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CASE REPORTS
AWAKE CRANIOTOMY
ROCHANA G BAKHSHI*, JYOTI D BORKAR**
An awake craniotomy is an amazing procedure, which seems almost unbelievable at first thought. The procedure is very similar to a standard craniotomy, but with one difference - the patient is fully awake during the middle of the procedure. In surgery, once the brain is accessible by the surgeon, the general anaesthetic chemical level is dropped, and the patient returns to consciousness, able to talk and move as normal, although head movement is of course restricted because of a head clamp. The awake part of the procedure lasts typically between 10 and 40 minutes. There is no pain while being awake, local anaesthetics make sure of this, and there are no pain receptors actually in the brain.
INTRODUCTION
A great concern during any surgery on the brain is how we can best preserve the person’s level of functioning. This is especially important when an abnormality such as a brain tumour lies close to an area of the brain that controls vital functions such as speech , movement etc. Awake craniotomy literally means a procedure where patient is awake during critical portions of the surgery so that his vital functions such as speech and movement can be monitored continuously.1 Patient cooperation is critical for the success of the procedure.Along with this functional mapping may be done which ensures that the outer edges of the operation will not overlap areas of the brain that control speech and movement.
Following is the description of an awake craniotomy that we conducted in our institution . The awake craniotomy was recommended as the tumour was close to specialized areas of the brain that control movement or speech. The purpose of this surgery was to have an awake patient at the time of resection of the tumour , which would reduce the operative risk of damaging the vital areas and also achieving maximum tumour resection by simultaneous probing of the surrounding eloquent regions e.g speech, senses and movement, thus identifying them and avoiding them.
CASE REPORT
A 25 year old male patient came with history of off and on episodes of convulsions, generalised tonic clonic, since the previous 3 to 4 months.
Patient also complained of occasional episodes of headache and diminished vision. There was no other positive medical or surgical history.
The C.T scan brain revealed a left fronto parietal hyperdense lesion diagnosed as an oligodendroglioma.
General examination of the patient was normal .
Preoperative investigations were as follows:
Hb : 13 gm% ; CBC:7000/ cu.mm DC: N52 L46 E02 M0
BUN: 11 mg%; Electrolytes : Na - 142 Meq/L, K - 3.5
Meq/L Xray chest and ECG were within normal limits .
Patient was on tablet Eptoin 100 mg three times a day since 3 months .
Patient was posted for awake craniotomy.
He was explained that initially for 1-2 hours he would be asleep and completely unaware. Later he would be woken up during a part of the procedure and his first sign of awareness would be that of hearing someone calling out his name. He was assured that there would be no pain and he should not panic or be scared.The reason for waking him up was explained. He was told that his speech or movement of any limb would be tested. He would have to report any weakness or any other unusual sensation in the body without movement of his head on the headrest. He would be kept awake till tumour tissue is resected. The time required to keep him awake would be approximately 10 to 30 minutes depending on tumour size.
After resection of the tumour patient would be anaesthetized for the rest of the surgery.
On the day of surgery written informed consent for awake craniotomy was taken and starvation was confirmed. Patient received his morning dose of Eptoin with sips of water.
He was premedicated with inj. Atropine 0.6 mg I.M half an hour prior to surgery.
I.V line was secured with 18 gauge venflon on the left hand. Patient was given inj Pentazocine 0.3 mg/kg and inj Midazolam 0.03 mg/kg I.V. patient was also given injection Ranitidine 50 mg I.V , injection Ondansetron 4 mg I.V and injection Dexamethasone 8 mg.
Hudson’s mask with provision for end tidal CO2 monitoring was attached.Monitors used were pulse oximeter and cardioscope
throughout the procedure.
Induction was done with 2 mg/kg propofol. After induction second I.V line was secured on the left leg and propofol infusion was started at the rate of 4 mg/kg/hour. After opening duramater surgeons informed us to awaken the patient. The infusion was discontinued and within 5 minutes patient responded to his name being called out. He was comfortable with no pain at the surgical site nor any difficulty in breathing. Patient was kept awake till resection was complete and during this time he was asked afew questions to test intactness of his speech, motor and sensory power of his upper and lower limbs and memory .
At the time of dura closure propofol infusion was restarted and continued till the end of the procedure. Patient was awake within 7 to 8 minutes.
Postoperatively vital parameters were recorded and were same as preop and intraop values (pulse 80 - 90 / min and B.P 110 - 120 mm Hg systolic and diastolic 70 - 80 mm Hg ). Patient was observed for half an hour postop and then shifted to recovery room on Oxygen by mask.
