In most brain tumours radical removal of the tumour offers the best possibility of cure or long term survival. The surgical approach, however, can be very difficult in some cases. Other tumours may be easier to approach, but may be difficult to operate on due to their location: they may be in, or close to, brain eloquent areas, which control speech, comprehension, sensitivity and movement.
What can we do then? In selected cases, surgical resection with the patient awake (awake craniotomy) is an alternative. This is, however, only recommended for procedures which have such a high risk of neurological sequelae that only 3 options will be left: the risk to be accepted (craniotomy), a partial resection to be performed, or an awake craniotomy to be chosen to assess better the neurological status of the patient during the surgical intervention.
This is, however, not recommended for procedures which can be carried out under general anaesthesia and do not have an especially high risk of neurological sequelae.
WHAT IS A LESION IN A BRAIN ELOQUENT AREA?
Some brain lesions are located in areas which rule functions so important as sensitivity, movement, speech and comprehension. These are the so-called brain eloquent areas.
A lesion in one of these areas is usually already causing neurological symptoms at the time of diagnosis: speech deficit, difficulties for oral comprehension, arm and/or leg paralysis, etc.
And the problem can be even worse when the optimal treatment is surgery. There is an important risk of neurological sequelae, which can appear in up to 80-95% of patients operated under general anaesthesia.
So the question is: if the best treatment is surgery, what can be done to avoid or at least reduce any neurological postoperative sequelae?
Brain eloquent areas
WHAT ARE THE POSSIBILITIES OF SURGICAL TREATMENT?
When a lesion that needs to be treated by surgery is known to be localised in a brain eloquent area, two attitudes can be taken.
Glioma in the motor area
However, a craniotomy has a high risk of neurological sequelae. The surgeon may perform a partial resection under general anaesthesia to avoid taking this risk, trying to prevent neurological sequelae by removing only what is far from the brain eloquent areas, but when a portion of the lesion is left behind, even if small, the risk of recurrence increases dramatically. If total resection is preferred, there will be an intra-operative identification of the lesion and its anatomical relationships, in addition to an intra-operative neurological control of the brain functions at risk. The best way to achieve this is the awake craniotomy.
MAY NEW TECHNOLOGIES ENABLE ME NOT TO BE AWAKE DURING THE SURGERY?
Current imaging techniques, like spiral CT scan, MRI, angioresonance, and PET scans, give us a very accurate picture of the brain lesions. New optic technologies such as the surgical microscope with built-in neuronavigation device assemble all the pictures to create 3D images, making it easier to reach the lesion through the best route. And in addition, we also have the possibility of carrying out the procedure inside the open MRI premises, such that a neuroimage of the brain can be obtained at any moment during the surgery and confirm the extent of the removal.
Nevertheless, the challenge of preserving the brain functions at risk remains. The best neurological test is clinical evaluation, for which the patient has to be awake.
We can monitor sensory-motor functions with intra-operative evoked potentials, but to identify and evaluate brain areas related to speech and comprehension (Broca and Wernicke areas) the best option is performing the surgery with the patient awake. This kind of surgery requires a very qualified team and the cooperation of the patient, but has a significantly lower risk of neurological sequelae.
WHAT ADVANTAGES DOES THE AWAKE CRANIOTOMY OFFER AS OPPOSED TO GENERAL ANAESTHESIA?
General anaesthesia is preferred by both the neurosurgeon and the neuroanaesthesiologist because it allows a better control of the possible intra-operative complications, such as bleeding, epileptic seizures, cough, reduction of brain oxygenation, etc. Still, when the risk of neurological sequelae is high, either this functional risk is accepted or some of the tumour will have to be left in place, increasing the risk of recurrence.
When the procedure is performed in awake conditions, under local anaesthesia and sedation, we can control intra-operatively the functions at risk through a continuous neurological clinical evaluation. This means we can obtain greater resections with lower risk of neurological deficits.
The anaesthesiologist, who must be trained in neuroanaesthesia and especially skilled in this sort of surgery, will be next to the patient during the whole surgery, controlling their vital signs and continuously monitoring the functions at risk.
WHAT WILL HAPPEN DURING A SURGICAL PROCEDURE?
The day before surgery the patient will have a pre-anaesthetic interview with the neuroanaesthesiologist, who will get information about the medical and surgical history, as well as physical and neurological status. The neuroanaesthesiologist will also speak to the patient about the procedure in detail and about the need for their cooperation.
The importance of the interview lies in that surgeon, neuroanaesthesiologist and patient will constitute a team on the day of the surgery. Patient cooperation is as essential as coordination between surgeon and neuroanaesthesiologist, and this is why they must know in advance how the events will proceed and that their cooperation will be required.
Once in the operating theatre the patient will have some vascular access lines inserted (arterial, peripheral vein and central vein –arm or neck– lines) and a urinary indwelling catheter. Head nerves will be anaesthetised with local anaesthesia. During almost all this time the patient will be under light sedation for optimal comfort. Also to optimise comfort, surgical drapes will be placed so that patient and neuroanaesthesiologist will be permanently in both visual and verbal contact.
The most important step is the proper lesion resection. During that period of time the patient will be kept completely awake to be continuously neurologically monitored. He will be asked to open or close their hands, bend their knees, count from 1 to 10, and to follow some other simple orders.
When the resection of the lesion is finished the patient is sedated again for comfort until the end of surgery.
Patient undergoing awake craniotomy
Once the surgery is finished, the patient is transferred to the Intensive Care Unit for observation during the following 24 hours, as if the procedure would have been performed under general anaesthesia. The objective of this measure is the close surveillance of vital and neurological signs during the early postoperative hours.
The day after surgery the patient will be transferred to the Ward, where they will stay for the next 3-5 days.
The objective of the awake craniotomy is to maintain the neurological status as that previous to the operation, and this is what happens in most cases.
WHAT ARE THE POSSIBLE COMPLICATIONS?
It is uncommon to have intra-operative complications, which may be the same as in any craniotomy. The additional risk lies in that if the patient needs to be intubated, it will have to be done in a very fast way, and an emergency intubation always has higher risk than a regular one.
WHAT ARE THE RESULTS?
In our experience the results are very advantageous. In our series more than 80% patients have no additional neurological sequelae. Around 15% have some neurological deficit which recovers in about one month time, and only a 5% suffer long lasting neurological deficits.
Awake craniotomy under local anaesthesia and sedation is an option to be considered for lesions in brain eloquent areas.