Neurosurgery Blog


Daily bibliographic review of the Neurosurgery Department. La Fe University Hospital. Valencia, Spain

Patient Selection and Clinical Efficacy of Urgent Superficial Temporal Artery-Middle Cerebral Artery Bypass in Acute Ischemic Stroke Using Advanced Magnetic Resonance Imaging Techniques

Operative Neurosurgery 13:552–559, 2017

Selected patients with acute ischemic stroke might benefit from superficial temporal artery-middle cerebral artery (STA-MCA) bypass, but the indications for urgent STA-MCA bypass are unknown.

OBJECTIVE: To report our experiences of urgent STA-MCA bypass in patients requiring urgent reperfusion who were ineligible for other reperfusion therapies, using advanced magnetic resonance imaging (MRI) techniques.

METHODS: The inclusion criteria for urgent STA-MCA bypass were as follows: acute infarct volume <70 mL with a ratio of perfusion/diffusion lesion volume ≥1.2, and a regional cerebral blood volume ratio >0.85. FromJanuary 2013 to October 2015, 21 urgent STA-MCA bypass surgeries were performed. The control group included 19 patients who did not undergo bypass surgery mainly due to refusal of surgery or the decision of the neurologist. Clinical and radiological data were compared between the surgery and control group.

RESULTS: The median age of the control group (70 years, interquartile range [IQR] 58-76) was higher than that of the surgery group (62 years, IQR 49-66), but the median preoperative diffusion and perfusion lesion volumes of the surgery group (13.8 mL, IQR 7.5-26.0 and 120.9 mL, IQR 84.9-176.0, respectively) were higher than those of the control group (5.6 mL, IQR 2.1-9.1 and 69.7 mL, IQR 23.9-125.3, respectively). Sixteen (76.2%) patients in the surgery group and 2 (10.5%) patients in the control group had favorable outcomes (P < .001). Logistic regression analysis identified bypass surgery as the strongest predictive factor.

CONCLUSION: STA-MCA bypass can be used as a therapeutic tool for acute ischemic stroke.Advanced MRI techniques are helpful for selecting patients and for decision making.


Anterior lumbar discectomy and fusion for acute cauda equina syndrome caused by recurrent disc prolapse

J Neurosurg Spine 27:352–356, 2017

There is a lack of information and consensus regarding the optimal treatment for recurrent disc herniation previously treated by posterior discectomy, and no reports have described an anterior approach for recurrent disc herniation causing cauda equina syndrome (CES). Revision posterior decompression, irrespective of the presence of CES, has been reported to be associated with significantly higher rates of dural tears, hematomas, and iatrogenic nerve root damage.

The authors describe treatment and outcomes in 3 consecutive cases of patients who underwent anterior lumbar discectomy and fusion (ALDF) for CES caused by recurrent disc herniations that had been previously treated with posterior discectomy. All 3 patients were operated on within 12 hours of presentation and were treated with an anterior retroperitoneal lumbar approach. Follow-up ranged from 12 to 24 months. Complete retrieval of herniated disc material was achieved without encountering significant epidural scar tissue in all 3 cases. No perioperative infection or neurological injury occurred, and all 3 patients had neurological recovery with restoration of bladder and bowel function and improvement in back and leg pain.

ALDF is one option to treat CES caused by recurrent lumbar disc prolapse previously treated with posterior discectomy. The main advantage is that it avoids dissection around epidural scar tissue, but the procedure is associated with other risks and further evaluation of its safety in larger series is required.

Limitations of the endonasal endoscopic approach in treating olfactory groove meningiomas

Acta Neurochir (2017) 159:1875–1885

To review current management strategies for olfactory groove meningioma (OGM)s and the recent literature comparing endoscopic endonasal (EEA) with traditional transcranial (TCA) approaches.

Methods A PubMed search of the recent literature (2011– 2016) was performed to examine outcomes following EEA and TCA for OGM. The extent of resection, visual outcome, postoperative complications and recurrence rates were analyzed using percentages and proportions, the Fischer exact test and the Student’s t-test using Graphpad PRISM 7.0Aa (San Diego, CA) software.

Results There were 444 patients in the TCA group with a mean diameter of 4.61 (±1.17) cm and 101 patients in the EEA group with a mean diameter of 3.55 (± 0.58) cm (p = 0.0589). GTR was achieved in 90.9% (404/444) in the TCA group and 70.2% (71/101) in the EEA group (p < 0.0001). Of the patients with preoperative visual disturbances, 80.7% (21/26) of patients in the EEA cohort had an improvement in vision compared to 12.83%(29/226) in the TCA group (p < 0.0001). Olfaction was lost in 61% of TCA and in 100% of EEA patients. CSF leaks and meningitis occurred in 25.7% and 4.95% of EEA patients and 6.3% and 1.12% of TCA patients, respectively (p < 0.0001; p = 0.023).

