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Endovascular Treatment of Side Wall Aneurysms Using a Liquid Embolic Agent: A US Single-Center Prospective Trial

Neurosurgery 67:855-860, 2010 DOI: 10.1227/01.NEU.0000374772.22745.C3

Onyx HD-500 is a liquid embolic agent consisting of ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide and mixed with tantalum. This viscous embolic agent was designed to treat intracranial side wall aneurysms, but there have been no prospective published series from the United States. From this early experience, we developed several protocol revisions, technical details, and clinical pearls that have not been published for liquid embolic embolization of aneurysms.

CLINICAL PRESENTATION:We present our single-center prospective series of patients treated with Onyx HD-500 from a multicenter, randomized, controlled trial. Thirteen patients received Onyx HD-500, and their ages ranged from 43 to 81 years. Twelve patients had aneurysms on the internal carotid artery, and 1 patient had an aneurysm the vertebral artery. Every patient had an immediate postangiographic result with 90% or more occlusion by an independent core laboratory assessment. In 1 patient, the Onyx HD-500 injection was aborted, and the aneurysm was embolized with coils. Eleven of 13 patients (85%) underwent 6-month follow-up angiography that demonstrated persistent durable occlusion with no recanalization. There was 1 complication (8%) and no deaths.

CONCLUSION: This is the only prospective series of intracranial aneurysms treated with Onyx HD-500 in the United States. This is also the first publication that describes detailed procedure techniques, recommended protocol revisions, lessons learned from early complications, clinical pearls, and advantages and disadvantages of liquid embolic embolization of aneurysms.

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Diffusion tensor imaging tractography in patients with intramedullary tumors: comparison with intraoperative findings and value for prediction of tumor resectability

J Neurosurg Spine 13:371–380, 2010. DOI: 10.3171/2010.3.SPINE09399

The aim of this retrospective study was to evaluate the predictive value of diffusion tensor (DT) imaging with respect to resectability of intramedullary spinal cord tumors and to determine the concordance of this method with intraoperative surgical findings.

Methods. Diffusion tensor imaging was performed in 14 patients with intramedullary lesions of the spinal cord at different levels using a 3-T magnet. Routine MR imaging scans were also obtained, including unenhanced and enhanced T1-weighted images and T2-weighted images. Patients were classified according to the fiber course with respect to the lesion and their lesions were rated as resectable or nonresectable. These results were compared with the surgical findings (existence vs absence of cleavage plane). The interrater reliability was calculated using the κ coefficient of Cohen.

Results. Of the 14 patients (7 male, 7 female; mean age 49.2 ± 15.5 years), 13 had tumors (8 ependymomas, 2 lymphomas, and 3 astrocytoma). One lesion was proven to be a multiple sclerosis plaque during further diagnostic workup. The lesions could be classified into 3 types according to the fiber course. In Type 1 (5 cases) fibers did not pass through the solid lesion. In Type 2 (3 cases) some fibers crossed the lesion, but most of the lesion volume did not contain fibers. In Type 3 (6 cases) the fibers were completely encased by tumor. Based on these results, 6 tumors were considered resectable, 7 were not. During surgery, 7 tumors showed a good cleavage plane, 6 did not. The interrater reliability (Cohen κ) was calculated as 0.83 (p < 0.003), which is considered to represent substantial agreement. The mean duration of follow-up was 12.0 ± 2.9. The median McCormick grade at the end of follow-up was II.

Conclusions. These preliminary data suggest that DT imaging in patients with spinal cord tumors is capable of predicting the resectability of the lesion. A further prospective study is needed to confirm these results and any effect on patient outcome.

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A Comparative Analysis of the Results of Vertebroplasty and Kyphoplasty in Osteoporotic Vertebral Compression Fractures

Neurosurgery 67[ONS Suppl 1]:ons171-ons188, 2010 DOI: 10.1227/01.NEU.0000380936.00143.11

The most common complication of osteoporosis is vertebral fractures, which occur more frequently than all other fractures (hip, wrist, and ankle).

OBJECTIVE: To prospectively analyze vertebroplasty compared with kyphoplasty for the treatment of osteoporotic vertebral compression fractures using improvement in pain, functional capacity, and quality of life as outcome measures.

