Neurosurgery Blog

Neurosurg Rev (2012) 35:381–391 DOI 10.1007/s10143-012-0374-5

Stereotactic biopsies represent a routine neurosurgical procedure for the diagnosis of intracranial lymphomas and selected diffusely infiltrating gliomas. Acquisition of tissue samples that do not allow correct tumor typing and grading is, however, not uncommon. Five-aminolevulinic acid (5-ALA) has been shown to accumulate in malignant tumor tissue. The aim of this study was to prospectively investigate the clinical usability of 5-ALA for intraoperative detection of representative tissue in stereotactic tumor biopsies.

Fifty consecutive patients underwent frameless stereotactic biopsy for a suspected brain tumor. 5-ALA was administered 4 h before anesthesia. Serial biopsy samples were obtained and intraoperatively checked for 5-ALA fluorescence (strong, vague, or none) using a modified neurosurgical microscope. All samples were examined for the presence of representative tumor tissue according to neuroimaging (MRI, positron emission tomography, and/or chemical shift imaging) and histopathological parameters.

Visible 5-ALA fluorescence was observed in 43/50 patients (strong in 39 and vague fluorescence in four cases). At biopsy target, 52/53 samples of glioblastomas, 9/10 samples of gliomas grade III, and 14/16 samples of lymphomas revealed strong 5-ALA fluorescence. Samples with strong 5-ALA fluorescence were only observed at, but not outside the biopsy target. All tissue samples with strong 5-ALA fluorescence were representative according to our neuroimaging and histopathological criteria (positive predictive value of 100%). Our data indicate that strong 5-ALA fluorescence is a reliable and immediately available intraoperative marker of representative tumor tissue of malignant gliomas and intracranial lymphomas in stereotactic biopsies. Thereby, the application of 5- ALA in stereotactic brain tumor biopsies may in future reduce costs for operating room and neuropathology and may decrease procedure-related morbidity.

Neurosurgery 71:74–79, 2012 DOI: 10.1227/NEU.0b013e3182517938

Subdural hematoma (SDH) in patients with cancer is poorly described, and its frequency and causes may have changed with recent oncologic advances.

OBJECTIVE: We conducted an analysis of the clinical and radiographic features, etiologies, treatments, and outcomes of patients with SDHs and cancer.

METHODS: We retrospectively identified patients at Memorial Sloan-Kettering Cancer Center with a diagnosis of SDH and cancer from January 2000 to December 2007. We analyzed clinical and radiographic data; multivariate Cox regression was performed to associate tumor type and etiology with survival outcome.

RESULTS: There were 90 patients; 66 had acute or subacute SDHs, 9 chronic SDHs, 11 subdural hygromas, and 4 SDHs of unclear chronicity. Gliomas (16%), leukemias (14%), and prostate cancers (14%) were the most frequent malignancies. The most common single etiologies were coagulopathy (27%) and trauma (11%). SDHs with multiple etiologies occurred in 25 patients (28%) with the combination of coagulopathy and trauma occurring in 15. Sixty patients (67%) were either completely or partially independent after SDH, and 1-year survival was 43% (95% confidence interval: 32.1-52.9). Overall survival correlated with etiology (P , .0001) and whether the malignancy was in remission (P = .005). Trauma was associated with the best overall survival compared with coagulopathy.

CONCLUSION: Leukemia and prostate cancer are the most common systemic cancers associated with SDH, and gliomas may predispose to SDH more often than previously recognized. Coagulopathy is common and associated with the worst outcome, but many patients experience good functional outcome and survival.

Neurosurg Rev (2012) 35:359–368

Foramen magnum meningioma poses a challenge for neurosurgeons. Prognosis has generally improved with diagnostic and surgical advances over the past two decades; however, it may ultimately depend more on the surgeon’s ability to tailor the approach and interpret intraoperative risks in single cases.

The series comprised 64 patients operated on for ventral and ventrolateral foramen magnum meningioma. All patients underwent preoperative magnetic resonance imaging and received surgery via the dorsolateral route, rendering the series homogeneous in neuroradiological workup and surgical treatment. Particular to this series was that the majority of patients were of advanced age (n=29; age, >65 years), had serious functional impairment (n=30, Karnofski score <70), and large tumors (mean diameter, 3.5 cm).

