Author: cba

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Anatomy and Pathology of the Cranial Emissary Veins: A Review With Surgical Implications

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.

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Long-Term Surgical Outcomes of Spinal Meningiomas

Spine 2012 ; 37 : E617 – E623 

Although previous studies have demonstrated favorable surgical outcomes for spinal meningioma, with a low incidence of tumor recurrence, few have examined longterm surgical outcomes.

Methods. The influence of patient age, surgical margin status (Simpson grade), tumor location, and histological subtype on tumor recurrence were examined retrospectively. In addition, the resected dura mater from Simpson grade I cases was examined for invasive tumor cells and compared with the presence or absence of a dural tail sign on magnetic resonance image.

Results. Complete resection (Simpson grades I and II) was performed in 62 patients. Among them, the tumor recurrence rate was 9.7%, all in patients who underwent grade II resection for ventral spinal lesions. The mean duration to reoperation in these patients was 12.2 ± 5.2 years. Of the 6 patients who underwent incomplete resection (Simpson grade III/IV), all required reoperation for tumor recurrence or regrowth, 5 years later on average. Patients younger than 50 years at the initial surgery had a significantly higher recurrence rate than those aged 50 years or older. Histologic examination of 43 dura mater specimens from Simpson grade I-resection patients revealed tumor cell invasion between the inner and outer layers in 15 patients. This invasion was noted in 8 (29%) of 28 patients who were negative for the dural tail sign on magnetic resonance image, and in 7 (47%) of 15 patients who showed a positive dural tail sign. The MIB-1 index reached about 10% for dumbbell-type meningiomas invading the vertebral body; these were associated with repeated recurrence and unfavorable prognosis.

Conclusion. Long-term follow-up after surgery for meningiomas indicated that Simpson grade I resection should be selected whenever practicable when treating younger patients or dumbbelltype meningiomas. Tumors recurred at 12 years, on average, in approximately 30% of patients who underwent grade II resection.

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Surgical results of an endoscopic endonasal approach for clival chordomas

Acta Neurochir (2012) 154:879–886. DOI 10.1007/s00701-012-1317-1

The surgical approaches for clival chordomas remain controversial, although the extent of resection is one of the most important factors for long survival rates. Recently an endoscopic endonasal approach in good collaboration with otolaryngologists has attracted major attention as a surgical approach for clival chordomas. We describe our experience with the endoscopic endonasal approach and provide a review of the literature.

Methods Between 2008 and 2011, six operations were performed via the endoscopic endonasal approach for clivus chordomas. The mean tumor size was 35 mm in diameter. The tumor location was mainly from the upper to middle clivus. The tumor extended into the cavernous sinus in five cases and intradurally in three cases. A binostril approach was performed in four cases, while a one nostril approach was performed in two cases.

Results Gross total removal was achieved in three cases. The analysis of cases with incomplete resection suggested that residual tumors were observed epidurally and subdurally. The residual on the epidura was observed from the posterior clinoid to the posterior compartment of the cavernous sinus. On the other hand, the residual on the subdural was observed behind the upper part of the pituitary gland. There was no postoperative cerebrospinal fluid (CSF) leakage using vascularized nasoseptal flaps in any of the cases.

Conclusions The endoscopic endonasal transclival approach allows an appropriate extent of resection with acceptable complication rates in comparison with other approaches. In our series, the accomplishment of gross total removal was associated with the relationship between the tumors and surrounding structures, such as the pituitary gland and the cavernous portion of the intracranial carotid artery (ICA).

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Predictive Value and Safety of Intraoperative Neurophysiological Monitoring With Motor Evoked Potentials in Glioma Surgery

Neurosurgery 70:1060–1071, 2012 DOI: 10.1227/NEU.0b013e31823f5ade

Resection of gliomas in or adjacent to the motor system is widely performed with intraoperative neuromonitoring (IOM). Despite the fact that data on the safety of IOM are available, the significance and predictive value of the procedure are still under discussion. Moreover, cases of false-negative monitoring affect the surgeon’s confidence in IOM.

OBJECTIVE: To examine cases of false-negative IOM to reveal structural explanations.

METHODS: Between 2007 and 2010, we resected 115 consecutive supratentorial gliomas in or close to eloquent motor areas using direct cortical stimulation for monitoring of motor evoked potentials (MEPs). The monitoring data were reviewed and related to new postoperative motor deficit and postoperative imaging. Clinical outcomes were assessed during follow-up.

