The impact of a brain tumour is more accurately determined when patients stay awake during the surgery, writes Kasmiah Mustapha
IN one episode of Grey’s Anatomy, a musician has a tremor in his right hand caused by multiple sclerosis. As he is about to go on tour, the surgeon has to operate on his brain to stop the tremor.
The musician is not only awake during surgery but he also plays the guitar as this allows doctors to locate the part of the brain causing the tremor, without affecting his motor function.
Awake brain surgery is not an exaggeration on a television show as it was introduced more than 50 years ago to treat epilepsy. With the evolution of technology, it is now the common method to treat patients with brain tumour and other neurological conditions.
In Malaysia, it was introduced eight years ago.
According to John Hopkins Medicine, the procedure, also known as intraoperative brain mapping, enables neurosurgeons to remove tumours that would otherwise be inoperable because they are too close to the areas of the brain that control vision, language and motor movements. Normal surgery may result in significant loss of these functions.
Beacon Hospital consultant neurosurgeon Dr Lee Foo Chiang says based on the magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI), surgeons can detect if the tumour has encroached the areas of the brain that control these movements.
“However, the accuracy of the tumour’s impact is limited unless we do awake brain surgery. Certain functions of the brain can only be determined from the patient’s feedback. In awake brain surgery, the risks of complications to these movements is minimised,” he says.
While the process is similar to normal surgery, there are additional steps that surgeons need to be prepared for.
In his experience, it is important to have a trial run with the anaesthetist before the surgery to make sure the laryngeal mask that keeps the airway open can be reintubated in case of emergency during the procedure.
“It is important to have a trial run because the success of the surgery depends on the ability to secure the airway as failure to do it can lead to the patient dying,” he says.
PERFORM SIMPLE TASKS
Another step is to inject the patient with anti-epileptic medication as he may suffer from seizures during the surgery due to the electrical charges to the brain. Surgeons will also prepare sterile cold saline in the operating theater to stop the fits.
“The surgery involves three phases. First, the patient is put under anaesthesia as surgeon removes part of the skull. Soon after, the anaesthesia is withdrawn, and the patient slowly wakes up. Then, local anaesthesia is injected on the brain’s membrane before the incision is made.
“During the surgery, surgeon will probe the area around the tumour with mild electrical current while asking the patient to move his hands and legs. The patient is also asked to identify objects, words or pictures by the speech therapist.”
He says if the patient fails to perform the tasks, such as forgetting words or the patient cannot move his hands, the surgeon knows which area he has to avoid. Throughout the surgery, the patient continues to be engaged in a conversation as the surgeon monitors the brain function. It is also to help the patient stay calm. When the tumour is removed, the patient is put back to sleep and the surgery is completed.
He says it takes about one hour to remove the tumour, which is faster than normal surgery. There is also a greater percentage of tumour removal with less side effects.
However, he says, the option for awake brain surgery depends on the tumour location and patient’s psychological condition.
“If the tumour does not touch the key functions of the brain, it can be removed in normal surgery. Some patients find the idea of being awake during surgery scary. It can be dangerous if patients are stressed. If a patient changes his mind during surgery, we can put them back on anaesthesia, but problems can happen,” says Dr Lee.
“While we know the brain anatomy, we cannot determine how the tumour affects the patient’s functions. In normal surgery, a surgeon operates based on a scan.
“But every human has unique mapping of their brain function. When surgeons need to cut near these vital areas, they will suggest awake brain surgery because the impact is different for each patient. That is why patients who opt for normal surgery need to be made aware of the risks they could be facing.”