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Increasing Flow Diversion for Cerebral Aneurysm Treatment Using a Single Flow Diverter

Increasing Flow Diversion for Cerebral Aneurysm Treatment Using a Single Flow Diverter

Neurosurgery 75:286–294, 2014

A neurovascular flow diverter (FD), aiming at inducing embolic occlusion of cerebral aneurysms through hemodynamic changes, can produce variable mesh densities owing to its flexible mesh structure.

OBJECTIVE: To explore whether the hemodynamic outcome would differ by increasing FD local compaction across the aneurysm orifice.

METHODS: We investigated deployment of a single FD using 2 clinical strategies: no compaction (the standard method) and maximum compaction across the aneurysm orifice (an emerging strategy). Using an advanced modeling technique, we simulated these strategies applied to a patient-specific wide-necked aneurysm model, resulting in a relatively uniform mesh with no compaction (C1) and maximum compaction (C2) at the aneurysm orifice. Pre- and posttreatment aneurysmal hemodynamics were analyzed using pulsatile computational fluid dynamics. Flow-stasis parameters and blood shear stress were calculated to assess the potential for aneurysm embolic occlusion.

RESULTS: Flow streamlines, isovelocity, and wall shear stress distributions demonstrated enhanced aneurysmal flow reduction with C2. The average intra-aneurysmal flow velocity was 29% of pretreatment with C2 compared with 67% with C1. Aneurysmal flow turnover time was 237% and 134% of pretreatment for C2 and C1, respectively. Vortex core lines and oscillatory shear index distributions indicated that C2 decreased the aneurysmal flow complexity more than C1. Ultrahigh blood shear stress was observed near FD struts in inflow region for both C1 and C2.

CONCLUSION: The emerging strategy of maximum FD compaction can double aneurysmal flow reduction, thereby accelerating aneurysm occlusion. Moreover, ultrahigh blood shear stress was observed through FD pores, which could potentially activate platelets as an additional aneurysmal thrombosis mechanism.

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Surgical Management of Trigeminal Neuralgia: Use and Cost-Effectiveness From an Analysis of the Medicare Claims Database

SnapShotPNGOID_38_20121112T070408_110023

Neurosurgery 75:220–226, 2014

Trigeminal neuralgia is a relatively common neurosurgical pathology with multiple management options. Microvascular decompression (MVD) is nonablative and is considered the gold standard. However, stereotaxic radiosurgery (SRS) and percutaneous stereotaxic rhizotomy (PSR) are 2 noninvasive but ablative options that have rapidly gained support.

OBJECTIVE: To use Medicare claims data in conjunction with a literature review to assess the usage, effectiveness, and cost-effectiveness of the 3 different invasive treatments for trigeminal neuralgia.

METHODS: All of the claims of trigeminal neuralgia treatment were extracted from the 2011 5% Inpatient and Outpatient Limited Data Set. Current Procedural Terminology, 4th Edition/International Classification of Diseases, Ninth Revision codes for the 3 different surgical treatment modalities were used to further classify these claims. Kaplan-Meier survival curves in key articles were used to calculate quality-adjusted life years and costeffectiveness for each procedure.

RESULTS: A total of 1582 claims of trigeminal neuralgia were collected. Ninety-four (6%) patients underwent surgical intervention. Forty-eight (51.1%) surgical patients underwent MVD, 39 (41.5%) underwent SRS, and 7 (7.4%) underwent PSR. The average weighted costs for MVD, SRS, and PSR were $40 434.95, $38 062.27, and $3910.64, respectively. The qualityadjusted life yearswere 8.2 forMVD, 4.9 for SRS, and 6.5 for PSR. The cost per quality-adjusted life year was calculated as $4931.1, $7767.8, and $601.64 for MVD, SRS, and PSR, respectively.

CONCLUSION: This study shows that the most frequently used surgical management of trigeminal neuralgia is MVD, followed closely by SRS. PSR, despite being the most cost-effective, is by far the least utilized treatment modality.

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Aneurysms of the anterior and posterior cerebral circulation: comparison of the morphometric features

Aneurysms of the anterior and posterior cerebral circulation- comparison of the morphometric features

Acta Neurochir (2014) 156:1647–1654

Intracranial aneurysms (IAs) located in the posterior circulation are considered to have higher annual bleed rates than those in the anterior circulation. The aim of the study was to compare the morphometric factors differentiating between IAs located in the anterior and posterior cerebral circulation.

