathology increases with age – people older than 50-55 years suffer 1.8–2 times more often with each subsequent decade, but there is a steady trend towards rejuvenation of the disease. The gender structure of vertebrobasilar strokes is usually dominated by men, although some forms are more characteristic of women. Representatives of the black race get sick more often than Europeans, the lowest risk is recorded in Asians.
Causes
Cerebrovascular pathology occurs under the influence of a complex of factors. The development of a brain stem stroke is caused by a sharp decrease in hemodynamics along the arteries of the vertebral-basilar system or hemorrhage into the brain tissue that disrupts its normal functioning. Based on modern ideas about the etiopathogenesis of ACVA, there are several causes of ischemic damage:
- Atherothrombosis. Atherothrombotic occlusion of the extra- or intracerebral arteries is the leading factor in the occurrence of brain stem stroke, responsible for half of the cases. It has clinical significance in vascular lumen obturation by more than 50%. Unstable plaques in the precerebral arteries can lead to embolization.
- Cardiogenic embolism. Most severe strokes are caused by cardioembolism. The main causes of cerebral vascular damage are atrial fibrillation, myocardial infarction, pathology of the valvular apparatus. Cardiogenic embolisms are more common in young and elderly patients.
- Hemodynamic disorders. Cerebral hypoperfusion can occur with a combination of local (atherosclerosis, external compression, developmental abnormalities) and systemic hemodynamic disorders. The latter include arterial hypotension, cardiac arrhythmias, reduction or redistribution of CBV.
Arterial hypertension is recognized as an important cause of the development of strokes – against the background of the crisis course of the disease, cerebral hemorrhages occur, cerebral microangiopathy provokes the development of deep lacunar foci. Diabetes mellitus, hyperlipidemia, disorders of rheological properties of blood (hyper- or hypocoagulation) have a significant impact on the prognosis. Other risk factors are bad habits (smoking, alcohol consumption), overweight, low physical activity.
Pathogenesis
Stem structures (medulla oblongata, midbrain, bridge) have a number of features that determine the development of cerebrovascular damage. Compared with the convexital surface, blood circulation is less intense here, the superficial capillary network is not pronounced, but intracerebral collaterals are more developed. Stem neurons are less sensitive to hypoxic-ischemic processes, but with a sudden and pronounced reduction in blood flow or after extensive hemorrhages, compensatory mechanisms are depleted.
A local decrease in perfusion leads to the formation of the so-called penumbra zone (penumbra) around the infarction zone, the death of cells of which expands the focus. Cerebral hemorrhages are accompanied by the formation of a hematoma that compresses the medulla and provokes secondary ischemia. In both cases, a cascade of pathological reactions is triggered: lipid peroxidation, glutamate excitotoxicity, calcium damage. At the same time, there are reparative processes involving protective molecules aimed at limiting the focus and regeneration.
Classification
Brain stem stroke is a special case of acute impairment of cerebral blood flow through vertebrobasilar vessels. It can be of two types – ischemic and hemorrhagic (parenchymal or intraventricular hemorrhage). In its development, the disease goes through several stages: acute, subacute, organization (recovery). Given the etiopathogenetic features, there are several types of ischemic strokes:
- Atherothrombotic. They occur against the background of atherosclerosis of the cerebral arteries, progress gradually. Acute ischemia may be preceded by transient disturbances of cerebral blood flow.
- Cardioembolic. Accompanied by complete or partial occlusion of the lumen of the main artery by an embolus of extracranial (cardiogenic) origin. They begin suddenly, are characterized by a severe course, the presence of a hemorrhagic component, and have a serious prognosis.
- Hemodynamic. The development of strokes is caused by disorders of systemic hemodynamics, combined with pathology of extracranial and intracranial arteries in the absence of significant atherosclerotic occlusion, sources of cardiogenic embolism. Occur acutely or gradually.
- Lacunar. Caused by damage to the perforant arteries. Lacunar stroke is characterized by the formation of limited areas of ischemia located in the subcortical nuclei, the white matter of the brain.
When making a diagnosis, the localization of pathological foci, the prevalence of the process, and the side of the lesion are taken into account. Taking into account the location in the trunk, there are strokes of the varolium bridge, thalamus, medulla oblongata and medulla. In addition to isolated injuries, two or more departments may be involved. The lesion of stem structures is rarely mild, usually the condition varies from moderate to extremely severe.