RESULTS: Monitoring of MEPs was successful in 112 cases (97.4%). Postoperatively, 30.3% of patients had a new motor deficit, which remained permanent in 12.5%. Progression- free follow-up was 9.7 months (range, 2 weeks-40.6 months). In 65.2% of all cases, MEPs were stable throughout the operation, but 8.9% showed a new temporary motor deficit, whereas 4.5% (5 patients) presented with permanently deteriorated motor function representing false-negative monitoring at first glance. However, these cases were caused by secondary hemorrhage, ischemia, or resection of the supplementary motor area.

CONCLUSION: Continuous MEP monitoring provides reliable monitoring of the motor system, influences the course of operation in some cases, and has to be regarded as the standard for IOM of the motor system. In our series, we found no false-negative MEP results.

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Ventricular Catheter Location and the Clearance of Intraventricular Hemorrhage

Neurosurgery 70:1258–1264, 2012 DOI: 10.1227/NEU.0b013e31823f6571

There is no consensus regarding optimal position of an external ventricular drain (EVD) with regard to clearance of intraventricular hemorrhage (IVH).

OBJECTIVE: To assess the hypothesis that EVD laterality may influence the clearance of blood from the ventricular system with and without administration of thrombolytic agent.

METHODS: The EVD location was assessed in 100 patients in 2 Clot Lysis Evaluating Accelerated Resolution of Intraventricular Hemorrhage (CLEAR IVH) phase II trials assessing the safety and dose optimization of thrombolysis through the EVD to accelerate the clearance of obstructive IVH. Laterality of catheter was correlated with clearance rates.

RESULTS: Clearance of IVH over the first 3 days was significantly greater when thrombolytic compared with placebo was administered regardless of catheter laterality (P , .005; 95% confidence interval, 214.0 to 24.14 for contralateral EVD and 224.7 to 25.44 for ipsilateral EVD). When thrombolytic was administered, there was a trend toward more rapid clearance of total IVH through an EVD placed on the side of dominant intraventricular blood compared with an EVD on the side with less blood (P = .09; 95% confidence interval, 29.62 to 0.69). This was not true when placebo was administered. Clearance of third and fourth ventricular blood was unrelated to EVD laterality.

CONCLUSION: It is possible that placement of EVD may be optimized to enhance the clearance of total IVH if lytic agents are used. Catheters on either side can clear the third and fourth ventricles with equal efficiency.

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Staged resection of large vestibular schwannomas

J Neurosurg 116:1126–1133, 2012.(http://thejns.org/doi/abs/10.3171/2012.1.JNS111402)

Staged resection of large vestibular schwannomas (VSs) has been proposed as a strategy to improve facial nerve outcomes and morbidity. The authors report their experience with 2-stage resections of large VSs and analyze the indications, facial nerve outcomes, surgical results, and complications. The authors compare these results with those of a similar cohort of patients who underwent a single-stage resection.

Methods. A retrospective review of all patients (age > 18 years) who underwent surgery from 2002 to 2010 for large (≥ 3 cm) VSs at the authors’ institution with a minimum of 6 months follow-up was undertaken. A first-stage retrosigmoid approach (without meatal drilling) was performed to remove the cerebellopontine angle portion of the tumor and to decompress the brainstem. A decision to stage the operation was made intraoperatively if there was cerebellar or brainstem edema, excessive tumor adherence to the facial nerve or brainstem, a poorly stimulating facial nerve, or a thinned or splayed facial nerve. A second-stage translabyrinthine approach was performed at a later date to remove the remaining tumor. The single-stage resection consisted of a retrosigmoid approach with meatal drilling. Patient charts were evaluated for tumor size, extent of resection, tumor recurrence, House-Brackmann facial nerve function grade, and complications.

