Decompressive craniectomy is a type of surgery in which a piece of the skull is removed to reduce the pressure inside it. The pressure inside the skull, known as the intracranial pressure, can rise after a stroke, a brain hemorrhage, or when brain swelling occurs following a traumatic brain injury. As the brain swells inside the enclosed space, the pressure increases and further brain damage could develop as a result. The use of decompressive craniectomy is controversial because there is not enough evidence to support it as an effective treatment. Some researchers found that this type of surgery could reduce intracranial pressure in people with brain injuries but, in spite of this, death rates were not improved.
Although the theory behind decompressive craniectomy suggests that it should be a very effective way of relieving pressure on the brain, in practice not enough reliable clinical trials have been carried out to determine whether this is true. The neurosurgical procedure involves removing a large section of skull. If only a small part of the skull is removed this carries a risk that part of the brain will push through the opening. Blood vessels might become squashed and blocked, leading to death of brain tissue, and swelling around the edges of the opening might worsen.
Different decompressive craniectomy methods may be used depending on the exact location of the problem inside the brain. Bone may be removed from one or both sides of the skull. Following the surgical removal procedures, there is typically a delay of several months before the missing piece of skull is replaced, in a process known as cranioplasty. During this time, the skull opening is covered by a skin flap, leaving the patient vulnerable to complications of decompressive craniectomy.
Immediately following surgery, existing areas of leaked blood may expand, new areas of bleeding may arise and the brain could continue to swell and protrude out of the skull opening in a way that causes further damage. In the week following surgery, the circulation of cerebrospinal fluid around the brain could be disturbed, leading to a leak of fluid into the tissue layers that surround the brain. Later, problems with thinking, nervous system disorders or psychological conditions could develop.
The most serious complication of decompressive craniectomy is known as a persistent vegetative state. This is a condition similar to a coma where patients have no awareness of themselves or of anything around them, although, unlike coma patients, they are awake. Although decompressive craniectomy carries the risk of such a serious outcome, this has to be weighed against the fact that the operation is normally only performed as a last resort in a life-threatening situation.