Intraoperative imaging technology to maximise extent of resection for glioma: a network meta-analysis

BACKGROUND

Multiple studies have identified the prognostic relevance of extent of resection in the management of glioma. Different intraoperative technologies have emerged in recent years with unknown comparative efficacy in optimising extent of resection. One previous Cochrane Review provided low- to very low-certainty evidence in single trial analyses and synthesis of results was not possible. The role of intraoperative technology in maximising extent of resection remains uncertain. Due to the multiple complementary technologies available, this research question is amenable to a network meta-analysis methodological approach.

OBJECTIVES

To establish the comparative effectiveness and risk profile of specific intraoperative imaging technologies using a network meta-analysis and to identify cost analyses and economic evaluations as part of a brief economic commentary.

SEARCH METHODS

We searched CENTRAL (2020, Issue 5), MEDLINE via Ovid to May week 2 2020, and Embase via Ovid to 2020 week 20. We performed backward searching of all identified studies. We handsearched two journals, Neuro-oncology and the Journal of Neuro-oncology from 1990 to 2019 including all conference abstracts. Finally, we contacted recognised experts in neuro-oncology to identify any additional eligible studies and acquire information on ongoing randomised controlled trials (RCTs).

SELECTION CRITERIA

RCTs evaluating people of all ages with presumed new or recurrent glial tumours (of any location or histology) from clinical examination and imaging (computed tomography (CT) or magnetic resonance imaging (MRI), or both). Additional imaging modalities (e.g. positron emission tomography, magnetic resonance spectroscopy) were not mandatory. Interventions included fluorescence-guided surgery, intraoperative ultrasound, neuronavigation (with or without additional image processing, e.g. tractography), and intraoperative MRI.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the search results for relevance, undertook critical appraisal according to known guidelines, and extracted data using a prespecified pro forma.

MAIN RESULTS

We identified four RCTs, using different intraoperative imaging technologies: intraoperative magnetic resonance imaging (iMRI) (2 trials, with 58 and 14 participants); fluorescence-guided surgery with 5-aminolevulinic acid (5-ALA) (1 trial, 322 participants); and neuronavigation (1 trial, 45 participants). We identified one ongoing trial assessing iMRI with a planned sample size of 304 participants for which results are expected to be published around winter 2020. We identified no published trials for intraoperative ultrasound. Network meta-analyses or traditional meta-analyses were not appropriate due to absence of homogeneous trials across imaging technologies. Of the included trials, there was notable heterogeneity in tumour location and imaging technologies utilised in control arms. There were significant concerns regarding risk of bias in all the included studies. One trial of iMRI found increased extent of resection (risk ratio (RR) for incomplete resection was 0.13, 95% confidence interval (CI) 0.02 to 0.96; 49 participants; very low-certainty evidence) and one trial of 5-ALA (RR for incomplete resection was 0.55, 95% CI 0.42 to 0.71; 270 participants; low-certainty evidence). The other trial assessing iMRI was stopped early after an unplanned interim analysis including 14 participants; therefore, the trial provided very low-quality evidence. The trial of neuronavigation provided insufficient data to evaluate the effects on extent of resection. Reporting of adverse events was incomplete and suggestive of significant reporting bias (very low-certainty evidence). Overall, the proportion of reported events was low in most trials and, therefore, issues with power to detect differences in outcomes that may or may not have been present. Survival outcomes were not adequately reported, although one trial reported no evidence of improvement in overall survival with 5-ALA (hazard ratio (HR) 0.82, 95% CI 0.62 to 1.07; 270 participants; low-certainty evidence). Data for quality of life were only available for one study and there was significant attrition bias (very low-certainty evidence).

AUTHORS' CONCLUSIONS

Intraoperative imaging technologies, specifically 5-ALA and iMRI, may be of benefit in maximising extent of resection in participants with high-grade glioma. However, this is based on low- to very low-certainty evidence. Therefore, the short- and long-term neurological effects are uncertain. Effects of image-guided surgery on overall survival, progression-free survival, and quality of life are unclear. Network and traditional meta-analyses were not possible due to the identified high risk of bias, heterogeneity, and small trials included in this review. A brief economic commentary found limited economic evidence for the equivocal use of iMRI compared with conventional surgery. In terms of costs, one non-systematic review of economic studies suggested that, compared with standard surgery, use of image-guided surgery has an uncertain effect on costs and that 5-ALA was more costly. Further research, including completion of ongoing trials of ultrasound-guided surgery, is needed.

