Neurosurgery Blog

Neurosurgery 72:590–595, 2013

Although exceedingly rare, wrong-site surgery (WSS) remains a persistent problem in the United States. The incidence is thought to be 2 to 3 per 10 000 craniotomies and about 6 to 14 per 10 000 spine surgeries. In July 2004, the Joint Commission mandated the Universal Protocol (UP) for all accredited hospitals.

OBJECTIVE: To assess the effect of UP implementation on the incidence of neurosurgical WSS at the University of Illinois College of Medicine at Peoria/Illinois Neurological Institute.

METHODS: The Morbidity and Mortality Database in the Department of Neurosurgery was reviewed to identify all recorded cases of WSS since 1999. This was compared with the total operative load (excluding endovascular procedures) of all attending neurosurgeons to determine the incidence of overall WSS. A comparison was then made between the incidences before and after UP implementation.

RESULTS: Fifteen WSS events were found with an overall incidence of 0.07% and Poisson 95% confidence interval of 8.4 to 25. All but one of these were wrong-level spine surgeries (14/15). There was only 1 recorded case of wrong-side surgery and this occurred after implementation of the UP. A statistically greater number of WSS events occurred before (n = 12) in comparison with after (n = 3) UP implementation (P < .001).

CONCLUSION: A statistically significant reduction in overall WSS was seen after implementation of the UP. This reduction can be attributed to less frequent wronglevel spine surgery. There was no case of wrong procedure or patient surgery and the 1 case of wrong-side surgery occurred after UP implementation.

Neurosurg Rev (2013) 36:205–214

Historically, brain tumour resection has relied upon standardised anatomical atlases and classical mapping techniques for successful resection. While these have provided adequate results in the past, the emergence of new technologies has heralded a wave of less invasive, patient-specific techniques for the mapping of brain function.

Functional magnetic resonance imaging (fMRI) and, more recently, diffusion tensor imaging (DTI) are two such techniques. While fMRI is able to highlight localisation of function within the cortex, DTI represents the only technique able to elucidate white matter structures in vivo. Used in conjunction, both of these techniques provide important presurgical information for thorough preoperative planning, as well as intraoperatively via integration into frameless stereotactic neuronavigational systems.

Together, these techniques show great promise for improved neurosurgical outcomes. While further research is required for more widespread clinical validity and acceptance, results from the literature provide a clear road map for future research and development to cement these techniques into the clinical setup of neurosurgical departments globally.

Neurosurgery 72[ONS Suppl 1]:ons35–ons46, 2013

This study proposes a 3-dimensional (3-D) template of the insula in the bicommissural reference system with posterior commissure (PC) as the center of coordinates.

OBJECTIVE: Using the bicommissural anterior commissure (AC)–PC reference system, this study aimed to define a template and design a method for the 3-D reconstruction of the human insula that may be used at an individual level during stereotactic surgery.

METHODS: Magnetic resonance imaging (MRI)–based morphometric analysis was performed on 100 cerebral cortices with normal insulae based on a 3-step procedure: Step 1: AC-PC reference system–based reconstruction of the insula from the 1-mm thick 3-D T1-weighted MRI slices. Step 2: Digitalization and superposition of the data obtained in the 3 spatial planes. Step 3: Representation of pixels as colors on a scale corresponding to the probability of localization of each insular anatomic component.

RESULTS: The morphometric analysis of the insula confirmed our previously reported findings of a more complex shape delimited by 4 peri-insular sulci. A very significant correlation between the coordinates of the main insular structures and the length of AC-PC was demonstrated. This close correlation allowed us to develop a method that allows the 3-D reconstruction of the insula from MRI slices and only requires the localization of AC and PC. This process defines an area deemed to contain insula with 100% probability.

CONCLUSION: This 3-D reconstruction of the insula should be useful to improve its localization and other cortical areas and allow the differentiation of insular cortex from opercular cortex. KEY WORDS:

Acta Neurochir (2013) 155:345–353

Monitoring of brain function and metabolism during surgery may be of benefit for patient outcome. Microdialysis is the only sampling technique to date that allows continuous monitoring of drug or metabolite concentrations in the extracellular fluid of multiple tissues in the brain. This qualitative systematic review aimed to determine whether microdialysis is a valid tool for detecting changes in tissue composition as would be expected upon changes in (induced) tissue metabolic composition during brain surgery.