Results. Twenty-eight and 19 patients underwent 2- or single-stage resection of a large VS, respectively. The average tumor size was 3.9 cm (range 3.2–7 cm) in the 2-stage group and 3.9 cm (range 3.1–5 cm) in the single-stage group. The mean follow-up was 36 ± 19 months in the 2-stage group versus 24 ± 14 months in the single-stage group. Gross-total or near-total resection was achieved in 27 (96.4%) of 28 patients in the 2-stage group and 15 (79%) of 19 patients in the single-stage group (p < 0.01). Anatomical facial nerve preservation was achieved in all but 1 patient (94.7%), and there were no recurrences on follow-up imaging in the 2-stage group. Good facial nerve functional outcome (House-Brackmann Grades I and II) at last follow-up was achieved in 23 (82%) of 28 patients in the 2-stage group and 10 (53%) of 19 patients in the single-stage group (p < 0.01). Cerebrospinal fluid leak–related complications (intracranial hypotension, blood patch, and lumboperitoneal shunt for pseudomeningocele) were more common in the 2-stage group. There were no postoperative strokes, hemorrhages, or deaths in either group.

Conclusions. The authors’ results suggest that staged resection of large VSs may potentially achieve better facial nerve outcomes. There does not appear to be added neurological morbidity with staged resections

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The intermediate trunk of the middle cerebral artery

J Neurosurg 116:1024–1034, 2012

(http://thejns.org/doi/abs/10.3171/2012.1.JNS111013)

The branching structure of the middle cerebral artery (MCA) remains a debated issue. In this study the authors aimed to describe this branching structure in detail.

Methods. Twenty-seven fresh, human brains (54 hemispheres) obtained from routine autopsies were used. The cerebral arteries were first filled with colored latex and contrast agent, followed by fixation with formaldehyde. All dissections were done under a microscope. During examination, the trunk structures of the MCA and their relations with cortical branches were demonstrated. Lateral radiographs of the same hemispheres were then obtained and comparisons were made. Angles between the MCA trunks were measured on 3D CT cerebral angiography images in 25 patients (50 hemispheres), and their correlations with the angles obtained in the cadaver brains were evaluated.

Results. A new classification was made in relation to the terminology of the intermediate trunk, which is still a subject of debate. The intermediate trunk was present in 61% of cadavers and originated from a superior trunk in 55% and from an inferior trunk in 45%. Cortical branches supplying the motor cortex (precentral, central, and postcentral arteries) significantly originated from the intermediate trunk, and the diameter of the intermediate trunk significantly increased when it originated from the superior trunk. In measurements of the angles between the superior and intermediate trunks, it was found that the intermediate trunk had significant dominance in supplying the motor cortex as the angle increased. The intermediate trunk was classified into 3 types based on the angle values and the distance to the bifurcation point as Group A (pseudotrifurcation type), Group B (proximal type), and Group C (distal type). Group A trunks were seemingly closer to the trifurcation structure that has been reported on in the literature and was seen in 15%. Group B trunks were the most common type (55%), and Group C trunks were characterized as the farthest from the bifurcation point. Group C trunks also had the smallest diameter and fewest cortical branches. Similarities were found between the angles in cadaver specimens and on 3D CT cerebral angiography images. Beyond the separation point of the MCA, trunk structures always included the superior trunk and inferior trunk, and sometimes the intermediate trunk.

Conclusions. Interrelations of these vascular structures and their influences on the cortical branches originating from them are clinically important. The information presented in this study will ensure reliable diagnostic approaches and safer surgical interventions, particularly with MCA selective angiography.

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Clinical presentation and prognostic factors of spinal dural arteriovenous fistulas

Neurosurg Focus 32 (5):E17, 2012. (http://thejns.org/doi/abs/10.3171/2012.1.FOCUS11376)

Spinal dural arteriovenous fistulas (AVFs), the most common type of spinal cord vascular malformation, can be a challenge to diagnose and treat promptly. The disorder is rare, and the presenting clinical symptoms and signs are nonspecific and insidious at onset.

Spinal dural AVFs preferentially affect middle-aged men, and patients most commonly present with gait abnormality or lower-extremity weakness and sensory disturbances. Symptoms gradually progress or decline in a stepwise manner and are commonly associated with pain and sphincter disturbances. Surgical or endovascular disconnection of the fistula has a high success rate with a low rate of morbidity. Motor symptoms are most likely to improve after treatment, followed by sensory disturbances, and lastly sphincter disturbances.

Patients with severe neurological deficits at presentation tend to have worse posttreatment functional outcomes than those with mild or moderate pretreatment disability. However, improvement or stabilization of symptoms is seen in the vast majority of treated patients, and thus treatment is justified even in patients with substantial neurological deficits.