Conclusions Our updated literature review demonstrates that despite more experience with endoscopic resection and skull base reconstruction, the literature still supports TCA over EEA with respect to the extent of resection and complications. EEA may be an option in selected cases where visual improvement is the main goal of surgery and postoperative anosmia is acceptable to the patient or in medium-sized tumors with existing preoperative anosmia. Nevertheless, based on our results, it seems more prudent at this time to use TCA for the majority of OGMs.

Stereoelectroencephalography Using Magnetic Resonance Angiography for Avascular Trajectory Planning

Neurosurgery 81:688–695, 2017

Stereoelectroencephalography (SEEG) requires high-quality angiographic studies because avascular trajectory planning is a prerequisite for the safety of this procedure. Some epilepsy surgery groups have begun to use computed tomography angiography and magnetic resonance T1-weighted sequence with contrast enhancement for this purpose.

OBJECTIVE: To present the first series of patients with avascular trajectory planning of SEEG based on magnetic resonance angiography (MRA).

METHODS: Thirty-six SEEG explorations for drug-resistant focal epilepsy were performed from January 2013 to December 2015. A retrospective analysis of this consecutive surgical series was then performed. Magnetic resonance imaging included MRA with a modified contrast-enhanced magnetic resonance venography (MRV) protocol with a short acquisition delay, which allowed simultaneous arterial and venous visualization. Our criteria for satisfactoryMRAwere the visualization of at least first-order branches of the angular artery, paracentral and calcarine artery, and third-order tributaries of the superficial Sylvian vein, vein of Labbe, and vein of Trolard.

RESULTS: Thirty-four patients underwent 36 SEEG explorations with 369 electrodes carrying 4321 contacts. Contrast-enhanced MRA using the MRV protocol was judged satisfactory for SEEG planning in all explorations. Postoperative complications were not observed in our series of 36 SEEG explorations, which included 50 transopercular insular trajectories.

CONCLUSION: MRA using an MRV protocol may be applied for avascular trajectory planning during SEEG procedures. This technique provides a simultaneous visualization of cortical arteries and veins without the need for additional radiation exposure or intraarterial catheter placement.


Microendoscopic laminotomy versus conventional laminoplasty for cervical spondylotic myelopathy: 5-year follow-up study

J Neurosurg Spine 27:403–409, 2017

The goal of this study was to characterize the long-term clinical and radiological results of articular segmental decompression surgery using endoscopy (cervical microendoscopic laminotomy [CMEL]) for cervical spondylotic myelopathy (CSM) and to compare outcomes to conventional expansive laminoplasty (ELAP).

METHODS Consecutive patients with CSM who required surgical treatment were enrolled. All enrolled patients (n = 78) underwent CMEL or ELAP. All patients were followed postoperatively for more than 5 years. The preoperative and 5-year follow-up evaluations included neurological assessment (Japanese Orthopaedic Association [JOA] score), JOA recovery rates, axial neck pain (using a visual analog scale), the SF-36, and cervical sagittal alignment (C2–7 subaxial cervical angle).

RESULTS Sixty-one patients were included for analysis, 31 in the CMEL group and 30 in the ELAP group. The mean preoperative JOA score was 10.1 points in the CMEL group and 10.9 points in the ELAP group (p > 0.05). The JOA recovery rates were similar, 57.6% in the CMEL group and 55.4% in the ELAP group (p > 0.05). The axial neck pain in the CMEL group was significantly lower than that in the ELAP group (p < 0.01). At the 5-year follow-up, cervical alignment was more favorable in the CMEL group, with an average 2.6° gain in lordosis (versus 1.2° loss of lordosis in the ELAP group [p < 0.05]) and lower incidence of postoperative kyphosis.

CONCLUSIONS CMEL is a novel, less invasive technique that allows for multilevel posterior cervical decompression for the treatment of CSM. This 5-year follow-up data demonstrates that after undergoing CMEL, patients have similar neurological outcomes to conventional laminoplasty, with significantly less postoperative axial pain and improved subaxial cervical lordosis when compared with their traditional ELAP counterparts.

A Prospective Study of Interbody Fat Graft ApplicationWith the Anterior Contralateral Cervical Microdiscectomy to Preserve Segmental Mobility

Neurosurgery 81:627–637, 2017

Any surgical procedure aims at protecting mobile segments at the operated level, and the sagittal balance of the columna vertebralis. Interbody fusion has become an often applied technique in anterior cervical discectomy.

OBJECTIVE: To indicate that a minimally invasive technique in which we use interbody fat graft placement showed great results and effectiveness, especially in patients who were suffering from cervical paramedian disc herniation.

