Awake surgery with continuous motor testing for resection of brain tumors in the primary motor area

Functional MRI applications for intra-axial brain tumours: uses and nuances in surgical practise

PURPOSE

Functional MRI (fMRI) has well-established uses to inform risks and plan maximally safe approaches in neurosurgery. In the field of brain tumour surgery, however, fMRI is currently in a state of clinical equipoise due to debate around both its sensitivity and specificity.

MATERIALS AND METHODS

In this review, we summarise the role and our experience of fMRI in neurosurgery for gliomas and metastases. We discuss nuances in the conduct and interpretation of fMRI that, based on our practise, most directly impact fMRI's usefulness in the neurosurgical setting.

RESULTS

Illustrated examples in which fMRI in our hands directly influences the neurosurgical treatment of brain tumours include evaluating the probability and nature of functional risks, especially for language functions. These presurgical risk assessments, in turn, help to predict the resectability of tumours, select or deselect patients for awake surgery, indicate the need for neurophysiological monitoring and guide the optimal use of intra-operative stimulation mapping. A further emerging application of fMRI is in measuring functional adaptation of functional networks after (partial) surgery, of potential use in the timing of further surgery.

CONCLUSIONS

In appropriately selected patients with a clearly defined surgical question, fMRI offers a valuable complementary tool in the pre-surgical evaluation of brain tumours. However, there is a great need for standards in the administration and analysis of fMRI as much as in the techniques that it is commonly evaluated against. Surprisingly little data exists that evaluates the accuracy of fMRI not just against complementary methods, but in terms of its ultimate clinical aim of minimising post-surgical morbidity.

Surgical Management of Brain Metastases in the Perirolandic Region

Brain metastases (BM) are the most frequent intracranial tumors, which may result in significant morbidity and mortality when the lesions involve the perirolandic region. Surgical intervention for BM in the perirolandic region is still under discussion even though prompt relief of mass effect and avoidance of necrosis together with brain edema may not be achieved by radiotherapy. More recently, several researchers attempt to evaluate the benefit of surgery for BM within this pivotal sensorimotor area. Nevertheless, data are sparse and optimal treatment paradigm is not yet widely described. Since the advance in intraoperative neuroimaging and neurophysiology, resection of BM in the perirolandic region has been proven to be safe and efficacious, sparing this eloquent area while retaining reasonably low morbidity rates. Although management of BM becomes much more tailored and multimodal, surgery remains the cornerstone and principles of resection as well as indications for surgery should be well defined. This is the first review concerning the characteristics of BM involving the perirolandic region and the current impact of surgical therapy for the lesions. Future perspectives of advanced neurosurgical techniques are also presented.

The sensory-motor profile awake-A new tool for pre-, intra-, and postoperative assessment of sensory-motor function

OBJECTIVES

Awake craniotomy is a well-established procedure in surgery of intracranial tumors in eloquent areas. However, sufficiently standardized instruments for the assessment of sensory-motor function before, during and after the operation are currently lacking, despite their importance for evaluation of operative outcome.

PATIENTS AND METHODS

To address this issue, we designed a standardized assessment tool (the "sensory-motor profile awake scale"; SMP-a). The final scale consists of three motor sections (face, arm and leg) assessing both gross and fine motor skills and one sensory section. It differentiates between six grades of impairment and its tasks are applicable for intraoperative continuous monitoring of sensory-motor functions and supporting processes. We analyzed the data of 17 patients with intracranial tumors eligible for awake craniotomy who were preoperatively assessed with the SMP-a. In addition, we present an exemplary case.

RESULTS

Our data support the assumption that the SMP-a is feasible in patients eligible for awake craniotomy, even in patients with symptoms of mild aphasia or more severe sensory-motor deficits caused by tumor recurrence. The exemplary case demonstrates the feasibility of repeated measures with the SMP-a in a tumor patient, including the adaption of tasks to the individual requirements of an intraoperative setting.

CONCLUSION

This exploratory study suggests that the SMP-a might be a feasible rating scale in patients with intracranial tumors. The flexibility of the scale enables individual adaption, but preserves the standardized scoring system to allow comparison between assessment dates, patients and, hopefully in the future, institutions. However, future studies are mandatory to provide data on the instrument's diagnostic properties with respect to feasibility, objectivity, validity and reliability.