Access to Technology and Education for the Development of Minimally Invasive Spine Surgery Techniques in Latin America

OBJECTIVE

To evaluate access to the technologies and education needed to perform minimally invasive spine surgery (MISS) in Latin America.

METHODS

We designed a questionnaire to evaluate surgeons' practice characteristics, access to different technologies, and training opportunities for MISS techniques. The survey was sent to members and registered users of AO Spine Latin from January 6-20, 2020. The major variables studied were nationality, specialty (orthopedics or neurosurgery), level of hospital (primary, secondary, tertiary), number of surgeries performed per year by the spine surgeon, types of spinal pathologies commonly managed, and number of MISS performed per year. Other variables involved specific access to different technologies: intraoperative fluoroscopy, percutaneous screws, cages, tubular retractors, microscopy, intraoperative computed tomography, neuronavigation imaging, and bone morphogenetic protein. Finally, participants were asked about main obstacles to performing MISS and their access to education on MISS techniques in their region.

RESULTS

The questionnaires were answered by 306 members of AO Spine Latin America across 20 different countries. Most answers were obtained from orthopedic surgeons (57.8%) and those with over 10 years of experience (42.4%). Most of the surgeons worked in private practice (46.4%) and performed >50 surgeries per year (44.1%), but only 13.7% performed >50 MISS per year, mainly to manage degenerative pathologies (87.5%). Most surgeons always had access to fluoroscopy (79%). Only 26% always had access to percutaneous screws, 24% to tubular retractors, 34.3% to cages (anterior lumbar interbody fusion, lateral lumbar interbody fusion, or transforaminal lumbar interbody fusion), and 43% to microscopy. Regarding technologies, 71% reported never having access to navigation, 83% computed tomography, and 69.3% bone morphogenetic protein. The main limitations expressed for widely used MISS technologies were the high implant costs (69.3%) and high navigation costs (49.3%). Most surgeons claimed access to online education activities (71%), but only 44.9% reported access to face-to-face events and 28.8% to hands-on activities, their limited access largely because the courses were expensive (62.7%) or few courses were available on MISS in their region (51.3%).

CONCLUSIONS

Most surgeons in Latin America have limited resources to perform MISS, even in private practice. The main constraints are implant costs, access to technologies, and limited face-to-face educational opportunities.

Use of frameless neuronavigation for bedside placement of external ventricular catheters

Neuronavigation for placement of ventricular catheters has been described. At our institution, electromagnetic neuronavigation is frequently utilized for difficult ventricular catheter placement. In patients who develop a trapped ventricle as a result of an intraparenchymal or intraventricular mass lesion, successful catheter placement may be difficult, as the location and trajectory are unfamiliar. The authors report their experience using electromagnetic neuronavigation for bedside placement of external ventricular catheters in patients with trapped ventricles. The technique for bedside placement of external ventricular catheters utilizing electromagnetic neuronavigation is reviewed. The benefits of this technique and those patients in whom it may be most useful are discussed. Utilization of bedside electromagnetic neuronavigation for placement of difficult external ventricular catheters into trapped ventricles is an option for accurate navigated catheter placement. Bedside electromagnetic neuronavigation offers accurate catheter placement in awake patients. This technique may be utilized in patients with high perioperative risk factors as it does not require general anesthesia. The procedure is well tolerated as it does not require rigid head fixation.

Endoscopic and keyhole endoscope-assisted neurosurgical approaches: a qualitative survey on technical challenges and technological solutions

INTRODUCTION

The literature reflects a resurgence of interest in endoscopic and keyhole endoscope-assisted neurosurgical approaches as alternatives to conventional microsurgical approaches in carefully selected cases. The aim of this study was to assess the technical challenges of neuroendoscopy, and the scope for technological innovations to overcome these barriers.

