Comparison of Conscious Sedation and General Anesthesia
Comparison of Conscious Sedation and General Anesthesia
Object: The surgical treatment of tumors located near eloquent cortex carries a high risk of inducing worsening neurological deficits. Intraoperative electrocorticography techniques have been developed to help identify these areas at the time of surgery in an effort to minimize such risks. The optimal anesthetic technique for conducting these procedures, however, has never been determined.
Methods: The authors conducted a retrospective study to compare patients who underwent intraoperative motor mapping between September 2000 and May 2002. Demographic and neurophysiological monitoring data were collected from the hospital records. Patients were divided into two groups based on the anesthetic technique used for surgery: in Group 1 general anesthesia was used, and in Group 2 conscious sedation.
Group 1 comprised 24 patients (mean age 47 years) with 16 right-and eight left-sided lesions. Group 2 consisted of 21 patients (mean age 46 years) with 18 right-and three left-sided lesions. Pathological diagnoses were similar between the two groups. Motor stimulation was elicited in 12 patients (50%) in Group 1 and in 21 patients (100%) in Group 2 (p < 0.001). In addition, the mean stimulation amplitude required was significantly higher (13 mA) in patients in whom conscious sedation was used as opposed to general anesthesia (5 mA, p < 0.0001). Electrographic evidence of seizures was seen in 29% of Group 1 cmpared with 10% of Group 2 patients (p > 0.05).
Conclusions: The use of conscious sedation as an anesthetic technique for motor mapping not only improves the chances of achieving successful stimulation and identification of motor cortex in relationship to the lesion, but it also allows for repetitive monitoring of the patient's motor function during resection of the lesion.
The primary goal for resection of brain tumors has been maximal tumor resection while minimizing the risks of postoperative neurological deficits. In cases in which lesions abut or invade motor and speech centers, however, the ability of the surgeon to achieve these goals becomes progressively more difficult. Numerous technological advances have been developed in an attempt to make safer the resection of lesions located near functionally important cortex. These include systems designed to localize functional cortex preoperatively such as fMR imaging, MEG, Wada testing, and intraoperative modalities designed to identify and differentiate tumor from surrounding brain (intraoperative ultrasonography, surgical navigation systems, and intraoperative MR imaging).
The gold standard for identifying functional cortex, however, has remained direct ECS at the time of surgery. This technique has been described in conjunction with both general and "alert" anesthesia (conscious sedation), with the latter being predominantly reserved for speech mapping. The development of newer anesthetic agents, however, has made "awake" craniotomy simpler and more tolerable for patients. As a result of these advances, we have tended over the past 2 years to perform more conscious sedation assisted craniotomies. To date, no comparison has been performed to evaluate the effects of these two types of anesthesia on the success of intraoperative motor mapping; therefore, we conducted a retrospective review to address this issue.
Object: The surgical treatment of tumors located near eloquent cortex carries a high risk of inducing worsening neurological deficits. Intraoperative electrocorticography techniques have been developed to help identify these areas at the time of surgery in an effort to minimize such risks. The optimal anesthetic technique for conducting these procedures, however, has never been determined.
Methods: The authors conducted a retrospective study to compare patients who underwent intraoperative motor mapping between September 2000 and May 2002. Demographic and neurophysiological monitoring data were collected from the hospital records. Patients were divided into two groups based on the anesthetic technique used for surgery: in Group 1 general anesthesia was used, and in Group 2 conscious sedation.
Group 1 comprised 24 patients (mean age 47 years) with 16 right-and eight left-sided lesions. Group 2 consisted of 21 patients (mean age 46 years) with 18 right-and three left-sided lesions. Pathological diagnoses were similar between the two groups. Motor stimulation was elicited in 12 patients (50%) in Group 1 and in 21 patients (100%) in Group 2 (p < 0.001). In addition, the mean stimulation amplitude required was significantly higher (13 mA) in patients in whom conscious sedation was used as opposed to general anesthesia (5 mA, p < 0.0001). Electrographic evidence of seizures was seen in 29% of Group 1 cmpared with 10% of Group 2 patients (p > 0.05).
Conclusions: The use of conscious sedation as an anesthetic technique for motor mapping not only improves the chances of achieving successful stimulation and identification of motor cortex in relationship to the lesion, but it also allows for repetitive monitoring of the patient's motor function during resection of the lesion.
The primary goal for resection of brain tumors has been maximal tumor resection while minimizing the risks of postoperative neurological deficits. In cases in which lesions abut or invade motor and speech centers, however, the ability of the surgeon to achieve these goals becomes progressively more difficult. Numerous technological advances have been developed in an attempt to make safer the resection of lesions located near functionally important cortex. These include systems designed to localize functional cortex preoperatively such as fMR imaging, MEG, Wada testing, and intraoperative modalities designed to identify and differentiate tumor from surrounding brain (intraoperative ultrasonography, surgical navigation systems, and intraoperative MR imaging).
The gold standard for identifying functional cortex, however, has remained direct ECS at the time of surgery. This technique has been described in conjunction with both general and "alert" anesthesia (conscious sedation), with the latter being predominantly reserved for speech mapping. The development of newer anesthetic agents, however, has made "awake" craniotomy simpler and more tolerable for patients. As a result of these advances, we have tended over the past 2 years to perform more conscious sedation assisted craniotomies. To date, no comparison has been performed to evaluate the effects of these two types of anesthesia on the success of intraoperative motor mapping; therefore, we conducted a retrospective review to address this issue.
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