Continuous physical examination during subcortical resection in awake craniotomy patients: Its usefulness and surgical outcome

OBJECTIVES

To evaluate the value of physical examination as a monitoring tool during subcortical resection in awake craniotomy patients and surgical outcomes.

PATIENTS AND METHODS

Authors reviewed medical records of patients underwent awake craniotomy with continuous physical examination for pathology adjacent to the eloquent area.

RESULTS

Between January 2006 and August 2015, there were 37 patients underwent awake craniotomy with continuous physical examination. Pathology was located in the left cerebral hemisphere in 28 patients (75.7%). Thirty patients (81.1%) had neuroepithelial tumors. Degree of resections were defined as total, subtotal, and partial in 16 (43.2%), 11 (29.7%) and 10 (27.0%) patients, respectively. Median follow up duration was 14 months. The reasons for termination of subcortical resection were divided into 3 groups as follows: 1) by anatomical landmark with the aid of neuronavigation in 20 patients (54%), 2) by reaching subcortical stimulation threshold in 8 patients (21.6%), and 3) by abnormal physical examination in 9 patients (24.3%). Among these 3 groups, there were statistically significant differences in the intraoperative (p=0.002) and early postoperative neurological deficit (p=0.005) with the lowest deficit in neuronavigation group. However, there were no differences in neurological outcome at later follow up (3-months p=0.103; 6-months p=0.285). There were no differences in the degree of resection among the groups.

CONCLUSION

Continuous physical examination has shown to be of value as an additional layer of monitoring of subcortical white matter during resection and combining several methods may help increase the efficacy of mapping and monitoring of subcortical functions.

Topographical risk factor analysis of new neurological deficits following precentral gyrus resection

BACKGROUND

Precentral gyrus resections (PGRs) have been regarded as excessively hazardous interventions because of the risk of postoperative major neurological complications.

OBJECTIVE

To evaluate the neurological deterioration that follows PGRs and to assess the topographical risk factors associated with these morbidities.

METHODS

We reviewed 33 consecutive patients who experienced pharmacologically intractable epilepsy and underwent PGR with intraoperative cortical stimulation and mapping while under awake anesthesia. The etiological diagnoses were brain neoplasm in 26 patients (78.8%), cortical lesion in 4 (12.1%), and no lesion in 3 (9.1%). The mean follow-up period was 62.6 months (range, 12-146 months). All topographical analyses of the resected quadrant area were performed based on postoperative magnetic resonance images.

RESULTS

After PGR, 22 patients (66.7%) experienced neurological worsening, including 5 permanent deficits (15.2%) and 17 transient deficits (51.5%). Permanent deficits included 2 instances of weakness, 1 dysarthria, 1 dysesthesia, and 1 fine-movement disturbance of the hand. While the neurological risk for anterior lower quadrant PGR was 20.0% (1/5), the risk for posterior upper quadrant PGR was 100.0% (10/10). The anterior upper and posterior lower quadrant PGR caused neurological deteriorations in 60.0% (6/10) and 62.5% (5/8) of the patients, respectively. In a multivariate analysis, PGR of the posterior and upper quadrant sections were significant risk factors for post-PGR neurological deteriorations (P = .022 and 0.030, respectively).

CONCLUSION

The posterior upper quadrant of the precentral gyrus was vulnerable to post-resective neurological impairment.