METHODS: The study population included 28 patients in the vertebroplasty group and 24 patients in the kyphoplasty group. The mean follow-up period was 42.2 weeks and 42.3 weeks in the vertebroplasty and kyphoplasty groups, respectively. Outcomes were measured pre- and postoperatively using the visual analogue scale, the Oswestry Disability Index, the EuroQol-5D questionnaire, and the Short-Form 36 Health Survey.

RESULTS: In the vertebroplasty group, visual analogue scale scores improved from a mean of 8.0 cm to 5.5 cm at last follow-up (P = .001). Preoperatively, the Oswestry Disability Index was 57.6, which improved to 38.4 (P = .006). The EuroQol-5D score preoperatively was 0.157 and improved to 0.504 (P = .001). The Short-Form 36 Health Survey showed greatest improvement in the areas of physical health, role physical, body pain, and vitality. In the kyphoplasty group, visual analogue scale scores improved from a mean of 7.5 cm preoperatively to 2.5 cm postoperatively (P = .000001). The mean Oswestry Disability Index preoperatively was 50.7 and improved to 28.8 (P = .002). The EuroQol-5D score improved from a mean of 0.234 preoperatively to 0.749 (P = .00004). The Short-Form 36 Health Survey showed greatest improvement in the areas of physical health, physical functioning, role physical, body pain, and social functioning.

CONCLUSION: Both vertebroplasty and kyphoplasty are effective at improving pain, functional disability, and quality of life; however, kyphoplasty provides better results, which are maintained over long-term follow-up.

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Surgical approaches to brainstem cavernous malformations

Neurosurg Focus 29 (3):E8, 2010. DOI: 10.3171/2010.6.FOCUS10128

Brainstem cavernous malformations (CMs) are low-flow vascular lesions in eloquent locations. Their presentation is often marked with symptomatic hemorrhages that appear to occur more frequently than hemorrhage from supratentorial cavernomas.

Brainstem CMs can be removed using 1 of the 5 standard skull-base approaches: retrosigmoid, suboccipital (with or without telovelar approach), supracerebellar infratentorial, orbitozygomatic, and far lateral.

Patients being referred to a tertiary institution often have lesions that are aggressive with respect to bleeding rates. Nonetheless, the indications for surgery, in the authors’ opinion, are the same for all lesions: those that are symptomatic, those that cause mass effect, or those that abut a pial surface. Patients often have relapsing and remitting courses of symptoms, with each hemorrhage causing a progressive and stepwise decline.

Many patients experience new postoperative deficits, most of which are transient and resolve fully. Despite the risks associated with operating in this highly eloquent tissue, most patients have had favorable outcomes in the authors’ experience. Surgical treatment of brainstem CMs protects patients from the potentially devastating effects of rehemorrhage, and the authors believe that the benefits of intervention outweigh the risks in patients with the appropriate indications.

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Colloid Cysts of the Third Ventricle: Endoscopic Versus Microsurgical Removal

Neurosurg Q 2010;20:142–145

Study Design: A comparative randomized prospective clinical study.

Background and Purpose: The endoscopic approach to colloid cysts of the third ventricle is receiving increasing interest. However, its effectiveness is a matter of discussion. The aim of the study was to present a direct and long-term outcome after endoscopy of a colloid cyst versus microsurgery.

Materials and Methods: Ten patients with colloid cysts were prospectively analyzed. Group A consisted of 5 patients treated endoscopically, whereas 5 patients treated using a transcorticaltransventricular approach comprised group B. Clinically, symptoms of raised intracranial pressure were predominant. All patients had hydrocephalus. Tumor diameter ranged from 10 to 27 mm. The mean follow-up period was 22 months.

Results: The mean surgery time was 122 minutes in group A and 201 minutes in group B. Hospital stay was 1.5 days in the intensive care unit and 2.5 days in the ward in group A as compared with 3.5 days in the intensive care unit and 7 days in the ward in group B.

Postoperative complications in group A were in the form of 1 transient hemiparesis and 1 transient short-term memory loss. Two patients in group B suffered transient short-term memory loss postoperatively and 1 patient suffered from transient hemiparesis. Clinically, the preoperative symptoms resolved in all the patients. One patient who underwent microsurgery required a ventriculoperitoneal shunt postoperatively. All patients who underwent endoscopy remained shunt independent.

Conclusions: The endoscopic approach to colloid cysts of the third ventricle is safe, effective, and carries a low complication rate. Endoscopy may be recommended as a treatment option.