Methods A total number of 254 IAs diagnosed between 2009 and 2012 were retrospectively analyzed. All patients qualified for diagnostic, three-dimensional rotational angiography. IAs were assigned to either the anterior or posterior cerebral circulation subsets for the analysis. Means were compared with a t-test. The univariate and stepwise logistic regression analyses were used to determine the predictors of morphometric differences between the groups. For the defined predictors, ROC (receiver-operating characteristic) curves and interactive dot diagrams were calculated with the cutoff values of the morphometric factors.

Results The number of anterior cerebral circulation IAs was 179 (70.5 %); 141 (55.5 %) aneurysms were ruptured. Significant differences between anterior and posterior circulation IAs were found for: the parent artery size (5.08±1.8 mm vs. 3.95±1.5mm; p<0.05), size ratio (2.22±0.9 vs. 3.19±1.8; p< 0.045) and aspect ratio (AR) (1.91±0.8 vs. 2.75±1.8; p= 0.02). Predicting factors differentiating anterior and posterior circulation IAs were: theAR (OR=2.20; 95%CI 1.80–270; Is 270 correct or should it be 2.70 and parent artery size (OR= 0.44; 95 % CI 0.38–0.54). The cutoff point in the ROC curve was 2.185 for the AR and 4.89 mm for parent artery size.

Conclusions Aspect ratio and parent artery size were found to be predictive morphometric factors in differentiating between anterior and posterior cerebral IAs.

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Development and validation of an artificial wetlab training system for the lumbar discectomy

Development and validation of an artificial wetlab training system for the lumbar discectomy

Eur Spine J (2014) 23:1978–1983

An initial research indicated that realistic haptic simulators with an adapted training concept are needed to enhance the training for spinal surgery.

Methods A cognitive task analysis (CTA) was performed to define a realistic and helpful scenario-based simulation. Based on the results a simulator for lumbar discectomy was developed. Additionally, a realistic training operating room was built for a pilot. The results were validated.

Results The CTA showed a need for realistic scenariobased training in spine surgery. The developed simulator consists of synthetic bone structures, synthetic soft tissue and an advanced bleeding system. Due to the close interdisciplinary cooperation of surgeons between engineers and psychologists, the iterative multicentre validation showed that the simulator is visually and haptically realistic. The simulator offers integrated sensors for the evaluation of the traction being used and the compression during surgery. The participating surgeons in the pilot workshop rated the simulator and the training concept as very useful for the improvement of their surgical skills.

Conclusions In the context of the present work a precise definition for the simulator and training concept was developed. The additional implementation of sensors allows the objective evaluation of the surgical training by the trainer. Compared to other training simulators and concepts, the high degree of objectivity strengthens the acceptance of the feedback. The measured data of the nerve root tension and the compression of the dura can be used for intraoperative control and a detailed postoperative evaluation.

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Volumetric MRI assessment of glioblastoma

Volumetric MRI assessment of GBM.jpg

J Neurosurg 121:536–542, 2014

Robust methodology that allows objective, automated, and observer-independent measurements of brain tumor volume, especially after resection, is lacking. Thus, determination of tumor response and progression in neurooncology is unreliable. The objective of this study was to determine if a semi-automated volumetric method for quantifying enhancing tissue would perform with high reproducibility and low interobserver variability.

Methods. Fifty-seven MR images from 13 patients with glioblastoma were assessed using our method, by 2 neuroradiologists, 1 neurosurgeon, 1 neurosurgical resident, 1 nurse practitioner, and 1 medical student. The 2 neuroradiologists also performed traditional 1-dimensional (1D) and 2-dimensional (2D) measurements. Intraclass correlation coefficients (ICCs) assessed interobserver variability between measurements. Radiological response was determined using Response Evaluation Criteria In Solid Tumors (RECIST) guidelines and Macdonald criteria. Kappa statistics described interobserver variability of volumetric radiological response determinations.

Results. There was strong agreement for 1D (RECIST) and 2D (Macdonald) measurements between neuroradiologists (ICC = 0.42 and 0.61, respectively), but the agreement using the authors’ novel automated approach was significantly stronger (ICC = 0.97). The volumetric method had the strongest agreement with regard to radiological response (k = 0.96) when compared with 2D (k = 0.54) or 1D (k = 0.46) methods. Despite diverse levels of experience of the users of the volumetric method, measurements using the volumetric program remained remarkably consistent in all users (0.94).