Symptoms
Ischemic stroke
The clinical picture of the ACVA of the brain stem is quite polymorphic, determined by the nature of the focus (ischemic, hemorrhagic), its location, size. For strokes of the vertebrobasilar system, a predominant development in the daytime is typical, a rapid (from several minutes to hours) increase in focal symptoms. Motor disorders (hemiparesis or hemiplegia) on the opposite side from the focus are supplemented by hemianesthesia, if the main artery is involved, then all limbs suffer.
With great constancy, patients have alternating syndromes when conduction disorders are combined with signs of damage to the nuclei of cranial nerves. The defeat of the midbrain is accompanied by Weber syndrome with dysfunction of the III pair of CN – pupil dilation, ptosis, divergent strabismus. Varoliev bridge stroke is manifested by weakness of the facial muscles of half of the face, a focus in the medulla oblongata disrupts the work of the sublingual nerve with deviation of the tongue in the opposite direction and atrophy of its muscles (Jackson syndrome).
Small infarctions of the bridge base may be accompanied by involuntary contractions of skeletal muscles, contralateral hemiparesis. Clonic movements resembling convulsions are also observed when the visual mound is affected. They are often accompanied by symptoms of central facial nerve paresis, hemianopia. Bilateral bridge strokes are manifested by the syndrome of “isolation”: paralysis of skeletal muscles and aphasia against the background of preservation of skin sensitivity, consciousness. Similar foci in the midbrain lead to decerebration rigidity.
The lesion of the medulla oblongata is characterized by bulbar syndrome, rarely isolated dysphagia becomes the only manifestation of cerebral blood flow reduction. Lateral trunk strokes are accompanied by difficulty breathing (stridor), dysphonia due to paresis of the vocal folds. Vestibulo-atactic syndrome with dizziness, postural tone disorder, nystagmus is often detected. Patients are concerned about burning pains of central genesis, cardiovascular disorders develop (hypotension, arrhythmias).
Hemorrhagic stroke
Hemorrhagic brain stem stroke is characterized by a sudden onset, rapid development, and severe course. The process proceeds with pronounced cerebral symptoms, supplemented by focal signs. Psychomotor agitation, visual hallucinations are typical, consciousness is oppressed up to a deep coma. There is repeated vomiting, breathing is disturbed, the temperature rises. Hemorrhages in the thalamic zone with paresis of the eye, sensory deficiency, meningeal signs are common.
Complications
Pathology poses a serious danger to the patient’s life. Extensive hemorrhages in the medulla oblongata threaten to disrupt vital functions – respiratory arrest, cardiac activity. Frequent complications of a brain stem stroke are swelling, occlusive hydrocephalus, convulsions. After the formation of a hematoma, dislocation of cerebral structures with tentorial insertion may develop, sharply aggravating the patient’s condition and worsening the prognosis.
In conditions of damage to the stem centers, multiple organ failure develops rapidly, which is manifested by respiratory distress syndrome, decreased myocardial contractility, deep vein thrombosis and PE. A quarter of patients have falls after a stroke, and some of them end in serious injuries, including a hip fracture. Prolonged immobilization is accompanied by bedsores, delayed complications are depression, epilepsy.
Diagnostics
It is possible to assume a brain stem stroke by the rapid increase in focal neurological symptoms, the presence of appropriate risk factors. An important diagnostic and prognostic value is the assessment of the level of consciousness on the coma scale. Standard laboratory tests include UAC, coagulation and lipidogram, and biochemical analysis. But the key role in the recognition of cerebrovascular pathology is assigned to neuroimaging methods:
- Computed tomography. CT of the brain allows you to see hemorrhages as foci of increased density immediately after their occurrence. The study is the method of choice for the initial examination, but it allows you to diagnose only half of stem infarcts. Perfusion CT in ischemic injuries shows a higher informative value.
- Magnetic resonance imaging. Routine MRI better visualizes the structures of the posterior cranial fossa, and therefore has an advantage over CT. The method determines the morphological features of foci, gives an idea of the dynamics of changes, is characterized by the absence of artifacts from bone structures. The images show hyperintensive foci of various sizes corresponding to the stage of necrosis.
- Angiography. Noninvasive visualization of cerebral arteries is carried out by spiral CT or MR angiography. Studies allow us to assess the degree of arterial occlusion, the state of collateral blood flow, and identify the risk of focal expansion. Radiopaque angiography is performed when planning endovascular interventions.