Surgery on motor area metastasis

The role of surgery on central area metastasis remains unclear, and outcome data are still controversial. The aim of our study is to analyze the predictive value of clinical and surgical data on motor and functional outcome of patients, taking into account new emerging data on boundary irregularity of brain metastasis. We retrospectively analyzed 47 consecutive patients who underwent surgery assisted by neurophysiologic monitoring for a solitary metastasis in central area between 2010 and 2013. Inclusion criteria were as follows: good functional status (Karnofsky Performance Status (KPS) ≥70), controlled systemic disease, and absence of extra-cranial dissemination. At 1-month follow up, motor and functional outcomes were compared with preoperative clinical status, response to corticosteroids, extent of tumor resection, boundary irregularity, and size of tumor. Gross total resection was achieved in 93.6% of cases. In preoperative symptomatic patients, motor outcome (according to Medical Research Council grading scale) improved in 55.5% and worsened in 16.7%, while functional outcome (according to KPS score) improved in 50% and worsened in 14.2% of cases. No worsening occurred in preoperative asymptomatic patients. Motor outcome resulted to be not correlated with preoperative deficits, tumor volume, or preoperative response to corticosteroid treatment. Remarkably, motor outcome and extent of surgical resection appeared strongly correlated with tumor boundary irregularity (p < 0.05). Surgery with neurophysiologic monitoring on motor area metastasis can improve functional and motor condition in selected patients. Tumor volume does not represent a limit in surgery. The high correlation between clinical outcome, resection rate, and tumor boundary irregularity strengthens a new belief on the infiltrative growing pattern of brain metastasis. Motor function was evaluated according to Medical Research Council grading scale (Ott et al. 2014) while functional status was assessed according to KPS score.

Experiences in surgery of primary malignant brain tumours in the primary sensori-motor cortex practical recommendations and results of a single institution

OBJECTIVE

Tumour resection in the Rolandic region is a challenge. Aim of this study is to review a series of patients malignant glioma surgery in the Rolandic region which was performed by combinations of neuronavigation, sonography, 5-aminolevulinic acid fluorescence guided (5-ALA) surgery and intraoperative electrophysiological monitoring (IOM).

METHODS

29 patients suffering malignant gliomas in the motor cortex (17) and sensory cortex (12) were analyzed with respect to functional outcome and grade of resections.

RESULTS

Improvement of motor function was seen in 41.5% one week after surgery, 41.5% were stable, only 17% deteriorated. After three months patients had an improvement of motor function in 56%, of Karnofsky Score (KPS) 27% and sensory function was improved in 8%. Deterioration of motor function was seen in 16%, in sensory function 4% and in KPS 28% after three months. 25% showed no residual tumour in early post surgical contrast enhanced MRI. 10% had less than 2% residual tumour and 15% had 2-5% residual tumour.

CONCLUSIONS

Preoperative functional neuroimaging, neuronavigation for planning the surgical approach and resection margins, intraoperative sonography and 5-ALA guided surgery in combination with the application of IOM shows that functional outcome and total to subtotal resection of malignant glioma in the Rolandic region is feasible.

Intraoperative Motor Symptoms during Brain Tumor Resection in the Supplementary Motor Area (SMA) without Positive Mapping during Awake Surgery

Awake surgery could be a useful modality for lesions locating in close proximity to the eloquent areas including primary motor cortex and pyramidal tract. In case with supplementary motor area (SMA) lesion, we often encounter with intraoperative motor symptoms during awake surgery even in area without positive mapping. Although the usual recovery of the SMA syndrome has been well documented, rare cases with permanent deficits could be encountered in the clinical setting. It has been difficult to evaluate during surgery whether the intraoperative motor symptoms lead to postoperative permanent deficits. The purpose of this study was to demonstrate the intraoperative motor symptoms could be reversible, further to provide useful information for making decision to continue surgical procedure of tumor resection. Eight consecutive patients (from July 2012 to June 2014, six men and two women, aged 33–63 years) with neoplastic lesions around the SMA underwent an awake surgery. Using a retrospective analysis of intraoperative video records, intraoperative motor symptoms during tumor resection were investigated. In continuous functional monitoring during resection of SMA tumor under awake conditions, the following motor symptoms were observed during resection of the region without positive mapping: delayed motor weakness, delay of movement initiation, slowness of movement, difficulty in dual task response, and coordination disturbance. In seven patients hemiparesis observed immediately after surgery recovered to preoperative level within 6 weeks. During awake surgery for SMA tumors, the above-mentioned motor symptoms could occur in area without positive mapping and might be predictors for reversible SMA syndrome.

