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Why we still use intravenous drugs as the basic regimen for neurosurgical anaesthesia.

PURPOSE OF REVIEW: Evolution of neurosurgery mainly trends towards minimally invasive and functional procedures including endoscopies, small-size craniotomies, intraoperative imaging and stereotactic interventions. Consequently, new adjustments of anaesthesia should aim at providing brain relaxation, minimal interference with electrophysiological monitoring, rapid recovery, patients' cooperation during surgery and neuroprotection. RECENT FINDINGS: In brain tumour patients undergoing craniotomy, propofol anaesthesia is associated with lower intracranial pressure and cerebral swelling than volatile anaesthesia. Hyperventilation used to improve brain relaxation may decrease jugular venous oxygen saturation below the critical threshold. It decreases the cerebral perfusion pressure in patients receiving sevoflurane, but not in those receiving propofol. The advantage of propofol over volatile agents has also been confirmed regarding interference with somatosensory, auditory and motor evoked potentials. Excellent and predictable recovery conditions as well as minimal postoperative side-effects make propofol particularly suitable in awake craniotomies. Finally, the potential neuroprotective effect of this drug could be mediated by its antioxidant properties which can play a role in apoptosis, ischaemia-reperfusion injury and inflammatory-induced neuronal damage. SUMMARY: Although all the objectives of neurosurgical anaesthesia cannot be met by one single anaesthetic agent or technique, propofol-based intravenous anaesthesia appears as the first choice to challenge the evolution of neurosurgery in the third millennium.

Anesthesia↗

Surgery in primary supratentorial intracerebral hematoma: a meta-analysis of randomized trials.

OBJECTIVES: To examine through a meta-analysis whether a treatment strategy of surgery plus the routine medical management saves lives and reduces disability in survivors of primary supratentorial intracerebral hematoma compared to routine medical management alone. MATERIAL AND METHODS: Computerized bibliographic search of published research, conference proceedings, monographs and experts yielded 373 articles, of which only four were randomized trials. The methodological quality of the trials was assessed by two observers (weighted kappa = 0.8). Two independent reviewers abstracted the data on patient sample, type of surgery and outcomes in terms of death and dependence versus independence. Based on the nature of the intervention and the results of test for homogeneity, we analyzed the results of craniotomy and endoscopic evacuation separately. RESULTS: Review of the three trials of craniotomy suggests that it increases the risk of death or dependence (pooled risk difference 13%, 95% CI 3% to 23%), though the study with the largest sample size was conducted in the pre-CT period. Reanalysis of the endoscopic evacuation trial data showed decrease in risk of death or dependence (risk difference -18%, 95% CI -36% to 0%), the effect being similar across the different subgroups of patients according to the site of hematoma, but probably larger in patients aged less than 60 years or hematoma size of more than 50 cc. CONCLUSIONS: The role of craniotomy and stereotactic surgery has not been adequately studied in randomized trials. The results of a single trial suggest that endoscopic evacuation is a promising form of treatment in patients with primary supratentorial intracerebral hematoma, but this finding needs confirmation in a larger trial.

Activities of Daily Living↗

Expansion of an air-filled subdural space during nitrous oxide anesthesia.

The long-term administration of nitrous oxide anesthesia during craniotomy as well as following closure of the parietal craniotomy flap (under no tension) leads to significant expansion of the residual air bubble trapped under the dura. A case is presented in which an extracerebral avascular space, filled only with gas, caused a marked shift of the intracranial structures and uncal herniation secondary to nitrous oxide anesthesia during craniotomy and postcraniotomy angiography.

Adult↗

High-field strength interventional magnetic resonance imaging for pediatric neurosurgery.