METHODS: In this study, 432 patients were observed from 2000 to 2013. All these consecutive patients had paramedian disc herniation. The initial 239 patients (group 1) underwent microdiscectomy without graft placement, whereas the remaining 193 patients (group 2) had a microdiscectomy with interbody fat graft insertion. The Neck Disability Index (NDI) and Short Form-36 (SF-36)were used to evaluate clinical outcomes. Theywere followed up for 5.3 years (range 2-13 years).

RESULTS: Spontaneous radiological fusionwas noticed in 12%of group 1 patients and none of the group 2 patients. It has been observed that the mean overall cervical curvature (C2- 7) angles and segmental lordosis did not change significantly in late follow-up findings. During both early and late follow-ups, all patients indicated a decreasing NDI score, but in late follow-up, an improving SF-36 score.

CONCLUSION: This surgical technique provides good direct decompression and preserves mobility at the treated level, while preventing disc collapse.

Accuracy of 320-detector row nonsubtracted and subtracted volume CT angiography in evaluating small cerebral aneurysms

J Neurosurg 127:725–731, 2017

The study aimed to assess the diagnostic accuracy of 320-detector row nonsubtracted and subtracted volume CT angiography (VCTA) in detecting small cerebral aneurysms (< 3 mm) compared with 3D digital subtraction angiography (3D DSA).

METHODS Six hundred sixty-two patients underwent 320-detector row VCTA and 3D DSA for suspected cerebral aneurysms. Five neuroradiologists independently reviewed VCTA and 3D DSA images. The 3D DSA was considered the reference standard, and the sensitivity, specificity, and accuracy of nonsubtracted and subtracted VCTA in depicting small aneurysms were analyzed. A p value < 0.05 was considered a significant difference.

RESULTS According to 3D DSA images, 98 small cerebral aneurysms were identified in 90 of 662 patients. Nonsubtracted VCTA depicted 90 small aneurysms. Ten small aneurysms were missed, and 2 small aneurysms were misdiagnosed. The missed small aneurysms were located almost in the internal carotid artery, near bone tissue. The sensitivity, specificity, and accuracy of nonsubtracted VCTA in depicting small aneurysms were 89.8%, 99.2%, and 96.5%, respectively, on a per-aneurysm basis. Subtracted VCTA depicted 97 small aneurysms. Three small aneurysms were missed, and 2 small aneurysms were misdiagnosed. The sensitivity, specificity, and accuracy of subtracted VCTA in depicting small aneurysms were 96.9%, 99.2%, and 98.6%, respectively, on a per-aneurysm basis. There was no difference in accuracy between subtracted VCTA and 3D DSA (p = 1.000). However, nonsubtracted VCTA had significantly less sensitivity than 3D DSA and subtracted VCTA (p = 0.039 and 0.016, respectively).

CONCLUSIONS Subtracted 320-detector row VCTA is sensitive enough to replace 3D DSA in the diagnosis of small cerebral aneurysms (< 3 mm). The accuracy rate of nonsubtracted VCTA was lower than that of subtracted VCTA and 3D DSA, especially in the assessment of small internal carotid artery aneurysms adjacent to the skull base.

Surgical resection of skull-base chordomas: experience in case selection for surgical approach according to anatomical compartments and review of the literature

Acta Neurochir (2017) 159:1835–1845

Chordoma is a rare bony malignancy known to have a high rate of local recurrence after surgery. The best treatment paradigm is still being evaluated. We report our experience and review the literature. We emphasize on the difference between endoscopic and open craniotomy in regard to the anatomical compartment harboring the tumor, the limitations of the approaches and the rate of surgical resection.

Method: We retrospectively collected all patients with skullbase chordomas operated on between 2004 and 2014. Detailed radiological description of the compartments being occupied by the tumor and the degree of surgical resection is discussed.

Results: Eighteen patients were operated on in our facility for skull-base chordoma. Seventeen endoscopic surgeries were done in 15 patients, and 7 craniotomies were done in 5 patients. The mean age was 48.9 years (±19.8 years). When reviewing the anatomical compartments, we found that the most common were the upper clivus (95.6%) and lower clivus (58.3%), left cavernous sinus (66.7%) and petrous apex (∼60%). Most of the patients had intradural tumor involvement (70.8%). In all craniotomy cases, there was residual tumor in multiple compartments. In the endoscopic cases, the most difficult compartments for total resection were the lower clivus, and lateral extensions to the petrous apex or cavernous sinus.

Conclusions: Our experience shows that the endoscopic approach is a good option for midline tumors without significant lateral extension. In cases with very lateral or lower extensions, additional approaches should be added trying to achieve complete resection.