Conclusions. Interobserver variability using this new semi-automated method is less than the variability with traditional methods of tumor measurement. This new method is objective, quick, and highly reproducible among operators with varying levels of expertise. This approach should be further evaluated as a potential standard for response assessment based on contrast enhancement in brain tumors.

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A Road Map to the Internal Carotid Artery in Expanded Endoscopic Endonasal Approaches to the Ventral Cranial Base

A Road Map to the Internal Carotid Artery in Expanded Endoscopic Endonasal Approaches to the Ventral Cranial Base

Operative Neurosurgery 10:448–471, 2014

Injuring the internal carotid artery (ICA) is a feared complication of endoscopic endonasal approaches.

OBJECTIVE: To introduce a comprehensive ICA classification scheme pertinent to safe endoscopic endonasal cranial base surgery.

METHODS: Anatomic dissections were performed in 33 cadaveric specimens (bilateral). Anatomic correlations were analyzed.

RESULTS: Based on anatomic correlations, the ICA may be described as 6 distinct segments: (1) parapharyngeal (common carotid bifurcation to ICA foramen); (2) petrous (carotid canal to posterolateral aspect of foramen lacerum); (3) paraclival (posterolateral foramen lacerum to the superomedial aspect of the petrous apex); (4) parasellar (superomedial petrous apex to the proximal dural ring); (5) paraclinoid (from the proximal to the distal dural rings); and (6) intradural (distal ring to ICA bifurcation). Corresponding surgical landmarks included the Eustachian tube, the fossa of Rosenmü ller, and levator veli palatini for the parapharyngeal segment; the vidian canal and V3 for the petrous segment; the fibrocartilage of foramen lacerum, foramen rotundum, maxillary strut, lingular process of the sphenoid bone, and paraclival protuberance for the paraclival segment; the sellar floor and petrous apex for the parasellar segment; and the medial and lateral opticocarotid and lateral tubercular recesses, as well as the distal osseous arch of the carotid sulcus for the paraclinoid segment.

CONCLUSION: The proposed endoscopic classification outlines key anatomic reference points independent of the vessel’s geometry or the sinonasal pneumatization, thus serving as (1) a practical guide to navigate the ventral cranial base while avoiding injury to the ICA and (2) further foundation for a modular access system.

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Full endoscopic endonasal expanded approach to the petroclival region: optimizing the carotid-clival window

Full endoscopic endonasal expanded approach to the petroclival region- optimizing the carotid-clival window

Acta Neurochir (2014) 156:1627–1629

The petroclival junction (PCJ) is a challenging skull base location from neurosurgical point of view, especially if the retrocarotid space has to be reached.

Method In response to this challenge, this report provides a detailed full description of the endoscopic endonasal expanded approach (EEA) to the petroclival region and retrocarotid space. We present the technique step by step, introducing a critical concept about the optimization of the petroclival drilling, generating the carotid-clival window (CCW). The CCW is delimited by the paraclival segment of the internal carotid artery ICA anterolaterally, the petrous bone posterolaterally, the clival dura medially, the synchondrosis inferiorly, and the cavernous sinus superiorly; therefore, this approach exposes an important nuance to augment the previous approaches for PCJ and retrocarotid space.

Conclusion This technique provides a good surgical window and carries minimal risk.

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Missed cervical disc bulges diagnosed with kinematic magnetic resonance imaging

Kinematic MRI

Eur Spine J (2014) 23:1725–1729

To determine if adding flexion and extension MRI studies to the traditional neutral views would be beneficial in the diagnosis of cervical disc bulges.

Methods Five hundred patients underwent MRI in neutral, flexion and extension positions. The images were analyzed using computer software to objectively quantify the amount of disc bulge.

Results Compared to the neutral position, cervical disc bulges were significantly increased in the extension position (P<0.05), but on flexion position, there was no significant difference (P>0.05). For patients without or <3 mm of disc bulge in neutral, 2.97 % demonstrated an increase in bulge to ≥3 mm bulge in flexion, and 16.41 % demonstrated an increase to ≥3 mm bulge in extension. For patients in the neutral view that had a baseline disc bulge of 3-5 mm, 3.73 % had increased bulges to ≥5 mm in flexion and 11.57 % had increased bulges to ≥5 mm in extension.