Total tumor removal was achieved in 52 (81 %) patients; operative mortality was nil. Early outcome varied depending on difficulties encountered at surgery (cranial nerve position and type of involvement in particular) and type of preoperative dysfunction. Long-tract signs and cerebellar deficits improved in 74 and 77 % of cases, respectively, but only 27 % of cranial nerve deficits did so. Surgical complications most often involved the cranial nerves: cranial nerve impairment, especially of the 9th through the 12th cranial nerves, due to stretching or encasement was noted in 44 cases. At final outcome assessment, two thirds of the cranial nerve deficits cleared, and all but two patients returned to a normal productive life. One patient was reoperated on during the follow-up period.

Foramen magnum meningiomas behave like clival or spinal tumors depending on their prevalent extension. A dorsolateral approach tailored to tumor position and extension and meticulous surgical technique allow for definitive control of surgical complications. Scrupulous postoperative care may prevent dysphagia, a major persistent complication of surgery. Long-term observation of indolent tumor behavior at follow-up suggests that incomplete resection may be a viable surgical treatment option.

J Neurosurg Spine 17:30–36, 2012

Incidental durotomies (IDs) are an unfortunate but anticipated potential complication of spinal surgery. The authors surveyed the frequency of IDs for a single spine surgeon and analyzed the major risk factors as well as the impact on long-term patient outcomes.

Methods. The authors conducted a prospective review of elective spinal surgeries performed over a 15-year period. Any surgery involving peripheral nerve only, intradural procedures, or dural tears due to trauma were excluded from analysis. The incidence of ID was categorized by surgery type including primary surgery, revision surgery, and so forth. Incidence of ID was also examined in the context of years of physician experience and training. Furthermore, the incidence and types of sequelae were examined in patients with an ID.

Results. Among 3000 elective spinal surgery cases, 3.5% (104) had an ID. The incidence of ID during minimally invasive procedures (3.3%) was similar, but no patients experienced long-term sequelae. The incidence of ID during revision surgery (6.5%) was higher. There was a marked difference in incidence between cervical (1.3%) and thoracolumbar (5.1%) cases. The incidence was lower for cases involving instrumentation (2.4%). When physician training was examined, residents were responsible for 49% of all IDs, whereas fellows were responsible for 26% and the attending for 25%. Among all of the cases that involved an ID, 7.7% of patients went on to experience a neurological deficit as compared with 1.5% of those without an ID. The overall failure rate of dural repair was 6.9%, and failure was almost 3 times higher (13%) in revision surgery as compared with a primary procedure (5%).

Conclusions. The authors established a reliable baseline incidence for durotomy after spine surgery: 3.5%. They also identified risk factors that can increase the likelihood of a durotomy, including location of the spinal procedure, type of procedure performed, and the implementation of a new procedure. The years of physician training or resident experience did not appear to be a major risk for ID.

Neurosurgery 71:117–125, 2012 DOI: 10.1227/NEU.0b013e3182532e71

The management of spinal column tumors continues to be a challenge for clinicians. The mechanisms of tumor recurrence after surgical intervention as well as resistance to radiation and chemotherapy continue to be elucidated. Furthermore, the pathophysiology of metastatic spread remains an area of active investigation.

There is a growing body of evidence pointing to the existence of a subset of tumor cells with high tumorigenic potential in many spine cancers that exhibit characteristics similar to those of stem cells. The ability to self-renew and differentiate into multiple lineages is the hallmark of stem cells, and tumor cells that exhibit these characteristics have been described as cancer stem cells (CSCs).

The mechanisms that allow nonmalignant stem cells to promote normal developmental programming by way of enhanced proliferation, promotion of angiogenesis, and increased motility may be used by CSCs to fuel carcinogenesis.

The purpose of this review is to discuss what is known about the role of CSCs in tumors of the osseous spine. First, this article reviews the fundamental concepts critical to understanding the role of CSCs with respect to chemoresistance, radioresistance, and metastatic disease. This discussion is followed by a review of what is known about the role of CSCs in the most common primary tumors of the osseous spine.

Neuroradiology (2012) 54:719–726 DOI 10.1007/s00234-011-0950-3

The authors present a series of patients in whom early rebleeding occurred after coiling for ruptured aneurysms. We investigated the incidence and possible mechanisms of early rebleeding.