The management and outcome for patients with chronic subdural hematoma: a prospective, multicenter, observational cohort study in the United Kingdom

J Neurosurg 127:732–739, 2017

Symptomatic chronic subdural hematoma (CSDH) will become an increasingly common presentation in neurosurgical practice as the population ages, but quality evidence is still lacking to guide the optimal management for these patients. The British Neurosurgical Trainee Research Collaborative (BNTRC) was established by neurosurgical trainees in 2012 to improve research by combining the efforts of trainees in each of the United Kingdom (UK) and Ireland’s neurosurgical units (NSUs). The authors present the first study by the BNTRC that describes current management and outcomes for patients with CSDH throughout the UK and Ireland. This provides a resource both for current clinical practice and future clinical research on CSDH.

METHODS Data on management and outcomes for patients with CSDH referred to UK and Ireland NSUs were collected prospectively over an 8-month period and audited against criteria predefined from the literature: NSU mortality < 5%, NSU morbidity < 10%, symptomatic recurrence within 60 days requiring repeat surgery < 20%, and unfavorable functional status (modified Rankin Scale score of 4–6) at NSU discharge < 30%.

RESULTS: Data from 1205 patients in 26 NSUs were collected. Bur-hole craniostomy was the most common procedure (89%), and symptomatic recurrence requiring repeat surgery within 60 days was observed in 9% of patients. Criteria on mortality (2%), rate of recurrence (9%), and unfavorable functional outcome (22%) were met, but morbidity was greater than expected (14%). Multivariate analysis demonstrated that failure to insert a drain intraoperatively independently predicted recurrence and unfavorable functional outcome (p = 0.011 and p = 0.048, respectively). Increasing patient age (p < 0.00001), postoperative bed rest (p = 0.019), and use of a single bur hole (p = 0.020) independently predicted unfavorable functional outcomes, but prescription of high-flow oxygen or preoperative use of antiplatelet medications did not.

CONCLUSIONS: This is the largest prospective CSDH study and helps establish national standards. It has confirmed in a real-world setting the effectiveness of placing a subdural drain. This study identified a number of modifiable prognostic factors but questions the necessity of some common aspects of CSDH management, such as enforced postoperative bed rest. Future studies should seek to establish how practitioners can optimize perioperative care of patients with CSDH to reduce morbidity as well as minimize CSDH recurrence. The BNTRC is unique worldwide, conducting multicenter trainee-led research and audits. This study demonstrates that collaborative research networks are powerful tools to interrogate clinical research questions.

Impact of Timing of Intervention Among 397 Consecutively Treated Brainstem Cavernous Malformations

Neurosurgery 81:620–626, 2017

Surgical resection of brainstem cavernous malformations (BSCMs) is challenging, and patient selection and timing of intervention remain controversial.

OBJECTIVE: To evaluate the impact of surgical timing and predictors of neurological outcome after surgical resection of BSCMs.

METHODS: Consecutive adult patients (≥18 years) with BSCMs undergoing surgical resection between 1985 and 2014 by the senior author (RFS)were retrospectively reviewed. Patient demographics, lesion characteristics, imaging results, surgical approach, and perioperative and long-term neurological morbidity were analyzed.

RESULTS: Data were analyzed for a total of 397 adult patients (160, 40% male).On univariate analysis, a greater proportion of patients treated within 6 weeks of hemorrhage had an improved Glasgow Outcome Scale score (P = .06). On logistic regression analysis, patients treated within 6weeks of hemorrhage experienced improved clinical outcomes (odds ratio = 1.73; 95% confidence interval = 1.06-2.83; P = .03).

CONCLUSIONS: Although BSCM surgery is associated with significant perioperative morbidity and mortality, favorable long-term hemorrhage rates and symptom resolution can be achieved in a carefully selected group of patients. Overall, patients treated acutely, within 6 weeks, benefited the most from surgical intervention.

Cervical Spine Deformity—Part 2: Management Algorithm and Anterior Techniques

Neurosurgery 81:561–567, 2017

A sound operative plan based on solid understanding of the pathology and biomechanics is the most important part of cervical deformity correction.

Many different surgical options exist for operative management of cervical spine deformities. However, selecting the correct approach that ensures the optimal clinical outcome can be challenging and often controversial.

In Part 2 of this three-part review series, we discuss the pre-operative planning, management algorithm, and anterior surgical techniques for cervical deformity correction.


Ventriculostomy-associated hemorrhage: a risk assessment by radiographic simulation

J Neurosurg 127:532–536, 2017

Ventriculostomy entry sites are commonly selected by freehand estimation of Kocher’s point or approximations from skull landmarks and a trajectory toward the ipsilateral frontal horn of the lateral ventricles. A recognized ventriculostomy complication is intracranial hemorrhage from cortical vessel damage; reported rates range from 1% to 41%. In this report, the authors assess hemorrhagic risk by simulating traditional ventriculostomy trajectories and using CT angiography (CTA) with venography (CTV) data to identify potential complications, specifically from cortical draining veins.

