Decompressive craniectomy
Encyclopedia
Decompressive craniectomy is a neurosurgical
procedure in which part of the skull
is removed to allow a swelling brain
room to expand without being squeezed. It is performed on victims of traumatic brain injury
and stroke
. Use of the surgery is controversial.
The procedure evolved from a primitive form of surgery known as trephining or trepanning. The older procedure, while common in prehistoric times, was deprecated in favor of other, less invasive treatments as they were developed; although it was still performed with some frequency prior to the twentieth century, its resurgence in modern form became possible only upon the development of precision cutting tools and sophisticated post-operative care such as antibiotics.
(ICP), the pressure within the skull. Raised intracranial pressure is very often debilitating or fatal because it causes compression of the brain and restricts cerebral blood flow
. The aim of decompressive craniectomy is to reduce this pressure. The part of the skull that is removed is called a bone flap. A study has shown that the larger the removed bone flap is, the more ICP is reduced.
. This was a randomized trial comparing decompressive craniectomy to best medical therapy run between 2002 and 2010 to assess the optimal management of patients with medically refractory ICP following diffuse non-penetrating head injury. The study investigators found that decompressive craniectomy was associated with worse functional outcomes, as measured by a standard metric, than best medical care. There were no differences in deaths between groups. However, the results of the DECRA trial have been rejected or at least questioned by many practicing neurosurgeons, and a concurrently published editorial raises several study weaknesses. First, the threshold for defining increased ICP, and the time allowed before declaring ICP medically refractory, are not what many practicing physicians would consider increased or refractory. Second, out of almost 3500 potentially eligible patients, only 155 patients were enrolled, showing that the study cannot be generalized to all patients with severe non-penetrating brain injury. Lastly, despite being randomized, more patients in the craniectomy arm had unreactive pupils (after randomization but before surgery) than patients in the medical therapy arm, a potential confounding factor.
and cerebral blood flow
in head injured patients.
Decompressive craniectomy is also used to manage major strokes, associated with "malignant" edema
and intracranial hypertension
. The pooled evidence from three randomised controlled trials in Europe supports the retrospective observations that early (within 48 hours) application of decompressive craniectomy after "malignant" stroke may result in improved survival and functional outcome in patients under the age of 55, compared to conservative management alone.
The procedure is recommended especially for young patients in whom ICP is not controllable by other methods. Age of greater than 50 years is associated with a poorer outcome after the surgery.
or brain abscess
can occur after decompressive craniectomy.
This is the only prospective randomised controlled study to date to support the potential benefit of decompressive craniectomy following traumatic brain injury.
When the patient has healed sufficiently, the opening in the skull is usually closed with a cranioplasty
. If possible, the original skull fragment is preserved after the craniectomy in anticipation of the cranioplasty.
Neurosurgery
Neurosurgery is the medical specialty concerned with the prevention, diagnosis, treatment, and rehabilitation of disorders which affect any portion of the nervous system including the brain, spine, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system.-In the United States:In...
procedure in which part of the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
is removed to allow a swelling brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
room to expand without being squeezed. It is performed on victims of traumatic brain injury
Traumatic brain injury
Traumatic brain injury , also known as intracranial injury, occurs when an external force traumatically injures the brain. TBI can be classified based on severity, mechanism , or other features...
and stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
. Use of the surgery is controversial.
The procedure evolved from a primitive form of surgery known as trephining or trepanning. The older procedure, while common in prehistoric times, was deprecated in favor of other, less invasive treatments as they were developed; although it was still performed with some frequency prior to the twentieth century, its resurgence in modern form became possible only upon the development of precision cutting tools and sophisticated post-operative care such as antibiotics.
Reduction of intracranial pressure
Though the procedure is considered a last resort, some evidence suggests that it does improve outcomes by lowering intracranial pressureIntracranial pressure
Intracranial pressure is the pressure inside the skull and thus in the brain tissue and cerebrospinal fluid . The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF...
(ICP), the pressure within the skull. Raised intracranial pressure is very often debilitating or fatal because it causes compression of the brain and restricts cerebral blood flow
Cerebral blood flow
Cerebral blood flow, or CBF, is the blood supply to the brain in a given time. In an adult, CBF is typically 750 millitres per minute or 15% of the cardiac output. This equates to 50 to 54 millilitres of blood per 100 grams of brain tissue per minute. CBF is tightly regulated to meet the brain's...
