Ocular orbit

Cerebral contusion

Cerebral contusion, Latin contusio cerebri, a form of traumatic brain injury, is a bruise of the brain tissue. Like bruises in other tissues, cerebral contusion can be caused by multiple microhemorrhages, small blood vessel leaks into brain tissue. Contusion occurs in 20–30% of severe head injuries. The injury can cause a decline in mental function and may result in brain herniation, a life-threatening condition in which parts of the brain are squeezed past parts of the skull. Treatment aims to prevent dangerous rises in intracranial pressure, the pressure within the skull. Contusions are likely to heal on their own without medical intervention.

Signs and symptoms

Contusion can present with weakness, lack of motor coordination, numbness, aphasia, and memory and cognitive problems. Signs depend on the contusion's location in the brain.

Causes

Often caused by a blow to the head, contusions commonly occur in coup or contre-coup injuries. In coup injuries, the brain is injured directly under the area of impact, while in contrecoup injuries it is injured on the side opposite the impact.

Contusions occur primarily in the cortical tissue, especially under the site of impact or in areas of the brain located near sharp ridges on the inside of the skull. The brain may be contused when it collides with bony protuberances on the inside surface of the skull. The protuberances are located on the inside of the skull under the frontal and temporal lobes and on the roof of the ocular orbit. Thus, the tips of the frontal and temporal lobes located near the bony ridges in the skull are areas where contusions frequently occur and are most severe. For this reason, attention, emotional and memory problems, which are associated with damage to frontal and temporal lobes, are much more common in head trauma survivors than are syndromes associated with damage to other areas of the brain.

Features

Contusions, which are frequently associated with edema, are especially likely to cause increases in intracranial pressure (ICP) and concomitant crushing of delicate brain tissue. Contusions are also more likely to result in hemorrhage than is diffuse axonal injury because they occur more often in the cortex, an area with more blood vessels.

Contusions typically form in a wedge-shape with the widest part in the outermost part of the brain.

The distinction between contusion and intracerebral hemorrhage is blurry because both involve bleeding within the brain tissue; however, an arbitrary cutoff exists that the injury is a contusion if two thirds or less of the tissue involved is blood and a hemorrhage otherwise.

The contusion may cause swelling of the surrounding brain tissue, which may be irritated by toxins released in the contusion. The swelling is worst at around four to six days after the injury.

Extensive contusion associated with subdural hematoma is called burst lobe. Cases of a burst frontal or temporal lobe are associated with high mortality and morbidity.

Multiple petechial hemorrhages

Numerous small contusions from broken capillaries that occur in grey matter under the cortex are called multiple petechial hemorrhages or multifocal hemorrhagic contusion. Caused by shearing injuries at the time of impact, these contusions occur especially at the junction between grey and white matter and in the upper brain stem, basal ganglia, thalamus and areas near the third ventricle. The hemorrhages can occur as the result of brain herniation, which can cause arteries to tear and bleed. A type of diffuse brain injury, multiple petechial hemorrhages are not always visible using current imaging techniques like CT and MRI scans. This may be the case even if the injury is quite severe, though these may show up days after the injury. Hemorrhages may be larger than in normal contusions if the injury is quite severe. This type of injury has a poor prognosis if the patient is comatose, even with no apparent causes for the coma.

Cerebral lacerations

A cerebral laceration occurs when the tissue of the brain is mechanically cut or torn. According to their respective definitions, the pia-arachnoid membranes and are torn over the site of injury in laceration and are not torn in contusion. Lacerations require greater physical force to cause than contusions, but the two types of injury are grouped together in the ICD-9 and ICD-10 classification systems.

Frequently occurring in the same areas as contusions, lacerations are particularly common in the inferior frontal lobes and the poles of the temporal lobes. When associated with diffuse axonal injury, the corpus callosum and the brain stem are common locations for laceration. Lacerations are very common in penetrating and perforating head trauma and frequently accompany skull fractures; however, they may also occur in the absence of skull fracture. Lacerations, which may result when brain tissue is stretched, are associated with intraparenchymal bleeding (bleeding into the brain tissue).

Treatment

Since cerebral swelling presents a danger to the patient, treatment of cerebral contusion aims to prevent swelling. Measures to avoid swelling include prevention of hypotension (low blood pressure), hyponatremia (insufficient sodium), and hypercapnia (excess carbon dioxide in the blood). Due to the danger of increased intracranial pressure, surgery may be necessary to reduce it. People with cerebral contusion may require intensive care and close monitoring.

See also

References

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