Methods A systematic review was conducted by performing a MEDLINE search using the terms “Intraoperative Period” (Medical Subject Heading [MeSH]) OR “Surgery” [Subheading] OR “Monitoring, Intraoperative” [MeSH] AND “Microdialysis” [MeSH] AND “Brain” [MeSH]. Two reviewers independently assessed the methodological quality of the studies. For each study the grades of recommendation were determined.

Results The search strategy yielded 46 publications in Medline. Data extraction was performed on 16 studies. The methodological quality of studies was low, with overall scores of 4 or 5. A quantitative analysis could not be performed because of lack of sufficient data. A qualitative analysis was positive with regard to the detection of different states of tissue composition by microdialysis. However, the levels of recommendation on the outcome statements were low, resulting in a grade D level of recommendation on all statements.

Conclusions The available evidence for the validity of cerebral microdialysis as a diagnostic tool during brain surgery is of low scientific quality. In order to develop cerebral microdialysis as a valid instrument for monitoring of brain metabolism during surgery, standardised clinical prospective studies in homogeneous patient populations are required.

Neurosurgery 72:A54–A62, 2013

During the past decades, medical applications of virtual reality technology have been developing rapidly, ranging from a research curiosity to a commercially and clinically important area of medical informatics and technology. With the aid of new technologies, the user is able to process large amounts of data sets to create accurate and almost realistic reconstructions of anatomic structures and related pathologies.

As a result, a 3-dimensional (3-D) representation is obtained, and surgeons can explore the brain for planning or training. Further improvement such as a feedback system increases the interaction between users and models by creating a virtual environment. Its use for advanced 3-D planning in neurosurgery is described. Different systems of medical image volume rendering have been used and analyzed for advanced 3-D planning: 1 is a commercial “ready-to-go” system (Dextroscope, Bracco, Volume Interaction, Singapore), whereas the others are open-source-based software (3-D Slicer, FSL, and FreesSurfer).

Different neurosurgeons at our institution experienced how advanced 3-D planning before surgery allowed them to facilitate and increase their understanding of the complex anatomic and pathological relationships of the lesion. They all agreed that the preoperative experience of virtually planning the approach was helpful during the operative procedure.

Virtual reality for advanced 3-D planning in neurosurgery has achieved considerable realism as a result of the available processing power of modern computers. Although it has been found useful to facilitate the understanding of complex anatomic relationships, further effort is needed to increase the quality of the interaction between the user and the model.

Neurosurgery 71:1023–1031, 2012

Assessment of the vasculature is critical for overall success in cranial vascular neurological surgery procedures. Although several methods of monitoring cortical perfusion intraoperatively are available, not all are appropriate or convenient in a surgical environment. Recently, 2 optical methods of care have emerged that are able to obtain high spatial resolution images with easily implemented instrumentation: indocyanine green (ICG) angiography and laser speckle contrast imaging (LSCI).

OBJECTIVE: To evaluate the usefulness of ICG and LSCI in measuring vessel perfusion.

METHODS: An experimental setup was developed that simultaneously collects measurements of ICG fluorescence and LSCI in a rodent model. A 785-nm laser diode was used for both excitation of the ICG dye and the LSCI illumination. A photothrombotic clot model was used to occlude specific vessels within the field of view to enable comparison of the 2 methods for monitoring vessel perfusion.

RESULTS: The induced blood flow change demonstrated that ICG is an excellent method for visualizing the volume and type of vessel at a single point in time; however, it is not always an accurate representation of blood flow. In contrast, LSCI provides a continuous and accurate measurement of blood flow changes without the need of an external contrast agent.

CONCLUSION: These 2 methods should be used together to obtain a complete understanding of tissue perfusion.

Neurosurgery 70:1312–1319, 2012 DOI: 10.1227/NEU.0b013e31824388f8

Emissary veins connect the extracranial venous system with the intracranial venous sinuses. These include, but are not limited to, the posterior condyloid, mastoid, occipital, and parietal emissary veins.

A review of the literature for the anatomy, embryology, pathology, and surgery of the intracranial emissary veins was performed.

Detailed descriptions of these venous structures are lacking in the literature, and, to the authors’, knowledge, this is the first detailed review to discuss the anatomy, pathology, anomalies, and clinical effects of the cranial emissary veins.

Our hope is that such data will be useful to the neurosurgeon during surgery in the vicinity of the emissary veins.