BACKGROUND: Interventional magnetic resonance (MR) imaging allows neurosurgeons to interactively perform surgery using MR guidance. High-field (1.5-Tesla) strength imaging provides exceptional visualization of intracranial and spinal pathology. The full capabilities of this technology for pediatric neurosurgery have not been defined or determined. MATERIALS AND METHODS: From January 1997 through June 1998, 10 of 85 cases performed in the interventional MR unit were in the pediatric population (mean age 8.3, median 8, range 2-15 years). Procedures included 2 brain biopsies, 5 craniotomies for tumor, 2 thoracic laminectomies for syringomyelia, and placement of a reservoir into a cystic brainstem tumor. The biopsies and reservoir placement were performed using MR-compatible equipment. Craniotomies and spinal surgery were performed with conventional instrumentation outside the 5-Gauss magnetic footprint. Interactive and intraoperative imaging was performed to assess the goals of surgery. RESULTS: Both brain biopsies were diagnostic for cerebral infarct and anaplastic astrocytoma and the reservoir was optimally placed within the tumor cyst. Of the 5 tumor resections, all were considered radiographically complete. One biopsy patient and 1 tumor resection patient experienced transient neurological deficits after surgery. The patient with the thoracic syrinx required reoperation when the syringosubarachnoid shunt migrated into the syrinx 3 months after initial placement. No patient sustained a postoperative hemorrhage. Tumor histologies found at craniotomy were craniopharyngioma, ganglioglioma, and 3 low-grade gliomas. No evidence of tumor progression has been seen in any of these patients at a mean follow-up of 5.3 (range 4-8) months. The goals of the procedure were achieved in all 10 cases. There were no untoward events experienced related to MR-compatible instrumentation or intraoperative patient monitoring, despite the present inability to monitor core body temperature. CONCLUSIONS: 1.5-Tesla interventional MR is a safe and effective technology for assisting neurosurgeons to achieve the goals of pediatric neurosurgery. Preliminary results suggest that surgical resection of histologically benign tumors is enhanced in the interventional MR unit. The incidence of surgically related morbidity is low.

Adolescent↗

Value of surgical intervention in the treatment of glioma.

The benefit of cytoreductive surgery in the management of glioma remains speculative. We therefore reviewed all confirmed deaths in our Neuro-Oncology Program and examined various clinical factors related to survival. There were 63 patients (34 males/29 females), with an average age of 57.6 years. The pathology was glioblastoma in 44 and anaplastic astrocytoma in 19; median survival was 12 months. Forty patients underwent at least one craniotomy, following which 22.5% achieved a gross total resection, 23 had biopsy only. Only age and gross total resection of tumor as judged by postoperative MR (CT in 2 cases) correlated significantly with outcome. The subtotal craniotomy group and biopsy only cohort were indistinguishable (median survival 11 vs. 10 months, respectively). Although craniotomy associated with gross total resection results in enhanced survival (median 27 months), subtotal tumor excision offers little beyond a diagnosis. Therefore, careful and realistic preoperative assessment of glioma patients ought to be performed to determine optimal surgical management.

Biopsy↗

Diagnostic evaluation of patients with a brain mass as the presenting manifestation of cancer.

BACKGROUND: Patients with a newly detected brain mass and no history of cancer often undergo extensive diagnostic testing in search of a systemic primary neoplasm prior to selection of a biopsy site, potentially leading to unnecessary expense and delay. We sought patterns in the evaluation of these patients to allow rapid selection of a biopsy site. METHODS: We compared the diagnostic evaluation of 176 patients with newly detected brain masses who were ultimately determined to have a metastatic or primary lesion. RESULTS: In 88 patients presenting with brain metastasis, lung cancer was markedly overrepresented as a primary tumor, occurring in 82% of patients. Brain MRI and chest CT together identified the site for diagnostic biopsy in all except for two of the 176 patients. One-half of the patients with metastasis had brain biopsy as the primary diagnostic procedure, with 80% undergoing a craniotomy rather than needle biopsy. The initial management decision in the majority of metastasis patients was whether to perform a craniotomy for resection of tumor. Whereas patients with single and cerebellar lesions were most likely to undergo craniotomy, the extent of systemic disease did not affect the decision to recommend a neurosurgical procedure. The average time to biopsy for patients with metastatic and primary tumors was 4.7 days and 6.0 days. In this retrospective population, we estimated that evaluation with brain MRI and chest CT, followed by an early neurosurgical decision, could reduce the time to diagnosis by at least 10%. CONCLUSIONS: Chest CT and brain MRI, if used together as initial diagnostic studies, would have identified a biopsy site in 97% of patients with a newly detected brain mass.

Biopsy↗

Intracranial suppuration: a modern decade of postoperative subdural empyema and epidural abscess.