METHODS Radiographic analysis was completed on 50 consecutive dynamic CTA/CTV studies obtained at a tertiarycare academic neurosurgery department. Image sections were 0.5 mm thick, and analysis was performed on a venous phase that demonstrated high-quality opacification of the cortical veins and sagittal sinus. Virtual ventriculostomy trajectories were determined for right and left sides using medical diagnostic imaging software. Entry points were measured along the skull surface, 10 cm posteriorly from the nasion, and 3 cm laterally for both left and right sides. Cannulation was simulated perpendicular to the skull surface. Distances between the software-traced cortical vessels and the virtual catheter were measured. To approximate vessel injury by twist drill and ventricular catheter placement, veins within a 3-mm radius were considered a hemorrhage risk.

RESULTS In 100 virtual lines through Kocher’s point toward the ipsilateral ventricle, 19% were predicted to cause cortical vein injury and suspected hemorrhage (radius ≤ 3 mm). Little difference existed between cerebral hemispheres (right 18%, left 20%). The average (± SD) distance from the trajectory line and a cortical vein was 7.23 ± 4.52 mm. In all 19 images that predicted vessel injury, a site of entry for an avascular zone near Kocher’s point could be achieved by moving the trajectory less than 1.0 cm laterally and less than 1.0 cm along the anterior/posterior axis, suggesting that empirical measures are suboptimal, and that patient-specific coordinates based on preprocedural CTA/CVA imaging may optimize ventriculostomy in the future.

CONCLUSIONS In this institutional radiographic imaging analysis, traditional methods of ventriculostomy site selection predicted significant rates of cortical vein injury, matching described rates in the literature. CTA/CTV imaging potentiates identification of patient-specific cannulation sites and custom trajectories that avoid cortical vessels, which may lessen the risk of intracranial hemorrhage during ventriculostomy placement. Further development of this software is underway to facilitate stereotactic ventriculostomy and improve outcomes.

Stereotactic radiosurgery for cerebellar arteriovenous malformations: an international multicenter study

J Neurosurg 127:512–521, 2017

Cerebellar arteriovenous malformations (AVMs) represent the majority of infratentorial AVMs and frequently have a hemorrhagic presentation. In this multicenter study, the authors review outcomes of cerebellar AVMs after stereotactic radiosurgery (SRS).

METHODS: Eight medical centers contributed data from 162 patients with cerebellar AVMs managed with SRS. Of these patients, 65% presented with hemorrhage. The median maximal nidus diameter was 2 cm. Favorable outcome was defined as AVM obliteration and no posttreatment hemorrhage or permanent radiation-induced complications (RICs). Patients were followed clinically and radiographically, with a median follow-up of 60 months (range 7–325 months).

RESULTS: The overall actuarial rates of obliteration at 3, 5, 7, and 10 years were 38.3%, 74.2%, 81.4%, and 86.1%, respectively, after single-session SRS. Obliteration and a favorable outcome were more likely to be achieved in patients treated with a margin dose greater than 18 Gy (p < 0.001 for both), demonstrating significantly better rates (83.3% and 79%, respectively). The rate of latency preobliteration hemorrhage was 0.85%/year. Symptomatic post-SRS RICs developed in 4.5% of patients (n = 7). Predictors of a favorable outcome were a smaller nidus (p = 0.0001), no pre-SRS embolization (p = 0.003), no prior hemorrhage (p = 0.0001), a higher margin dose (p = 0.0001), and a higher maximal dose (p = 0.009). The Spetzler-Martin grade was not found to be predictive of outcome. The Virginia Radiosurgery AVM Scale score (p = 0.0001) and the Radiosurgery-Based AVM Scale score (p = 0.0001) were predictive of a favorable outcome.

CONCLUSIONS: SRS results in successful obliteration and a favorable outcome in the majority of patients with cerebellar AVMs. Most patients will require a nidus dose of higher than 18 Gy to achieve these goals. Radiosurgical and not microsurgical scales were predictive of clinical outcome after SRS.

Quantitative anatomical analysis and clinical experience with mini-pterional and mini-orbitozygomatic approaches for intracranial aneurysm surgery

J Neurosurg 127:646–659, 2017

The aim of this investigation was to modify the mini-pterional and mini-orbitozygomatic (mini-OZ) approaches in order to reduce the amount of tissue traumatization caused and to compare the use of the 2 approaches in the removal of circle of Willis aneurysms based on the authors’ clinical experience and quantitative analysis.

METHODS Three formalin-fixed adult cadaveric heads injected with colored silicone were examined. Surgical freedom and angle of attack of the mini-pterional and mini-OZ approaches were measured at 9 anatomical points, and the measurements were compared. The authors also retrospectively reviewed the cases of 396 patients with ruptured and unruptured single aneurysms in the circle of Willis treated by microsurgical techniques at their institution between January 2006 and November 2014.

