Surgical reconstruction following head injury

25 June 2012

Mr Tony Belli discussed some of the challenges and opportunities presented in the field of surgical reconstruction following head injury.

Scale of the problem

Mr Belli outlined how trauma in general and head trauma in particular are serious problems for the NHS.

Trauma is the leading cause of death for people under the age of 45 in the western world, and accounts for 700,000 visits to emergency departments in England and Wales every year.

Head injury accounts for around a third of these traumas, but for around half of deaths from trauma.

The number of trauma patients is increasing around the world for a number of reasons, including greater road usage in the developing world and an ageing population.

The WHO estimates that by 2020 trauma will be the leading cause of death.

Preserve or reconstruct?

The issue of whether to carry out a surgical procedure is complicated by the nature of head trauma.

As well as the primary injury or injuries, caused over a relatively short period of time and often irreversible, clinicians must consider secondary injury and secondary insults.

Secondary injury can be a delayed process, taking place over hours, days or even months after the primary injury. These injuries are often closely tied in to the brain’s own biochemistry and immune response.

Secondary insult can include seizures and infections, as well as damage caused during patient transport, scanning or surgery.

Role of the surgeon

Surgical intervention to treat head injury is not a traditional neurosurgical specialty, but has become increasingly important

Among the procedures now frequently carried out in dealing with such injuries are:

Haematoma evacuation
This is a procedure in which a blood clot is removed from the brain. This can be to restore or improve blood flow which has been blocked by the clot (haematoma), or to reduce pressure on the brain.

Invasive neuromonitoring
Surgeons can implant sensors in the brain to provide detailed data about the patient’s condition as they recover from their injury.

Decompressive craniectomy
This is a procedure in which part of the skull is removed to allow a swelling brain room to expand without being squeezed. It can be used for patients who have suffered either traumatic brain injury or stroke, but the value of its use is still being debated.

Cerebrospinal fluid (CSF) diversion
This procedure is used to drain CSF from the brain. Draining the fluid can help to reduce the pressure within the brain, and is usually achieved by inserting a tube called a shunt into the brain and threading this to another part of the body, such as the abdomen.

Deep brain stimulation (DBS)
DBS is a technique in which a small device is implanted in the brain to provide precise electrical stimulation. It has been used for several years for disorders such as Parkinson’s disease, dystonia, chronic pain and depression. Some trials have been undertaken to test its effectiveness on patients who have suffered traumatic brain injury.

Missile injuries

Head injuries caused by missiles provide a unique set of challenges, many of which have been faced by surgeons at QEHB when treating British military personnel.

He described one example in which a large missile fragment caused significant to the front of the patient’s skull and remained in place until removed by surgeons.

Decompressive craniectomy

Surgery to decompress the brain after such injuries was pioneered by Swiss surgeon Theodor Kocher in 1901. It developed from the more primitive procedure of trepanning, in which a hole is drilled in the skull to reduce pressure. Examples of trepanation has been found on skulls up to 6500 years old.

The modern approach is based on an improved understanding of the structure of the skull and brain, sophisticated cutting tools and antibiotics.

Mr Belli outlined its apparent value in stopping the “vicious circle” of increased pressure within the skull after traumatic brain injuries.

The procedure can provide up to an extra 92.6cm3 space for the brain, a potentially life saving method of reducing pressure.

It is not just used for head injuries, and is also used to treat stroke.

Decompressive craniectomy trials

Mr Belli described three major trials underway around the world which have either reported or are still studying different applications of decompressive craniectomy.

DECRA

This eight-year Australasian trial compared decompressive craniectomy with best medical therapy for patients who had suffered a non-penetrating head injury.

Patients were recruited based on their intracranial blood pressure during the first 72 hours after injury, and the results suggested poorer overall outcomes for the surgical intervention compared with medical treatment.

RESCUE-ICP

This ongoing multi-national trial is looking at the use of decompressive craniectomy for treating patients who have uncontrolled elevation of intracranial pressure.

It differs from DECRA in a number of ways:

  • The patient’s intracranial pressure must be higher, thereby focusing the study on patients whose condition is more severe.
  • Surgery can take place at any time, compared with the 72 hours used in DECRA.
  • RESCUE-ICP also has a longer follow-up period.

Led by surgeons at the University of Cambridge Neurosurgery Unit, the trial is recruiting in 19 countries, including China, Peru, Canada, the United States, Brazil, Italy and Saudi Arabia.

Mr Belli helped to recruit a number of patients to the study while working at Southampton University Hospital and is now looking to open recruitment at QEHB.

RESCUE-ASDH

This trial looks at the relative merits of two different forms of surgical intervention to reduce intracranial pressure in patients who had suffered an acute subdural haematoma (ASDH). An ASDH is a bleed between two layers of tissue which surround the brain, the dura mater and the arachnoid mater.

The trial aims to recruit 600 patients and will compare the outcomes for those patients who undergo a craniectomy with those who undergo a craniotomy.

A craniotomy is a procedure in which part of the skull is removed to access the brain, after which the skull segment is replaced. In a craniectomy the bone segment is not replaced; it can be discarded permanently or placed in an different part of the body temporarily for replacement later.

Risks of decompressive craniectomy

Mr Belli explained that intrancranial pressure (ICP) is a valuable marker for clinicians treating patients with head trauma. However, many other important metabolic and vascular indicators of brain health are not linked to ICP, so improvement in ICP might coincide with positive outcomes for the patient.

This means that addressing increased ICP using decompressive craniectomy carries risks.

These include:

  • epilepsy (a broad set of brain conditions characterised by seizures)
  • herniation (where a part of the brain shifts across structures within the skull)
  • hydrocephalus (excess cerebrospinal fluid in the cavities of the brain)
  • cerebrospinal fluid leakage
  • infection
  • blossoming of contusions (the leakage of blood from new or existing ruptures in blood vessels after the pressure on them is reduced)

The risks of these complications developing are related to the severity of the original head trauma and related age.