Transient facial nerve palsy after auriculotemporal nerve block in awake craniotomy patients

In this case series, we describe transient postoperative facial nerve palsy in patients after awake craniotomy using selective scalp nerve blocks. In a 1-year period, 7 of the 42 patients receiving scalp nerve blocks at our institutions developed this complication. This is significant because there is only 1 previously reported case of postoperative facial nerve palsy related to scalp nerve blocks. The exact cause of transient postoperative facial nerve palsy after auriculotemporal nerve block is unknown and likely multifactorial. This technique may need to be refined to avoid such complications.

Awake craniotomy for brain lesions within and near the primary motor area: A retrospective analysis of factors associated with worsened paresis in 102 consecutive patients

Background:

We analyzed factors associated with worsened paresis in a large series of patients with brain lesions located within or near the primary motor area (M1) to establish protocols for safe, awake craniotomy of eloquent lesions.

Methods:

We studied patients with brain lesions involving M1, the premotor area (PMA) and the primary sensory area (S1), who underwent awake craniotomy (n = 102). In addition to evaluating paresis before, during, and one month after surgery, the following parameters were analyzed: Intraoperative complications; success or failure of awake surgery; tumor type (A or B), tumor location, tumor histology, tumor size, and completeness of resection.

Results:

Worsened paresis at one month of follow-up was significantly associated with failure of awake surgery, intraoperative complications and worsened paresis immediately after surgery, which in turn was significantly associated with intraoperative worsening of paresis. Intraoperative worsening of paresis was significantly related to preoperative paresis, type A tumor (motor tract running in close proximity to and compressed by the tumor), tumor location within or including M1 and partial removal (PR) of the tumor.

Conclusions:

Successful awake surgery and prevention of deterioration of paresis immediately after surgery without intraoperative complications may help prevent worsening of paresis at one month. Factors associated with intraoperative worsening of paresis were preoperative motor deficit, type A and tumor location in M1, possibly leading to PR of the tumor.

Stereotactic iodine-125 brachytherapy for the treatment of WHO grades II and III gliomas located in the central sulcus region

BACKGROUND

Resection of gliomas located in eloquent brain areas remains a neurosurgical challenge. The reported incidence of transient or permanent neurological deficits after microsurgery in eloquent brain ranges 20%-100%, or 0%-47% among contemporary neurosurgical series. The aim of this study was to assess the feasibility of stereotactic brachytherapy (SBT) as a local treatment alternative to microsurgical resection for patients with gliomas in highly eloquent areas, located in the central sulcus region (CSR).

METHOD

Between 1997 and 2010, 60 patients with World Health Organization (WHO) grades II and III gliomas located in the CSR were treated with SBT (iodine-125 seeds; cumulative therapeutic dose, 50-65 Gy). Following SBT, WHO grade III glioma patients additionally received percutaneous radiotherapy (median boost dose, 25.2 Gy). We evaluated procedure-related complications, clinical outcome, and progression-free survival.

RESULTS

Procedure-related mortality was zero. Within 30 days of SBT, 3 patients (5%) had transient neurological deficits, and 8 patients (13%) had temporarily increased seizure activity. One patient (1.6%) deteriorated permanently. Space-occupying cysts (6 patients) and radiation necrosis (1 patient) developed after a median of 38 months and required surgical intervention. Seizure activity, rated 12 months following SBT, decreased in 82% of patients (Engel classes I-III). Median progression-free survivals were 62.2 ± 19.7 months (grade II gliomas) and 26.1 ± 17.9 months (grade III gliomas).

CONCLUSIONS

Compared with microsurgical resection, SBT harbors a low risk of procedural complications, is minimally invasive, and seems to be an effective local treatment option for patients with inoperable, eloquent WHO grade II and III gliomas in the CSR. However, the value of SBT for treating gliomas still needs to be determined in prospective, randomized studies.

Training anesthesiology residents in providing anesthesia for awake craniotomy: learning curves and estimate of needed case load

STUDY OBJECTIVE

To measure the learning curves of residents in anesthesiology in providing anesthesia for awake craniotomy, and to estimate the case load needed to achieve a "good-excellent" level of competence.

DESIGN

Prospective study.

SETTING

Operating room of a university hospital.

SUBJECTS

7 volunteer residents in anesthesiology.