A retrospective study of subdural empyema and epidural abscess spanning 11 years and encompassing 41 patients was performed, demonstrating that the clinical characteristics of intracranial suppuration have changed over time. Sinusitis and otitis media, previously the predominant etiologies, were predisposing factors in only 29% of patients. A prior craniotomy had been performed in 66% of cases and was the most common risk factor for abscess development. The postoperative patients were subjected to detailed analysis. Patients who had undergone a prior craniotomy were notable for the following features: older age, lack of fever, evidence of wound infection, frequent false-negative computed tomographic scans, and a high percentage of Gram negative aerobic organisms or skin flora as pathogens. The population at highest risk for abscess development ranged from 50 to 60 years old, older than in previous series. Older age and an advanced degree of encephalopathy were indicative of a poor prognosis. Patients with subdural empyema had a worse prognosis as well. Hyponatremia was a frequent complicating factor. A much greater percentage of Gram-negative aerobic bacteria were isolated than in previous studies. Computed tomographic scans, half of which were performed with intravenous contrast material, were nondiagnostic in 30% of patients. The mortality rate was 18.5%, and delay in treatment correlated with increased risk of poor outcome. All patients were treated with a craniotomy. Repeated operations were required in three patients and were associated with the development of intraparenchymal abscess.

Adolescent↗

Racial considerations in acoustic neuroma removal with hearing preservation via the retrosigmoid approach.

Racial differences in the size, shape and structure of the cranium exist. This paper evaluates the importance of race in influencing the required sizes of craniotomies for gaining access to the lateral end of the internal auditory meatus without breaching the labyrinth via the retrosigmoid approach. Fine-cut CT scans of the temporal bones (axial cuts) of 34 Chinese and 34 Europeans were studied. The relevant distances and angles of the posterior cranial fossa and temporal bone were measured and statistically significant differences between the two races were found. This led us to the conclusion that a larger craniotomy is required in Europeans than in Chinese. In recommending an optimal size for a retrosigmoid craniotomy to remove acoustic neuromas completely and preserve hearing, the racial factor must be considered.

Adult↗

The initial experience with the Cosman-Roberts-Wells stereotactic system.

The Cosman-Roberts-Wells stereotactic instrument is a recently developed modification, based on an arc-radius design, of the Brown-Roberts-Wells stereotactic frame utilizing the existing fixation and fiducial components of the Brown-Roberts-Wells stereotactic system to localize and verify target data. The design modification has been made with a view to facilitating technical approaches both in stereotactic biopsy and in stereotactic craniotomy, whilst encompassing the same stereotactic space. Initial experience with the Cosman-Roberts-Wells instrument is reported. Over a 5-month period 55 procedures were performed which included 40 stereotactic biopsies, five CT-guided stereotactic craniotomies, three stereotactic placements of a Bennett Ball for thalamotomy, three stereotactic implantations of intracranial electrodes for recording in drug-resistant epilepsy, three aspirations of cyst or haematoma and one implantation of a Gutin catheter for interstitial brachytherapy. There was minimal morbidity and no mortality related to operation. This frame offers rapid targeting without the need to pre-determine entry points, as well as allowing direct lateral passes and unimpeded stereotactic craniotomy.

Adolescent↗

Influence of intraoperative antibiotic choice on the incidence of early postcraniotomy seizures.

Because of a suspicion that intraoperative penicillin antibiotics might be causing early postoperative seizures in craniotomy patients, a deliberate effort was initiated in 1987 to avoid these agents in favor of nonpenicillin antibiotics. This permitted a retrospective comparison of the incidence of early postoperative seizures in craniotomy patients who did and who did not receive intraoperative penicillins. Records of patients treated between July 1, 1984, and July 1, 1985, and between July 1, 1987, and July 1, 1988, were reviewed, for a total of 1316 procedures. There were no seizures in the 323 patients who underwent suboccipital craniectomy. However, among the 993 patients receiving supratentorial procedures there were 30 with seizures within the first 6 hours postoperatively, 19 of which were generalized seizures. The incidence of early seizures was 4.7% (20 cases) of the 427 patients given penicillins and only 1.8% (10 cases) of the 566 not given penicillins (p less than 0.01). Since patients undergoing surgery for intractable seizures have a high incidence of early postoperative seizures (11 of 92 in this series, or 12%), creation of a subgroup eliminated these from consideration but did not alter the relationship of penicillins to early seizures (p less than 0.02). The authors conclude that intraoperative (and early postoperative) penicillin antibiotic administration should be avoided, if possible, in patients undergoing craniotomy for supratentorial pathology.

