Awake craniotomy-A case report

Dr K.Gunasekaran1 Dr D.Ram kumar2

1 Associate professor, Department of Anaesthesiology, Saveetha medical college,

Thandalam, Kancheepuram district.

2 Post graduate, Department of Anaesthesiology, Saveetha medical college,

Thandalam, Kancheepuram district

ABSTRACT:

Awake craniotomy for eloquent area surgery can be managed with different

anaesthetic techniques ranging from local anaesthetic with or without intravenous

sedation to intermittent general anaesthesia with or without instrumentation of the

airway, known as awake---awake---awake, asleep---awake---awake and asleep---

awake---asleep craniotomy. We present a case of 34 year old male who was

diagnosed to have Right frontal low grade glioma. Tumor resection was planned

and decided to perform craniotomy with the patient being awake during the

procedure, to allow intraoperative cortical mapping in order to preserve the

language and motor functions.

This case was managed with nerve blocks and conscious sedation without

airway instrumentation. We reviewed the literature for the patient management

during awake craniotomy

KEY WORDS:

Awake craniotomy, Nerve block, Conscious sedation, dexmedetomidine

INTRODUCTION:

Brain surgery, with the patient being awake, has been practised long before

the introduction of anaesthesia. It was W. Penfield in 1920s, who did craniotomy

under conscious sedation, for location of epileptic foci and surgical management (1,

4). There is also a report dating from 1929, about a awake craniotomy performed

under local anaesthesia, for resection of a large brain tumor by Dr Harvey

Williams Cushing (1, 4). In 1950, H. Olivecrona performed awake craniotomy by

combining nerve block and conscious sedation for the resection of brain tumors. (1,

4)

Awake craniotomy for tumor resection presents many challenges for the

neurosurgeon and anesthetist. However, it is widely used for the resection of

lesions close to or within eloquent areas. (5, 6)

Awake craniotomy was introduced for surgical treatment of epilepsy, and

has subsequently been used in patients with supratentorial tumors, arterio-venous

malformations, deep brain stimulation, and mycotic aneurysms near critical regions

of brain.

Awake craniotomy allows for intra operative monitoring of speech, motor,

and sensory testing, with the goal of maximum tumor resection while preserving

normal tissue. Hence it avoids postoperative neurological morbidity and facilitates

early discharge from the hospital.

The goal of anesthetic management in awake craniotomy is to provide

sedation, analgesia, respiratory and hemodynamic control, in addition to an awake

and responsive patient for neurological testing intraoperatively (5, 6, 7).

CASE REPORT:

A 34-year-old, 70-kg male was scheduled for resection of Right frontal

glioma. Awake craniotomy under an awake---awake---awake anaesthetic technique

with cortical mapping was planned. The patient was diagnosed 8 months earlier

after sudden onset of seizures. Patient was on tab phenytoin 200mg once daily and

tab levetracetam 500mg thrice daily for past 8months. Laboratory results were

reviewed and were within normal limits. Preoperative vital signs were heart rate of

78/min and blood pressure of 120/80 mm Hg. Patient was kept nil by mouth for 8

hours prior to surgery. Informed written consent was obtained after explaining the

procedure. The premedication regime, Tab. Metoclopramide 10mg, Tab.

Alprazolam 0.5mg and Tab. Ranitidine 150mg and Inj. levetracetam 500mg IV,

was administered 2hours before the surgery. Once the patient was shifted to

Operating room, Standard monitors were placed, including electrocardiography

(ECG), non invasive blood pressure monitoring, pulse oximetry, and capnography.

Patient was informed about the procedure and he was advised to raise his hand if in

case he experiences pain, discomfort or an aura for seizures. A wide bore 16G

intravenous cannula was inserted in left cephalic vein and RL was started. The

patient was premedicated with Inj. Glycopyrrolate 0.2mg IV, Inj. Midazolam 2mg

IV and oxygen through Hudson mask @ 6L/min. The loading dose of inj.

Dexmedetomedine 80microgram bolus was administered over a period of 30mins

by using syringe pump. Nerve blocks were performed on the right side of the scalp

under the guidance of ultra sound with 3- 5ml of 0.25% bupivacaine for each

nerve. The nerves blocked were supraorbital nerve, supratrochlear nerve,

zygomaticotemporal nerve, auriculotemporal nerve, lesser occipital nerve, and

greater occipital nerve. Dexmedetomidine infusion was started at

0.3microgram/kg/hr after the bolus. After confirming the effectiveness of the

blockade, the patient was placed in supine position and head was turned to the left.