Radionuclide scintigraphy can be used to detect focal changes in brain tissue, but the method has not found wide application in practical neurology. All patients are shown to perform an ECG, chest X-ray, EEG, spinal artery ultrasound, spinal puncture are performed from additional studies. A comprehensive examination involves the consultation of a neurologist, an ophthalmologist with an examination of the fundus.
Already during the initial examination of the patient, it is necessary to differentiate ischemic ACVA from hemorrhagic ones with a more serious prognosis. Comprehensive diagnostics makes it possible to distinguish brain stem strokes from diseases that have a similar localization of the pathological process: neuroinfections, traumatic brain injuries, tumors and metastases. A rapid increase in neurological symptoms is noted in paroxysmal (epilepsy, migraine, syncopation) and comatose states.
Treatment
Conservative therapy
Acute disorders of cerebral circulation of the stem zone require urgent hospitalization in a specialized vascular center or neurological hospital – optimally in the first 3 hours from the start. The basis of therapy is conservative measures that begin at the prehospital stage with the provision of emergency care, oxygenation, symptomatic correction (hypotensive, anticonvulsant). Early treatment helps to improve the prognosis even with severe lesions.
- Restoration of vital functions, including ventilation, is carried out in the intensive care unit, where, after determining the characteristics of a brain stem stroke, specific treatment is started. It is aimed at restoring blood flow through the vessels of the vertebrobasilar bed, preventing complications and eliminating them, minimizing the risk of relapse, normalizing the basic physiological and biochemical constants. The key areas of drug therapy are:
- Intravenous thrombolysis. The introduction of thrombolytic agents (recombinant plasminogen activator) is indicated in the acute period of the ischemic process. Despite the high efficiency of recanalization of arterial stenoses, such treatment has a lot of contraindications, increases the risk of hemorrhagic complications.
- Anticoagulants and antiplatelet agents. The progressive course of a brain stem stroke requires the use of anticoagulants – first low molecular weight heparins, then oral agents. They are also prescribed for preventive purposes after stabilization of cerebral hemorrhages. In all cases of acute stem ischemia, antiplatelet agents (acetylsalicylic acid) are needed.
- Neuroprotectors. Neuroprotectors are used to improve cerebral perfusion, increase the regenerative potential of the affected nervous tissue, and accelerate the restoration of impaired functions. These include vasoactive (vinpocetine, pentoxifylline), neurotrophic agents (a complex of cerebral peptides or hemoderivate of animal blood), antioxidants (thioctic, ascorbic acid, inosine).
Neurorehabilitation
Early comprehensive rehabilitation is essential for eliminating the consequences of a brain stem stroke and restoring the functional capabilities of patients. The medical direction is based on ongoing neuroprotective therapy, treatment of spasticity and contractures is carried out with muscle relaxants, concomitant emotional and mental disorders are corrected with antidepressants.
Neurorehabilitation involves the use of kinesiotherapy, physical therapy, massage. Modern hardware technologies are being introduced into everyday practice in the form of robot simulators working on the biofeedback mechanism. Cyclic exercises allow you to activate the patient, restore movement, coordination and walking function. The possibilities of complex rehabilitation are expanded by physiotherapy, psychotherapy, social and labor adaptation.
Surgical treatment
Radical correction of stem ischemic stroke involves the use of intravascular recanalization methods. Taking into account the clinical situation, selective intraarterial thrombolysis, mechanical or aspiration thrombectomy, balloon angioplasty with stenting of extracranial vessels can be used. After intracranial hemorrhage with dislocation of brain structures, hematoma removal and decompression in the volume of hemicraniectomy are performed. Ventricular drainage surgery helps to eliminate acute hydrocephalus.
Experimental treatment
Given the low level of evidence of existing means of drug neuroprotection, a search for new drugs is underway. The possibilities of antagonists of glutamate and NMDA receptors (eliprodil, selfotel), cytoprotective agents (lubeluzol), antioxidants (tirilazide) are being investigated. Methods of stereotactic and endoscopic hematoma removal need further study, ventricular thrombolysis and local hemostasis with recombinant factor VIIa are at the testing stage.
Prognosis and prevention
The prognosis for a brain stem stroke is determined by its type, localization and size of the lesion. Due to damage to vital structures, mortality can reach 65-90%, but thanks to timely intensive therapy, the risk of adverse events can be reduced. Progressive and persistent neurological deficit is accompanied by disability, a decrease in the quality of life of patients. Preventive measures involve hypotensive, antiplatelet, hypolipidemic therapy. Pay attention to the rejection of bad habits, the fight against excess weight.