Anti-Bacterial Agents↗

Stereotactic management of colloid cysts: factors predicting success.

Stereotactic aspiration is a valuable surgical alternative for colloid cysts when used alone or in conjunction with microsurgical resection. Since 1981, the authors have performed computerized tomography (CT)-guided stereotactic aspiration as the initial procedure in 22 patients with colloid cysts; stereotactic aspiration alone was successful in 11 patients (50%). Of the 11 patients in whom aspiration failed, stereotactic endoscopic resection was attempted in three and was successful in one. Seven patients required a craniotomy and microsurgical removal of the cyst performed via a transcortical approach. The preoperative CT appearance in eight cases of a hypodense or isodense cyst correlated favorably with successful aspiration of the cyst in six patients. A hyperdense appearance on the preoperative CT scan in 14 cases was associated with subtotal aspiration in 13 patients; five required craniotomy for removal. Preoperative magnetic resonance (MR) imaging in eight patients provided excellent anatomical definition of the cyst and its relationship to other structures of the third ventricle, but it was not possible to correlate successful aspiration with cyst appearance on MR images with short or long relaxation time sequences. The authors' 9-year experience suggests that preoperative CT studies accurately determine size, predict viscosity, and help to define a group of colloid cyst patients for whom stereotactic cyst aspiration will likely be successful. Unsuccessful stereotactic aspiration was related to two features: the high viscosity of the intracystic colloid material (nine patients), or deviation of the cyst away from the aspiration needle due to small cyst volume (two patients). Because of its simplicity and low risk, stereotactic surgery can be offered to selected patients as the initial procedure of choice. Craniotomy can be reserved for those whose imaging studies predict failure or for those whose cyst cannot be aspirated.

Adult↗

Resection for solitary brain metastasis. Role of adjuvant radiation and prognostic variables in 229 patients.

The authors reviewed 229 consecutive patients treated intramurally by resection of solitary cerebral metastasis. Patients were classified into four groups on the basis of whether a gross total resection or subtotal resection was performed and whether systemic disease was present or absent at the time of craniotomy. Group 1 had gross total resection and no systemic disease; Group 2 had subtotal resection and no systemic disease; Group 3 had subtotal resection and systemic disease; and Group 4 had gross total resection and systemic disease. All four groups were further subdivided into Subgroup A (adjuvant whole-brain radiation therapy) or Subgroup B (no adjuvant radiation). Data were collected regarding multiple patient and tumor variables for multivariate analysis. Survival data for the 46 patients in Group 1A (median 1.3 years, 2-year survival rate 41%, 5-year survival rate 21%) were markedly better than those for the 75 in Group 1B (median 0.7 year, 2-year survival rate 19%, 5-year survival rate 4%). The 20 patients in Group 2A also had superior survival data (median 1.1 years, 2-year survival rate 30%, 3-year survival rate 30%) when compared with the eight patients in Group 2B (median 3 months, 1-year survival rate 0%). However, the 16 and 22 patients in Groups 3A and 4A, respectively, had no discernible differences compared to the seven and 35 patients in their Group 3B and 4B counterparts. Multivariate analyses were performed to assess the association of survival with multiple patient, disease, and treatment variables. Poor neurological status and systemic disease were significantly associated with inferior survival, while longer (greater than 36 months) intervals between primary diagnosis and craniotomy were significantly associated with improved survival. After adjusting for the effects of other patient, disease, and treatment characteristics, adjuvant whole-brain radiotherapy was significantly associated with improved survival times. These data support the continued use of craniotomy followed by adjuvant whole-brain radiation therapy for treatment of solitary brain metastasis. However, this aggressive therapy appears relatively contraindicated in the face of either systemic disease or substantial neurological deficit.

Adolescent↗

Intraoperative transdural functional mapping. Technical note.