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A retrospective analysis of pedicle screws in contact with the great vessels

J Neurosurg Spine 13:403–406, 2010.DOI: 10.3171/2010.3.SPINE09657

Pedicle screws placed in the thoracic, lumbar, and sacral spine occasionally come in contact with the aorta, vena cava, or iliac vessels. When such screws are seen on postoperative imaging in an asymptomatic patient, the surgeon must decide whether it is riskier to revise the screw or to observe it. The authors hypothesized that the incidence of screw placement causing perioperative vessel injury is low and, further, that screws placed in contact with major vessels do not always result in vessel injury.

Methods. A retrospective review of the operative records of 182 consecutive patients undergoing thoracic, lumbar, and lumbosacral pedicle screw fusion was performed to determine the frequency of intraoperative vessel injury. Postoperative imaging for 107 patients was available to determine the incidence of screws in contact with major vessels. Charts were examined to determine if any adverse sequelae had resulted from malpositioned screws. Patient outcomes were documented.

Results. There were no intraoperative vessel injuries or deaths in 182 consecutive operations. One hundred seven patients with available postoperative films had 680 pedicle screws placed between T-3 and the sacrum during 115 operations. No patient had arterial screw penetration or deformation on postoperative imaging. Thirty-three of the 680 inserted screws were in contact with a major vessel on routine postoperative imaging. The contacted vessels included the aorta (4 cases), the iliac artery (7 cases), and the iliac veins (22 cases). Patients were followed up until death or November 2009, for a mean follow-up of 44 months (median 44 months, range 5–109 months). None of the patients with vessel contact was noted to suffer symptoms or sequelae as a result of vessel contact. Radiographic follow-up as long as 50 months after surgery revealed no detectable vessel abnormality at the contacted site.

Conclusions. Placing pedicle screws in contact with major vessels is a known risk of spinal surgery. The risk of repositioning a screw in contact with a major vessel but causing no symptoms must be weighed against the relative risk of leaving it in place.

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Utility and the Limit of Motor Evoked Potential Monitoring for Preventing Complications in Surgery for Cerebral Arteriovenous Malformation

Neurosurgery 67[ONS Suppl 1]:ons222-ons228, 2010 DOI: 10.1227/01.NEU.0000374696.84827.22

OBJECTIVE: To evaluate the usefulness of motor evoked potential (MEP) monitoring andmapping in arteriovenous malformation surgery.

METHODS: Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area.

RESULTS: In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus.

CONCLUSION: In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

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Choosing the best operation for chronic subdural hematoma: a decision analysis

J Neurosurg 113:615–621, 2010.DOI: 10.3171/2009.9.JNS08825

Chronic subdural hematoma (CSDH), a condition much more common in the elderly, presents an increasing challenge as the population ages. Treatment strategies for CSDH include bur-hole craniostomy (BHC), twist-drill craniostomy (TDC), and craniotomy. Decision analysis was used to organize existing data and develop recommendations for effective treatment.

Methods. A Medline search was used to identify articles about treatment of CSDH. Direct assessment by health care professionals of the relative health impact of common complications and recurrences was used to generate utility values for treatment outcomes. Monte Carlo simulation and sensitivity analyses allowed comparisons across treatment strategies. A second simulation examined whether intraoperative irrigation or postoperative drainage affect the outcomes following BHC.

Results. On a scale from 0 to 1, the utility of BHC was found to be 0.9608, compared with 0.9202 for TDC (p = 0.001) and 0.9169 for craniotomy (p = 0.006). Sensitivity analysis confirmed the robustness of these values. Craniotomy yielded fewer recurrences, but more frequent and more serious complications than did BHC. There were no significant differences for BHC with or without irrigation or postoperative drainage.

Conclusions. Bur-hole craniostomy is the most efficient choice for surgical drainage of uncomplicated CSDH. Bur-hole craniostomy balances a low recurrence rate with a low incidence of highly morbid complications. Decision analysis provides statistical and empirical guidance in the absence of well-controlled large trials and despite a confusing range of previously reported morbidity and recurrence.

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Direct visualization of deep brain stimulation targets in Parkinson disease with the use of 7-tesla magnetic resonance imaging

J Neurosurg 113:639–647, 2010.DOI: 10.3171/2010.3.JNS091385

A challenge associated with deep brain stimulation (DBS) in treating advanced Parkinson disease (PD) is the direct visualization of brain nuclei, which often involves indirect approximations of stereotactic targets. In the present study, the authors compared T2*-weighted images obtained using 7-T MR imaging with those obtained using 1.5- and 3-T MR imaging to ascertain whether 7-T imaging enables better visualization of targets for DBS in PD.