Methods This study consisted of 1,167 consecutive patients who underwent coiling for a ruptured saccular aneurysm. Clinical and radiological data were collected retrospectively from three institutions. Early rebleeding was defined as occurrence of further bleeding within 30 days after coiling with worsening of the patient’s condition. We divided early rebleeding into hyperacute, subacute, and delay groups depending on the timing of rebleeding after coil embolization.

Results Incidence of early rebleeding after coiling of a ruptured saccular aneurysm was 1.1% (13 of 1,167), and mortality was 31% (4 of 13) in our series. Out of ten patients in hyperacute group, three (30%) had incomplete occlusion result and six patients (60%) underwent intraarterial (IA) infusion of abciximab or tirofiban during the procedures. Seven patients (70%) had an intracerebral hemorrhage (ICH) on initial computed tomography. Four patients died, another four sustained severe disabilities, and the others had good recovery. All three patients in subacute and delay group showed recanalization on post-rebleeding angiography and made an excellent recovery.

Conclusion Early rebleeding was associated with high mortality and morbidity. IA abciximab infusion or thrombolytic interventions during the procedure, maintenance of anticoagulation after the procedure, incomplete treatment of the aneurysms, and presence of ICH seemed to be related to hyperacute early rebleeding after coiling. Increased aneurysmal size and coil compaction could induce subacute and delayed early rebleeding.

J Neurosurg: Spine / July 17, 2012. DOI: 10.3171/2012.6.SPINE11915

Axial lumbar interbody fusion (AxiaLIF) is a minimally invasive presacral surgical technique that damages neither the anulus fibrosus nor the anterior or posterior longitudinal ligaments. The technique was initially designed and used for L5–S1 interbody fusions and recently was extended to 2-level fusions (L4–5 and L5–S1). Until now, only biomechanical and radiological studies have discussed the feasibility of this new indication, and no clinical study has been published. The purpose of this article is to report results and complications associated with 2-level presacral AxiaLIF with a minimum of 24 months of follow-up.

METHODS
In this prospective, nonrandomized, single-center study, 27 patients underwent presacral AxiaLIF surgery at the L4–5 and L5–S1 levels. Clinical outcomes were assessed using the visual analog scale for back and leg symptoms and the Oswestry Disability Index. Radiographic parameters, such as disc height, segmental lordosis, and bone fusion, were analyzed using radiographs and CT scans. Complications and revision surgeries were recorded as needed. The minimum follow-up was 24 months (up to 72 months).

RESULTS
There were no intraoperative complications. One major complication was observed: a patient developed septicemia that resolved after proper care. Clinical outcomes scores showed overall improvement in pain and physical function. During follow-up, the following complications were observed in the construct: screw breakage (14.8%), proximal/distal transsacral rod detachment (11.1%), radiolucency around the transsacral rod (52%), and cephalic rod migration (24%). Disc height gain was reported early after surgery, but at the 24-month follow-up the disc space was diminished in comparison with the preoperative status. Compared with preoperative values, the 24-month results showed loss of segmental lordosis. Only 22% of all treated levels were considered to have solid fusion at the 24-month radiological evaluation.

CONCLUSIONS
Patients undergoing presacral 2-level AxiaLIF experienced satisfactory short-term clinical outcomes; however, complications were commonly seen on imaging studies obtained 24 months postoperatively. Additional studies are required to better understand the 2-level indications for this technique.

J Neurosurg 117:20–25, 2012

In this paper, the authors’ goals were to clarify the characteristics of growing unruptured cerebral aneurysms detected by serial MR angiography and to establish the recommended follow-up interval.

Methods. A total of 1002 patients with 1325 unruptured cerebral aneurysms were retrospectively identified. These patients had undergone follow-up evaluation at least twice. Aneurysm growth was defined as an increase in maximum aneurysm diameter by 1.5 times or the appearance of a bleb.

Results. Aneurysm growth was observed in 18 patients during the period of this study (1.8%/person-year). The annual rupture risk after growth was 18.5%/person-year. The proportion of females among patients with growing aneurysms was significantly larger than those without growing aneurysms (p = 0.0281). The aneurysm wall was reddish, thin, and fragile on intraoperative findings. Frequent follow-up examination is recommended to detect aneurysm growth before rupture.

