Brain dislocation is the displacement of cerebral structures in a limited intracranial space. The clinic is characterized by a combination of varying degrees of impaired consciousness with focal neurological deficit. Respiratory disorders and palpitations are possible. Diagnosis is carried out on the basis of anamnesis, symptoms, neurological examination, results of Echo-EG, CT or MRI of the brain. Drug therapy is aimed at reducing cerebral edema and intracranial pressure, relieving symptoms. Surgical decompression is indicated for patients.
G93.5 Compression of the brain
Brain dislocation is a displacement of the structures of the hemispheres of the brain or cerebellum, their protrusion into anatomical holes and crevices. Pathology is a complication of a pronounced increase in intracranial pressure (ICP), due to brain edema or various volumetric formations. It is most often observed in severe traumatic brain injuries (TBI) and intracranial tumors. Rapid brain dislocation is considered the main cause of mortality in patients with severe TBI, which reaches 70-75%. Progressive dislocation syndrome in neoplasms without radical treatment is also the cause of death of patients.
The main etiofactor is intracranial hypertension. The threat of dislocation occurs when the pressure increases to 20 mmHg. For volumetric processes of the temporal lobe, the occurrence of displacement is possible at lower pressure figures. There are the following factors that lead to an increase in ICP:
- Brain injuries. Bruises and fractures of cerebral tissues cause necrosis and swelling with increasing weight. Post-traumatic hematomas, formed by blood spilled as a result of vascular damage, lead to an increase in pressure inside the skull.
- Cerebral tumors. Intracranially growing neoplasms cause an increasing mass effect as they increase. Germination of the formation in the circulation pathway of cerebrospinal fluid, blocks its outflow, causing hydrocephalus.
- Vascular anomalies. Aneurysms and arteriovenous malformations of cerebral vessels accompanied by thinning of the vascular wall, which leads to its rupture. The accumulation of leaking blood forms a hematoma that compresses the underlying tissues.
- Swelling of the brain. It develops as a complication of severe infectious lesions of the central nervous system (encephalitis, purulent meningitis empyema), intoxication, subarachnoid hemorrhage. It can occur with anasarca caused by an allergic reaction, decompensated heart failure.
- Stroke. Hemorrhagic stroke is accompanied by the outpouring of blood into the cerebral substance with the formation of a hematoma. Malignant extensive ischemic stroke is complicated by increasing hemispheric edema.
The intracranial space is limited by the bones of the skull. An increase in the volume of the contents of the cranial box, which occurs with edema, hemorrhage, the appearance of a neoplasm, causes a mass effect with an increase in intracranial pressure. The consequence is the displacement of cerebral tissues, their protrusion into the free spaces existing inside the skull. The compensatory role is played by the reserve cerebral spaces, including the subarachnoid space and the ventricular system.
With a further increase in the mass effect, compensatory mechanisms are not enough, there is a protrusion of the medulla into the cracks and holes. Pathogenetically, there are 3 stages of brain dislocation: protrusion, wedging, infringement. The last stage leads to irreversible damage to the affected cerebral structures. The most dangerous infringement of the brain stem, since vital centers are localized in it.
Depending on the location in relation to the outline of the cerebellum in clinical neurology, all cerebral dislocations are divided into supra- and subtentorial. Lateral and axial dislocation are classified according to the direction of displacement. External dislocation is singled out separately — swelling of tissues through a post-traumatic or postoperative defect of the cranial vault. According to the classification according to the anatomical structure through which the protrusion occurs, there are 5 main types of insertion:
- Transtentorial — unilateral dislocation of the temporal lobe under the namet.
- Central — bilateral insertion of the temporal lobes.
- Subserpoid (subfalx) — displacement of the angular gyrus under the cerebral sickle.
- The insertion of the tonsils of the cerebellum is a protrusion of the cerebellum into the large occipital foramen.
- Ascending transtentorial insertion — dislocation of the cerebellum into the opening of the mouth.
Depending on the severity of pathological changes, there are 2 types of dislocation syndrome:
- Simple — there is no strangulation furrow, morphological changes in the nervous tissue are reversible. With the rapid elimination of the etiofactor, there is a regression of symptoms and restoration of function.
- Complex — the insertion is accompanied by the formation of a strangulation line, petechial hemorrhages, ischemic foci. Leads to persistent loss of nervous function.
The most typical signs of dislocation are disorders of consciousness, ranging from lethargy to coma. The rapid development of dislocation syndrome is characterized by symptoms of extensive brain damage: decortication or decerebration rigidity, gormetonia, muscular atony. Disorders of consciousness are combined with focal symptoms in the form of contralateral hemiparesis, hemihypesthesia, homonymous hemianopsia, hemiataxia. Hyperkinesis, oculomotor disorders, bulbar syndrome are possible.