Methods. The authors compared 1.5-, 3-, and 7-T MR images obtained in 11 healthy volunteers and 1 patient with PD.

Results. With 7-T imaging, distinct images of the brain were obtained, including the subthalamic nucleus (STN) and internal globus pallidus (GPi). Compared with the 1.5- and 3-T MR images of the STN and GPi, the 7-T MR images showed marked improvements in spatial resolution, tissue contrast, and signal-to-noise ratio.

Conclusions. Data in this study reveal the superiority of 7-T MR imaging for visualizing structures targeted for DBS in the management of PD. This finding suggests that by enabling the direct visualization of neural structures of interest, 7-T MR imaging could be a valuable aid in neurosurgical procedures.

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Comparison of percutaneous balloon compression and glycerol rhizotomy for the treatment of trigeminal neuralgia

J Neurosurg 113:486–492, 2010.DOI: 10.3171/2010.1.JNS091106

The aim of this study was to compare percutaneous balloon compression (PBC) and percutaneous retrogasserian glycerol rhizotomy (PRGR) in terms of effectiveness, complications, and technical aspects.

Methods. Sixty-six consecutive PBC procedures were performed in 45 patients between January 2004 and December 2008, and 120 PRGR attempts were performed in 101 patients between January 2006 and December 2008. The PRGR procedures were not completed due to technical reasons in 19 cases. Five patients in the Balloon Compression Group and 9 patients in the Glycerol Group were lost to follow-up and were excluded from the study. The medical records and the intraoperative fluoroscopic images from the remaining cases were retrospectively examined, and the follow-up was completed with telephone contact, when necessary. The 2 groups were compared in terms of initial effect, duration of effect, and rates of complications as well as severity and type of complications.

Results. The rates for immediate pain relief were 87% for patients treated with glycerol injection and 85% for patients treated with balloon compression. The Kaplan-Meier plots for the 2 treatment modalities were similar. The 50% recurrence time was 21 months for the balloon procedure and 16 months for the glycerol procedure. When the groups were broken down by the “previous operations” criterion, the 50% recurrence time was 24 months for the Glycerol First Procedure Group, 6 months for the Balloon First Procedure Group, 8 months for the Glycerol Previous Procedures Group, and 21 months for the Balloon Previous Procedures Group. The rates of complications (excluding numbness) were 11% for PRGR and 23% for PBC, and this difference was statistically significant (chi-square test, p = 0.04).

Conclusions. Both PRGR and PBC are effective techniques for the treatment of trigeminal neuralgia, with PRGR presenting some advantages in terms of milder and fewer complications and allowing lighter anesthesia without compromise of analgesia. For these reasons the authors consider PRGR as the first option for the treatment of trigeminal neuralgia in patients who are not suitable candidates or are not willing to undergo microvascular decompression, while PBC is reserved for patients in whom the effect of PRGR has proven to be short or difficult to repeat due to cisternal fibrosis.

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Gamma Knife Surgery for Cavernous Hemangiomas in the Cavernous Sinus

Neurosurgery 67:611-616, 2010 DOI: 10.1227/01.NEU.0000378026.23116.E6

Cavernous hemangioma in the cavernous sinus (CS) is a rare vascular tumor. Direct microsurgical approach usually results in massive hemorrhage. Radiosurgery has emerged as a treatment alternative to microsurgery.

OBJECTIVE: To further investigate the role of Gamma Knife surgery (GKS) in treating CS hemangiomas.

METHODS: This was a retrospective analysis of 7 patients with CS hemangiomas treated by GKS between 1993 and 2008. Data from 84 CS meningiomas treated during the same period were also analyzed for comparison. The patients underwent follow-up magnetic resonance imaging at 6-month intervals. Data on clinical and imaging changes after radiosurgery were analyzed.