Neurosurgery 70[ONS Suppl 1]:ons65–ons74, 2012 DOI: 10.1227/NEU.0b013e31822f7d7c

Intraoperative measurements of cerebral blood flow are of interest during vascular neurosurgery. Near-infrared indocyanine green (ICG) fluorescence angiography was introduced for visualizing vessel patency intraoperatively. However, quantitative information has not been available.

OBJECTIVE: To report our experience with a microscope with an integrated dynamic ICG fluorescence analysis system supplying semiquantitative information on blood flow.

METHODS: We recorded ICG fluorescence curves of cortex and cerebral vessels using software integrated into the surgical microscope (Flow 800 software; Zeiss Pentero) in 30 patients undergoing surgery for different pathologies. The following hemodynamic parameters were assessed: maximum intensity, rise time, time to peak, time to halfmaximal fluorescence, cerebral blood flow index, and transit times from arteries to cortex.

RESULTS: For patients without obvious perfusion deficit, maximum fluorescence intensity was 177.7 arbitrary intensity units (AIs; 5-mg ICG bolus), mean rise time was 5.2 seconds (range, 2.9-8.2 seconds; SD, 1.3 seconds), mean time to peak was 9.4 seconds (range, 4.9-15.2 seconds; SD, 2.5 seconds), mean cerebral blood flow index was 38.6 AI/s (range, 13.5-180.6 AI/s; SD, 36.9 seconds), and mean transit time was 1.5 seconds (range, 360 milliseconds-3 seconds; SD, 0.73 seconds). For 3 patients with impaired cerebral perfusion, time to peak, rise time, and transit time between arteries and cortex were markedly prolonged (.20, .9 , and .5 seconds). In single patients, the degree of perfusion impairment could be quantified by the cerebral blood flow index ratios between normal and ischemic tissue. Transit times also reflected blood flow perturbations in arteriovenous fistulas.

CONCLUSION: Quantification of ICG-based fluorescence angiography appears to be useful for intraoperative monitoring of arterial patency and regional cerebral blood flow.

Neurosurgery 68:280–290, 2011 DOI: 10.1227/NEU.0b013e3181ff9cbb

Surgery remains the first and most important treatment modality for the majority of solid tumors. Across a range of brain tumor types and grades, postoperative residual tumor has a great impact on prognosis. The principal challenge and objective of neurosurgical intervention is therefore to maximize tumor resection while minimizing the potential for neurological deficit by preserving critical tissue.

OBJECTIVE: To introduce the integration of desorption electrospray ionization mass spectrometry into surgery for in vivo molecular tissue characterization and intraoperative definition of tumor boundaries without systemic injection of contrast agents.

METHODS: Using a frameless stereotactic sampling approach and by integrating a 3-dimensional navigation system with an ultrasonic surgical probe, we obtained image-registered surgical specimens. The samples were analyzed with ambient desorption/ ionization mass spectrometry and validated against standard histopathology. This new approach will enable neurosurgeons to detect tumor infiltration of the normal brain intraoperatively with mass spectrometry and to obtain spatially resolved molecular tissue characterization without any exogenous agent and with high sensitivity and specificity.

RESULTS: Proof of concept is presented in using mass spectrometry intraoperatively for real-time measurement of molecular structure and using that tissue characterization method to detect tumor boundaries. Multiple sampling sites within the tumor mass were defined for a patient with a recurrent left frontal oligodendroglioma, World Health Organization grade II with chromosome 1p/19q codeletion, and mass spectrometry data indicated a correlation between lipid constitution and tumor cell prevalence.

CONCLUSION: The mass spectrometry measurements reflect a complex molecular structure and are integrated with frameless stereotaxy and imaging, providing 3-dimensional molecular imaging without systemic injection of any agents, which can be implemented for surgical margins delineation of any organ and with a rapidity that allows real-time analysis.

Neurosurgery 67:1483–1496, 2010 DOI: 10.1227/NEU.0b013e3181f7eb68

Resection of an intraventricular mass can result in life-altering complications. Many advocate transcallosal rather than transcortical approaches to these lesions, citing differential postoperative seizure risk.

OBJECTIVE: To test the hypothesis that the complication rates and patient outcomes are no different between these ventricular approaches.

METHODS: The medical records of 127 patients (93 adults and 34 children) operated on for intraventricular lesions between 1996 and 2007 were retrospectively analyzed. Risk factors for specific postoperative complications and outcome were assessed by multivariate analysis.