The extent of intramedullary spinal cord T2 signal abnormality does not correlate with outcomes and should not be used as a prognostic factor.

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Influence of Navigated Transcranial Magnetic Stimulation on Surgical Planning for Tumors in or Near the Motor Cortex

Neurosurgery 70:1248–1257, 2012 DOI: 10.1227/NEU.0b013e318243881e 

Brain tumor surgery near the motor cortex requires careful planning to achieve the optimal balance between completeness of tumor resection and preservation of motor function. Navigated transcranial magnetic stimulation (nTMS) can be used to map functionally essential motor areas preoperatively.

OBJECTIVE: To evaluate how much influence, benefit, and impact nTMS has on the surgical planning for tumors near the motor cortex.

METHODS: This study reviewed the records of 73 patients with brain tumors in or near the motor cortex, mapped preoperatively with nTMS. The surgical team prospectively classified how much influence the nTMS results had on the surgical planning. Stepwise regression analysis was used to explore which factors predict the amount of influence, benefit, and impact nTMS has on the surgical planning.

RESULTS: The influence of nTMS on the surgical planning was as follows: it confirmed the expected anatomy in 22% of patients, added knowledge that was not used in 23%, added awareness of high-risk areas in 27%, modified the approach in 16%, changed the planned extent of resection in 8%, and changed the surgical indication in 3%.

CONCLUSION: nTMS had an objective benefit on the surgical planning in one fourth of the patients and a subjective benefit in an additional half of the patients. It had an impact on the surgery itself in just more than half of the patients. By mapping the spatial relationship between the tumor and functional motor cortex, nTMS improves surgical planning for tumors in or near the motor cortex.

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Intraoperative 3D fluoroscopy in stereotactic surgery

Acta Neurochir (2012) 154:815–821. DOI 10.1007/s00701-012-1288-2

Intraoperative localisation of a stereotactic probe remains challenging. Stereotactic X-ray, the “gold standard”, as well as intraoperative magnetic resonance (MRI) and computed tomography (CT), require a dedicated operating room (OR). Fluoroscopy with crosshairs confirms only grossly the target position. An alternative would be a mobile three-dimensional (3D) fluoroscopy C-arm. To our knowledge, this is the first report on 3D C-arm fluoroscopy to verify stereotactical trajectories. The objective was to assess the feasibility of using a 3D C-arm to verify the intraoperative trajectory and target.

Methods A total of 12 stereotactic trajectories in 10 patients were analysed, comprising 8 biopsies and 4 electrode trajectories. The fluoroscopic scan was performed after implantation of the deep brain stimulation electrode or after advancing the biopsy needle to the tumour. An image set is acquired during a rotation of the 3D C-arm. The image set is reconstructed and merged to the preoperative CT scan. Calculating the vector error and the deviation assesses target and trajectory accuracy.

Results The mean trajectory deviation was 0.6 mm (±0.54 mm) and the mean vector error was 1.44 mm (±1.43 mm). There was no influence on the surgical time and the mean irradiation dosage was 401.9 cGy/cm2.

Conclusions This target and trajectory verification is feasible. Its accuracy seems comparable with MRI and CT. There is no additional time consumption. Irradiation is comparable with stereotactic X-ray.

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Frameless robotically targeted stereotactic brain biopsy

J Neurosurg 116:1002–1006, 2012. (http://thejns.org/doi/abs/10.3171/2012.1.JNS111746)

Frameless stereotactic brain biopsy has become an established procedure in many neurosurgical centers worldwide. Robotic modifications of image-guided frameless stereotaxy hold promise for making these procedures safer, more effective, and more efficient. The authors hypothesized that robotic brain biopsy is a safe, accurate procedure, with a high diagnostic yield and a safety profile comparable to other stereotactic biopsy methods.

Methods. This retrospective study included 41 patients undergoing frameless stereotactic brain biopsy of lesions (mean size 2.9 cm) for diagnostic purposes. All patients underwent image-guided, robotic biopsy in which the Surgi-Scope system was used in conjunction with scalp fiducial markers and a preoperatively selected target and trajectory. Forty-five procedures, with 50 supratentorial targets selected, were performed.