Conclusions. Despite the relatively short period, the annual rupture risk of growing unruptured cerebral aneurysms detected by MR angiography was not as low as previously reported. Surgical or endovascular treatment can be considered if aneurysm growth is detected during the follow-up period.

J Neurosurg 117:141–149, 2012

The aim of this study was to evaluate and compare CSF flow after endoscopic third ventriculostomy (ETV) and endoscopic aqueductoplasty (EAP) in patients presenting with obstructive hydrocephalus caused by aqueductal stenosis.

Methods. In patients harboring aqueductal stenosis who underwent EAP (n = 8), ETV (n = 8), and both ETV and EAP (n = 6), CSF flow through the restored aqueduct and through the ventriculostomy was investigated using cine cardiac-gated phase-contrast MRI. For qualitative evaluation of CSF flow, an in-plane phase-contrast sequence in the midsagittal plane was used. The MR images were displayed in a closed-loop cine format. Quantitative through-plane measurements were performed in the axial plane perpendicular to the aqueduct and/or floor of the third ventricle.

Results. Evaluation revealed significantly higher CSF flow through the ventriculostomies compared with flow through the aqueducts. This was true both when comparing the ETV group with the EAP group and when comparing the flow of the ventriculostomy and aqueduct within the ETV and EAP group. There was no difference in aqueductal CSF flow between patients who underwent EAP alone and patients who underwent ETV and EAP. There was also no difference in ventriculostomy CSF flow between patients who underwent ETV alone and patients who underwent ETV and EAP. Fifty percent of the restored aqueducts became occluded at a mean of 46 months after surgery (range 18–126 months). In contrast, all ETVs remained patent in the mean follow-up period of 110 months after surgery, although 1 patient required shunt placement after 66 months.

Conclusions. Cerebrospinal fluid flow through ventriculostomies is significantly higher than aqueductal CSF flow after EAP. This could be one factor to explain why the reclosure rate of aqueducts after EAP is higher than the reclosure rate of the ventriculostoma after ETV.

J Neurosurg 117:78–88, 2012. (http://thejns.org/doi/abs/10.3171/2012.3.JNS111541)

In this study, the authors used preoperative simulation employing 3D computer graphics (interactive computer graphics) to fuse all imaging data for brainstem cavernous malformations. The authors evaluated whether interactive computer graphics or 2D imaging correlated better with the actual operative field, particularly in identifying a developmental venous anomaly (DVA).

Methods. The study population consisted of 10 patients scheduled for surgical treatment of brainstem cavernous malformations. Data from preoperative imaging (MRI, CT, and 3D rotational angiography) were automatically fused using a normalized mutual information method, and then reconstructed by a hybrid method combining surface rendering and volume rendering methods. With surface rendering, multimodality and multithreshold techniques for 1 tissue were applied. The completed interactive computer graphics were used for simulation of surgical approaches and assumed surgical fields. Preoperative diagnostic rates for a DVA associated with brainstem cavernous malformation were compared between conventional 2D imaging and interactive computer graphics employing receiver operating characteristic (ROC) analysis.

Results. The time required for reconstruction of 3D images was 3–6 hours for interactive computer graphics. Observation in interactive mode required approximately 15 minutes. Detailed anatomical information for operative procedures, from the craniotomy to microsurgical operations, could be visualized and simulated three-dimensionally as 1 computer graphic using interactive computer graphics. Virtual surgical views were consistent with actual operative views. This technique was very useful for examining various surgical approaches. Mean (± SEM) area under the ROC curve for rate of DVA diagnosis was significantly better for interactive computer graphics (1.000 ± 0.000) than for 2D imaging (0.766 ± 0.091; p < 0.001, Mann-Whitney U-test).

Conclusions. The authors report a new method for automatic registration of preoperative imaging data from CT, MRI, and 3D rotational angiography for reconstruction into 1 computer graphic. The diagnostic rate of DVA associated with brainstem cavernous malformation was significantly better using interactive computer graphics than with 2D images. Interactive computer graphics was also useful in helping to plan the surgical access corridor.