MATERIALS AND METHODS

All full members of the Society of British Neurosurgeons (SBNS) were electronically invited to participate in an online survey. The open-ended structured survey asked three questions; firstly, whether the surgeon presently utilises or has experience with endoscopic or endoscope-assisted approaches; secondly, what they consider to be the major technical barriers to adopting such approaches; and thirdly, what technological advances they foresee improving safety and efficacy in the field. Responses were subjected to a qualitative research method of multi-rater emergent theme analysis.

RESULTS

Three clear themes emerged: 1) surgical approach and better integration with image-guidance systems (20%), 2) intra-operative visualisation and improvements in neuroendoscopy (49%), and 3) surgical manipulation and improvements in instruments (74%).

DISCUSSION

The analysis of responses to our open-ended survey revealed that although opinion was varied three major themes could be identified. Emerging technological advances such as augmented reality, high-definition stereo-endoscopy, and robotic joint-wristed instruments may help overcome the technical difficulties associated with neuroendoscopic approaches.

CONCLUSIONS

Results of this qualitative survey provide consensus amongst the technology end-user community such that unambiguous goals and priorities may be defined. Systems integrating these advances could improve the safety and efficacy of endoscopic and endoscope-assisted neurosurgical approaches.

Magnetic resonance neurography and diffusion tensor imaging: origins, history, and clinical impact of the first 50,000 cases with an assessment of efficacy and utility in a prospective 5000-patient study group

OBJECTIVE

Methods were invented that made it possible to image peripheral nerves in the body and to image neural tracts in the brain. The history, physical basis, and dyadic tensor concept underlying the methods are reviewed. Over a 15-year period, these techniques-magnetic resonance neurography (MRN) and diffusion tensor imaging-were deployed in the clinical and research community in more than 2500 published research reports and applied to approximately 50,000 patients. Within this group, approximately 5000 patients having MRN were carefully tracked on a prospective basis.

METHODS

A uniform Neurography imaging methodology was applied in the study group, and all images were reviewed and registered by referral source, clinical indication, efficacy of imaging, and quality. Various classes of image findings were identified and subjected to a variety of small targeted prospective outcome studies. Those findings demonstrated to be clinically significant were then tracked in the larger clinical volume data set.

RESULTS

MRN demonstrates mechanical distortion of nerves, hyperintensity consistent with nerve irritation, nerve swelling, discontinuity, relations of nerves to masses, and image features revealing distortion of nerves at entrapment points. These findings are often clinically relevant and warrant full consideration in the diagnostic process. They result in specific pathological diagnoses that are comparable to electrodiagnostic testing in clinical efficacy. A review of clinical outcome studies with diffusion tensor imaging also shows convincing utility.

CONCLUSION

MRN and diffusion tensor imaging neural tract imaging have been validated as indispensable clinical diagnostic methods that provide reliable anatomic pathological information. There is no alternative diagnostic method in many situations. With the elapsing of 15 years, tens of thousands of imaging studies, and thousands of publications, these methods should no longer be considered experimental.

Safety and efficacy of frameless and frame-based intracranial biopsy techniques

BACKGROUND

Frameless stereotaxy or neuronavigation has evolved into a feasible technology to acquire intracranial biopsies with good accuracy and little mortality. However, few studies have evaluated the diagnostic yield, morbidity, and mortality of this technique as compared to the established standard of frame-based stereotactic brain biopsy. We report our experience of a large number of procedures performed with one or other technique.

PATIENTS AND METHODS

We retrospectively assessed 465 consecutive biopsies done over a ten-year time span; Data from 391 biopsies (227 frame-based and 164 frameless) were available for analysis. Patient demographics, peri-operative characteristics, and histological diagnosis were reviewed and then information was analysed to identify factors associated with the biopsy not yielding a diagnosis and of it being followed by death.