MEASUREMENTS

Residents underwent a dedicated training program of clinical characteristics of anesthesia for awake craniotomy. The program was divided into three tasks: local anesthesia, sedation-analgesia, and intraoperative hemodynamic management. The learning curve for each resident for each task was recorded over 10 procedures. Quantitative assessment of the individual's ability was based on the resident's self-assessment score and the attending anesthesiologist's judgment, and rated by modified 12 mm Likert scale, reported ability score visual analog scale (VAS). This ability VAS score ranged from 1 to 12 (ie, very poor, mild, moderate, sufficient, good, excellent). The number of requests for advice also was recorded (ie, resident requests for practical help and theoretical notions to accomplish the procedures).

MAIN RESULTS

Each task had a specific learning rate; the number of procedures necessary to achieve "good-excellent" ability with confidence, as determined by the recorded results, were 10 procedures for local anesthesia, 15 to 25 procedures for sedation-analgesia, and 20 to 30 procedures for intraoperative hemodynamic management.

CONCLUSIONS

Awake craniotomy is an approach used increasingly in neuroanesthesia. A dedicated training program based on learning specific tasks and building confidence with essential features provides "good-excellent" ability.

Damage to the left ventral, arcuate fasciculus and superior longitudinal fasciculus-related pathways induces deficits in object naming, phonological language function and writing, respectively

The anatomic localization of brain functions can be characterized via diffusion tensor imaging in patients with brain tumors and neurological symptoms. The goal of the present study was to evaluate the function of the ventral, arcuate fasciculus (AF) and the superior longitudinal fasciculus (SLF)-related language pathways using these techniques by analyzing 9 patients treated in our hospital between 2007 and 2011. In cases 1-3, the left ventral pathways, namely, the inferior longitudinal fasciculus, uncinate fasciculus or inferior fronto-occipital fasciculus, were mainly damaged, and the common dysfunction experienced by these patients was a deficit in object naming. In cases 4-6, the left SLF was mainly damaged, and the common deficit was dysgraphia. In cases 7-9, the left AF was mainly damaged, and almost all language functions related to phonology were abnormal. These results suggest that the left ventral, AF and SLF-related pathways are closely related to visual, auditory and hand-related language function, respectively.

Awake mapping for resection of cavernous angioma and surrounding gliosis in the left dominant hemisphere: surgical technique and functional results: clinical article

OBJECT

Maximal resection of symptomatic cavernous angioma (CA), including its surrounding gliosis if possible, has been recommended to minimize the risk of seizures or (re)bleeding. However, despite recent neurosurgical advances, such extensive CA removal is still a challenge in eloquent areas. The authors report a consecutive series of patients who underwent awake surgery for CA within the left dominant hemisphere in which intraoperative cortical-subcortical electrical stimulation was used.

METHODS

Nine patients harboring a CA that was revealed by seizures in 6 cases and bleeding in 3 cases underwent resection. All CAs were located in the left dominant hemisphere: 3 temporal, 2 insular, 2 parietal, and 2 in the parietotemporal region. Awake mapping was performed in all cases by using intraoperative cortical-subcortical electrical stimulation and ultrasonography (except in 1 insular CA in which a neuronavigation system was used).

RESULTS

Total removal of the CA was achieved in all patients, with identification and preservation of language and sensory-motor structures. In addition, the pericavernomatous gliosis was removed in 7 cases, according to the functional boundaries provided by intraoperative subcortical stimulation. In 2 cases, subcortical mapping revealed eloquent areas within the surrounding gliosis, which was voluntarily avoided. There was no postsurgical permanent deficit, no rebleeding, and no epilepsy in 7 cases (2 patients had rare seizures in the 1st year or two after surgery, and then complete arrest), with a mean follow-up of 28.5 months (range 3-64 months).

CONCLUSIONS

These results suggest that intraoperative cortical-subcortical stimulation in awake patients represents a valuable adjunct to image-guided surgery with the aim of selecting the safer surgical approach for CAs involving eloquent areas. Moreover, such online mapping can be helpful when removing the pericavernomatous gliosis while preserving functional structures, which can persist within the hemosiderin rim. Thus, the authors propose that awake surgery be routinely considered, both to optimize the resection and to improve the quality of life through seizure control and avoidance of (re)bleeding for CAs located in the left dominant hemisphere.