Conclusion A significant increase in the degree of cervical disc bulge was found by examining extension views when compared with neutral views alone. Kinematic MRI views provide valuable added information, especially in situations where symptomatic radiculopathy is present without any abnormalities demonstrated on traditional neutral MRI.

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Lateral retroperitoneal approach for discitis and osteomyelitis

Direct lateral retroperitoneal approach for the surgical treatment of lumbar discitis and osteomyelitis

Neurosurg Focus 37 (2):E5, 2014

The medical management of discitis and osteomyelitis with long-term antibiotic therapy and bracing usually results in eradicated infection. Surgical management is appropriate when medical management fails and in some cases with pyogenic deformity or neurological deficit. The success of surgery depends on adequate debridement of the necrotic infected disc and vertebral body, along with anterior column reconstruction and vertebral stabilization. Debridement is typically performed via an anterior retroperitoneal approach, which can necessitate mobilization of the great vessels for proper exposure. Mobilization can be technically difficult and lead to vascular injury. The purpose of this study was to evaluate an alternative technique for the surgical treatment of lumbar discitis and osteomyelitis using a direct lateral retroperitoneal approach, which allows for thorough debridement and anterior column reconstruction while avoiding the need to mobilize the great vessels.

Methods. A retrospective chart analysis was performed for all patients who had presented with lumbar discitis and osteomyelitis and had undergone surgical management via the direct lateral retroperitoneal approach in the period from 2006 to 2013. Collected data included surgical blood loss, perioperative complications (wound infection, vascular injury, approach-related complications, and neurological injury), need for secondary procedures, microbiological and laboratory results, and efficacy of infection eradication. Imaging studies were reviewed as well.

Results. Ten patients, 7 male and 3 female, underwent this procedure at the authors’ institution in the defined period. Average blood loss was 272 ml (range 150–800 ml, with 800 ml in the only 2-level case). There were no vascular injuries. Average follow-up was 680 days, although 4 patients did not complete the follow-up beyond 6 months. Eight patients underwent immediate posterior pedicle screw instrumentation. Two patients did not undergo posterior instrumentation, and one of these developed a kyphotic deformity that required a secondary posterior procedure. Infection was eradicated in all patients according to a history, physical examination, imaging studies, and laboratory parameters (complete blood count, erythrocyte sedimentation rate, and C-reactive protein). One patient developed a painful neuroma at the iliac crest harvest site, and one patient had a retroperitoneal hematoma. Otherwise, there were no approach-related neurological injuries or complications. Neither was there any postoperative surgical site infection.

Conclusions. The direct lateral approach for the surgical treatment of lumbar discitis and osteomyelitis allows for thorough debridement and spinal reconstruction without the need to mobilize the great vessels. This technique effectively eradicated infection in all cases, with reasonable blood loss and no vascular injuries. This approach should be considered as an alternative to the open anterior approach. The authors recommend posterior instrumentation to prevent the development of kyphosis.

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Case-control studies in neurosurgery

logo-strobe

J Neurosurg 121:285–296, 2014

Observational studies, such as cohort and case-control studies, are valuable instruments in evidencebased medicine. Case-control studies, in particular, are becoming increasingly popular in the neurosurgical literature due to their low cost and relative ease of execution; however, no one has yet systematically assessed these types of studies for quality in methodology and reporting.

Methods. The authors performed a literature search using PubMed/MEDLINE to identify all studies that explicitly identified themselves as “case-control” and were published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Each paper was evaluated for 22 descriptive variables and then categorized as having either met or missed the basic definition of a case-control study. All studies that evaluated risk factors for a well-defined outcome were considered true case-control studies. The authors sought to identify key features or phrases that were or were not predictive of a true case-control study. Those papers that satisfied the definition were further evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist.

Results. The search detected 67 papers that met the inclusion criteria, of which 32 (48%) represented true case-control studies. The frequency of true case-control studies has not changed with time. Use of odds ratios (ORs) and logistic regression (LR) analysis were strong positive predictors of true case-control studies (for odds ratios, OR 15.33 and 95% CI 4.52–51.97; for logistic regression analysis, OR 8.77 and 95% CI 2.69–28.56). Conversely, negative predictors included focus on a procedure/intervention (OR 0.35, 95% CI 0.13–0.998) and use of the word “outcome” in the Results section (OR 0.23, 95% CI 0.082–0.65). After exclusion of nested case-control studies, the negative correlation between focus on a procedure/intervention and true case-control studies was strengthened (OR 0.053, 95% CI 0.0064–0.44). There was a trend toward a negative association between the use of survival analysis or Kaplan-Meier curves and true case-control studies (OR 0.13, 95% CI 0.015–1.12). True case-control studies were no more likely than their counterparts to use a potential study design “expert” (OR 1.50, 95% CI 0.57–3.95). The overall average STROBE score was 72% (range 50–86%). Examples of reporting deficiencies were reporting of bias (28%), missing data (55%), and funding (44%).