After checking the surgical incision site for sensory block, Neuro surgeon started

the surgery. Patient was comfortable and obeyed commands during surgery. Before

incision, heart rate was around 72/min and blood pressure was 110/86mmHg. After

skin incision and throughout craniotomy, blood pressure remained stable, with a

systolic range of 96 to108mmHg over a diastolic range of 60 to 80 mmHg; heart

rate was around 70 to 80/min. During the resection of the tumor, patient

experienced an aura with uprolling of eye ball. This was indicated by the patient

himself by raising his left upper limb.

Fig 1: Showing anaesthetist performing nerve blocks under

ultrasound guidance.

Boluses of inj. propofol 40mg and inj. phenytoin 100mg were given. After

10mins, patient became normal and alert. Resection of the tumor was done

successfully in one hour. Monitored anaesthesia care was given by communicating

with the patient by checking the speech, motor, and sensory testing throughout the

procedure. Cranium was closed and skin was sutured with patient remaining

comfortable, alert and oriented throughout the surgery. He was able to move all

extremities. There was no airway obstruction, haemodynamic instability or

seizures. The patient remembered the intra operative events and stated he was

comfortable throughout the operation. The postoperative period was uneventful

and patient was discharged home successfully without any morbidity.

FIG 2&3 showing patient obeying commands by protruding tongue and

raising the hand during the surgical procedure.

DISCUSSION:

All anaesthetic techniques for managing awake craniotomy are designed

to allow resection and/or neurological functional mapping with greater protection

of areas of the brain that control both motor function and speech (5,12) The

techniques published in the literature vary from local anaesthetic with or without

intravenous sedation to intermittent general anaesthesia with or without

instrumentation of the airway, known as awake---awake---awake, asleep---

awake---awake and asleep---awake---asleep craniotomy. In our case, we opted for

conscious sedation with nerve blocks (awake---awake---awake technique) (5, 6).

The challenges posed for the anaesthetist are during craniotomy and

resection. During craniotomy and brain exposure, the challenges are to provide

sedation, anxiolysis and optimal analgesia. During resection, the challenges are to

provide immobility, comfort and maximum level of alertness for mapping and

tumour resection, while also avoiding hypoxaemia, hypercapnia, seizures and

haemodynamic instability (6, 7).

Blocking the following nerves, are vital in successfully managing the

awake craniotomy with awake – awake – awake technique. The nerves to be

blocked are supraorbital nerve, supratrochlear nerve, zygomaticotemporal nerve

auriculotemporal nerve, lesser occipital nerve, and greater occipital nerve. The

nerves blocked provide adequate postoperative analgesia and reduce opioid

consumption. In our case, we used bupivacaine because it has prolonged effect

and residual analgesia with excellent result (9).

Both dexmedetomidine and propofol allow early wake-up once the infusion

is stopped because they have a shorter context sensitive half-life, and this makes

them the preferred drugs for performing awake craniotomy (8, 11,13).

A wide range of intravenous agents are reported in the literature, but the

most commonly used ones are dexmedetomidine, propofol and short-acting opioids

(14).

The use of dexmedetomidine in craniotomy is widespread as intraoperative

neurophysiological monitoring is feasible. Also, it does not cause respiratory

depression making this drug an attractive option in awake craniotomy. However,

the effect of this drug induced bradycardia and hypotension over the cerebral blood

flow, metabolism and oxygen consumption are still unknown (8). Pertaining to our

patient, we did not experience any alteration in heart rate or blood pressure that

might affect cerebral haemodynamics.

Awake craniotomy is now the preferred and most widely used method for

functional neurosurgery. Intraoperative mapping with direct cortical stimulation is

the gold standard for resection of brain lesions near eloquent areas and the motor

cortex. The main benefits of awake craniotomy are shorter hospital stay, reduction

in hospital costs, perioperative morbidity, and improvement in postoperative

functional status. Short hospital stay also limits nosocomial infections and

thromboembolism (15).

Relative contraindications for awake craniotomy include an uncooperative

patient, anxiety, deterioration in neurological status, psychiatric disorders,

difficulty following orders, inability to concentrate, emotional instability,

anticipated difficult airway, chronic obstructive pulmonary disease, obstructive

sleep apnoea, obesity, gastro-oesophageal reflux and large brain tumours with

midline shift. Contraindications inherent to the surgical procedure include

estimated times of over 5h, the need to conduct multiple neurological tests and

lateral and prone positioning (5, 14). In our case the total duration of surgery is

2hours.

The main complications of awake craniotomy are seizures, airway

obstruction, acute and chronic pain, nausea and vomiting. In our case, the patient

did not experience any complications and the patient felt satisfactory(6).

CONCLUSION:

Awake craniotomy is performed for resection of tumors near the eloquent

areas. There are various techniques of awake craniotomy. We opted for awake-

awake- awake technique of awake craniotomy in our patient and it proved to be an

excellent option for complete resection, intraoperative neurophysiologic

monitoring and an alert patient with stable haemodynamics.

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