RESULTS A significant difference in surgical freedom was found in favor of the mini-pterional approach for access to the ipsilateral internal carotid artery (ICA) and middle cerebral artery (MCA) bifurcations, the most distal point of the ipsilateral posterior cerebral artery (PCA), and the basilar artery (BA) tip. No statistically significant differences were found between the mini-pterional and mini-OZ approaches for access to the posterior clinoid process, the most distal point of the superior cerebellar artery (SCA), the anterior communicating artery (ACoA), the contralateral ICA bifurcation, and the most distal point of the contralateral MCA. A trend toward increasing surgical freedom was found for the mini-OZ approach to the ACoA and the contralateral ICA bifurcation. The lengths exposed through the mini-OZ approach were longer than those exposed by the mini-pterional approach for the ipsilateral PCA segment (11.5 ± 1.9 mm) between the BA and the most distal point of the P2 segment of the PCA, for the ipsilateral SCA (10.5 ± 1.1 mm) between the BA and the most distal point of the SCA, and for the contralateral anterior cerebral artery (ACA) (21 ± 6.1 mm) between the ICA bifurcation and the most distal point of the A2 segment of the ACA. The exposed length of the contralateral MCA (24.2 ± 8.6 mm) between the contralateral ICA bifurcation and the most distal point of the MCA segment was longer through the mini-pterional approach. The vertical angle of attack (anteroposterior direction) was significantly greater with the minipterional approach than with the mini-OZ approach, except in the ACoA and contralateral ICA bifurcation. The horizontal angle of attack (mediolateral direction) was similar with both approaches, except in the ACoA, contralateral ICA bifurcation, and contralateral MCA bifurcation, where the angle was significantly increased in the mini-OZ approach.

CONCLUSIONS The mini-pterional and mini-OZ approaches, as currently performed in select patients, provide less tissue traumatization (i.e., less temporal muscle manipulation, less brain parenchyma retraction) from the skin to the aneurysm than standard approaches. Anatomical quantitative analysis showed that the mini-OZ approach provides better exposure to the contralateral side for controlling the contralateral parent arteries and multiple aneurysms. The mini-pterional approach has greater surgical freedom (maneuverability) for ipsilateral circle of Willis aneurysms.


Multimodality Treatment of Skull Base Chondrosarcomas

Neurosurgery 81:520–530, 2017

Limited data exist to guide the multimodality management of chondrosarcomas (CSAs) arising in the skull base.

OBJECTIVE : To determine the impact of histological subtype/grade on progression-free survival (PFS) and the indications for surgery, radiation, and chemotherapy based on histology.

METHODS: A retrospective review was performed of 37 patients (conventional type: 81%, mesenchymal: 16.2%, dedifferentiated: 2.7%) treated at The University of Texas M.D. Anderson Cancer Center. Of the conventional subtype, 23% were grade 1, 63% were grade 2, and 14% were grade 3. In addition to surgery, mesenchymal/dedifferentiated CSAs (18% of the cohort) underwent neoadjuvant chemotherapy and 48.6% of the overall cohort received adjuvant radiotherapy. Histological grade/subtype and treatment factors were assessed for impact on median PFS (primary outcome).

RESULTS: Conventional subtype vs mesenchymal/dedifferentiated was positively associated with median PFS (166 vs 24 months, P < .05). Increasing conventional grade inversely correlated with median PFS (P < .05). Gross total resection positively impacted PFS in conventionalCSAs (111.8 vs 42.9months, P=.201) and mesenchymal/dedifferentiated CSAs (58.2 vs 1.0 month, P < .05). Adjuvant radiotherapy significantly impacted PFS in conventional grades 2 and 3 (182 vs 79 months, P < .05) and a positive trend with mesenchymal/dedifferentiated CSAs (43.5 vs 22.0 months). Chemotherapy improved PFS for mesenchymal/dedifferentiated CSAs (50 vs 9 months, P = .089).

CONCLUSION: There is a potential need for histological subtype/grade specific treatment protocols. For conventional CSAs, surgery alone provides optimal results grade 1 CSAs, while resection with adjuvant radiotherapy yields the best outcomefor grade 2 and 3 CSAs. Improvements in PFS seen with neoadjuvant therapy in mesenchymal/dedifferentiated CSAs indicate a potential role for systemic therapies. Larger studies are necessary to confirm the proposed treatment protocols.

Frontal Sinus Breach During Routine Frontal Craniotomy

Neurosurgery 81:504–511, 2017

Frontotemporal craniotomies are commonly performed for a variety of neurosurgical pathologies. Infections related to craniotomies cause significant morbidity. We hypothesized that the risk of cranial surgical site infections (SSIs) may be increased in patients whose frontal sinuses are breached during craniotomy.