Conclusions. The results of this analysis show that the majority of studies in the neurosurgical literature that identify themselves as “case-control” studies are, in fact, labeled incorrectly. Positive and negative predictors were identified. The authors provide several recommendations that may reverse the incorrect and inappropriate use of the term “case-control” and improve the quality of design and reporting of true case-control studies in neurosurgery.

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Full endoscopic endonasal suprapetrous approach to Meckel’s cave

Full endoscopic endonasal suprapetrous approach to Meckel’s cave

Acta Neurochir (2014) 156:1623–1626

Meckel’s cave is an anatomically complex region that can be approached surgically via several routes, namely the posterolateral, lateral, anterolateral, and, due to recent advancements, anteromedial routes, with the latter being represented by the expanded endonasal approaches.

Method We describe in detail the surgical technique of the suprapetrous endonasal approach to Meckel’s cave and highlight the main anatomical key elements involved in this approach as well as the technical aspects for avoiding surgical complications.

Conclusion The suprapetrous endonasal approach to Meckel’s cave avoids the brain tissue retraction, and thereby prevents postoperative brain edema.

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Are Aneurysms Treated With Balloon-Assisted Coiling and Stent-Assisted Coiling Different?

Are Aneurysms Treated With Balloon-Assisted Coiling and Stent-Assisted Coiling Different?

Neurosurgery 75:145–151, 2014

In the endovascular treatment of wide-necked unruptured aneurysms, there is controversy over which adjunctive device (stent vs balloon) is appropriate. At the payer level it has been posited that stents and balloons treat the same aneurysms, and, as such, the more expensive stents should not be reimbursed.

OBJECTIVE: We challenge this assertion, and instead hypothesize that aneurysms treated with stent assistance are morphologically different than those selected for balloon assistance.

METHODS: Retrospective review of unruptured aneurysms treated with an adjunctive device between 2008 and 2010. Morphological analysis was performed on the pretreatment 2-D catheter angiogram. The immediate posttreatment Raymond score was compared with that seen on the 12-month follow-up angiogram.

RESULTS: One hundred six unruptured aneurysms were treated with an adjunctive device and followed for a mean of 24.5 months. Morphological analysis revealed a lower dome-to-neck ratio (1.5 vs 1.2) and aspect ratio (1.44 vs 1.16) in the aneurysms treated with stent assistance vs balloon assistance. Of the 15.3% that were worse on follow-up angiography, there was no statistical difference between those treated with a stent vs a balloon (17.1% vs 14.2%). The overall re-treatment rate was 10.2% and was not statistically different between the 2 groups (12.7% vs 5.7%).

CONCLUSION: We found that unruptured aneurysms selected for treatment with stent-assisted coiling are morphologically different from those selected for treatment with balloon assistance. Despite the more challenging morphology, Raymond scores and re-treatment rates at 1 year were not statistically different between the 2 groups, suggesting an important role for stents in the treatment of unruptured aneurysms.

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Relevance of early head CT scans following neurosurgical procedures

early CT postcranio

J Neurosurg 121:307–312, 2014

Early postoperative head CT scanning is routinely performed following intracranial procedures for detection of complications, but its real value remains uncertain: so-called abnormal results are frequently found, but active, emergency intervention based on these findings may be rare. The authors’ objective was to analyze whether early postoperative CT scans led to emergency surgical interventions and if the results of neurological examination predicted this occurrence.

Methods. The authors retrospectively analyzed 892 intracranial procedures followed by an early postoperative CT scan performed over a 1-year period at Rush University Medical Center and classified these cases according to postoperative neurological status: baseline, predicted neurological change, unexpected neurological change, and sedated or comatose. The interpretation of CT results was reviewed and unexpected CT findings were classified based on immediate action taken: Type I, additional observation and CT; Type II, active nonsurgical intervention; and Type III, surgical intervention. Results were compared between neurological examination groups with the Fisher exact test.