Right temporal lobe plays a role in verbal memory

OBJECTIVES

Comparison of preoperative and postoperative neurological functions in patients undergoing resection of brain tumors, in combination with data from diffusion tensor imaging (DTI) studies, can provide direct evidence of anatomical localization of brain function. The goal of the present study was to use these techniques to characterize memory function of the right temporal lobe in five patients with right temporal lobe brain tumors.

METHODS

Memory function was tested using the Wechsler Memory Scale-Revised (WMS-R) before and after surgery in five patients with right temporal lobe brain tumors. Preoperative DTI was performed in four of five cases.

RESULTS

In all cases, general and verbal memory, including verbal paired association, significantly improved after surgery (P<0.05). The right inferior longitudinal fasciculus (ILF) was compressed by the tumor in all cases.

CONCLUSION

These results suggest that the right temporal lobe plays a role in verbal memory and that this function may be associated with the right ILF.

Left or right temporal lesion might induce aggression or escape during awake surgery, respectively: role of the amygdala

OBJECTIVE

Some patients with temporal lobe brain tumours show aggressive or escape behaviour during awake surgery. As the amygdala plays a critical role in coping with stress, we evaluated whether the left or right amygdala was involved in aggressive or escape behaviour in six patients undergoing awake surgery for temporal lobe brain tumours.

METHODS

Brain tumours were located in the left temporal lobe in cases 1-3 and in the right temporal lobe in cases 4-6. In cases 1, 2, 4 and 5, the tumours invaded the amygdala.

RESULTS

In case 1, the patient showed aggressive behaviour before partial removal of the left amygdala during awake surgery; just after partial removal of left amygdala, the patient was calm and cooperative. In case 2, the patient showed aggressive behaviour when the tumour near the left amygdala was removed. In case 3, the patient showed aggressive behaviour when awakening during awake surgery. In case 4, the patient showed escape behaviour when removal of the tumour near the right amygdala was initiated. In cases 5 and 6, patients showed escape behaviour upon awakening and upon initiation of tumour removal from the temporal lobe.

CONCLUSION

In conclusion, these results suggest that left or right temporal lesions might induce aggressive or escape behaviour during awake surgery, respectively, and that the amygdala on the respective side may play a role in these behaviours.

Operative treatment of subcortical metastatic tumours in the central region

The operative treatment of subcortical metastatic tumours within the paracentral area is still under discussion. Against the background of possible new postoperative neurological deficits and of evolving new radio oncological techniques, the indication for surgery is limited only to a subgroup of patients. In this retrospective study we present the clinical results after operative treatment of metastases within the central and paracentral brain region, with an emphasis on the short-term and mid-term functional outcome. We report on 20 patients suffering from subcortical brain metastases within the primary sensorimotor area, with a median volume on MRI-scans of 8.18 cm³. Patients were admitted to our department with a progressive hemiparesis (n = 11), focal seizures (n = 6) or other unspecific symptoms (n = 3) like headache, nausea, and neuropsychological disturbances, respectively. After updated MRI- and fMRI-scanning, intensive electrophysiological testing including MEP-brain mapping and interdisciplinary tumour-board discussion of each case, those patients were evaluated for surgery. Early postoperative control was done by MRI within the first 48 h. Follow-up took place in our outpatient department, assessing clinical criteria two and 6 weeks postoperatively, followed by clinical control and MRI-scans every 3 months. In all patients, surgery was performed under general anaesthesia, cranial neuro navigation and intraoperative motor cortex stimulation. Surgery and the early postoperative course were uneventful in all cases. After a 6 months follow-up, two patients had died. The motor deficits improved in seven patients and remained unchanged in four cases. One patient suffered from a new persistent hemiparesis. A temporary paresis occurred in two cases. In five patients there was no motor deficit pre- and postoperatively. The Karnofsky Performance Status improved in ten patients 6 months after surgery. Quality of Life, measured by the FACT-Br score, improved in 12 patients and remained unchanged in one patient. With modern techniques like fMRI-guided cranial neuronavigation and intraoperative neuromonitoring including direct stimulation of the motor cortex, microsurgical resection of subcortical paracentral metastases is feasible with an acceptable risk of neurological deterioration. Even preexistent deficits can improve with positive influence on the quality of life for oncological patients, being disabled by the symptoms caused by the cerebral lesion.