RESULTS: Six months after GKS, magnetic resonance imaging revealed an average of 72% tumor volume reduction (range, 56%-83%). After 1 year, tumor volume decreased 80% (range, 69%-90%) compared with the pre-GKS volume. Three patients had > 5 years of follow- up, which showed the tumor volume further decreased by 90% of the original size. The average tumor volume reduction was 82%. In contrast, tumor volume reduction of the 84 cavernous sinus meningiomas after GKS was only 29% (P < .001 by Mann-Whitney U test). Before treatment, 6 patients had various degrees of ophthalmoplegia. After GKS, 5 improved markedly within 6 months. Two patients who suffered from poor vision improved after radiosurgery.

CONCLUSION: GKS is an effective and safe treatment modality for CS hemangiomas with long-term treatment effect. Considering the high risks involved in microsurgery, GKS may serve as the primary treatment choice for CS hemangiomas.

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Postoperative Assessment of Clipped Aneurysms With 64-Slice Computerized Tomography Angiography

Neurosurgery 67:844-854, 2010 DOI: 10.1227/01.NEU.0000374684.10920.A2

Multidetector computerized tomography angiography (MDCTA) is now a widely accepted technique for the management of intracranial aneurysms.

OBJECTIVE: To evaluate its accuracy for the postoperative assessment of clipped intracranial aneurysms.

METHODS:We analyzed a consecutive series of 31 patients that underwent direct surgical clipping procedures of 38 aneurysms. A 64 slice MDCT scanner (Aquilion 64, Toshiba) was used and results were compared with digital subtraction angiographies (DSA). Two independent neuroradiologists analyzed the following data: examination quality, artifacts, aneurysm remnant, and patency of collateral branches. Interobserver agreement, sensitivity, and specificity were calculated.

RESULTS: Seventy-nine percent of the aneurysms were located in the anterior circulation. Significant artifacts were found with multiple and cobalt-alloy clips. According to DSA, remnants >2 mm were found in 21% of the cases, and 2 patients had one collateral branch occluded. Sensitivity and specificity of 64-MDCTA for the detection of aneurysm remnants were 50% and 100%, respectively. Sensitivity and specificity of 64-MDCTA for the detection of a significant remnant (>2 mm) and the detection of the occlusion of a collateral branch were, respectively, 67% and 100% and 50% and 100%. No relationship was found with the location, type, shape, size, or number of clips, but missed remnants tended to be larger with cobalt-alloy clips.

CONCLUSIONS: 64-MDCTA is a valuable technique to assess the presence of a significant postoperative remnant in single titanium clip application cases and might be useful for longterm follow-up. DSA remains the most accurate postoperative radiological examination.

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Near-infrared indocyanine green videoangiography versus microvascular Doppler sonography in aneurysm surgery

Acta Neurochir (2010) 152:1519–1525.DOI 10.1007/s00701-010-0723-5

The quality of surgical treatment of intracranial aneurysms is determined by complete aneurysm occlusion and restoration of flow in the parent, branching and perforating vessels. In postoperative digital subtraction angiography (DSA), unexpected aneurysm residuals and vessel occlusions are frequently detected. Here, the value of two nearly noninvasive and cost-effective techniques for intraoperative flow evaluation (near-infrared indocyanine green video angiography (ICG-VA) and microvascular Doppler sonography (mDs)) is investigated in a prospective study.

Patients and methods Over a period of 10months, the authors surgically clipped 50 aneurysms under intraoperative pre- and post-clipping evaluation of flow in the parent, branching and perforating vessels and the aneurysm sack by the two techniques. Intraoperative applicability of each technique was compared to each other and to postoperative digital subtraction angiography as standard evaluation technique.

Results Forty-five aneurysms were totally occluded without vessel compromise (90%). Intraoperatively, ICG-VA was considered useful in 43 cases (86%) and mDs in 44 cases (88%), respectively. Both techniques could compensate each other’s weak points to a certain degree; but two branch occlusions (4%) and three neck remnants (6%) were revealed by postoperative DSA.

Conclusion Both techniques have specific drawbacks that could be compensated by each other, to a certain extent. Intraoperatively, ICG-VA and mDs should not be considered competitive, but complementary. This study implicates that the combination of both applications on a routine basis assures the quality of aneurysm surgery by nearly noninvasive and cost-effective techniques. However, DSA remains the gold standard for evaluation of aneurysm occlusion.

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Endoscopic Treatment of Arachnoid Cysts: A Detailed Account of Surgical Techniques and Results

Neurosurgery 67:824-836, 2010 DOI: 10.1227/01.NEU.0000377852.75544.E4

Surgical treatment of arachnoid cysts remains under debate. Although many authors favor endoscopic techniques, others attribute a higher recurrence rate to the endoscope.