Acta Neurochir (2012) 154:1169–1175 DOI 10.1007/s00701-012-1354-9

Cerebral cavernous malformations (CCMs) are known to be vascular anomalies with low perfusion because of being angiographically occult. We attempted direct visualization of blood flow within CCMs and orbital cavernous angiomas (CAs), and analyzed flow dynamics using indocyanine green videoangiography (ICG-VAG).

Methods This series included seven CCMs and two orbital CAs. ICG-VAG was performed to visualize blood flow of the lesions before resection. Time to peak of staining was evaluated by reviewing recorded ICG-VAG.

Results In five of seven CCMs, stain was identified. CCMs were seen as avascular areas in both arterial and venous phases, and were stained gradually. Stain was maximized late after venous phase. The orbital CAs were also stained lately, but more intensely than CCMs.

Conclusions The present study directly demonstrated slow and low perfusion within CCM and orbital CA using ICGVAG. On the basis of characteristic flow dynamics of CCMs, intraoperative ICG-VAG provides useful information in microsurgical resection.

SPINE Volume 37, Number 16, pp E-985–E992

We compared the sizes of the dural sac among conventional magnetic resonance imaging (MRI), axial loaded MRI, and upright myelography in patients with lumbar spinal canal stenosis (LSCS).

Objective. To determine whether axial loaded MRI can demonstrate similar positional changes of the dural sac size as were detected by upright myelography in LSCS.

Summary of Background Data. In patients with LSCS, constriction of the dural sac is worsened and symptoms are aggravated during standing or walking. To disclose such positional changes, upright myelography has been widely used. Recently, axial loaded MRI, which can simulate a standing position, has been developed. However, there has been no study to compare the dural sac size between axial loaded MRI and upright myelography.

Methods. Forty-four patients underwent conventional MRI, axial loaded MRI, and myelography. Transverse and anteroposterior diameters and the cross-sectional areas of the dural sac from L2– L3 to L5–S1 were compared. Pearson correlations of the diameters between the MRIs and the myelograms were analyzed. On the basis of the myelograms, all disc levels were divided into severe and nonsevere constriction groups. In each group, the diameters and the cross-sectional areas were compared. Sensitivity and specifi city to detect severe constriction were calculated for the conventional and axial loaded MRI.

Results. Transverse and anteroposterior diameters at L4–L5 in the axial loaded MRI and myelogram were signifi cantle smaller than those observed in the conventional MRI ( P < 0.001). Crosssectional areas in the axial loaded MRI were signifi cantly smaller than those in the conventional MRI at L2–L3, L3–L4, and L4–L5 ( P < 0.001). Between the axial loaded MRI and the myelography, Pearson correlation coeffi cients of the transverse and anteroposterior diameters were 0.85 and 0.87, respectively ( P < 0.001), which were higher than those for conventional MRI. Reductions of the dural sac sizes in the axial loaded MRI were more evident in the severe constriction group. The axial loaded MRI detected severe constriction with a higher sensitivity (96.4%) and specifi city (98.2%) than the conventional MRI.

Conclusion. The axial loaded MRI demonstrated a significant reduction in the dural sac size and signifi cant correlations of the dural sac diameters with the upright myelogram. Furthermore, the axial loaded MRI had higher sensitivity and specifi city than the conventional MRI for detecting the severe constriction observed in the myelogram. Therefore, the axial loaded MRI can be used to represent positional changes of the dural sac size detected by the upright myelography in patients with LSCS.

Neurosurgery 71:100–108, 2012 DOI: 10.1227/NEU.0b013e318256c042

Conus medullaris arteriovenous malformations (AVMs) are rare, challenging spinal vascular lesions that cause progressive debilitating myeloradiculopathy. Only sporadic reports of conus AVMs have been published.

OBJECTIVE: To better define the presentation, prognosis, and optimal treatment of these lesions, we present the first case series of conus AVMs, reflecting over 2 decades of experience with a multimodality endovascular and surgical approach.

METHODS: We retrospectively reviewed the charts of 16 patients with a conus AVM evaluated at our institution from 1989 to 2010. For each patient, the following clinical data were collected: age, sex, symptoms, angiographic findings, type of treatment, complications, degree of angiographic obliteration, recurrence at follow-up, and need for re-treatment. Ambulatory status, Frankel Grade, motor function, and bladder/bowel function were assessed before treatment, at discharge, and at last follow-up.

