M Syam, I Omer, O Nofal, A Zafrullah
anesthesia, awake craniotomy, brain mapping, brain tumor, neuro-oncology
M Syam, I Omer, O Nofal, A Zafrullah. Neuroanesthesia For Awake Craniotomy; Initial Experience At KFMC. The Internet Journal of Anesthesiology. 2008 Volume 21 Number 2.
Awake craniotomy allows accurate localization of the eloquent areas of the brain. This is crucial during brain tumor resection in order to minimize risk of neurological injury. Awake craniotomy is a well-tolerated procedure with low rate of conversion to general anesthesia and low rate of complications. It is also important to recognize the potential problems in the anesthetic management of awake craniotomy.. Vigilant monitoring of the patient with frequent adjustments of the depth of moderate to deep sedation with adequate local anesthesia to ensure patient safety and maximal comfort is crucial Resection of brain tumors may cause neurological sequlae, according to the site and size of the brain tissue removed. Awake craniotomy has been proposed as a surgical approach to satisfy criteria of radical surgery while minimizing eloquent brain damage.The most critical aspect of awake craniotomy is to maintain adequate patient comfort, analgesia, immobility and cooperation during a long surgical operation, at the same time ensuring the safety, control and maintenance of vital functions. Apart from pharmacological, surgical, technical knowledge and skillfulness, the ability to maintain close psycho-emotionalcontact and support with the patient throughout the operation is a fundamental task that the anesthesiologist has to pursue for the operation to be successfully managed.
The main challenge of oncological surgery is the radical removal of a tumor. A general assertion states that the larger the resection the lower the risk of recurrence of the lesion and the higher the chance of the patient's survival. But an extensive tissue excision may favor the occurrence of an unpredictable degree of loss of function
Patients and Method
We explained the procedure to all patients the procedure preoperatively. All patients agreed and they gave their consent in writing..
During operation Routine monitoring of non-invasive blood pressure, electrocardiogram and pulse oximetry were used.
We did four awake craniotomies using Propofol at induction and for maintaining sedation (70-80mic/kg/min). Fentanyl was used as well in two cases (third +forth case) for induction and maintenance .Oxygen supplementation was given by face mask in two cases and by nasal canula in two cases. All patients were awakened during surgery, whenever needed for evaluation. Only two patients (50%) developed convulsion ,intraoperativly, and were treated with boluses of Propofol. We did not have any other complication.
The published neurosurgical literature remains unclear on the correlation between the extent of surgical resection and survival. Resection of 89% or more of tumor volume was necessary to improve survival after surgery. In addition, there was a significant survival advantage in patients with resections of 98% or more of tumor . The rationale for awake craniotomy in tumor resection is that it allows for brain mapping, which facilitates maximum resection and minimizes the risk of postoperative neurological deficits .Continuous assessment of neurological function has also facilitated the excision of tumors that might otherwise be considered inoperable.
Confusion, decreased level of consciousness and communication difficulties (e.g., profound dysphasia or language barrier) and extreme anxiety are some contraindications to awake craniotomy. Routine monitoring of non-invasive blood pressure, electrocardiogram and pulse oximetry are essential. it is no longer routine to have an arterial blood pressure monitoring for the patient undergoing an awake craniotomy .A combination of propofol (continuous or target controlled infusion) and fentanyl or remifentanil is most commonly used.
Dexmedetomidine has been shown to provide sedation and analgesia without significant respiratory depression .Hypotension and bradycardia are common side effects.
Deep anesthesia can be achieved without compromising the patient’s safety.
The patient is fully awakened for intraoperative neurological evaluation.
This technique is suitable for patients who are not able to tolerate craniotomy
with sedation alone, especially the longer procedures. This technique has been
used in pediatric patients. The laryngeal mask airway (LMA) is now most commonly used during the “asleep” phase of this technique. Patients can either be breathing spontaneously or mechanically ventilated.
nausea and vomiting,
decreased level of consciousness,
Loss of patient cooperation.
Respiratory depression and airway obstruction,
hypercapnia and brain swelling,
Homodynamic instability (hypertension),
Transient neurological deficit,
Deep venous thrombosis, urinary tract infection and pneumonia,