Awake Craniotomy-A Case Report

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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