. The aim of decompressive craniectomy is to reduce this pressure. The part of the skull that is removed is called a bone flap. A study has shown that the larger the removed bone flap is, the more ICP is reduced.
DECRA trial
In March 2011, investigators from Australia and several other countries published the results of the DECRA trial in the New England Journal of MedicineNew England Journal of Medicine
The New England Journal of Medicine is an English-language peer-reviewed medical journal published by the Massachusetts Medical Society. It describes itself as the oldest continuously published medical journal in the world.-History:...
. This was a randomized trial comparing decompressive craniectomy to best medical therapy run between 2002 and 2010 to assess the optimal management of patients with medically refractory ICP following diffuse non-penetrating head injury. The study investigators found that decompressive craniectomy was associated with worse functional outcomes, as measured by a standard metric, than best medical care. There were no differences in deaths between groups. However, the results of the DECRA trial have been rejected or at least questioned by many practicing neurosurgeons, and a concurrently published editorial raises several study weaknesses. First, the threshold for defining increased ICP, and the time allowed before declaring ICP medically refractory, are not what many practicing physicians would consider increased or refractory. Second, out of almost 3500 potentially eligible patients, only 155 patients were enrolled, showing that the study cannot be generalized to all patients with severe non-penetrating brain injury. Lastly, despite being randomized, more patients in the craniectomy arm had unreactive pupils (after randomization but before surgery) than patients in the medical therapy arm, a potential confounding factor.
Other effects
In addition to reducing ICP, studies have found decompressive craniectomy to improve cerebral perfusion pressureCerebral perfusion pressure
Cerebral perfusion pressure, or CPP, is the net pressure gradient causing blood flow to the brain . It must be maintained within narrow limits because too little pressure could cause brain tissue to become ischemic , and too much could raise intracranial pressure .-From resistance:CPP can be...
and cerebral blood flow
Cerebral blood flow
Cerebral blood flow, or CBF, is the blood supply to the brain in a given time. In an adult, CBF is typically 750 millitres per minute or 15% of the cardiac output. This equates to 50 to 54 millilitres of blood per 100 grams of brain tissue per minute. CBF is tightly regulated to meet the brain's...
in head injured patients.
Decompressive craniectomy is also used to manage major strokes, associated with "malignant" edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
and intracranial hypertension
Intracranial pressure
Intracranial pressure is the pressure inside the skull and thus in the brain tissue and cerebrospinal fluid . The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF...
. The pooled evidence from three randomised controlled trials in Europe supports the retrospective observations that early (within 48 hours) application of decompressive craniectomy after "malignant" stroke may result in improved survival and functional outcome in patients under the age of 55, compared to conservative management alone.
The procedure is recommended especially for young patients in whom ICP is not controllable by other methods. Age of greater than 50 years is associated with a poorer outcome after the surgery.
Complications
Infections such as meningitisMeningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
or brain abscess
Brain abscess
Brain abscess is an abscess caused by inflammation and collection of infected material, coming from local or remote infectious sources, within the brain tissue...
can occur after decompressive craniectomy.
Children
In severely head injured children, a study has shown that decompressive craniectomy resulted in good recovery in all children in the study, suggesting the procedure has an advantage over non-surgical treatment in children. In one of the largest studies on pediatric patients, Jagannathan et al. found a net 65% favorable outcomes rate in pediatric patients for accidental trauma after craniectomy when followed for more than five years. Only three patients were dependent on caregivers.This is the only prospective randomised controlled study to date to support the potential benefit of decompressive craniectomy following traumatic brain injury.
Follow-up treatment
After a craniectomy, the risk of brain injury is increased, particularly after the patient heals and becomes mobile again. Therefore, special measures must be taken to protect the brain, such as a helmet or a temporary implant in the skull.When the patient has healed sufficiently, the opening in the skull is usually closed with a cranioplasty
Cranioplasty
Cranioplasty is a surgical repair of a defect or deformity of a skull. Cranioplasty is almost as ancient as trepanation. There is evidence that Incan surgeons were performing cranioplasty using precious metals and gourds...
. If possible, the original skull fragment is preserved after the craniectomy in anticipation of the cranioplasty.