OBJECTIVE: To compare the rate of cranial SSIs in patients undergoing frontotemporal craniotomies with and without frontal sinus breach (FSB).

METHODS: We performed a retrospective analysis of all patients undergoing frontotemporal craniotomies for the management of cerebral aneurysms from 2005 to 2014. This study included 862 patients undergoing 910 craniotomies. Primary outcomeof interest was occurrence of a cranial SSI. Standard statistical methods were utilized to explore associations between a variety of variables including FSB, cranial SSI, and infections requiring reoperation.

RESULTS: Of the 910 craniotomies, 141 (15.5%) involved FSB. Of those involving FSB, 22 (15.6%) developed a cranial SSI, compared to only 56 of the 769 without FSB (7.3%; P = .001). Cranial SSI requiring reoperation wasmuch more likely in patients with FSB compared to those without a breach (7.8% vs 1.6%; P < .001). In those presenting with cranial SSIs, epidural abscess formation was more common with FSB compared to no FSB (27.3% vs 5.4%; P = .006). In multivariate analysis, breach of the frontal sinus was significantly associated with cranial SSI (OR 2.16; 95% CI 1.24-3.78; P = .01) and reoperation (OR 4.20; 95% CI 1.66-10.65; P = .003).

CONCLUSION: Patients undergoing frontotemporal craniotomies are at significantly greater risk of serious cranial SSIs if the frontal sinus has been breached.

Nerve atrophy in trigeminal neuralgia due to neurovascular compression and its association with surgical outcomes after microvascular decompression

Acta Neurochir (2017) 159:1699–1705

Idiopathic trigeminal neuralgia (TN) is caused by neurovascular compression and is often related to morphological changes in the trigeminal nerve. The aim of this study was to quantitatively measure atrophic changes of trigeminal nerves in patients with TN, and to further investigate whether nerve atrophy affected the efficacy of microvascular decompression (MVD).

Methods We conducted a prospective case-control study of 60 consecutive patients with TN and 30 sex- and age-matched healthy controls. All subjects underwent high-resolution three-dimensional MRI. The volume of the cisternal segment of trigeminal nerves was measured and compared using 3D Slicer software. Patients with TN underwent primary MVD and regular follow-up for at least 2 years. Associations of nerve atrophy with patient characteristics and operative outcomes were analyzed.

Results The mean volume of the affected trigeminal nerve was significantly reduced in comparison to that of the nonaffected side (65.8 ± 21.1 versus 77.9 ± 19.3 mm3, P = 0.001) and controls (65.8 ± 21.1 versus 74.7 ± 16.5 mm3, P = 0.003). Fifty-two patients (86.7%) achieved complete pain relief without medication immediately after surgery, and 77.6% of patients were complete pain relief at the 2-year follow-up. The Spearman correlation test showed that there was a positive correlation (r=0.46, P = 0.018) between the degree of trigeminal nerve indentation and nerve atrophy. In multivariate logistic regression analysis, two factors, indentation on nerve root (OR = 2.968, P = 0.022) and degree of nerve atrophy (OR = 1.18, P = 0.035), were associated with the long-term outcome.

Conclusions TN is associated with atrophy on the affected nerve. Furthermore, greater nerve atrophy is associated with more severe trigeminal nerve indentation and better long-term outcome following MVD.

Clinical course of untreated thalamic cavernous malformations: hemorrhage risk and neurological outcomes

J Neurosurg 127:480–491, 2017

The natural history of cerebral cavernous malformations (CMs) has been widely studied, but the clinical course of untreated thalamic CMs is largely unknown. Hemorrhage of these lesions can be devastating. The authors undertook this study to obtain a prospective hemorrhage rate and provide a better understanding of the prognosis of untreated thalamic CMs.

METHODS This longitudinal cohort study included patients with thalamic CMs who were diagnosed between 2000 and 2015. Clinical data were recorded, radiological studies were extensively reviewed, and follow-up evaluations were performed.