Results. Patients with unexpected neurological changes or in the sedated or comatose group had significantly more unexpected findings on the postoperative CT (p < 0.001; OR 19.2 and 2.3, respectively) and Type II/III interventions (p < 0.001) than patients at baseline. Patients at baseline or with expected neurological changes still had a rate of Type II/III changes in the 2.2%–2.4% range; however, no patient required an immediate return to the operating room.

Conclusions. Over a 1-year period in an academic neurosurgery service, no patient who was neurologically intact or who had a predicted neurological change required an immediate return to the operating room based on early postoperative CT findings. Obtaining early CT scans should not be a priority in these patients and may even be cancelled in favor of MRI studies, if the latter have already been planned and can be performed safely and in a timely manner. Early postoperative CT scanning does not assure an uneventful course, nor should it replace accurate and frequent neurological checks, because operative interventions were always decided in conjunction with the neurological examination.

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Surgical treatment of pathological loss of lumbar lordosis (flatback)

Flatback

J Neurosurg Spine 21:160–170, 2014

Increased sagittal vertical axis (SVA) correlates strongly with pain and disability for adults with spinal deformity. A subset of patients with sagittal spinopelvic malalignment (SSM) have flatback deformity (pelvic incidence–lumbar lordosis [PI-LL] mismatch > 10°) but remain sagittally compensated with normal SVA. Few data exist for SSM patients with flatback deformity and normal SVA. The authors’ objective was to compare baseline disability and treatment outcomes for patients with compensated (SVA < 5 cm and PI-LL mismatch > 10°) and decompensated (SVA > 5 cm) SSM.

Methods. The study was a multicenter, prospective analysis of adults with spinal deformity who consecutively underwent surgical treatment for SSM. Inclusion criteria included age older than 18 years, presence of adult spinal deformity with SSM, plan for surgical treatment, and minimum 1-year follow-up data. Patients with SSM were divided into 2 groups: those with compensated SSM (SVA < 5 cm and PI-LL mismatch > 10°) and those with decompensated SSM (SVA ≥ 5 cm). Baseline and 1-year follow-up radiographic and health-related quality of life (HRQOL) outcomes included Oswestry Disability Index, Short Form–36 scores, and Scoliosis Research Society–22 scores. Percentages of patients achieving minimal clinically important difference (MCID) were also assessed.

Results. A total of 125 patients (27 compensated and 98 decompensated) met inclusion criteria. Compared with patients in the compensated group, patients in the decompensated group were older (62.9 vs 55.1 years; p = 0.004) and had less scoliosis (43° vs 54°; p = 0.002), greater SVA (12.0 cm vs 1.7 cm; p < 0.001), greater PI-LL mismatch (26° vs 20°; p = 0.013), and poorer HRQOL scores (Oswestry Disability Index, Short Form-36 physical component score, Scoliosis Research Society-22 total; p ≤ 0.016). Although these baseline HRQOL differences between the groups reached statistical significance, only the mean difference in Short Form–36 physical component score reached threshold for MCID. Compared with baseline assessment, at 1 year after surgery improvement was noted for patients in both groups for mean SVA (compensated –1.1 cm, decompensated +4.8 cm; p ≤ 0.009), mean PI-LL mismatch (compensated 6°, decompensated 5°; p < 0.001), and all HRQOL measures assessed (p ≤ 0.005). No significant differences were found between the compensated and decompensated groups in the magnitude of HRQOL score improvement or in the percentages of patients achieving MCID for each of the outcome measures assessed.

Conclusions. Decompensated SSM patients with elevated SVA experience significant disability; however, the amount of disability in compensated SSM patients with flatback deformity caused by PI-LL mismatch but normal SVA is underappreciated. Surgical correction of SSM demonstrated similar radiographic and HRQOL score improvements for patients in both groups. Evaluation of SSM should extend beyond measuring SVA. Among patients with concordant pain and disability, PI-LL mismatch must be evaluated for SSM patients and can be considered a primary indication for surgery.

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The Impact of Sedation on Brain Mapping

Brain Mapping

Neurosurgery 75:117–123, 2014

During awake craniotomies, patients may either be awake for the entire duration of the surgical intervention (awake-awake-awake craniotomy, AAA) or initially sedated (asleep-awake-asleep craniotomy, SAS).