Results. The mean operative time was 44.6 minutes for the robotic biopsy procedures. This decreased over the second half of the study by 37%, from 54.7 to 34.5 minutes (p < 0.025). The diagnostic yield was 97.8% per procedure, with a second procedure being diagnostic in the single nondiagnostic case. Complications included one transient worsening of a preexisting deficit (2%) and another deficit that was permanent (2%). There were no infections.

Conclusions. Robotic biopsy involving a preselected target and trajectory is safe, accurate, efficient, and comparable to other procedures employing either frame-based stereotaxy or frameless, nonrobotic stereotaxy. It permits biopsy in all patients, including those with small target lesions. Robotic biopsy planning facilitates careful preoperative study and optimization of needle trajectory to avoid sulcal vessels, bridging veins, and ventricular penetration.

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Transplantation of mesenchymal stem cells after spinal cord injury

Neurosurgery 70:1238–1247, 2012

DOI: 10.1227/NEU.0b013e31824387f9

Although the transplantation of mesenchymal stem cells (MSCs) after spinal cord injury (SCI) has shown promising results in animals, less is known about the effects of autologous MSCs in human SCI.

OBJECTIVE: To describe the long-term results of 10 patients who underwent intramedullary direct MSCs transplantation into injured spinal cords.

METHODS: Autologous MSCs were harvested from the iliac bone of each patient and expanded by culturing for 4 weeks. MSCs (8 · 106) were directly injected into the spinal cord, and 4 x 10(7) cells were injected into the intradural space of 10 patients with American Spinal Injury Association class A or B injury caused by traumatic cervical SCI. After 4 and 8 weeks, an additional 5 x 10(7) MSCs were injected into each patient through lumbar tapping. Outcome assessments included changes in the motor power grade of the extremities, magnetic resonance imaging, and electrophysiological recordings.

RESULTS: Although 6 of the 10 patients showed motor power improvement of the upper extremities at 6-month follow-up, 3 showed gradual improvement in activities of daily living, and changes on magnetic resonance imaging such as decreases in cavity size and the appearance of fiber-like low signal intensity streaks. They also showed electrophysiological improvement. All 10 patients did not experience any permanent complication associated with MSC transplantation.

CONCLUSION: Three of the 10 patients with SCI who were directly injected with autologous MSCs showed improvement in the motor power of the upper extremities and in activities of daily living, as well as significant magnetic resonance imaging and electrophysiological changes during long-term follow-up.

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Cervical Myelopathy After Cervical Total Disc Arthroplasty

Spine 2012 ; 37 : E624 – E628 

This article reports 2 cases in which the patients accepted revision surgery after cervical total disc arthroplasty (CTDA) because of iatrogenic neurological injury.

Summary of Background Data. CTDA has been increasingly investigated to treat cervical degenerative disc disease. However, there are limited reports focused on its complications, especially the neurological complications after the procedure.

Methods. A 52-year-old man underwent total disc arthroplasty for C5–C6, but immediately after surgery, he experienced paralysis of his upper and lower limbs. Radiographical images indicated residual compression to the spinal cord in the level of C5–C6. Another patient, a 60-year-old man, underwent total disc arthroplasty for C4–C5. Afterward, he experienced severe neck pain and paralysis of upper and lower limbs. He was unresponsive to conservative treatments; thus, a laminectomy was performed 3 months later. However, little improvement was observed. Radiographical images indicated kyphosis and spinal cord compression at the level of C4– C5. Furthermore, both cases showed a high signal in the spinal cord by T2-weighted magnetic resonance image, suggestive of spinal cord injuries.

Results. Revision surgeries were performed in both cases. Cervical implants were first removed by the anterior approach, and fusion was then performed after a complete decompression. Motor examination of the patient in case 1 showed grade 3 strength in both of his hands and feet 6 months after revision surgery. In case 2, the patient’s severe neck pain was resolved at the early postoperative stage. Motor examination showed grade 1 strength in both of his hands and feet 3 months after revision surgery.

Conclusion. On the basis of presented cases and other reports, the surgical goals in these patients were prioritized as follows: (1) safe and adequate neurological decompression and (2) establishment and maintenance of cervical sagittal balance. Moreover, a criterion for selecting patients undergoing CTDA needs to be established in order to reduce the occurrence of neurological complications associated with the procedure.