RESULTS A total of 121 patients were included in the study (56.2% female), with a mean follow-up duration of 3.6 years. The overall annual hemorrhage rate (subsequent to the initial presentation) was calculated to be 9.7% based on the occurrence of 42 hemorrhages over 433.1 patient-years. This rate was highest in patients (n = 87) who initially presented with hemorrhage and focal neurological deficits (FNDs) (14.1%) (c2 = 15.358, p < 0.001), followed by patients (n = 19) with hemorrhage but without FND (4.5%) and patients (n = 15) without hemorrhage regardless of symptoms (1.2%). The initial patient presentations of hemorrhage with FND (hazard ratio [HR] 2.767, 95% CI 1.336–5.731, p = 0.006) and associated developmental venous anomaly (DVA) (HR 2.510, 95% CI 1.275–4.942, p = 0.008) were identified as independent hemorrhage risk factors. The annual hemorrhage rate was significantly higher in patients with hemorrhagic presentation at diagnosis (11.7%, p = 0.004) or DVA (15.7%, p = 0.002). Compared with the modified Rankin Scale (mRS) score at diagnosis (mean 2.2), the final mRS score (mean 2.0) was improved in 37 patients (30.6%), stable in 59 patients (48.8%), and worse in 25 patients (20.7%). Lesion size (odds ratio [OR] per 0.1 cm increase 3.410, 95% CI 1.272–9.146, p = 0.015) and mRS score at diagnosis (OR per 1 point increase 3.548, 95% CI 1.815–6.937, p < 0.001) were independent adverse risk factors for poor neurological outcome (mRS score ≥ 2). Patients experiencing hemorrhage after the initial ictus (OR per 1 ictus increase 6.923, 95% CI 3.023–15.855, p < 0.001) had a greater chance of worsened neurological status.

CONCLUSIONS This study verified the adverse predictors for hemorrhage and functional outcomes of thalamic CMs and demonstrated an overall annual symptomatic hemorrhage rate of 9.7% after the initial presentation. These findings and the mode of initial presentation are useful for clinicians and patients when selecting an appropriate treatment, although the tertiary referral bias of the series should be taken into account.

Which Cerebral Cavernous Malformations are Most Difficult to Dissect From Surrounding Eloquent Brain Tissue?

Neurosurgery 81:498–503, 2017

Cerebral cavernous malformations (CCM) may lead to repetitive intracerebral hemorrhage. In selected cases, a surgical resection is indicated.

OBJECTIVE: To identify magnetic resonance imaging (MRI) features of CCM that correlate with the difficulty of dissection and postoperative outcome.

METHODS: This study prospectively analyzed pre- and postoperative MRI features, intraoperative findings (surgical questionnaire), and postoperative outcome of 41 patients with eloquent CCM. Based on the results of the surgeon’s questionnaire and postoperative MRI findings, all surgical procedureswere dichotomized in a “difficult”(groupA) or “not difficult” (group B) lesion dissection. Based on the correlation of preoperative MRI features with groups A and B, a 3-tiered classification was established and tested for sensitivity and specificity.

RESULTS: In 22 patients, dissection of the lesion was rated difficult. This was significantly correlated with amount of postoperative diffusion restriction on MRI (P=.001) and postoperative outcome(P=.05). Various preoperative MRI featureswere tested for correlation and combined in a 3-tiered classification. Receiver operating characteristics revealed excellent and good results for predicting difficulty of dissection for the different classification types.

CONCLUSION: We provide a meticulous analysis and new classification of preoperative MRI features that seem to be involved in the microsurgical resection of CCM.

Early retreatment after surgical clipping of ruptured intracranial aneurysms

Acta Neurochir (2017) 159:1627–1632

Although a rerupture after surgical clipping of ruptured intracranial aneurysms is rare, it is associated with high morbidity and mortality. The causes for retreatment and rupture after surgical clipping are not clearly defined.

Methods From a prospectively maintained database of 244 patients who had undergone surgical clipping of ruptured intracranial aneurysms, we selected patients who experienced retreatment or rerupture within 30 days after surgical clipping. Aneurysm occlusions were examined by microvascular Doppler ultrasonography and indocyanine green video-angiography. Indications for retreatment included rerupture and partial occlusion. We analyzed the characteristics and causes of early retreatment.

Results Six patients (2.5%, 95% CI 0.9 to 5.3%) were retreated within 30 days after surgical clipping, including two patients (0.8%, 95% CI 0.1 to 2.9%) who experienced a rerupture. The retreated aneurysms were found in the anterior communicating artery (AcomA) (n = 5) and basilar artery (n = 1). Retreatment of the AcomA (7.5%) was performed significantly more frequently than that of other arteries (0.56%) (p < 0.01). A laterally projected AcomA aneurysm (17.4%) was more frequently retreated than were other aneurysm types (2.3%). Cases of laterally projecting AcomA aneurysms tended to result from an incomplete clip placed using a pterional approach from the opposite side of the aneurysm projection.

Conclusions Despite developments, the rates of retreatment and rerupture after surgical clipping remain similar to those reported previously. Retreatment of the AcomA was significantly more frequent than was retreatment of other arteries. Patients underwent retreatment more frequently when they were originally treated for lateral type aneurysms using a pterional approach from the opposite side of the aneurysm projection. The treatment method and evaluation modalities should be considered carefully for AcomA aneurysms in particular.

Neurosurgery Department. “La Fe” University Hospital. Valencia, Spain


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