RESULTS

On average, nine tissue samples were taken with either stereotaxy technique. Overall, the biopsy led to a diagnosis on 89.4% of occasions. No differences were found between the two biopsy procedures. In a multiple regression analysis, it was found that left-sided lesions were less likely to result in a non-diagnostic tissue sample (p = 0.023), and cerebellar lesions showed a high risk of negative histology (p = 0.006). Postoperative complications were seen after 12.1% of biopsies, including 15 symptomatic haemorrhages (3.8%). There was not a difference between the rates of complication after either a frame-based or a frameless biopsy. Overall, peri-operative complications (p = 0.030) and deep-seated lesions (p = 0.060) increased the risk of biopsy-related death. Symptomatic haemorrhages resulting in death (1.5% of all biopsies) were more frequently seen after biopsy of a fronto-temporally located lesion (p = 0.007) and in patients with a histologically confirmed lymphoma (p = 0.039).

CONCLUSIONS

The diagnostic yield, complication rates, and biopsy-related mortality did not differ between a frameless biopsy technique and the established frame-based technique. The site of the lesion and the occurrence of a peri-operative complication were associated with the likelihood of failure to achieve a diagnosis and with death after biopsy. We believe that using intraoperative frozen section or cytologic smear histology is essential during a stereotactic biopsy in order to increase the diagnostic yield and to limit the number of biopsy specimens that need to be taken.

Comparison of Frame-Based and Frameless Stereotactic Hematoma Puncture and Subsequent Fibrinolytic Therapy for the Treatment of Supratentorial Deep Seated Spontaneous Intracerebral Hemorrhage

OBJECTIVE

This study compared the technical implications and clinical outcome of patients treated for an intracerebral hemorrhage using two minimally invasive procedures: frame-based stereotactic hematoma aspiration and frameless navigation-guided hematoma aspiration followed by fibrinolysis.

METHODS

Thirty patients with a spontaneous supratentorial intracerebral hemorrhage, which was treated by a frame-based (n=15) and frameless (n=15) hematoma aspiration followed by subsequent fibrinolysis with urokinase, were retrospectively reviewed. The data for the two subsets of patients were analyzed with regard to hematoma reduction, Glasgow Coma Scale (GCS), and degree of weakness.

RESULTS

In the frame-based stereotactic hematoma aspiration group, the volume of the hematoma was 15.4-100.0 mL (mean: 40.7+/-24.4), the GCS upon admission was 4-15 (mean: 10.1+/-3.0), and the grade of weakness upon admission was 1-5 (mean: 2.1+/-0.9). On the other hand, in the frameless navigation-guided hematoma aspiration group, the hematoma volume was 15.2-62.0 mL (mean: 30.0+/-15.2), the GCS upon admission was 7-15 (mean: 13.0+/-2.4), and the grade of weakness upon admission was 1-4 (mean: 2.3+/-1.2). The drainage catheter was in place for a mean duration of 5.1+/-2.4 days (range: 1-12 days). In the frame-based group, the initial hematoma was reduced by -115-88.5% (mean: 52+/-31.5) immediately after surgery, and 90.5% (41-100%) of the initial volume 14 days after surgery. In the frameless group, the initial hematoma was reduced by 11.7-90.8% (mean 57.3+/-25.1) immediately after surgery and 95.8% (87.7-100%) 14 days after surgery. The GCS score and the degree of weakness were evaluated 14 days after surgery, and the Glasgow outcome scale (GOS) score was evaluated at discharge. There were no statistically significant differences between the two groups.

CONCLUSION

The frame-based group and the frameless group followed by fibrinolysis had similar outcomes, and both procedures effectively reduced the intracerebral hemorrhage volume within a short period of time. In addition, these procedures are simple, precise, safe, and brief with a very low rebleeding rate and mortality.

Application of neuronavigation system to brain tumor surgery with clinical experience of 420 cases

A new era of neurosurgery has recently been unveiled with the advent of image-guided surgery. The use of neuronavigation is beginning to have a significant impact on a variety of intracranial procedures. Herein, we report our clinical experience using a neuronavigation system with different surgical applications and techniques for a variety of brain tumors. We used the BrainLab VectorVision neuronavigation system, which is a frameless and image-guided system. We operated on 420 cases having various types of brain tumor with the help of this system. The mean target localizing accuracy and mean volume were 1.15 mm and 30.8 mL (0.2-216.4 mL), respectively. We utilized this system to effectively make bone flaps, to detect critically located, deep-seated, subcortical, skull-base and skull bone tumors, and to operate on intraparenchymal lesions with grossly unclear margins, such as gliomas. We also performed tumor biopsy using the combination of a conventional stereotactic biopsy instrument and an endoscope. The application of the neuronavigation system not only revealed benefits for operative planning, appreciation of anatomy, lesion location and the safety of surgery, but also greatly enhanced surgical confidence.