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Surgery of Insular Nonenhancing Gliomas: Volumetric Analysis of Tumoral Resection, Clinical Outcome, and Survival in a Consecutive Series of 66 Cases

Neurosurgery 70:1081–1094, 2012.  DOI: 10.1227/NEU.0b013e31823f5be5

Despite intraoperative technical improvements, the insula remains a challenging area for surgery because of its critical relationships with vascular and neurophysiological functional structures.
OBJECTIVE: To retrospectively investigate the morbidity profile in insular nonenhancing gliomas, with special emphasis on volumetric analysis of tumoral resection.

METHODS: From 2000 to 2010, 66 patients underwent surgery. All surgical procedures were conducted under cortical-subcortical stimulation and neurophysiological monitor- ing. Volumetric scan analysis was applied on T2-weighted magnetic resonance images (MRIs) to establish preoperative and postoperative tumoral volume.

RESULTS: The median preoperative tumor volume was 108 cm3. The median extent of resection was 80%. The median follow-up was 4.3 years. An immediate postoperative worsening was detected in 33.4% of cases; a definitive worsening resulted in 6% of cases. Patients with extent of resection of . 90% had an estimated 5-year overall survival rate of 92%, whereas those with extent of resection between 70% and 90% had a 5-year overall survival rate of 82% (P , .001). The difference between preoperative tumoral volumes on T2-weighted MRI and on postcontrast T1-weighted MRI ([T2 2 T1] MRI volume) was computed to evaluate the role of the diffusive tumoral growing pattern on overall survival. Patients with preoperative volumetric difference , 30 cm3 demonstrated a 5-year overall survival rate of 92%, whereas those with a difference of . 30 cm3 had a 5-year overall survival rate of 57% (P = .02).

CONCLUSION: With intraoperative cortico-subcortical mapping and neurophysiologi- cal monitoring, a major resection is possible with an acceptable risk and a significant result in the follow-up.

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Intradural spinal metastases: a surgical series of 15 patients

Acta Neurochir (2012) 154:871–877. DOI 10.1007/s00701-012-1313-5

Intradural spinal metastases are rare, and little is known regarding surgical indications and outcomes.

Methods A retrospective search identified adults with intradural spinal metastases operated on at the Mayo Clinic from 1994-2011. Data were collected regarding demographics, tumor type and location, and outcomes.

Results Fifteen patients with intradural spinal metastases were investigated. The age range was 38-74 years (mean= 55 years; ±SD=11.1). Predominant tumor location and type were lumbosacral and adenocarcinoma, respectively: 3 intramedullary and 12 extramedullary. Patients were operated on to relieve or prevent progressive/intractable neurological sequelae and/or pain. Of 13 who underwent resection, gross total removal was reported in 10; simple biopsy was performed in 2. There was one surgical complication, no medical complications, and no surgical mortality. At median follow-up of 1 month postoperatively, 10 of 15 patients were stable or improved. Of 13 patients who underwent resection, 10 were stable or improved. Of two patients who underwent biopsy, neither was stable or improved at follow-up. Using the Modified McCormick Scale, 11 of 15 patients were “functional” preoperatively and 4 went from “functional” preoperatively to “non-functional” postoperatively. Three of those four died within 60 days of surgery from systemic disease progression. Median hospital stay was 8 days. Ten of 15 patients died by the end of the study period, and the median survival of 15 patients was 5 months.

Conclusions With improved outcomes in metastatic cancer, more patients are encountered in practice. An aggressive surgical approach is warranted for extramedullary lesions, whereas caution is advised for intramedullary lesions. Postoperative functional decline is more likely due to systemic disease progression rather than surgery.

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Optimal trajectory of endoscopic third ventriculostomy

J Neurosurg 116:1153–1157, 2012. http://thejns.org/doi/abs/10.3171/2012.2.JNS111287

An optimal entry point for endoscopic third ventriculostomy (ETV) helps protect critical structures from undue manipulation. A commonly accepted ideal entry point is 3 cm from the midline and 1 cm anterior to the coronal suture. The authors of this study reexamine this ideal entry point.

Methods. Trajectory views from MR images or CT scans used for cranial image guidance in 53 patients (age range 3–85 years) who had undergone ETV were retrospectively evaluated. The trajectory from the tuber cinereum back through the center of the foramen of Monro was projected to the surface of the head. The relation of the entry point to the midline and the coronal suture was established.