OBJECTIVE: The authors report their experience with endoscopic procedures for arachnoid cyst.

METHODS: All pure endoscopic procedures for arachnoid cysts performed by the authors were analyzed. Particular reference was given to surgical complications and patient outcome in relation to cyst location and endoscopic technique.

RESULTS: Sixty-six endoscopic procedures were performed in 61 patients (mean age, 28 years; range, 23 days to 74 years; 35 males, 26 females). The main presenting symptoms were cephalgia (61%), hemisymptoms (18%), and macrocephalus (18%). Cyst location was temporobasal (34%), suprasellar (21%), at the cisterna quadrigemina (18%), paraxial supratentorial (16%), and various (10%). Thirty cystocisternostomies, 14 ventriculocystostomies, 12 cystoventriculostomies, and 10 ventriculocystocisternostomies were performed. The overall clinical success rate was 90%. The endoscopic technique was abandoned in 4 cases (7%). Postoperative complications were found in 16%; there was only one permanent deficit (2%). Five recurrences (8%) occurred up to 7 years after the first procedure. Of the various locations, the temporobasal cysts were the most difficult to treat with lowest clinical success (81%), highest recurrence (19%), and highest complication rate (24%). Of the various endoscopic techniques, ventriculocystostomy and ventriculocystocisternostomy reached the highest success rates with 100%.

CONCLUSIONS: Endoscopic techniques provide very good results in arachnoid cyst treatment. The most frequent cyst location is the most difficult to treat. A long-term follow-up is recommended since recurrences can occur many years after the procedure

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Best surgical practices: a stepwise approach to the University of Pennsylvania deep brain stimulation protocol

Neurosurg Focus 29 (2):E3, 2010. (DOI: 10.3171/2010.4.FOCUS10103)

Deep brain stimulation (DBS) is the treatment of choice for otherwise healthy patients with advanced Parkinson disease who are suffering from disabling dyskinesias and motor fluctuations related to dopaminergic therapy. As DBS is an elective procedure, it is essential to minimize the risk of morbidity. Further, precision in targeting deep brain structures is critical to optimize efficacy in controlling motor features. The authors have already established an operational checklist in an effort to minimize errors made during DBS surgery. Here, they set out to standardize a strict, step-by-step approach to the DBS surgery used at their institution, including preoperative evaluation, the day of surgery, and the postoperative course. They provide careful instruction on Leksell frame assembly and placement as well as the determination of indirect coordinates derived from MR images used to target deep brain structures. Detailed descriptions of the operative procedure are provided, outlining placement of the stereotactic arc as well as determination of the appropriate bur hole location, lead placement using electrophysiology, and placement of the internal pulse generator. The authors also include their approach to preventing postoperative morbidity. They believe that a strategic, step-by-step approach to DBS surgery combined with a standardized checklist will help to minimize operating room mistakes that can compromise targeting and increase the risk of complication.

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Image-guided frameless stereotactic biopsy without intraoperative neuropathological examination. Clinical article