The Role of Cyberknife Radiosurgery/Radiotherapy for Brain Metastases of Multiple or Large-Size Tumors

OBJECTIVE

Focused, highly targeted radiosurgery and fractionated radiotherapy using the Cyberknife are useful treatments for multiple or large metastases. Here we present our results of Cyberknife radiosurgery for 71 patients with 148 metastatic brain lesions.

METHODS

There were 32 women and 39 men with a median age of 63 (range: 30-88) years. Radiographic follow-up was available for 60 patients with 104 lesions. The mean and median initial volumes of the tumor per lesion were 6.6 and 2.9 cm(3) (range: 0.1-53.2 cm(3)), respectively, at the time of the initial Cyberknife treatment. Forty patients (56%) had a single lesion, and 31 (44%) had multiple lesions (range: 2-7) at initial treatment. The number of fractions ranged from 1 to 3, and forty (27%) of 148 lesions were treated by a fractionated course of Cyberknife therapy. The mean marginal dose was 20.2 Gy (range 7.8-30.1 Gy, median: 20.7 Gy).

RESULTS

At 44 weeks of median follow-up, there were no permanent symptoms resulting from radiation necrosis. Overall 6-month and 1-year survival rates were 74% and 47%, respectively, and the median survival time was 56 weeks. The Karnofsky performance score and extracranial metastasis were significant prognostic factors at 6 months and 1 year, respectively, in both univariate and multivariate analyses. Age or multiple metastases did not influence prognosis at 6 months and 1 year. Local control was achieved in 83% (86 lesions). After additional radiosurgical or surgical salvage, no patient died as a result of intracranial disease. Twenty-five patients developed 92 new metastases (range 1-13) outside of the treated lesions with 22.4 weeks of median follow-up. Among them, 21 patients (84 lesions) were treated by salvage Cyberknife.

CONCLUSION

Despite the inclusion of an unfavorable group of patients with large tumors, our results for survival and tumor control rates are comparable to those of published series. The Cyberknife provides the advantage of allowing for fractionated treatment to multiple or large-size tumors.

Reliable registration of preoperative MRI with histopathology after temporal lobe resections

PURPOSE

Conventional and novel magnetic resonance imaging (MRI) techniques can detect cerebral abnormalities in patients with refractory focal epilepsies. Correlation of preoperative MRI and histopathology is important to validate MRI findings, but in practice is far from straightforward. Peroperative neuronavigation and placement of markers on tissue is of limited use in temporal lobe resections. MRI scanning of the resected specimen for registration with in vivo MRI is complicated by anisotropic tissue deformation. We have developed a method to facilitate registration of preoperative MRI with the resected specimen and to enable correlation of MRI findings with histopathology.

METHODS

Sixteen en bloc temporal lobe resections undertaken for refractory temporal lobe epilepsy were studied. The specimens were fixed in formalin and then cut coronally by using a cradle with parallel blades at 5-mm intervals to ensure evenly thick tissue slices in the same orientation. Volumetric T1-weighted preoperative MRIs were reformatted, and consecutive slices (0.94 mm) cut in the same orientation as the resected lobe were visually compared with photographs of tissue slices by two independent observers.

RESULTS

In 15 (94%) of 16 cases, a <2-mm difference was found between the two observers' matches of MRI slices with tissue slices. In the last case, a 4-mm difference was noted. In all cases, a consensus was reached by the two observers. The suggested MRI-histology matches were within the resections seen on postoperative scans.

CONCLUSIONS

Careful labelling and postoperative handling and slicing ensured histopathologic tissue slices of uniform thickness and slicing angle. This technique can be applied to a range of MRI datasets, enabling exploration of the pathologic basis of abnormalities on conventional and novel MRI acquisitions.