RESULTS: All 16 patients were treated. Eight (50%) patients underwent embolization followed by microsurgical resection, and 8 (50%) underwent microsurgical resection only. The rate of complete angiographic obliteration was 88%. At last follow-up (mean, 70 months), 43% of patients neurologically improved, 43% were stable, and 14% worsened in comparison with before treatment. During follow-up, 3 recurrences were detected, including the only 2 instances of long-term neurological decline. In the absence of recurrence, all patients ambulatory before treatment remained ambulatory at follow-up, whereas 75% of the initially nonambulatory patients regained the ability to walk.

CONCLUSION: Although conus AVMs are challenging to treat, excellent long-term outcomes are possible with a multimodality approach. Recurrence is associated with long-term neurological decline and calls for close follow-up.

J Neurosurg 117:121–128, 2012. http://thejns.org/doi/abs/10.3171/2012.3.JNS111945

Techniques for the surgical treatment of meningioma have undergone many improvements since Simpson established the neurosurgical dogma for meningioma surgery in his seminal paper published in 1957. This study aims to assess the clinical significance and limitations of the Simpson grading system in relation to modern surgery for WHO Grade I benign meningiomas and to explore the potential of the cell proliferation index to complement the limitations in predicting their recurrence.

Methods. The surgical records of patients who underwent resection of intracranial meningiomas at the University of Tokyo Hospital between January 1995 and August 2010 were retrospectively analyzed. The authors investigated the relationships between recurrence-free survival (RFS) and Simpson grade or MIB-1 labeling index value.

Results. A total of 240 patients harboring 248 benign meningiomas were included in this study. Simpson Grade IV resection was associated with a significantly shorter RFS than Simpson Grade I, II, or III resection (p < 0.001), while no statistically significant difference was noted in RFS between Simpson Grades I, II, and III. Among meningiomas treated by Simpson Grade II and III resections, however, multivariate analysis revealed that an MIB-1 index of 3% or higher was associated with a significantly shorter time to recurrence.

Conclusions. The clinical significance of the different management strategies related to Simpson Grade I–III resection may have been diluted in the modern surgical era. The MIB-1 index can differentiate tumors with a high risk of recurrence, which could be beneficial for planning tailored optimal follow-up strategies. The results of this study appear to provide a significant backing for the recent shift in meningioma surgery from attempting aggressive resection to valuing the quality of the patient’s life.

Neurosurg Pediatrics 10:39–43, 2012. http://thejns.org/doi/abs/10.3171/2012.4.PEDS1222

Electrolyte and endocrinological complications of endoscopic third ventriculostomy (ETV) are infrequent but serious events, likely due to transient hypothalamic-pituitary dysfunction. While the incidence of diabetes insipidus is relatively well known, hyponatremia is not often reported. The authors report on a series of 5 patients with post-ETV hyponatremia.

Methods. The records of patients undergoing ETV between 2008 and 2010 were reviewed. All ETVs were performed with a rigid neuroendoscope via a frontal bur hole, standard third ventricle floor blunt perforation, Fogarty catheter dilation, and intermittent normal saline irrigation. Postoperative MR images were evaluated for endoscope tract injury as well as the trajectory from the bur hole center to the fenestration site.

Results. Thirty-two patients (20 male and 12 female) underwent ETV. Their median age was 6 years (range 3 weeks–28 years). Hydrocephalus was most commonly due to nontumoral aqueductal stenosis (43%), nontectal tumor (25%), or tectal glioma (13%). Five patients (16%) had multicystic/loculated hydrocephalus. Five patients (16%) developed hyponatremia between 1 and 8 days following ETV, including 2 patients with seizures (1 of whom was still hospitalized at the time of the seizure and 1 of whom was readmitted as a result of the seizure) and 3 patients who were readmitted because of decline in their condition following routine discharge. No hypothalamic injuries were noted on imaging. Univariate risk factors consisted of age of 2 years or less (p = 0.02), presence of cystic lesions (p = 0.02), and ETV trajectory angle 10° or more from perpendicular (p = 0.001).