Surgery lasted for 2 hours and blood loss was about 150 ml.
DISCUSSION
The first and foremost thing about an awake craniotomy is that the patient is not awake the whole time but is asleep for first 1 to 2 hours and again at the end of the surgery. Certain patient selection criteria have been described such as:
1) Chronic refractory epilepsy
2) Motivated patient for general anaesthesia should this become necessary.
3) Uncomplicated airway.
4) Patient assessment with respect to psychological profile.Preoperative preparation of the patient includes a detailed verbal description of the procedure with a question and answer session. Videotape sessions including conduct of anaesthesia and surgery may be shown to patients preoperatively. Most importantly patient has to be explained that the awake part of the procedure will be painless. At the most he may feel sensation of pressure or occasional twinge during cold saline irrigation or an aching type of sensation. Regional scalp block may be given by blocking the greater occipital nerve 2 to 4 cm lateral to incision, just below superior nuchal line, lesser occipital nerve and greater auricular nerve 1.5 cm posterior to ear at the level of the tragus over 2 cm and auriculotemporal nerve 1cm anterior to tragus above the zygoma direct posteriorly then anteriorly. Alternatively local infiltration in and around the line of incision may be done. Newer anaesthetic agents such as Propofol, Alfentanil, Sufentanil, Fentanyl etc have made it possible for the patient to be awake during crucial parts of the operation. The newer synthetic opiods have a rapid onset are potent, and exhibit cardiovascular stability. They can be used in form of bolus as well as infusion,We used propofol infusion.2 The initial bolus dose required was 1 to 2 mg/kg followed by infusion rate varying between 4 and 7 mg/kg/hour. This was preceded by injection Pentazocine 0.3 mg/kg and injection Midazolam 0.03 to 0.05 mg/kg. Droperidol is a good neurolept analgesic having sedative and antiemetic properties.Onset of action is 6-8 minutes and duration may last from 6 to 12 hours.3
Propofol infusion continued from skin incision to bone flap, after dural exposure the infusion was reduced and after dural incision the infusion was completely stopped.2 The patient awakened 5 to10 mins after infusion was stopped. Patient was explained preoperatively that after being awake first awareness would be that of someone calling out his name followed by questions to test speech, movements of upper and lower limbs and intactness of memory. Accordingly our patient cooperated and did not develop any deficit. After tumour resection was complete and haemostasis achieved propofol infusion was restarted and continued till the end of surgery. The patient awoke within 6 to 8 minutes after discontinuing propofol. Our patient received anti emetic prophylaxis preoperatively and did not have vomiting.1
Patient was monitored for pulse rate, blood pressure, ECG, Oxygen saturation and end tidal carbon dioxide. Chest movement and respiratory rate were also observed throughout the procedure.
ACKNOWLEDGEMENT
To Dean and Dr. LD Naik Head Department of
Anaesthesiology, Seth GS Medical College and KEM Hospital,
Mumbai 400012
REFERENCES
1. Craen RA, Herrick IA. Seizure surgery: General considerations and specific problems associated with awake craniotomy. Anesthesiology Clinics of North America 1997; 15 (3) : 655-672.
2. Herrick IA, Craen RA, Gelb AW, et al. Propofol sedation during Awake Craniotomy for seizures: Electrocardiographic and Epileptogenic effects.Anesthesia and Analgesia 1997; 84 : 1280-84.
3. Propofol sedation during Awake Craniotomy for seizures:Patient Controlled Administration Versus Neurolept Analgesia . Anaesthesia and Analgesia 84 : 1285-91.
FOOD FOR THOUGHT
‘In populations with low average intake of dietary fibre, an approximate doubling of total fibre
intake from foods could reduce the risk of colorectal cancer by 40%’
Previous studies have shown no protective effect of dietary fibre on colonic adenomas and colorectal cancer. However, two papers in this week’s Lancet have challenged this conclusion. The European investigation into Cancer and Nutrition (EPIC) prospectively assessed the effect of dietary-fibre intake on incidence of colon cancer in 519 978 people in Europe. The Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Project team (PCLO) compared intake of dietary fibre between 3591 people who had at least one histologically-verified adenoma in the distal large bowel and 33 971 people who had no polyps. The results of both studies showed that intake of dietary fibre reduces the risk of colorectal cancer and colonic adenoma. In a Commentary, Lynnette Ferguson and Philip Harris say “eating a diet rich in plant foods, in the form of fruit, vegetables, and wholegrain cereals, probably remains the best option for reducing the risk of colon cancer, and for more general health protection”.
BMJ, 2003; 1487, 1491, 1496