Advantages and disadvantages of awake surgery for brain tumours in the primary motor cortex: institutional experience and review of literature

Patients undergoing awake surgery for resection of brain tumours in the primary motor cortex (M1) are at high risk of developing new motor deficits. Thus, use of this procedure requires consideration of several important points, including the optimal modality to localise M1 on the affected side and the overall advantages and disadvantages of the procedure. In our experience with awake surgery for 21 brain tumours located in the M1 from January 2004 through October 2008, we found that functional magnetic resonance imaging was the most reliable modality in terms of localising the M1 and that the anatomic relationship between motor tracts and brain tumours is a critical determinant of postoperative motor function. Other considerations, including potential complications of this procedure and relative efficacy and safety versus surgery under general anaesthesia for patients with brain tumours in the M1, are discussed.

Relationships between brain tumor and optic tract or calcarine fissure are involved in visual field deficits after surgery for brain tumor

PURPOSE

Diffusion tensor tractography provides useful information regarding the surgical strategy for brain tumors. The goal of the present study was to analyze relationships between visual field deficits and the locations of brain tumors compared with optic tracts as visualized by tractography, and compared with the calcarine fissure.

METHODS

Subjects comprised 11 patients with brain tumor in the occipital lobe or atrium of the lateral ventricle who underwent surgery between October 2006 and February 2009. Tumors were categorized as Type A, with almost all the optic tract in the occipital lobe or atrium of the lateral ventricle running close to and stretched by the brain tumor; and Type B, with the optic tract running at least partially distant to the brain tumor and remaining unstretched.

RESULTS

Those type A optic tracts that were laterally compressed by brain tumors (Cases 1-3) displayed hemianopsia after surgery. When the brain tumor was located rostro-medial to the calcarine fissure and optic tracts were compressed caudally by the tumor, lower quadrant hemianopsia remained after surgery (Cases 4, 5). In other cases, the visual field remained or improved to normal after surgery.

CONCLUSION

The relationship between optic tracts or the calcarine fissure, and brain tumors in the occipital lobe or atrium of the lateral ventricle is related to visual field deficits after surgery. In particular, those Type A optic tracts that are compressed laterally show hemianopsia of the visual field after surgery.

'Anesthesia' for awake neurosurgery

PURPOSE OF REVIEW

In this review we focus on recent findings in the anesthetic management of patients undergoing craniotomy while awake, and propose a structured approach to the clinical practice of 'anesthesia' for awake neurosurgery.

RECENT FINDINGS

The increasing use of functional neurosurgery and recent evidence favoring resection of tumor involving eloquent cortex has expanded the indications for awake craniotomy, a procedure needing a fully cooperative patient and expert intraoperative anesthetic management. Despite the shorter hospital stay, the more recently published studies have highlighted perioperative anesthetic complications and have proposed ways to improve anesthesia techniques for awake procedures in adults and children.

SUMMARY

Although anesthesia for awake craniotomy is usually a well tolerated procedure it requires an extensive knowledge of the principles underlying neuroanesthesia and of specific technical strategies including local anesthesia for scalp blockade, advanced airway management, dedicated sedation protocols, and skillful management of hemodynamics.

Damage to the right superior longitudinal fasciculus in the inferior parietal lobe plays a role in spatial neglect

Functional neurological changes after surgery combined with data from diffusion tensor imaging (DTI) studies can provide direct evidence of anatomical localization of brain function. The goal of the present study was to characterize mechanisms of spatial neglect using these techniques by analyzing two patients with development or worsening of left neglect after surgery at our hospital in 2008. In both cases, the surgical approach was via the right inferior parietal lobes, and damage to the superior longitudinal fasciculus (SLF) was demonstrated after surgery by DTI tractography. By contrast, neither the inferior longitudinal fasciculus (ILF) nor the inferior fronto-occipital fasciculus (IFOF) was damaged. These results suggest that damage to the right SLF in the inferior parietal lobe plays a critical role in the development of spatial neglect.