Treatment of cerebral edema, drugs and surgery

Treatment of cerebral edema is focused on therapy of the underlying cause and other life-threatening complications. It includes hyperventilation, osmotherapy, diuretics, corticosteroids and surgical decompression.

Treatment of cerebral oedema has two aims: to prevent further damage caused by cerebral oedema and to repair damage already caused by pressure oedema.

Correction of initial and persistent damage includes correction of metabolic disturbances, control of hypertension, removal of intracranial lesions, or shunting of hydrocephalus, depending on the causes of cerebral edema.

Osmotherapy

The most rapid and effective means of reducing the volume of water in the tissues and brain is osmotherapy.

Osmotic therapy is designed to remove water from the brain using an osmotic gradient and also reduces the viscosity of the blood. These changes reduce intracranial pressure and increase blood flow through the brain.

The most commonly used osmotic agent is mannitol. Not all the mechanisms by which mannitol reduces intracranial pressure are yet clear.

It is thought that mannitol reduces total brain volume by reducing water content and reduces blood volume by vasoconstriction (narrowing of blood vessels).

Mannitol may also improve cerebral perfusion by reducing the density or changing the ratio of red blood cells to plasma in the blood. Finally, mannitol may also have a protective effect against biochemical damage to the brain.

It is most appropriate to administer mannitol in lower doses. In this way, a sufficient effect is achieved. Also, hyperosmolar complications, which have been reported with frequent administration of high doses, are less likely to occur.

Long-term administration of mannitol has side effects such as electrolyte imbalance. The side effects may outweigh its benefits and should be monitored carefully.

Nursing care of the patient receiving mannitol requires careful monitoring of electrolytes, total fluid balance and monitoring for the development of cardiopulmonary complications in addition to neurological examination.

Diuretics

The osmotic effect of e.g. mannitol can be prolonged by the use of a diuretic. Such a diuretic is e.g. furosemide.

Excess fluid that is released from the brain tissues is rapidly eliminated from the body by these agents.

Corticosteroids

Corticosteroids reduce intracranial pressure, especially in vasogenic oedema.

They have a beneficial effect on blood vessels. They are less effective in cytotoxic oedema. They are not recommended in the treatment of oedema of secondary origin, e.g. ischaemic stroke or cerebral haemorrhage.

They are very effective in oedema caused by chronic meningitis and in acute bacterial meningitis under antibiotic cover.

Glucocorticoids are also frequently used in the treatment of malignant brain tumours, either primary or secondary, as adjunctive chemotherapy in some CNS tumours and perioperatively in brain surgery.

Swelling around brain tumors, especially around brain metastases, responds very rapidly and dramatically to treatment with high doses of dexamethasone.

Hyperventilation

Controlled hyperventilation with artificial pulmonary ventilation helps to reduce elevated intracranial pressure.

Cerebral blood vessels are most sensitive to changes in arterial carbon dioxide and begin to constrict when it is reduced.

The intracranial pressure begins to fall within minutes of initiating hyperventilation. Although the buffering mechanisms of the liquor and extracellular fluid soon restore the pH to normal carbon dioxide values, the beneficial effect may take several hours.

It is important to conscientiously monitor the effects of ventilation by blood gas analysis and chest X-ray. The partial pressure of carbon dioxide should not fall below 25 mmHg.

At this point, the vasoconstrictor effect of hypocarbia (low carbon dioxide levels) alone will cause hypoxia (lack of oxygen) and cells will become damaged by ischemia.

Surgical treatment

Surgical treatment is recommended for extensive edema with life-threatening changes to the brain.

Temporary ventriculostomy is the artificial creation of communication between the ventricles of the brain. It is performed to facilitate the outflow of lysate. It is mainly used to treat edema in hydrocephalus.

A craniectomy is an invasive neurosurgical procedure. It removes part of the cranial vault to make room for the swollen brain and reduce pressure in the skull. The removed bone is placed in a bone bank. After the condition is corrected, it is returned to the patient.

This procedure can quickly prevent the condition from worsening and save the patient's life.

Surgical removal of the lesions responsible for brain edema, such as a tumor, will also cure the edema caused by these lesions.

Other methods of supportive treatment include:

1. Extraventricular liquor drainage, such as ventriculoperitoneal drainage. This creates a connection between the brain ventricles and the abdominal cavity.
2. Avoidance of exertion and coughing, as involvement of the abdominal muscles also increases intracranial pressure in the skull.
3. Inducing paralysis in intubated patients improves the patient's tolerance to intubation.
4. Maintaining a straight-necked, head-elevated position promotes better cerebral circulation and facilitates fluid drainage from the head.
5. Inducing hypothermia, i.e. lowering the body temperature and thus slowing down cerebral metabolism. This therapy is only applied for a few days, as prolonged hypothermia makes the patient susceptible to systemic infections and low blood pressure.