Submillimetrische 3D-Navigation im Felsenbein

BACKGROUND

In order to evaluate the possible submillimeter application accuracy in computer-aided navigation in the petrous bone, we performed a set of approximately 3,000 measurements on a specially prepared anatomic specimen using the Zeiss STN intraoperative navigation system. This allowed direct measurements of relevant anatomic structures in and around the petrous bone which are usually not directly accessible.

RESULTS

We found that the best results can be achieved by exploiting contemporary multislice CT-imaging with 0.5 mm slice thickness and by direct radiologic imaging of the petrous bone; additionally, an extrinsic marker structure, the VBH-referencing element, served as an extension of the applied surface markers for the "patient-to-image" referencing procedure. Interestingly, the additional use of a surface registration, as provided by the STN-navigation system, to potentially optimize the registration, did not improve the results. In the best case, i.e. with high-resolution CT-imaging, 0.5 mm slice spacing, the use of surface markers, and the extrinsic referencing structure applied, an absolute difference between the calculated and actual position of the probe was 0.42+/-0.69 mm.

CONCLUSIONS

These results show that intraoperative 3-D navigation can be successfully transferred to a clinical application in the petrous bone or at the cerebellopontine angle with satisfactory accuracy in this highly sensitive anatomic region, even if only a restricted area of the patient can be used for the referencing procedure.

CyberKnife frameless single-fraction stereotactic radiosurgery for benign tumors of the spine

OBJECT

The role of stereotactic radiosurgery in the treatment of benign intracranial lesions is well established. Its role in the treatment of benign spinal lesions is more limited. Benign spinal lesions should be amenable to radiosurgical treatment similar to their intracranial counterparts. In this study the authors evaluated the effectiveness of the CyberKnife for benign spinal lesions involving a single-fraction radiosurgical technique.

METHODS

The CyberKnife is a frameless radiosurgery system in which an orthogonal pair of x-ray cameras is coupled to a dynamically manipulated robot-mounted linear accelerator possessing six degrees of freedom, whereby the therapy beam is guided to the intended target without the use of frame-based fixation. Cervical spine lesions were located and tracked relative to skull osseous landmarks; lower spinal lesions were tracked relative to percutaneously placed fiducial bone markers. Fifteen patients underwent single-fraction radiosurgery (12 cervical, one thoracic, and two lumbar). Histological types included neurofibroma (five cases), paraganglioma (three cases), schwannoma (two cases), meningioma (two cases), spinal chordoma (two cases), and hemangioma (one case). Radiation dose plans were calculated based on computerized tomography scans acquired using 1.25-mm slices. Planning treatment volume was defined as the radiographic tumor volume with no margin. The tumor dose was maintained at 12 to 20 Gy to the 80% isodose line (mean 16 Gy). Tumor volume ranged from 0.3 to 29.3 ml (mean 6.4 ml). Spinal canal volume receiving more than 8 Gy ranged from 0.0 to 0.9 ml (mean 0.2 ml). All patients tolerated the procedure in an outpatient setting. No acute radiation-induced toxicity or new neurological deficits occurred during the follow-up period. Pain improved in all patients who were symptomatic prior to treatment. No tumor progression has been documented on follow-up imaging (mean 12 months).

CONCLUSIONS

Spinal stereotactic radiosurgery was found to be feasible, safe, and effective for the treatment of benign spinal lesions. Its major potential benefits are the relatively short treatment time in an outpatient setting and the minimal risk of side effects. This new technique offers an alternative therapeutic modality for the treatment of a variety of benign spinal neoplasms in cases in which surgery cannot be performed, in cases with previously irradiated sites, and in cases involving lesions not amenable to open surgical techniques or as an adjunct to surgery.

Preliminary exploration of the clinical effect of bleomycin on craniopharyngiomas

OBJECTIVE

To investigate the antitumor effect of bleomycin on craniopharyngiomas.

METHODS

A series of cystic craniopharyngiomas were randomly divided into three groups: (A) intracystic chemotherapy with bleomycin; (B) intracystic chemo-radiotherapy with bleomycin and (32)P; (C) intracystic radiotherapy with (32)P and 0.9% saline. The agents were injected into the cysts through stereotactically inserted silicone tubes. Follow-up was done for a minimum of 6 months. Outcome was based on a comparison of the volume of cysts before treatment and at follow-up. The index and lactate dehydrogenase (LD) of the cystic fluids, blood and cerebrospinal fluids and the endocrine function of these patients were determined before and after therapy.