OBJECTIVE: To examine whether prior sedation in SAS may restrict brain mapping, we conducted neuropsychological tests in patients by means of a standardized anesthetic regimen comparable to an SAS.

METHODS: We prospectively examined patients undergoing surgery either under total intravenous anesthesia (TIVA) or under regional anesthesia with slight sedation (RAS). The tests included the DO40 picture-naming test, the digit span, the Regensburg Word Fluency Test, and the finger-tapping test. Each test was conducted 3 times for every patient in the TIVA and RAS groups, once before surgery and twice within about 35 minutes after the end of sedation. Patients undergoing AAA were examined preoperatively and intraoperatively.

RESULTS: In the AAA group, no significant difference was found between preoperative and intraoperative test results. In the TIVA and RAS groups, postoperative tests showed worse results than preoperative tests. In most tests, patients improved from the first to the second postoperative test.

CONCLUSION: Cognitive and motor performance were significantly influenced by prior sedation in the TIVA and RAS groups, but not in the AAA group. Therefore, prior sedation may be assumed to cause a change in the baselines, which may compromise brain mapping and thus endanger a patient’s neurological outcome in the case of an SAS.

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Complications of occipitocervical fusion: a 316 cases retrospective analysis

Occipito-cervical fusion

Eur Spine J (2014) 23:1720–1724

Disorders in occipitocervical region are difficult to treat. Complications often occur after fusion surgery and may be life-threatening in severe cases. This study is to investigate the causes and treatment strategies for the postoperative complications of occipitocervical fusion.

Methods Between May 1985 and May 2011, 316 patients with various occipitocervical diseases underwent occipitocervical surgery, with or without internal fixation. Two physicians were assigned for patients follow-up. Their medical records and radiographs were reviewed and the postoperative complications, including those at the occipitocervical region and donor site, were analyzed.

Results Three hundred cases were followed up from 24 months to 26 years with an average of 9 years and 8 months, and the follow-up rate was 94.9 %. There were 16 cases with complications after surgery in the uninstrumented fusion group; the incidence was 33.3 %. These included 11 patients (22.9 %) with complications in occipitocervical region and five patients (11.9 %) with donor-site complications. 45 complications presented in the instrumented fusion group, the incidence was 17.9 %. These included 30 patients (11.9 %) with complications in occipitocervical region and 15 patients (5.9 %) with donorsite complications. Perioperative complications included vertebral artery injury, spinal cord injury, nerve root injury, suffocation, cerebrospinal fluid leakage, and infection. Mid- to long-term complications included bone-graft displacement or absorption, aggravated vertebral dislocation, improper screw placement, spinous process fracture, and internal fixation breakage. Donor-site complications were hematoma, pain and infection.

Conclusion The surgery of occipitocervical fusion carries a relative high risk for complications, especially if no instrumentation is used. The key points in reducing complications are the surgeon’s familiarity with the anatomy of occipitocervical region and the appropriate internal fixation.

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Suprajugular extension of the retrosigmoid approach

Suprajugular extension retrosigmoid approach

J Neurosurg 121:397–407, 2014

Jugular foramen tumors often extend intra- and extracranially. The gross-total removal of tumors located both intracranially and intraforaminally is technically challenging and often requires a combined skull base approach. This study presents a suprajugular extension of the retrosigmoid approach directed through the osseous roof of the jugular foramen that allows the removal of tumors located in the cerebellopontine angle with extension into the upper part of the foramen, with demonstration of an illustrative case.

Methods. The cerebellopontine angles and jugular foramina were examined in dry skulls and cadaveric heads to clarify the microsurgical anatomy around the jugular foramen and to define the steps of the suprajugular exposure.

Results. The area drilled in the suprajugular approach is inferior to the acoustic meatus, medial to the endolymphatic depression and surrounding the superior half of the glossopharyngeal dural fold. Opening this area exposed the upper part of the jugular foramen and extended the exposure along the glossopharyngeal nerve below the roof of the jugular foramen. In the illustrative case, a schwannoma originating from the glossopharyngeal nerve in the cerebellopontine angle and extending below the roof of the jugular foramen and above the jugular bulb was totally removed without any postoperative complications.

Conclusions. The suprajugular extension of the retrosigmoid approach will permit removal of tumors located predominantly in the cerebellopontine angle but also extending into the upper part of the jugular foramen without any additional skull base approaches.