Results. The mean perpendicular distance from the ideal entry point to the midline was 30.1 ± 7 mm (median 31.9 mm, range 12.5–42.2 mm). The mean perpendicular distance to the coronal suture was 8.9 ± 14.1 mm posterior (median 10.4 mm), ranging from 30.6 mm anterior to 35.8 mm posterior. The entry point tended to be located more posteriorly in women and adults: 5.8 ± 15.4 mm posterior in males versus 13.1 ± 13.2 mm posterior in females (p = 0.08) and 9.1 ± 14.8 mm posterior in adults versus 8.2 ± 11.7 mm posterior in children (p = 0.84).

Conclusions. While the entry point may need to be modified from the ideal trajectory for other anatomical reasons, such as a trajectory through the motor cortex, in general, the authors found that the optimal entry point for ETV was more posterior than previously published and highly variable. Using image guidance or a customized trajectory based on analysis of a patient’s own imaging is highly preferable to using an empirical ideal trajectory.

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Supratentorial and infratentorial brain abscesses: surgical treatment, complications and outcomes—a 10-year single-center study

Acta Neurochir (2012) 154:903–911. DOI 10.1007/s00701-012-1299-z

To analyze the variables determining morbidity, mortality and outcome in subjects with brain abscesses treated at a single center over a 10-year period.

Methods A retrospective study was conducted on a series of 59 patients with brain abscesses surgically treated with stereotactically guided aspiration or open craniotomy excision. Such variables as age, gender, clinical presentation, number of days to diagnosis, location, number of lesions, predisposing factors, mechanism of infection, etiological agent, and therapy were analyzed independently. Complications were defined as any deviation from the normal postoperative course occurring within 30 days of surgery, and classified according to a four-point gradual severity scale. Postoperative outcome was appraised through the Glasgow Outcome Scale (GOS) 6 months after surgery, 0–4 points were considered poor outcome and 5 points good outcome.

Results Eighty abscesses were diagnosed and surgically managed in 59 patients. The mean age was 44.69 years (range: 0.16-77); 59.3% were female. The median number of days to diagnosis was 7. Most frequent clinical presentations included fever (52.5%), headache (42.4%), and focal neurologic deficits (39%). Mechanism of infection was mainly hematogenous spread (32.2%). Stereotactically guided aspiration was the treatment of choice for 74.6% of the patients, whereas 25.4% of the cases were managed through open craniotomy excision. Outcome was favorable in 81.35% (n048) of the subjects. General morbidity was 27.1%, and mortality stood at 10.16%. Out of a total 38.98% (n023) of complications, two-thirds were due to medical causes. The analysis of variables revealed that only age (p00.02), immunosuppression (OR 5.83; p00.012) and hematogenous spread (p<0.01) were associated with poor outcomes.

Conclusions Immunosuppression, hematogenous spread and advanced age were predictors of poor prognosis. Most of the complications following brain abscess management were not directly related to surgery or surgical technique.

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Effectiveness of Repeat Glycerol Rhizotomy in Treating Recurrent Trigeminal Neuralgia

Neurosurgery 70:1125–1134, 2012.  DOI: 10.1227/NEU.0b013e31823f5eb6

Percutaneous glycerol rhizotomy (GR) is used to treat trigeminal neuralgia (TN), with satisfactory pain relief lasting 2 to 3 years in most patients after the first intervention. The efficacy of subsequent GRs, however, has not been studied.

OBJECTIVE: To compare the pain relief and durability achieved by the first GR with those obtained after subsequent GRs in a retrospective cohort of TN patients.

METHODS: Between 1998 and 2010, 548 patients with TN underwent 708 GRs. After exclusions, 430 initial GRs (GR1) and 114 subsequent GRs (GR21) were compared in terms of initial pain relief, durability, sensory change, and complications. Durability was assessed by determining median time to treatment failure for all GRs achieving complete pain relief without medications (n = 375: 264 failures, 111 censored). Predictors of initial pain relief were assessed by logistic regression, and predictors of failure were assessed by Cox regression analysis.