During craniotomy for supratentorial intraparenchymal space-occupying lesions, with the patient either under general anesthesia or awake, a smaller durotomy designed to expose only the region of resection may be desirable because of brain swelling. Similarly, during repeat craniotomy or craniotomy following cerebral injury or infection, pial-dural adhesions increase the risk of damage to essential cortex, making a limited dural opening desirable. Intraoperative transdural somatosensory evoked potentials and transdural cortical stimulation mapping permit localization of functional cortex prior to durotomy. These techniques can be combined with intraoperative transdural ultrasonography to identify topographical landmarks and borders of mass lesions.

Brain Mapping↗

Cortical stimulation mapping of phantom limb rolandic cortex. Case report.

Findings of intraoperative rolandic cortex mapping during awake craniotomy for a tumor in a patient with a contralateral upper-extremity amputation are presented. This patient sustained a traumatic amputation at the mid-humerus 24 years previously. Initially he had experienced rare painless phantom limb sensations but none in the past 10 years. Functional mapping during an awake craniotomy was performed to maximize safe tumor resection. Typical temporal and frontal speech areas were identified; motor representation of face and jaw extended more superiorly than sensory representation. Shoulder movements were evoked more laterally than usual at the superior aspect of the craniotomy. A small region of precentral gyrus, between the jaw and shoulder representations, elicited no detectable effect when stimulated. Somatosensory mapping showed a similar topographical distribution of face and mouth cortex; however, posterior and inferior to the shoulder motor cortex, right arm and hand (phantom) sensations were evoked. Evidence suggests that significant motor reorganization occurs following an amputation, with expansion of neighboring homuncular representations without loss of somatosensory representation, despite a long period of time without any sensation referable to the amputated limb. Contrary to models of sensory cortex plasticity, the plasticity of the adult cortex may be system specific, with reorganization present in motor, but not in sensory, cortical systems.

Amputation, Traumatic↗

Mortality rates, hospital length of stay, and the cost of treating subarachnoid hemorrhage in older patients: institutional and geographical differences.

The risk of disability and death and the cost of medical care are particularly high for patients with aneurysmal subarachnoid hemorrhage (SAH) who are 65 years of age or older. A retrospective analysis of 47,408 Medicare patients treated over an 8-year period was performed to determine whether a relationship exists between the mortality rate and surgical volume for older patients with SAH. The mortality rate, length of stay in the hospital, and cost of treatment for patients with SAH in California and New York state were also compared. The mortality rate was 14.3% for patients with SAH who were 65 years old or older and who were treated surgically in hospitals in which an average of five or more craniotomies were performed per year; in hospitals averaging between one and five craniotomies annually the mortality rate was 18.4%; and in those averaging less than one such operation per year the rate was 20.5% (trend p = 0.01). There was no difference in the mortality rate for patients in California versus the rate for those in New York. Surgically and medically treated patients, respectively, left the hospital an average of 6.7 and 5.1 days sooner in California than in New York. The unadjusted average reimbursement from Medicare to hospitals for surgically treated patients averaged $1468 more in New York than in California (p < 0.0001), but was equivalent for medically treated patients in the two states. The mortality rate in older patients who are treated surgically for SAH may be inversely correlated with the annual number of craniotomies performed for SAH in patients 65 years of age or older at a given institution. Hospital stays for patients with SAH are significantly shorter in California than in New York.

Aged↗

Eyebrow incision for combined orbital osteotomy and supraorbital minicraniotomy: application to aneurysms of the anterior circulation. Technical note.

A modification of the supraorbital keyhole approach, the eyebrow incision-minisupraorbital craniotomy with orbital osteotomy, is described. Unique to this approach is a one-piece supraorbital craniotomy, measuring 2.5 x 3.5 cm, that incorporates the orbital rim and roof and the frontal process of the zygomatic bone through an eyebrow incision. The orbital osteotomy facilitates view of the anterior and middle cranial fossa through the operating microscope, as well as the maneuverability of instruments through a small craniotomy. A pericranial flap is elevated with its base at the orbit and used for closure of the frontal sinus, if necessary. The approach was used successfully in elective surgery of 10 aneurysms of the anterior circulation. The mean aneurysm size was 5.9 mm, with a range of 4 to 10 mm. Advantages of this approach include minimal disruption and exposure of normal brain tissue, reduced frontal lobe retraction, and an excellent postoperative cosmetic result. The approach is performed quickly by virtue of a limited skin incision with minimal temporalis muscle dissection and a small bone flap. The neuroendoscope, although helpful at times, is not essential and no special instruments or intraoperative image guidance is required. Relative contraindications include the presence of a large frontal sinus, severe brain edema, and recent subarachnoid hemorrhage. In addition, this approach has not been used for the treatment of giant intracranial aneurysms.

