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Phase 3: Asleep

Phase three of an awake brain surgery is explained in the following video by our anesthesiologist Professor Tony Absalom.
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When the mapping is finished, phase three of the operation begins. For the patient, the hardest work is over. At this stage, he is usually exhausted. If you lie immobile for more than 20 minutes or so, this can cause your muscles and joints to ache. And if you lie still for very long, like after a good night out, your muscles and joints can become very painful. At this stage, our patient will have been already lying immobile for several hours. But the more pain and tension he experiences, the sooner he will be exhausted.
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Add to this discomfort, the mental effort required to lie completely still for so many hours– [DUTCH:] To be honest I sort of have a headache. I think you are doing great, Tom. OK. The effort of concentrating on not moving or coughing, and most of all, the effort of cooperating with the testing of speech and other cognitive functions. So unless the patient is really anxious or restless, we only administer a very low dose of the anaesthetic agent at this phase sufficient to relax them to help them sleep. The anaesthetist must judge the dose very carefully. If too much is administered, the patient may stop breathing or may obstruct their airway, or both.
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Usually, anaesthetists can very easily deal with these events, such as airway obstruction or stopping breathing by applying so-called bag and mask ventilation. This involves using a special bag and mask to force oxygen into the lungs of the patient. However, patients are usually lying on their back. When a patient is lying on his side, such as this one, his head and neck is immobile. And this technique is not usually possible. So when a patient is in this position and stops breathing, his oxygen levels can fall to dangerously low levels with potentially fatal consequences. For the surgeon, on the other hand, there is plenty of work left to do.
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During phase two, he will have identified the areas that are safe to excise. And in phase three, now, he will start to do this, using a special instrument with three channels. One channel sends sound waves onto the tissues. And these pulverise the tumour tissue. The second channel sprays the area with fluid. And the third provides a vacuum to remove the fluid and pulverised tumour tissue. All the time the surgeon must meticulously seal all blood vessels to prevent and control bleeding. Unless this so-called haemostasis is performed perfectly, there is a risk of bleeding after the surgery.
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Bleeding inside the cranial cavity– once it is closed and sealed– can be disastrous because it’s a closed space and any bleeding will cause a significant increase in the pressure in the cavity, compressing and injuring vital structures. When as much of the tumour has been resected as is safe and possible, and the haemostasis is perfect, the surgeon must then suture closed the dura– this is a membrane around the brain– replace and secure the piece of skull that he had removed earlier, and then carefully suture the scalp closed. The scalp is very vascular, and so here too, careful haemostasis is important.
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Sometimes, during this final phase, the local anaesthetic is wearing off, requiring infiltration of more local anaesthetic into the scalp or even an intravenous infusion of strong pain killers. But this again brings potential dangers because these drugs can affect the breathing. Once the scalp has been sutured closed, the Mayfield head holder is removed and any infusions of sedative drugs are stopped. A tight bandage is wound around the scalp to help prevent any bleeding from the wounds. After stopping the infusions, the patient usually wakes up very quickly.
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Sometimes, if the patient has slept well during the final third phase, he will wake up remarkably bright and alert, and everyone will be congratulating him for doing so well for being able to lie still and put up with this very unpleasant operation. It is only after the Mayfield head holder has been removed that the patient can be safely allowed to move. Indeed, when the head is held immobile by that Mayfield holder, which is attached to the operating table, sudden gross movements of the body can cause injuries to the neck, including fractures of the cervical vertebrae.
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As things draw to a close, the team will be starting to relax and to enjoy the satisfaction that comes from knowing that they have done their job well and that they have helped the patient through a long and difficult journey.
Now that the language testing part is completed, the patient is sedated again. What happens next – the further resection and closing up – is explained in the following video by our anesthesiologist Professor Tony Absalom.

Warning – viewer discretion is advised. This video contains moving images of open brain surgery. This may be upsetting to some people.

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Language Testing During Awake Brain Surgery

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