RESULTS

19 patients finished the whole therapeutic course: 5 from group A, 9 from group B and 5 from group C. Four tumors in group A were polycystic, and the drug was selectively injected into the largest cyst. At follow-up, the volumes of the cysts in groups A and B regressed from 92 to 0%, while the drug-free cysts enlarged. In group B, 6 cysts almost disappeared and another 3 regressed from 78 to 57%. In group C, one cyst progressed and the others shrank by different degrees, but none disappeared completely or nearly. All patients in groups A and B had fever of different degrees, which resolved spontaneously in 8-24 h. The complications in group B included hyponatremia in 1 patient, and both adephagia obesity and cerebral infarction in 2 patients (1 of whom died after 6 months). Apart from the oculomotor paralysis occurring in 1 patient, the remainder of group C had no other severe complications. Blood chemistry, liver, kidney, pituitary and endocrinal functions changed little during the course in all these 19 patients. LD and its isoenzymes from the cystic fluids, CSF and serum showed no marked change after bleomycin injection.

CONCLUSION

Bleomycin injected into cysts of craniopharyngiomas causes the tumor to shrink. When (32)P is added, the therapeutic effect seems better than treatment with either (32)P or bleomycin alone. Blood chemistry, liver, kidney and endocrine functions change little irrespective of the therapy applied. However, the combination of chemotherapy and radiotherapy may severely disturb both serum electrolytes and endocrine function. LD and its isoenzymes in the cystic fluids, CSF and serum may not change after bleomycin treatment.

Primeros pasos en neuronavegación

INTRODUCTION

We try to evaluate the introduction of a neuronavigation system widely used in a neurosurgical department.

MATERIAL AND METHODS

We analyze the surgical procedures performed since the introduction of a neuronavigator in our hospital, the advantages and the problems related with its use.

RESULTS

From 21/12/00 to 31/12/01, 64 cranial and 5 spinal procedures were performed in our centre with the aid of the BrainLAB neuronavigation system. They were 19.37% of the elective surgeries: 45.7% of cranial and 2.8% of spinal procedures. The accuracy of registration was 1.6 mm; the number of trials for registration was 2.8 on average, although in 3 cases it was not possible; there were disarrangements during 9 surgical procedures (two of them after the lesions were reached). Magnetic resonance imaging (MRI) was used in 54 instances, computerized tomography (CT) in 5, fluoroscopy (Rx) in 1, CT plus MRI in 8, CT plus Rx in 1. Since Z-Touch localization system and software was available, it was used exclusively, disregarding the use of external fiducials.

DISCUSSION AND CONCLUSIONS

In our experience, neuronavigation needs extra time, but it helps in the election of the best position for the surgical approach, reduces the time required for scalp incision and craniotomy planning, and is useful for the opening of the dura and the corticectomy. As the operation proceeds, we found it less truhstworthy and necessary. The Z-touch system frees the imaging from the surgery. Its use in spinal operation is scarce and with limited results in our practice. We found the neuronavigation useful, and we employ it on a regular basis in every cranial procedure whenever it is possible.

Clinical experiences in neuronavigation

We have successfully used a navigation system in more than 120 neurosurgical operations for past two years. The neuronavigation system provides high levels of mechanical accuracy in surgical localization, especially for small deep-seated masses or epileptic foci, surgical planning for intrinsic and extrinsic brain tumors, and arteriovenous malformation and guidance of instrumentation of spinal surgery. The ages of the patients were from 12 months to 75 years. The sex distribution was equal. Computed tomography or magnetic resonance imaging with 2-3 mm thick slices were employed for image guidance. The clinical experiences included 50 cases of deep-seated mass, 50 cases of surgical planning for tumor or vascular mass excision and 20 cases of spinal instrumentation treatment. There were no mechanical failures. Neuronavigation definitely provides a good technology in frameless brain and spinal surgeries.