Mechanical Accuracy of a New Stereotactic Guide

Summary ? Objective. A new stereotactic guide using a navigational computer is developed for stereotactic procedures. In order to compare the mechanical accuracy of the guide to frame based systems, an error analysis study was designed.  Methods. A biopsy procedure was simulated using a phantom model. Targets with known co-ordinates in a three-dimensional Cartesian co-ordinate system were positioned inside the skull model. A biopsy needle was inserted along computer set trajectories from three different entry points. The position of the biopsy needle in the co-ordinate system was measured. Distance from needle tip to target was calculated and defined as the error of the system for each trial. The results were statistically analyzed for precision and biasedness.  Results. A total of 242 accuracy measurements (182 on two MRI scans, 60 on one CT scan) were carried out. Mean incision length along the trajectories was 59 mm. Mean error using MRI scans was 3.8 mm and for the CT scan 2.9 mm. The error of the stereotactic computer was found to be 1.0 mm with both MR and CT imaging. The main cause of error for the MRI based trials was distortion of the magnetic field.  Conclusion. The results indicate a stereotactic system with high degree of accuracy. This is confirmed by a clinical study of 39 biopsies where all tumours were reached. MRI affected the mechanical accuracy significantly due to distortion of the magnetic field. The accuracy is comparable to other studies performed on both stereotactic computers and frame based systems.     

CT-Based Needle Marking of Superficial Intracranial Lesions for Minimal Invasive Neurosurgery

A CT-based method of marking superficial intracranial lesions with a needle is presented. This form of neuronavigation can be applied in every neurosurgical centre. Owing to its rapid application it is also suitable for cases of emergency. The neurosurgical approach can be centred precisely over the lesion providing for a minimally invasive operation. The method has proved its efficacy in numerous cases of haematomas and cystic lesions.     

Biopsia cerebral estereotáctica sin marco: capacidad diagnóstica y complicaciones

ObjectiveThe aim of this study was to evaluate the variables that could modify the diagnostic yield of frameless stereotactic biopsy, as well as its complications.Materials and methodThis was a retrospective study of frameless stereotactic biopsies carried out between July 2008 and December 2011 at Donostia University Hospital. The variables studied were size, distance to the cortex, contrast uptake and location.ResultsA total of 70 patients were included (75 biopsies); 39 males and 31 females with an age range between 39 and 83 years.The total diagnostic yield in our series was 97.1%. For lesions >19 mm, the technique offered a sensitivity of 95.2% (95% CI: 86.9-98.4) and specificity of 57.1% (95% CI: 25.0-84.2). The yield was lower for lesions within 17 mm of the cortex: sensitivity of 74.6% (95% CI: 62.1-84.7) and specificity of 71.4% (95% CI: 29.0-96.3).Seven (10%) patients developed complications after the first biopsy and none after the second.ConclusionsThe diagnostic yield was lower for lesions less than 2 cm in size and located superficially.In this series we did not observe an increased rate of complications after a second biopsy.     

无框架机器人引导立体定向核团毁损手术治疗帕金森病的疗效分析

目的应用无框架脑立体定向仪（CAS-R-2型）进行机器人引导立体定向毁损术治疗帕金森病（PD）,观察其临床疗效。方法对2001年11月至2006年10月间,海军总医院神经外科行机器人引导立体定向单侧核团毁损术治疗帕金森病56例患者的临床及随访资料进行分析,取得术前及术后6个月、1年、3年、5年的帕金森病国际统一评定量表（uPDRS）的评分,并比较它们之间的差异。结果手术结果与术前相比,均有显著性差异（￡检验,P〈0．05）;术后6个月、1年、3年,“开”、“关”期UPDRS评分的改善率明显比术后5年高。结论核团毁损术治疗PD术后疗效肯定,但呈逐渐减退趋势,术后5年的改善率明显降低。机器人系统具有减轻患者痛苦、方便术者操作、提高手术安全性的优势。     