Conclusions. Endoscopic third ventriculostomy is a well-tolerated procedure but can result in serious complications. Hyponatremia is rare and may be more likely in younger patients or those with cystic loculations. Patients with altered craniometry may be at particular risk with a rigid endoscopic approach requiring greater manipulation of subforniceal or hypothalamic structures.

Acta Neurochir (2012) 154:1135–1144. DOI 10.1007/s00701-012-1397-y

We conducted a prospective study to investigate the clinical and radiological outcome in a surgical case series of 176 patients with 203 unruptured intracranial aneurysms (UIA).

Methods The success of aneurysm obliteration was assessed within 2 weeks after surgery by digital subtraction angiography (DSA). Patients also underwent angiography 5 years after surgery. Clinical outcomes were assessed using the modified Rankin Scale (mRS). All predictors of poor surgical outcomes were assessed using an exact logistic regression.

Results Overall, 83%of the patients had a good outcome (mRS score 0 or 1); 10.8 % of the patients had a slight disability (mRS score 2), and 6.2 % of the patients had a moderate or moderatesevere disability (mRS score 3 or 4). The mortality rate was 0% overall. The most important predictors of outcome were presence of history of ischemic cerebrovascular disease and postoperative stroke. Complete aneurysm occlusion was achieved in 93.5 % of all aneurysms. Sixty percent of treated aneurysms were checked with late follow-up DSA. No cases of hemorrhage from a surgically obliterated UIA were documented in this series during the 7.3±1.4 (SD)-year follow-up period.

Conclusions If patients are carefully selected and individually assigned to their optimum treatment modality, IUAs can be obliterated by surgery with a low percentage of unfavorable outcomes.

Neurosurgery 71:58–67, 2012 DOI: 10.1227/NEU.0b013e31824f4f96

Giant invasive spinal schwannoma (GISS) is defined as a lesion that extends over . 2 vertebral levels, erodes vertebral bodies, and extends posteriorly and laterally into the myofascial planes. Because of its rarity, few reports have been issued.

OBJECTIVE: To analyze the clinical features and outcomes of GISS and to discuss surgical strategies.

METHODS: We analyzed the medical records, pathological findings, and radiographic studies of patients with GISS.

RESULTS: Fourteen patients with GISS were surgically treated between 2002 and 2007. Five lesions were in the sacral region, 4 in the lumbosacral, 2 in the thoracolumbar, and 1 each in the cervical, cervicothoracic, and thoracic regions. Gross total resection was performed in 11 of the 14 patients. Satisfactory decompression was performed in all patients for neural compression. Postoperatively, all patients showed relief of pre- operative pain and paresthesia. The growth potential with the Ki-67 index was . 2% in 6 patients, and 4 of them experienced tumor regrowth or recurrence. All patients were followed up for at least 24 months. Final follow-up magnetic resonance images showed asymptomatic small tumor recurrence on the sacrum in 2 patients. Two patients required spinal stabilization. No instability was found on follow-up.

CONCLUSION: Total resection is the treatment of choice for patients with GISS and provides functional improvements, low permanent morbidity, and a low rate of recurrence. Total resection of the intraspinal portion and regular follow-up with con- sideration of the Ki-67 index is recommended when total resection is not achieved.

Neurosurgery 71:6–13, 2012 DOI: 10.1227/NEU.0b013e3182544e31

External ventricular drainage (EVD) catheters provide reliable and accurate means of monitoring intracranial pressure and alleviating elevated pressures via drainage of cerebrospinal fluid (CSF). CSF infections occur in approximately 9% of patients. Antibiotic-impregnated (AI) EVD catheters were developed with the goal of reducing the occurrence of EVD catheter-related CSF infections and their associated complications.

OBJECTIVE: To present an international, prospective, randomized, open-label trial to evaluate infection incidence of AI vs standard EVD catheters.

METHODS: Infection was defined as (1) proven infection, positive CSF culture and positive Gram stain or (2) suspected infection: (A) positive CSF culture with no organisms identified on initial Gram stain; (B) negative CSF culture with a gram-positive or -negative stain; (C) CSF leukocytosis with a white blood cell/red blood cell count .0.02.