RESULTS: After GR1, pain relief results were as follows: 285 patients (66%) were pain free without medications, 26 (6%) were pain free with medications, 66 (15%) improved, and 53 (12%) were unchanged. After GR21, results were as follows: 90 patients (79%) were pain free without medications, 6 (5%) were pain free with medications, 7 (6%) improved, and 11 (10%) were unchanged (P = .03). Median time to treatment failure was 26 months after GR1 and 25 months after GR21 (P = .34). On multivariate analysis, prior GR was a positive predictor of initial pain relief (odds ratio, 2.067; 95% confidence interval, 1.243-3.437; P = .005) and had no effect on durability.

CONCLUSION: TN patients experienced greater pain relief and equivalent durability after GR21 beyond the initial treatment.

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Fusion of MRI/MRA images for navigation in AVM surgery

Neurosurg Focus 32 (5):E7, 2012. http://thejns.org/doi/abs/10.3171/2012.1.FOCUS127

Microsurgical resection of arteriovenous malformations (AVMs) is facilitated by real-time image guidance that demonstrates the precise size and location of the AVM nidus. Magnetic resonance images have routinely been used for intraoperative navigation, but there is no single MRI sequence that can provide all the details needed for characterization of the AVM. Additional information detailing the specific location of the feeding arteries and draining veins would be valuable during surgery, and this detail may be provided by fusing MR images and MR angiography (MRA) sequences. The current study describes the use of a technique that fuses contrast-enhanced MR images and 3D time-of-flight MR angiograms for intraoperative navigation in AVM resection.

Methods. All patients undergoing microsurgical resection of AVMs at the Dartmouth Cerebrovascular Surgery Program were evaluated from the surgical database. Between 2009 and 2011, 15 patients underwent surgery in which this contrast-enhanced MRI and MRA fusion technique was used, and these patient form the population of the present study.

Results. Image fusion was successful in all 15 cases. The additional data manipulation required to fuse the image sets was performed on the morning of surgery with minimal added setup time. The navigation system accurately identified feeding arteries and draining veins during resection in all cases. There was minimal imaging-related artifact produced by embolic materials in AVMs that had been preoperatively embolized. Complete AVM obliteration was demonstrated on intraoperative angiography in all cases.

Conclusions. Precise anatomical localization, as well as the ability to differentiate between arteries and veins during AVM microsurgery, is feasible with the aforementioned MRI/MRA fusion technique. The technique provides important information that is beneficial to preoperative planning, intraoperative navigation, and successful AVM resection.

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Endoscopic Treatment of Isolated Fourth Ventricle: Clinical and Radiological Outcome

Neurosurgery 70:847–859, 2012 DOI: 10.1227/NEU.0b013e318236717f

Treatment of an isolated fourth ventricle should be considered when clinical symptoms or a significant mass effect occur.

OBJECTIVE: To report clinical and radiographic outcomes after endoscopic transaqueductal or transcisternal stent placement into the fourth ventricle. METHODS: In 19 patients (age, 34th week of gestation-20 years; median age, 17.5 months), 22 endoscopic procedures were performed. Either an aqueductoplasty or, in cases with a supratentorially extended fourth ventricular component, an interventricular fenestration was performed. In all patients, a stent connected to the cerebrospinal fluid–diverting shunt was placed through the fenestration. Surgical complications and radiological and clinical outcomes are reported.

RESULTS: All 19 patients had a mean follow-up of 26.9 ± 18.2 months. No persisting neurological complications were observed; 27.3% of patients experienced complete resolution of presenting symptoms, whereas 68.3% demonstrated partial resolution. Symptoms with short duration (< 4 weeks) resolved completely, whereas long-standing symptoms partially improved. Short-term shunt complications (n = 2; insufficient catheter placement and subdural hygroma) and a need for long-term stent revisions (n = 3; stent retraction and shunt revision for other causes) were observed. The mean fourth ventricular volume was reduced after surgery (44.2 ± 25.8 to 23.1 ± 21.9 mL; P < .01). Pontine diameter increased from 0.9 ± 0.3 to 1.2 ± 0.3 cm (P < .01) after surgery. Both effects were still demonstrated on later radiological follow-up of 24.4 ± 14.2 months (fourth ventricular size, 24.7 ± 28.1 mL; P < .01; pontine diameter, 1.3 ± 0.3 cm; P < .01).

CONCLUSION: The clinical and radiological outcomes after endoscopic aqueductoplasty and interventriculostomy in children with an isolated fourth ventricle indicate that this procedure is feasible, effective, and safe.

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