A 50 years old female was admitted with complaints of right sided weakness in the right upper and lower limb associated with occasional headaches. There was no history of vomiting and seizures. The patient was diagnosed with carcinoma in the right breast S/P BCS and underwent oncoplastic reconstruction in December 2021. There was a history of drug-induced toxicity EF of 48% along with a known case of DM, hypertension and bronchial asthma. An MRI was done and it showed a tumour in the left frontal lobe measuring 2.2*2.2 cm. As the lesion was close to the eloquent area, we performed awake craniotomy to allow monitoring of motor and language functions during the resection of the tumour.

PHYSICAL EXAMINATION

The patient (weight- 65.1 kg, height 145cm) was in good general condition with PR- 68/min, BP- 130/80 mm Hg, SpO2- 98 in room air. Her airway was evaluated with Mallampati grading of II and a neurologic examination of the patient showed motor weakness in the right upper limb and lower limb (power 4/5 in both upper and lower limb).

• Diagnosis- Left Motor Cortex Lesion Metastasis.
• Plan- Left frontoparietal awake craniotomy and gross total microsurgical excision under neuro navigation guidance.

ANAESTHESIA TECHNIQUE

A pre-anaesthetic evaluation was done a day before the surgery and pre-existing medical conditions were optimised before the surgery. The patient was informed in detail about the awake craniotomy procedure and how her flexion and extension of the right upper and lower limb would be assessed during the surgery. She had signed informed consent for anaesthesia and surgery. The patient was premedicated with injection pantoprazole 40mg and injection palanosetron 75mg one hour before surgery. Meticulous planning and good communication between the anaesthesiologist, surgeon and operating room team is needed throughout the entire surgical procedure. Two peripheral lines were inserted for the administration of drugs. She was attached to a five lead ECG, pulse oximetry and invasive blood pressure monitors via the radial artery. The patient was initially sedated with injection midazolam 1mg, injection ketamine 50mg, injection dexmedetomidine 50mcg and 1 g of paracetamol given for analgesia. A left sided scalp block was given using anatomical landmarks with 2% LOX with adrenaline 10ml, 0.25% bupivacaine 20ml and 4mg of dexamethasone. Local infiltrations were given at the site of insertion of a Mayfield pin. Anti-epileptic and anti-edema measures were taken during the surgery. Antibiotic prophylaxis was given.

The procedure started after 1 hour after the nerve block. Drilling of the skull was used to remove a bony flap and the dura was cut but before incising the dura. A gauze soaked with local anaesthetics was placed on top of the dura for 3 minutes to decrease the pain. During the resection of the tumour, the patient was constantly in communication with the anaesthesiologist and was asked to flex and extend her right upper and lower limbs to assess for any motor deficits. After we confirmed that the lesion had been removed and we had monitored for motor functions of the limbs, the closure of the skull began. The patient was transferred to ICU after surgery for postoperative management and treatment and continuous assessment of her motor function was also monitored. There were no motor function deficits associated with surgery and the patient was discharged on POD 3.

DISCUSSION

So what is an awake craniotomy? It is a surgical procedure where the patient is deliberately kept awake for a portion of the surgery, usually for mapping and resection of a tumour. Awake craniotomies are done for intraoperative cortical mapping of lesions close to eloquent areas and for localisation of epileptic foci during intraoperative electrocorticograms. A variety of anaesthetic techniques have been developed for awake craniotomy. In the present study, we used the technique “awake throughout.” The aim is to vary the levels of sedation according to the stage of surgery while maintaining spontaneous ventilation without any airway device. Sedation is deepened during application of Mayfield pins, skin incision and removal of bone flap and dura mater. It is then decreased or stopped for neurocognitive testing and can be restarted during closure. If the sedation is not titrated correctly, there can be airway obstruction leading to hypoxia and hypercarbia. We also gave a scalp block to this patient. This blocks the following nerves: supra orbital, supra trochlear, zygomatico temporal, auricurulo temporal and greater and lesser occipital nerves. The drugs that are commonly used are propofol, dexmedetomidine, remifentanyl (currently not available in India).

WHEN TO CONVERT INTO GENERAL ANAESTHESIA?

This is done when there are airway obstructions, hypoxia, local anaesthesia toxicity, pain, poor cooperation/agitation, and/or seizures. It is very difficult to convert to general anaesthesia during the surgery since the patient’s head is attached to Mayfield pins and flexed so the head cannot be extended to see the vocal cords and for intubation without removing the Mayfield pins.

CONCLUSION

Awake craniotomies are done for tumours involving sensory, motor and language areas. It needs a very understanding and cooperative patient. Near complete removal of the tumour with the least or no neurological deficit is possible only with meticulous planning and clear communication between the neurosurgeon, anaesthesiologist and the patient.