RESULTS: Four hundred thirty-four patients underwent implantation of an EVD catheter. One hundred seventy-six patients in the AI-EVD cohort and 181 in the standard EVD catheter cohort were eligible for evaluation of infection. The 2 groups were similar in all clinical characteristics. Proven infection was documented in 9 (2.5%) patients (AI: 4 [2.3%] vs standard: 5 [2.8%], P = 1.0). Suspected infection was documented in 31 (17.6%) patients receiving AI and 37 (20.4%) patients receiving standard EVD catheters, P = .504. Duration of time to suspected infection was prolonged in the AI cohort (8.8 6 6.1 days) compared with the standard EVD cohort (4.6 6 4.2 days), P = .002.

CONCLUSION: AI-EVD catheters were associated with an extremely low rate of catheter-related infections. AI catheters were not associated with risk reduction in EVD infection compared to standard catheters. Use of AI-EVD catheters is a safe option for a wide variety of patients requiring CSF drainage and monitoring, but the efficacy of AI-EVD catheters was not supported in this trial.

Neurosurgery 71:30–37, 2012 DOI: 10.1227/NEU.0b013e31824e512e

Artificial cervical disk replacements are commonly used to treat radiculomyelopathy caused by degenerative disk disease. However, long-term disk mobility and an effect on adjacent segment disease have yet to be demonstrated. We report improvements in clinical outcome after disk replacement but also demonstrate potential limitations.

OBJECTIVE: To review clinical and radiological outcomes after diskectomy and disk replacement with the Porous Coated Motion (PCM) artificial cervical disk.

METHODS: A retrospective review was done of consecutive patients who underwent 1- or 2-level PCM disk replacements. The following criteria were studied: arm pain, neck pain, Neck Disability Index and Short Form-36 questionnaires, and flexion-extension radiographs up to 2 years after surgery.

RESULTS: Eighty PCM artificial disks were implanted in 53 patients. Only 17 disks (21%) maintained physiological movement, and complete fusion was seen in 18.8%. One disk replacement was revised because of anterior displacement. There were no complications of infection, cerebrospinal fluid leak, dysphagia, or hoarse voice. Arm and neck pain improved significantly after diskectomy, but Neck Disability Index questionnaires demonstrated a slight improvement that was not sustained by 2 years. Short Form-36 scores demonstrated a trend toward better outcome with time, but it was significant only for the mental domain.

CONCLUSION: Clinical improvement was seen after PCM disk replacement, but adequate range of movement was sustained in only 21% of disk replacements over time. Unclear long-term results of this and other disk replacements suggest caution in adopting these new devices as the gold standard.

Neurosurgery 71:86–92, 2012 DOI: 10.1227/NEU.0b013e31825356f5

Percutaneous remodeling of the ligamentum flavum and lamina (PRLL), commercially known as minimally invasive lumbar decompression (mild technique), relies on fluoroscopy and epidural contrast to direct surgical instruments via a 6-mm cannula.

OBJECTIVE: To evaluate the safety and efficacy of PRLL and present, to our knowledge, the first reported imaging findings after PRLL.

METHODS: We performed a prospective study of PRLL for neurogenic claudication. Primary outcomes were Oswestry Disability Index, Short-Form 12 version 2.0 health survey, and visual analog scale for pain at 26 weeks. Analgesic use was also assessed. Postoperative magnetic resonance imaging was performed at 12 weeks. Long-term failure, defined as the poststudy need for secondary surgery, was assessed up to 18 months.

RESULTS: Ten subjects with an average age of 64 years (range, 41-81 years) were treated between September 2008 and January 2009. There were no major adverse events. Mean postoperative visual analog scale score remained significantly reduced throughout 26 weeks (P =.015, analysis of variance). Mean postoperative Oswestry Disability Index was also improved by 1 week and remained significant throughout 26 weeks (P = .024; analysis of variance). However, there was a trend toward increased reliance on narcotic type medications postoperatively. Imaging studies did not show significant decompression of the spinal canal in any patient. In the poststudy period, recurrent claudication requiring laminectomy developed in 6 patients (60%).

CONCLUSION: Throughout 26 weeks, pain and disability scores were decreased; however, PRLL did not improve the degree of stenosis on imaging studies. Although PRLL appears to be safe in this small cohort of patients, poststudy outcomes indicate that the failure rate is unacceptably high.