Introduction

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, depending on the location of the malignancy. Particularly in neuro-oncology, the neurological sequelae due to tumor excision may cause severe disability compromising the patient's social life. Therefore, the aim to remove the maximum amount of lesion without impairing neurological function, has pushed the physicians and industry to develop sophisticated surgical approaches to be performed in awake and responding patients, so as to evaluate neurological dysfunction before tissue removal.(1) Awake craniotomy dates back to the second half of the 19th century, and at that time, the indication was epilepsy surgery performed under local anesthesia. Subsequently, this surgical practice has been extended also to the resection of tumors involving the functional cortex and finally, in more recent years, the indications have further extended to include the removal of supratentorial tumors, regardless of the involvement of the cortex. (2) Craniotomy in awake patients has evolved and extended its indication as a direct consequence of the following driving forces: the huge improvement of diagnostic tools; the impressive development of intraoperative functional neurosurgical technology; the enhancement of anesthesia monitoring devices, the pharmacokinetic and pharmacodynamic properties of the new anesthetic agents and the modality by which they are delivered to the patients. (1) The main advantage for the awake neurosurgical approach is to facilitate intraoperative electrocorticography and cortical mapping for the accurate identification of brain areas which control motor function and speech. (3) Functional magnetic resonance imaging has produced considerable progresses in non-invasive mapping of brain functional areas, allowing very early tumor stratification. However, its employ during surgery is not feasible on a routine basis and intraoperative testing of language and motor function continues to be the gold standard for a radical surgical resection while minimizing eloquent brain damage. Apart from tumor anatomical location, mandatory prerequisites for awake craniotomy are a fully cooperative patient and optimal collaboration between anesthesia and neurosurgical staff, to realize what is defined as function-controlled neurosurgery. (4,5) Indeed, evolution of general anesthesia in neurosurgery has permitted adequate control of vital parameters, neurological function and intracranial pressure; at the same time these aspects ensure optimal working conditions for the neurosurgeon; but intraoperative monitoring of functional lesions of the central nervous system is severely inhibited by general anesthesia: some higher cortical brain functions (i.e. speech) cannot be monitored during surgery.

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.

Figure 1

Table-1. cases data [biodata]

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.

Figure 2

Table- 2. The details of anesthesia technique used in each case

Discussion

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.

Asleep-awake-asleep technique

Possible Complication