Aged↗

Cerebellar hemorrhage arising postoperatively as a complication of supratentorial surgery: a retrospective study.

OBJECT: Postoperative cerebellar hemorrhage as a complication of supratentorial surgery is an increasingly recognized clinical entity. So far, it has remained unclear whether this complication constitutes an intraoperative or postoperative event. The observation of such cases prompted the authors to analyze retrospectively their series of supratentorial craniotomies. The aim of this study was to determine the incidence of cerebellar hemorrhage and its temporal relationship to supratentorial surgery. METHODS: The authors reviewed discharge notes and reports on postoperative computerized tomography (CT) scans for 1650 patients who had undergone supratentorial craniotomy between January 1998 and February 2001. The retrospective study led to the identification of 10 patients who had sustained cerebellar hemorrhage as a complication of supratentorial surgery. Because it was routine to perform CT scanning following craniotomy, an early CT scan obtained within the 1st postoperative hour (mean 24 minutes after wound closure) was available in eight of the 10 patients. In seven of these patients no hemorrhage was found immediately after surgery, and in only one patient was there the suspicion of cerebellar hemorrhage. In the whole series of 10 patients, cerebellar hemorrhage was detected during the later postoperative course, after a mean interval of 7 hours and 35 minutes (range 1 hour and 49 minutes-144 hours) following surgery. The incidence of cerebellar hemorrhage was 0.6% of all patients who underwent supratentorial surgery. Among patients suffering from epilepsy the incidence was 4.6%, and in those patients who underwent temporal lobe resection it was 12.9%. CONCLUSIONS: The authors have demonstrated that cerebellar hemorrhage as a complication of supratentorial surgery arises not as an intraoperative event, but as a postoperative event. Resective nontumorous temporal lobe procedures place patients at particular risk for this complication. Evidence suggests that the complication might be precipitated by postoperative suction drainage.

Adult↗

Is there a "July phenomenon" in pediatric neurosurgery at teaching hospitals?

OBJECT: Concern for patient safety, among other reasons, recently prompted sweeping changes in resident work policies in the US. Some have speculated that the arrival of new interns and residents at teaching hospitals each July might cause an annual transient increase in poor patient outcomes and inefficient care. METHODS: Data were analyzed for 4323 craniotomies for tumor resection and 22,072 shunt operations performed in pediatric patients between 1988 and 2000 in US nonfederal hospitals (Nationwide Inpatient Sample, Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality, Rockville, MD). In-hospital mortality rates, discharge outcome, complications, and efficiency measures (length of stay [LOS] and hospital charges) for patients treated in July and August were compared with similar data for patients in other months. There were no significant increases in any adverse end point for either tumor or shunt operations in July and August. Odds ratios (95% confidence interval [CI]) for outcome of tumor craniotomies performed in July and August compared with outcome for tumor craniotomies performed in other months were as follows: for mortality rate, 0.43 (0.14-1.32); for adverse discharge disposition, 1.03 (0.71-1.51); for neurological complications, 1.00 (0.63-1.59); for transfusion, 0.70 (0.41-1.19). Hospital charges were 0.5% lower (range -6 to 5%) in July and August, and LOS was 3% shorter (range -8 to 3%). Odds ratios (95% CI) for July or August shunt surgery compared with shunt surgery performed in other months were as follows: for mortality rate, 0.96 (0.58-1.60); for adverse discharge disposition, 0.85 (0.66-1.11); for neurological complications, 1.27 (0.75-2.16); for transfusion, 0.81 (0.48-1.37). Hospital charges were 0.2% higher in July and August (range -3 to 3%), and LOS was 3% shorter (range -5 to 0.5%). CONCLUSIONS: Although moderate increases in some adverse end points could not be excluded, there was no evidence that brain tumor or shunt surgery performed in pediatric patients at US teaching hospitals during July and August is associated with more frequent adverse patient outcome or inefficient care than similar surgery performed during other months.

Brain Neoplasms↗