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Posterior C1–C2 screw and rod instrument for reduction and fixation of basilar invagination with atlantoaxial dislocation

Basilar invagination with C1-C2 dislocation surgery

Eur Spine J (2014) 23:1666–1672

To report the surgical technique and preliminary clinical results for the treatment of basilar invagination (BI) with atlantoaxial dislocation (AAD) by posterior C1–C2 pedicle screw and rod instrument.

Methods Between July 2012 and August 2013, 33 patients who had BI with AAD underwent surgery at our institution. Pre and postoperative three-dimensional computed tomographic (CT) scans were performed to assess the degree of dislocation. Magnetic resonance (MR) imaging was used to evaluate the compression of the medulla oblongata. For all patients, reduction of the AAD was conducted by two steps: fastening nuts and rods was performed to achieve the horizontal reduction. Distraction between C1 and C2 screws was performed to obtain the vertical reduction.

Results No neurovascular injury occurred during surgery. Follow-up ranged from 6 to 15 months (mean 10.38 months) in 32 patients. Post-operative three-dimensional CT showed that complete horizontal reduction was obtained in 30/33 (90.9 %), and complete vertical reduction was obtained in 31/33 (93.9 %). The repeated threedimensional CT and MR image demonstrated that bony fusion and the decompression of the medulla oblongata were obtained in all patients. Clinical symptoms improved significantly 3 months after surgery.

Conclusions This C1–C2 pedicle screw and rod instrument is a promising technique for the treatment of BI with AAD.

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Retrogasserian balloon compression for treatment of trigeminal neuralgia. Series of 901 patients

RGBC

Surgical Neurology International 2014, 5:118

The aim of our study was to describe the retrogasserian balloon compression (RGBC) procedure with some personal tricks and to assess the long‑term results.

Methods: Between 1985 and 2012, 901 patients, suffering from refractory trigeminal neuralgia (TN), underwent RGBC procedure in our department. Concerning the surgical technique, the introducer was in close contact with the posterior extremity of the horizontal plate of the palatine bone and had the direction of the bisector of the angle clivus‑superior edge of the petrous bone on an X‑rays sagittal view. No metallic material was inserted intracranially. The balloon was inflated with 0.7 cc of contrast medium for 6 min.

Results: At 1 month follow up, appreciable pain relief was obtained in 835 patients (92.7%). At 1 year, results were excellent in 605 patients (67.1%), satisfactory in 109 patients (12.1%), poor in 57 patients (6.3%), fair in 66 patients (7.3%), whereas recurrences were observed in the remaining 64 patients (7.2%). At mean follow up of 16,5 years, 559 (62%) patients remained pain free. Twenty six patients (2,8%) continued to experience severe pain. Recurrences occurred in two hundred and fifty patients (27,8%). Fifty two of them were operated on a third time and 22 underwent four procedures.

Conclusion: RGBC is an appropriate and effective procedure for treatment of refractory TN, ensuring a long lasting pain relief predicted on three factors: pear shape of the balloon, its volume, and duration as mentioned earlier.

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Repeat microvascular decompression for recurrent idiopathic trigeminal neuralgia

TN

DOI: 10.3171/2014.7.JNS132667

Microvascular decompression (MVD) is considered the method of choice to treat idiopathic trigeminal neuralgia (TN) refractory to medical treatment. However, repeat MVD for recurrent TN is not well established. In this paper, the authors describe a large case series in which patients underwent repeat MVD for recurrent TN, focusing on outcome, risk factors, and complication rates.

Methods. Between 1990 and 2012, a total of 33 consecutive patients underwent repeat MVD for recurrent TN at the University Medical Center Groningen. The authors performed a retrospective chart review and telephone interviews. Risk factors were analyzed by binary logistic regression analysis.

Results. After 12 months of follow-up, 22 (67%) operations were successful, of which 19 patients were completely free of pain without medication. With multivariate analysis significant risk factors for success were older age (OR 1.11, p < 0.01) and direct absence of pain after repeat MVD (OR 25.2, p < 0.01). Previous neurodestructive procedures did not influence success rates. Facial numbness occurred in 9 patients (27%), while other morbidity was minimal. There was no mortality.

Conclusions. This study demonstrates that repeat MVD is a feasible therapeutic option with good chances of success, even in patients who have undergone neurodestructive procedures. Complication rates, particularly facial numbness, can be avoided if only a limited neurolysis is performed.

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