Compression of the brain stem is characterized by the addition of heart rhythm disorders, breathing. Respiratory disorders include tachy- and bradypnea, shallow breathing, Cheyne–Stokes breathing. The symptoms depend on the type of brain dislocation. Dislocation syndrome caused by a cerebral tumor is characterized by a more gradual increase in symptoms. Hematomas, cerebral edema of infectious etiology, post-traumatic mass effect often lead to rapidly developing brain dislocation.
The most dangerous complication of brain dislocation is compression of the trunk with vascular and respiratory centers located in it. Emerging disorders of cardiac activity, paralysis of the respiratory center without emergency medical care lead to death. Timely radical treatment can prevent the development of complications and save the patient’s life.
The clinical picture, the presence in the anamnesis of data on the volume formation of intracranial localization helps the neurologist to suspect dislocation syndrome. In the neurological status, patients have anisocoria, dilation of one or both pupils, absence of a corneal reflex, hemiparesis, violation of the friendly movement of the eyeballs and other focal symptoms. An accurate diagnosis is possible based on the results of the following additional studies:
- Echo-EG. It is used as a primary diagnosis. The study can be carried out directly in the neurological office. The dislocation is indicated by the displacement of the middle M-echo.
- CT scan of the brain. Allows you to diagnose all types of dislocation, to identify the cause of the displacement. It is most effective for visualization of hematomas, post-traumatic conditions.
- MRI of the brain. It is informative in the diagnosis of various types of dislocation syndrome. Visualizes tumor formations, inflammatory changes, ischemic areas in more detail.
Brain dislocation is differentiated with Chiari anomaly and intracranial hypotension. The anomaly is characterized by a congenital low location of the medulla oblongata, cerebellum. It differs in the presence of pain in the back of the head, dizziness and fainting when turning the head. With intracranial hypotension, volumetric formation and mass effect are absent, with neuroimaging, thickening of the cerebral membranes, their contrast is determined.
Drug treatment is aimed at blocking the pathogenetic mechanisms of dislocation, relieving symptoms, and maintaining the functioning of cerebral structures. Conservative methods are used in patients with a simple type of syndrome, as a supplement to surgical treatment. The complex therapy includes:
- Cerebral dehydration. It is carried out with the use of drugs that improve the outflow of fluid from cerebral tissues into the vascular bed. It is possible to prescribe protein-colloidal agents, osmodiuretics, saluretics.
- Etiotropic treatment. In hemorrhages, hemostatic therapy, protease inhibitors that reduce perihemorrhagic swelling are used. Treatment of purulent lesions is carried out with antibiotics. Allergic anasarca requires the use of antihistamines and other antiallergic pharmaceuticals.
- Symptomatic therapy. Depending on the symptoms, it is possible to prescribe antiemetics, painkillers, anticonvulsants.
- Therapeutic hypothermia. Causes a decrease in blood circulation, a decrease in the vasogenic component of brain edema. Potentiates drug decongestant treatment.
The operation is performed in an urgent manner, regardless of the severity of the patient’s condition, since it allows saving the patient’s life. The main goal of the intervention is to reduce the level of intracranial hypertension. Simultaneous neurosurgical surgery to eliminate the etiological factor of dislocation is possible: removal of the tumor, drainage of the hematoma, resection of the crushing site, endovascular occlusion of the aneurysm. The main methods of cerebral decompression used by modern neurosurgery include:
- Decompressive craniotomy. Trepanation of the skull is indicated in supratentorial dislocations of the brain.
- External ventricular drainage. Allows you to achieve a rapid decrease in ICP and monitor it.
- Internal decompression. It is performed by resection of the temporal lobe. It allows to significantly reduce mortality.
- Tentoriotomy. It is carried out with transtentorial insertion with a special tentoriotome through the milling hole of the skull. It has been proven to reduce mortality in comatose patients.
- Bilateral suboccipital craniectomy. It is indicated when the cerebellar tonsils are inserted.
Prognosis and prevention
Brain dislocation refers to life-threatening conditions, without timely surgical decompression leads to the death of the patient. Surgical treatment can significantly increase the patient’s chances of life. After eliminating a simple dislocation, it is possible to restore the lost nerve functions. The long-term prognosis depends on the underlying disease. Prevention of dislocation syndrome consists in timely detection and adequate treatment of neurological diseases leading to it.