Journal of Neurosurgery, August 2010 Volume 113, Number 2
DOI: 10.3171/2009.12.JNS09573
Stereotactic biopsy is a safe and effective technique for the diagnosis of brain tumors. The use of intraoperative neuropathological examination has been routinely advocated to increase diagnostic yield, but the procedure lengthens surgical time, may produce false-negative and -positive results, and current biopsy techniques have a very low nondiagnostic rate. Therefore, the authors questioned the need for intraoperative histological evaluation.
Methods
The authors prospectively studied all patients undergoing image-guided biopsy under the care of a single surgeon (P.L.G.) between July 2005 and October 2007. A Stryker neuronavigation system with a trajectory guide was used to plan a single trajectory, and, using a side-cutting biopsy cannula, multiple biopsy samples were taken from between 1 and 4 sites within the tumor. Tissue was inspected macroscopically by the surgeon and was only submitted for neuropathological assessment postoperatively.
Results
One hundred thirty-four biopsies were performed during the study. A positive diagnosis was established in 133 cases (99.3%). One biopsy was negative (0.7%) and postoperative imaging (performed because the tissue was macroscopically normal) demonstrated inaccurate targeting of the lesion. Significant complications were seen in 3 patients (2.2%) who all had preoperative WHO performance scores of III or IV. Two patients suffered delayed deterioration and died due to probable surgical complications—one with thalamic glioblastoma multiforme (GBM) and one with gliomatosis cerebri. One patient with GBM suffered an intracerebral hematoma that was managed conservatively. Postoperative seizures were seen in 4 patients (3%), and 2 patients (1.5%) experienced a transient neurological deficit. Histological diagnosis showed a GBM in 64 cases, Grade III glioma in 19, Grade I or II in 23, metastasis in 10, lymphoma in 13, and other disease in 4. There were 32 patients discharged to home on the same day as surgery. Compared with the authors’ previous retrospective audit into 127 biopsies, this technique showed improved diagnostic yield (99.3 vs 94.5%, p = 0.032) with fewer complications (2.2 vs 4.7% [not statistically significant]).
Conclusions
This technique of image-guided biopsy has high diagnostic yield with acceptably low morbidity and may be performed as a day case. Intraoperative neuropathological examination would not have increased the diagnostic yield further in this study, and its routine use may not be necessary. In the authors’ department £70,350 (UK)/$114,522 (US) would have been saved by not using intraoperative neuropathology in this series. Therefore, intraoperative neuropathology should no longer be routinely recommended.

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Absence of an association between glucose levels and surgical site infections in patients undergoing craniotomies for brain tumors

J Neurosurg 113:161–166, 2010.DOI: 10.3171/2010.2.JNS09950

In select patient populations, hyperglycemia has been shown to increase the risk of surgical site infection (SSI), whereas stringent glucose control has improved outcomes. To date, no study has focused on whether SSIs in patients with brain tumors undergoing resection are associated with hyperglycemia. Methods. The authors performed a retrospective chart review of patients who underwent a craniotomy after receiving a diagnosis of brain tumor. From 2001 to 2008, 2485 patients underwent a craniotomy for tumor resection at the Brain Tumor & Neuro-Oncology Center at the Cleveland Clinic. Fifty-seven of these patients (2.3%) developed SSIs postoperatively. A matched case-control study design was used, with 57 patients who developed SSIs after craniotomy (cases) matched with 57 patients who did not develop SSIs (controls). The results were analyzed using both univariate and multivariate conditional logistic regression. Results. Glucose level was not a significant factor in postoperative SSI (p = 0.83) after adjusting for duration of surgery and adherence to antibiotic prophylaxis. However, duration of surgery was significantly associated with postoperative SSI (p = 0.047). Conclusions. For patients who undergo craniotomy for definitive resection of a brain tumor, duration of surgery described more variation in the model to predict SSI than blood glucose levels.

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Endoscopic Third Ventriculostomy Vs Cerebrospinal Fluid Shunt in the Treatment of Hydrocephalus in Children: A Propensity Score–Adjusted Analysis

Neurosurgery 67:588-593, 2010 DOI: 10.1227/01.NEU.0000373199.79462.21

Endoscopic third ventriculostomy (ETV) has preferentially been offered to patients with more favorable prognostic features compared with shunt.

OBJECTIVE: To use advanced statistical methods to adjust for treatment selection bias to determine whether ETV survival is superior to shunt survival once the bias of patientrelated prognostic factors is removed.

METHODS: An international cohort of children (≤ 19 years of age) with newly diagnosed hydrocephalus treated with ETV (n = 489) or shunt (n = 720) was analyzed. We used propensity score adjustment techniques to account for 2 important patient prognostic factors: age and cause of hydrocephalus. Cox regression survival analysis was performed to compare time-to-treatment failure in an unadjusted model and 3 propensity score—adjusted models, each of which would adjust for the imbalance in prognostic factors.

RESULTS: In the unadjusted Cox model, the ETV failure rate was lower than the shunt failure rate from the immediate postoperative phase and became even more favorable with longer duration from surgery. Once patient prognostic factors were corrected for in the 3 adjusted models, however, the early failure rate for ETV was higher than that for shunt. It was only after about 3 months after surgery did the ETV failure rate become lower than the shunt failure rate.

CONCLUSIONS: The relative risk of ETV failure is initially higher than that for shunt, but after about 3 months, the relative risk becomes progressively lower for ETV. Therefore, after the early high-risk period of ETV failure, a patient could experience a long-term treatment survival advantage compared with shunt. It might take several years, however, to realize this benefit.