RESULTS: The transcallosal (59%) or transcortical (41%) approach was used. Gross or nearly total resection was achieved in 87% of cases. The permanent neurological complication rate determined by a staff neurologist was 23.6%. Seizure attributable to surgery occurred after 8% of transcortical and 25% of transcallosal operations (P = .01). After controlling for a variety of factors, the transcallosal approach carried a 4.4-fold increased risk of seizure (95% confidence interval, 1.3-18.9). The operative approach was not a risk factor for any other postoperative complication. One year after surgery, 72% of patients had excellent functional outcome (Karnofsky Performance Score $ 70 and Glasgow Outcome Score = 5). High tumor grade and impaired preoperative Karnofsky Performance Score predicted poor outcome. More than 90% of patients operated on for symptomatic colloid cysts (n = 34) had an excellent outcome.

CONCLUSION: Although the 2 traditional approaches to the ventricular system had similar major complication rates, the transcallosal approach was associated with significantly increased seizure risk. Accordingly, the chosen operative corridor should optimize tumor access and the protection of vulnerable neurovascular structures.

Neurosurgery. 66(5):999-1004, May 2010. DOI: 10.1227/01.NEU.0000368443.43565.2A

Advances in medicine have largely followed advances in technology. Medical strides have been made when physicians and researchers have adapted growing science to target specific problems. A new medical field, telemedicine, has emerged that links physicians with colleagues and patients. Cell phone technology is affordable for almost everyone, and basic models include digital photography.

OBJECTIVE: We present a case series exhibiting the utility of digital pictures taken with patients’ cell phones.

CLINICAL PRESENTATION: Our patients had wound infections requiring daily intravenous antibiotics and dressing changes. Previously, these patients would have required prolonged hospitalizations. Currently, patients with these infections are discharged from the hospital, but close outpatient observation is required to monitor the wound. Our patients lived up to 8 hours away from the hospital. Daily appointments for wound checks in the clinic were impractical. Wounds were monitored via cell phone images without the inconvenience of travel and the expense of a local hotel, and unnecessary appointments in the clinic.

INTERVENTION: Wound evaluations were conducted with the patients’ cell phone cameras. These images were transmitted to the surgeon by text messaging and emails.

CONCLUSION: This application of cell phone technology has been documented in other literature and could become a legitimate method for close outpatient observation by neurosurgeons if medicolegal issues are addressed.

J Neurosurg 112:479–490, 2010. DOI: 10.3171/2009.6.JNS081161

The authors discuss their method for placement of deep brain stimulation (DBS) electrodes using interventional MR (iMR) imaging and report on the accuracy of the technique, its initial clinical efficacy, and associated complications in a consecutive series of subthalamic nucleus (STN) DBS implants to treat Parkinson disease (PD).

Methods. A skull-mounted aiming device (Medtronic NexFrame) was used in conjunction with real-time MR imaging (Philips Intera 1.5T). Preoperative imaging, DBS implantation, and postimplantation MR imaging were integrated into a single procedure performed with the patient in a state of general anesthesia. Accuracy of implantation was assessed using 2 types of measurements: the “radial error,” defined as the scalar distance between the location of the intended target and the actual location of the guidance sheath in the axial plane 4 mm inferior to the commissures, and the “tip error,” defined as the vector distance between the expected anterior commissure–posterior commissure (AC-PC) coordinates of the permanent DBS lead tip and the actual AC-PC coordinates of the lead tip. Clinical out- come was assessed using the Unified Parkinson’s Disease Rating Scale part III (UPDRS III), in the off-medication

state.Results. Twenty-nine patients with PD underwent iMR imaging–guided placement of 53 DBS electrodes into the STN. The mean (± SD) radial error was 1.2 ± 0.65 mm, and the mean absolute tip error was 2.2 ± 0.92 mm. The tip error was significantly smaller than for STN DBS electrodes implanted using traditional frame-based stereotaxy (3.1 ± 1.41 mm). Eighty-seven percent of leads were placed with a single brain penetration. No hematomas were visible on MR images. Two device infections occurred early in the series. In bilaterally implanted patients, the mean improvement on the UPDRS III at 9 months postimplantation was 60%.

Conclusions. The authors’ technical approach to placement of DBS electrodes adapts the procedure to a standard configuration 1.5-T diagnostic MR imaging scanner in a radiology suite. This method simplifies DBS implantation by eliminating the use of the traditional stereotactic frame and the subsequent requirement for registration of the brain in stereotactic space and the need for physiological recording and patient cooperation. This method has improved accuracy compared with that of anatomical guidance using standard frame-based stereotaxy in conjunction with pre- operative MR imaging.

