Increased pressure in the cranial cavity (in the skull) is technically known as the intracranial hypertension. It may be related to many conditions including head injuries and brain diseases. Intracranial hypertension has very unpleasant symptoms including some fatal consequences.
In an adult, the cranial cavity is tightly surrounded by the skull bones. The space within the skull is filled with the brain tissue, local blood vessels and cerebrospinal fluid (CSF). Cerebrospinal fluid is produced in the cavities inside the brain (brain ventricles) and then it flows through the connecting openings into the space around the brain. These three main components (brain, cerebrospinal fluid and blood vessels) fill the entire space and there is only little reserve for possible increase of the intracranial volume.
Intracranial pressure is increased in situations when there is increased volume of any of the above-mentioned components, i.e. either brain or cerebrospinal fluid or blood. The blood volume may increase when there is bleeding into the cranial cavity including hemorrhagic stroke, subdural hematoma, epidural hematoma and subarachnoid hemorrhage. The increase of brain tissue volume may have many causes including brain infections (encephalitis, meningitis), brain abscesses, brain tumors, brain metastases and brain injuries. The increase of the amount of cerebrospinal fluid is known as hydrocephalus. More information can be found in the relevant article, but generally speaking, the problem is caused either by blockage of the flow of the cerebrospinal fluid or by disrupted absorption of the CSF into local cranial blood veins.
In children, the skull bones are not tightly fused and slowly increasing intracranial volume may be compensated by pushing them away and enlargement of the head without causing any symptoms. However, in a rapid increase of intracranial volume, this mechanism does not have time to take effect, thus causing symptomatic intracranial hypertension similar to adults.
In adults, the skull bones are fused and the skull can not be compensatory enlarged. The only big hole in the skull is located at its base where the spinal cord enters the brain. Increased intracranial pressure may be only slightly compensated by pushing a certain amount of cerebrospinal fluid out of the skull, but this is not a sufficient mechanism and local intracranial pressure increases. This situation affects the brain and the person suffers from headache, dizziness and vomiting. Interestingly, vomiting in intracranial pressure may occur surprisingly without any previous nausea. Many neurological symptoms may be present including muscle paralysis and sensitivity disorders. If the pressure continues to rise, the brain tissue inserts into the hole in the skull base and it gets damaged. Unfortunately, the first damaged location is the area of the medulla oblongata containing vital brain centers including a center for breath control. This causes a rapid deterioration of consciousness, coma and death.
People with intracranial pressure often suffer from a sharply increased blood pressure. When the intracranial pressure elevates, local blood vessels get compressed. The body tries to ensure sufficient blood flow through brain and this is done by elevated blood pressure.
In addition to the above symptoms, we have to look for any information about recent head injury or any previously known brain diseases. If there is a malignant disease in patient’s personal history, we should always think about brain metastases. The most valuable examination methods are computed tomography and magnetic resonance imaging of the brain as they can show the majority of organic pathologies causing the intracranial hypertension.
Specialized centers can provide direct monitoring of intracranial pressure by a special electrode, which is inserted through the skull just to the vicinity of brain.
Patients with intracranial hypertension should never undergo the spinal tap with removal of the cerebrospinal fluid. This causes a decreased pressure in the spinal canal, which may further force the brain to be pushed into the base of the skull, causing sudden death.
The patient should be hospitalized, in ideal case in an ICU with continuous monitoring of their vital signs. The patient’s head should be elevated to the angle of 20-30° above the horizontal line to facilitate the drainage of venous blood from the brain. The doctors may administer special osmotically active substances reducing intracranial pressure such as the mannitol. When the increased intracranial pressure can not be handled by conservative means, it is necessary to perform a surgical intervention. The most common surgical intervention is so-called decompressive craniectomy. This operation means a therapeutic removal of a part of the skull to release the internal pressure. In addition to the management of the intracranial pressure, it is necessary to solve its underlying cause, if possible.