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Functional Magnetic Resonance Imaging and Diffusion Tensor Tractography Incorporated Into an Intraoperative 3-Dimensional Ultrasound-Based Neuronavigation System: Impact on Therapeutic Strategies, Extent of Resection, and Clinical Outcome

Neurosurgery 67:251-264, 2010 DOI: 10.1227/01.NEU.0000371731.20246.AC

Functional neuronavigation with intraoperative 3-dimensional (3D) ultrasound may facilitate safer brain lesion resections than conventional neuronavigation.

OBJECTIVE: In this study, functional magnetic resonance imaging (fMRI) and diffusion tensor tractography (DTT) were used to map eloquent areas. We assessed the use of fMRI and DTT for preoperative assessments and determined whether using these data together with 3D ultrasound during surgery enabled safer lesion resection.

METHODS:We reviewed 51 consecutive patients with intracranial lesions in whom fMRI with or without DTT was used to map eloquent areas. To assess a possible impact of fMRI/DTT, we reviewed and analyzed the quality of the fMRI/DTT data, any change in therapeutic strategies, lesion to eloquent area distance (LEAD), extent of resection, and clinical outcome.

RESULTS: As a result of the fMRI/DTT mapping, the therapeutic strategies were changed in 4 patients. The median tumor residue for glioma patients was 11% (n = 33) and 0% for nonglioma lesions (n = 12). For gliomas, there was a significant correlation between decreasing LEAD and increasing tumor residue. Of the glioma patients, 42% underwent gross total resection (≥ 95%) and 12% suffered neurological worsening after surgery as a result of complications. Of glioma patients with an LEAD of ≤ 5 mm, 24% underwent gross total resection and 10% experienced neurological deterioration.

CONCLUSION: This study demonstrates that preoperative fMRI and DTT had direct consequences for therapeutic strategies and indicates their impact on intraoperative strategies to spare eloquent cortex and tracts. Functional neuronavigation combined with intraoperative 3D ultrasound can, in most patients, enable resection of brain lesions with general anesthesia without jeopardizing neurological function.

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Risk Factors of Sagittal Decompensation After Long Posterior Instrumentation and Fusion for Degenerative Lumbar Scoliosis

SPINE Volume 35, Number 17, pp 1595–1601.

Study Design. A retrospective study of clinical results of operative treatment for degenerative lumbar scoliosis.

Objective. To determine the risk factors of sagittal decompensation after long instrumentation and fusion to L5 or S1. Summary of Background Data. Little is known about the risk factors for sagittal decompensation, which was defined in this study as sagittal C7 plumb falling anterior 8 cm from the posterosuperior corner of the sacrum.

Methods. Forty-five patients (mean age: 64.4 year) with adult degenerative lumbar scoliosis were reviewed retrospectively with a minimum 2 years. The mean number of levels fused was 6.1  1.6 segments. The upper instrumented vertebra ranged from T9 to L2. The lower instrumented vertebra was L5 and S1 in 24 and 21 patients, respectively.

Results. Sagittal decompensation (SD) developed in 19 patients. The most significant risk factors of SD were preoperative sagittal imbalance and high pelvic incidence. The preoperative sagittal C7 plumb was more positive (67.9 mm) in the decompensation group than in the balance group (37.0 mm) (P = 0.002). There was a significant difference in pelvic incidence between 61.7° in the decompensation and 54.9° in the balance group (P = 0.01). The preoperative lumbar lordosis was hypolordotic in the decompensation group, however, it was not found to be a risk factor. Pseudarthrosis was identified at the lumbosacral junction in 5 patients, and 4 of them (80%) had SD. SD developed in 55% of patients who had loosening of the distal screws and 50% of patients with hypolordotic lumbar fusion. Distal adjacent segment disease was more likely to cause SD than proximal adjacent segment disease.

Conclusion. Sagittal decompensation is common after long posterior instrumentation and fusion for degenerative lumbar scoliosis. It is mostly associated with complications at the distal segments, including pseudarthrosis and implant failure at the lumbosacral junction. Restoration of optimal lumbar lordosis and secure lumbosacral fixation is necessary especially in patients with preoperative sagittal imbalance and high pelvic incidence in order to prevent sagittal decompensation after surgery. Key words: adult spinal deformity, degenerative lumbar scoliosis, sagittal imbalance, sagittal decompensation, risk factor

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