Awake Craniotomy is a procedure where the patient is kept awake during brain surgery to reduce risk of post-operative disabilities.
Mr. R. was a successful manager at a bank and was looking forward to a promotion and transfer to a city. He was happily married and his sons were finishing their education. Life was good. One day his wife noticed that he was confusing words and sometimes using the wrong words. Investigations showed a tumour in the left side of the brain, which controlled his speech. He needed surgery but the big question was: could the tumour be removed without the patient’s speech being affected?
One of the major problems in brain surgery is to ensure that the patient does not suffer any new disabilities after the procedure. The surgeon has to be aggressive and remove the tumour completely while ensuring that the patient does not suffer a disability that will affect quality of life. Advances in technology and availability of new anaesthetic drugs have made neurosurgery on the brain safe, with the complication rate down to less than three per cent in most cases. But when the tumour lies in a part of the brain that is responsible for speech or for movement of limbs, it is a challenge.
Technological advances in radiology help overcome this challenge. Functional MRI (or fMRI) shows the exact relationship between the tumour and the important ‘functional’ areas of the brain. Diffusion Tensor Imaging (DTI), also called Tractography, helps the surgeon visualise the nerve fibres and connections from different parts of the brain and their displacement by the tumour. However, these images give surgeons only static information. What is needed is ‘dynamic’ information, as the surgeon operates to tell him/her where the critical areas are and, more importantly, when to stop operating.
“Awake Craniotomy” is a technique in which the patient is kept awake, is able to obey simple commands and talk during the surgery. Critical to this technique is the fact that the brain itself does not feel any pain. It is the scalp, the bone and the coverings of the brain that have the sensation. In order to perform “Awake Craniotomy”, it is essential to have a co-operative and well informed patient, as well as co-ordinated team work between the anaesthesiologists and the surgeons. Patients need to be counselled before surgery and assessed on whether they will be co-operative, as they will need to lie still and not move their head for the duration of the procedure. They also have to understand that they will be kept awake during their surgery. It is essential that the doctor explains that they will hear a lot of different sounds from the various equipment in the operation theatre, as this might raise anxiety levels.
During the procedure itself, providing the right balance of analgesia (pain relief) and sedation is the greatest challenge for the anaesthesiologists. Patients are given different levels of sedation at different stages to keep them comfortable. Brain surgery is performed using an operating microscope that allows the surgeon to visualise the normal and abnormal tissues with clarity making surgery precise to the millimetre.
The critical part is removing the peripheral part of the tumour. This is when there is a maximal chance of damage to the normal functioning brain. During this time if there is any decrease in function of the hand or leg or if there is any difficulty in speech, the surgeon immediately stops tumour removal knowing that it is a danger zone. A change in surgical technique may also be used. In this way, tumours in critical areas of the brain can be removed without giving the patient a major neurological disability.
This technique is used specifically for patients like Mr. R. with lesions and tumours in and around “eloquent” areas of the brain that control speech and limb movements. It requires great skill and expertise on the part of the anaesthesiology and the surgical teams, using technology to perform difficult and challenging surgical procedures and giving the patient a good quality of life.
How it works
Patients need to be counselled before surgery and assessed on whether they will be co-operative.
First the entire scalp is anesthetised by a “scalp block”, rendering the skin of the head completely numb and pain free.
Different monitoring devices are connected to the patient to ensure safe surgery. As the depth of sedation is crucial, the patient’s brain activity needs to be monitored.
The patient is put to sleep with a higher dose of sedatives to allow the surgeons to make an opening in the scalp and skull bone.
Once surgery on brain starts, the dose is titrated to awaken the patient and keep him/her awake during the next phase.
As surgery proceeds, the surgeon and anaesthesiologist talk to the patient and assess speech and movement and function of limbs. If there is any decrease in function of limbs or if difficulty in speech, the surgeon knows this is a danger zone and stops immediately.
Once the tumour is removed, sedation is increased so that the wound can be closed.
Post-surgery the patient is awake almost immediately and shifted to an intensive care ward.