磁共振导航引导下的无框架立体定向神经外科

目的 开放式磁共振结合导航系统，可以获得准确的手术定位、对手术器械的实时引导和术中监控。本文探讨磁共振导航应用于无框架立体定向神经外科的初步经验、可能的并发症及应用前景。方法 使用Philip公司的0．23T开放式磁共振结合iPath200光学导航系统，对4例脑占位及4例脑脓肿患者分别施行脑活检和脓肿穿刺抽吸术。结果 所有患者均获得穿刺针的准确定位。4例脑活检取得足够的组织样本，术后无并发症出现；4例脑脓肿术后影像资料证实脓肿腔体积缩小50％以上，1例小脑脓肿患者死亡，死亡原因为多器官功能衰竭，其余患者神经功能缺损症状均有不同程度的改善，未发生手术所致并发症。结论 磁共振导航应用于脑活检和脑内囊性病变的穿刺引流，手术成功率高，对患者损伤小，很少发生严重并发症。     

Stereotactic catheter placement for Ommaya reservoirs

Ommaya reservoirs are an important surgical therapy for the chronic intrathecal administration of chemotherapy for patients with leptomeningeal carcinomatosis. Surgical accuracy is paramount in these patients with typically normal sized ventricles, and may be improved with stereotactic guidance. This paper aimed to review a large series of stereotactic Ommaya catheter placements, examining accuracy and complications. We conducted a retrospective review of 109 consecutive adult patients who underwent stereotactic Ommaya catheter placement for leptomeningeal carcinomatosis or central nervous system lymphoma at Columbia University Medical Center, USA, from 1998–2013. The rate of accurate placement in the ventricular system was 99%, with the only poor catheter position due to post-placement migration. The rate of peri-operative complications was 6.4%. Hemorrhagic complications occurred in patients with thrombocytopenia or therapeutic anti-coagulation pre-operatively or during the post-operative period. Use of stereotaxy for catheter placement of Ommaya reservoirs is safe and effective, and should be considered when placing a catheter into non-hydrocephalic ventricles.     

Clinical evaluation of stereotactic brain biopsies with an MKM-mounted instrument holder

Summary ¶Object. The aim of this study was to assess the clinical usefulness and accuracy of robot-assisted frameless stereotactic brain biopsies with a recently introduced MKM-mounted instrument holder. Methods. Twenty-three patients with intracranial lesions participated in this study. Depending on the size of the intracranial lesion, fiducials for image-to-patient co-ordinate transformation consisted either of bone screws or adhesive markers. Shortly after surgery, postoperative MRI-imaging was performed to demonstrate the location of the biopsy site. These images were compared with the preoperative images to assess the biopsy localisation error. Results. Postoperative biopsy sites could be demonstrated in six patients with bone screws and in 14 with adhesive markers. These two subgroups yielded average biopsy localisation errors of 3.3mm (SD 1.7mm) and 4.5mm (SD 2.0mm) respectively. This difference was not statistically significant. One biopsy was located in a liquefied haematoma. All others yielded pathological tissue. There were two postoperative haemorrhages, of which only one was temporarily symptomatic. There was no mortality in the first 30 days after surgery. Conclusions. Robot-assisted frameless point-stereotactic techniques represent an alternative to frame-based techniques for the performance of stereotactic biopsies.Published online September 18, 2003     

A review of perioperative complications during frameless stereotactic surgery: our institutional experience

Purpose  Frameless stereotactic neurosurgery is increasingly being used for the biopsy of intracranial tumors and the resection of deep-seated lesions where reliance on surface anatomic landmarks can be misleading, as well as in movement disorders, psychiatric disorders, seizure disorders, and chronic refractory pain. Nascent biological approaches, including gene therapy and stem-cell and tissue transplants for movement disorders, also utilize neuronavigational techniques. These procedures are complex and involve understanding of the basic principles and factors affecting neuronavigation. The procedure may appear to be simple, but serious complications may occur. Methods  The purpose of this study was to review the intraoperative and postoperative complications occurring during frameless stereotaxy at our institution from January 2003 to July 2007. Results  Seventy-eight patients underwent various neurosurgical procedures under general anesthesia. Intraoperative complications seen were intraoperative brain bulge (n = 3), seizures (n = 3), failure to extubate (n = 4), and fresh neurodeficits (n = 6). No hemodynamic disturbances such as hypertension or hypotension or bradycardia or tachycardia requiring active intervention were observed. Conclusion  Awareness and vigilance can help in the early identification and better management of the above intraoperative complications.