J Neurosurg 112:233–246, 2010. (DOI: 10.3171/2009.12.JNS091600)

Object. The term “citation classic” has been used in reference to an article that has been cited more than 400 times. The purpose of this study is to identify such articles that pertain to clinical neurosurgery.

Methods. A list of search phrases relating to neurosurgery was compiled. A topic search was performed using the Institute for Scientific Information Web of Science for phrases. Articles with more than 400 citations were identified, and nonclinical articles were omitted. The journals, year of publication, topics, and study types were analyzed.

Results. There were 106 articles with more than 400 citations relating to clinical neurosurgery. These articles appeared in 28 different journals, with more than half appearing in the Journal of Neurosurgery or the New England Journal of Medicine. Fifty-three articles were published since 1990. There were 38 articles on cerebrovascular disease, 21 on stereotactic and functional neurosurgery, 21 on neurooncology, 19 on trauma, 4 on nontraumatic spine, 2 on CSF pathologies, and 1 on infection. There were 29 randomized trials, of which 86% appeared in the New England Journal of Medicine, Lancet, or the Journal of the American Medical Association, and half concerned the prevention or treatment of stroke. In addition, there were 16 prospective studies, 15 classification or grading systems, and 7 reviews. The remaining 39 articles were case series, case reports, or technical notes.

Conclusions. More than half of the citation classics identified in this study have been published in the past 20 years. Case series, classifications, and reviews appeared more frequently in neurosurgical journals, while randomized controlled trials tended to be published in general medical journals.

J Neurosurg 112:223–232, 2010.(DOI: 10.3171/2009.12.JNS091599)

Object. The number of citations a published article receives is a measure of its impact in the scientific community. This study identifies and characterizes the current 100 top-cited articles in journals specifically dedicated to neurosurgery.

Methods. Neurosurgical journals were identified using the Institute for Scientific Information Journal Citation Reports. A search was performed using Institute for Scientific Information Web of Science for articles appearing in each of these journals. The 100 top-cited articles were selected and analyzed.

Results. The 100 most cited manuscripts in neurosurgical journals appeared in 3 of 13 journals dedicated to neurosurgery. These included 79 in the Journal of Neurosurgery, 11 in the Journal of Neurology, Neurosurgery and Psychiatry, and 10 in Neurosurgery. The individual citation counts for these articles ranged from 287 to 1515. Seventy- seven percent of articles were published between 1976 and 1995. Representation varied widely across neurosurgical disciplines, with cerebrovascular diseases leading (43 articles), followed by trauma (27 articles), stereotactic and functional neurosurgery (13 articles), and neurooncology (12 articles). The study types included 5 randomized trials, 5 cooperative studies, 1 observational cohort study, 69 case series, 8 review articles, and 12 animal studies. Thirty articles dealt with surgical management and 12 with nonsurgical management. There were 15 studies of natural history of disease or outcomes after trauma, 11 classification or grading scales, and 10 studies of human pathophysiology.

Conclusions. The most cited articles in neurosurgical journals are trials evaluating surgical or medical therapies, descriptions of novel techniques, or systems for classifying or grading disease. The time of publication, field of study, nature of the work, and the journal in which the work appears are possible determinants of the likelihood of citation and impact.

Philip A. Starr, MD, Alastair J.Martin, PhD, Paul S. Larson, MD

Neurosurgery Clinics of North America

Volume 20, Issue 2, Pages 207-217 (April 2009)

The authors describe a method for placement of deep brain stimulator electrodes using interventional MRI in conjunction with a skull-mounted aiming device (Medtronic Nexframe). This approach adapts the procedure to a standard-configuration 1.5-T diagnostic MRI scanner in a radiology suite. Preoperative imaging, device implantation, and postimplantation MRI are integrated into a single procedure performed under general anesthesia, providing real-time, high-resolution magnetic resonance confirmation of electrode position. The method is conceptually simpler than the current standard technique for deep brain stimulator placement, as it eliminates the stereotactic frame, the subsequent requirement for registration of the brain in stereotactic space, physiologic testing, and the need for patient cooperation. With further technical refinement, the interventional MRI method should improve the accuracy, safety, and speed of deep brain stimulator electrode placement.