Analysis of PMMA versus CaP titanium-enhanced implants for cranioplasty after decompressive craniectomy: a retrospective observational cohort study.

Numerous materials of implants used for cranioplasty after decompressive craniectomy (DC) have been investigated to meet certain demanded key features, such as stability, applicability, and biocompatibility. We aimed to evaluate the feasibility and safety of biocompatible calcium-phosphate (CaP) implants for cranioplasty compared to polymethylmethacrylate (PMMA) implants. In this retrospective observational cohort study, the medical records of all patients who underwent cranioplasty between January 1st, 2015, and January 1st, 2022, were reviewed. Demographic, clinical, and diagnostic data were collected. Eighty-two consecutive patients with a mean age of 52 years (range 22-72 years) who received either a PMMA (43/82; 52.4%) or CaP (39/82; 47.6%) cranial implant after DC were included in the study. Indications for DC were equally distributed in both groups. Time from DC to cranioplasty was 143.8 ± 17.5 days (PMMA) versus 98.5 ± 10.4 days (CaP). The mean follow-up period was 34.9 ± 27.1 months. Postoperative complications occurred in 13 patients with PMMA and 6 in those with CaP implants (13/43 [30.2%] vs. 6/39 [15.4%]; p = 0.115). Revision surgery with implant removal was necessary for 9 PMMA patients and in 1 with a CaP implant (9/43 [20.9%] vs. 1/39 [2.6%]; p = 0.0336); 6 PMMA implants were removed due to surgical site infection (SSI) (PMMA 6/43 [14%] vs. CaP 0/39 [0%]; p = 0.012). In this study, a biocompatible CaP implant seems to be superior to a PMMA implant in terms of SSI and postoperative complications. The absence of SSI supports the idea of the biocompatible implant material with its ability for osseointegration.

Association of single and multiple aneurysms with tobacco abuse: an @neurIST risk analysis.

OBJECTIVE: Although several studies have suggested that the incidence of intracranial aneurysms (IAs) is higher in smokers, the higher prevalence of subarachnoid hemorrhage (SAH) in smokers remains uncertain. It is unclear whether smoking additionally contributes to the formation of multiple aneurysms and the risk of rupture. The aim of this study was to determine whether smoking is associated with IA formation, multiplicity, or rupture. METHODS: Patients from the prospective multicenter @neurIST database (n = 1410; 985 females [69.9%]) were reviewed for the presence of SAH, multiple aneurysms, and smoking status. The prevalence of smokers in the population of patients diagnosed with at least one IA was compared with that of smokers in the general population. RESULTS: The proportion of smokers was higher in patients with IAs (56.2%) than in the reference population (51.4%; p < 0.001). A significant association of smoking with the presence of an IA was found throughout group comparisons (p = 0.01). The presence of multiple IAs was also significantly associated with smoking (p = 0.003). A trend was found between duration of smoking and the presence of multiple IAs (p = 0.057). However, the proportion of smokers among patients suffering SAH was similar to that of smokers among patients diagnosed with unruptured IAs (p = 0.48). CONCLUSIONS: Smoking is strongly associated with IA formation. Once an IA is present, however, smoking does not appear to increase the risk of rupture compared with IAs in the nonsmoking population. The trend toward an association between duration of smoking and the presence of multiple IAs stresses the need for counseling patients with IAs regarding lifestyle modification.

Clival chordoma: a single-centre outcome analysis.

BACKGROUND: The treatment of clival chordomas remains challenging. Total tumour resection is often impossible without hampering adjacent anatomical structures and causing functional sequelae. On the other hand, chordomas show limited response to non-surgical treatment modalities. Up to now, no well-established interdisciplinary treatment algorithms for clival chordomas exist. In this regard, we analysed the data from all patients that underwent interdisciplinary treatment for clival chordoma in our institution over the last 10 years. METHOD: Retrospective report of all patients treated at the authors' institution from 2005 to 2015. RESULTS: Thirteen patients underwent 24 surgeries, of which 2 (8%) were gross total resections and 22 (92%) incomplete resections. Neurological deterioration, endocrinological disturbances and other surgical complications were observed in six (25%), three (13%) and nine (38%) cases, respectively. Three surgeries (13%) led to an improvement of the initial preoperative neurological condition. All patients were discussed on the interdisciplinary tumour board and all underwent one type of radiotherapy following initial surgery: proton beam in 11 cases (85%) and photon beam in two (15%) cases. In the course of their recurrent disease, three patients (23%) received systemic therapy (imatinib, pazopanib and nivolumab). One patient received a personalised cellular immunotherapy. One patient (8%) was lost to follow-up. Of the remaining 12 patients, four patients (33%) died in the period of analysis; all deaths were chordoma-related. The 5-year cumulative survival rate was 83% (52-97%, CI 95%), 5-year progression-free survival rate was 53% (26-79%, CI 95%). The eight patients (66%) still alive had favourable outcome (KPS, 90 ± 10.7%). SF36 analysis among the survivors revealed 43 points for the Physical Component Summary (12% above, 38% at and 50% below the general population norm) and 47 points for the Mental Component Summary (25% above, 38% at and 38% below). CONCLUSIONS: Our patients show a low rate of gross total resection but an outcome well comparable to other published results. This emphasises the importance of interdispiplinary treatment strategies, with surgery supplying maximal safe resection and avoiding severe neurological deficit, allowing patients to undergo adjusted radiotherapy and other treatment options in a good condition.

Clipping of ruptured intracranial aneurysms in a hybrid room environment-a case-control study.

BACKGROUND: Hybrid room treatment (HRT) provides the surgeon immediate intraoperative angiography control of aneurysm occlusion and vessel patency. Since it is relatively resource demanding, in clinical routine HRT is reserved for elective cases. However, since its introduction in our department in 2008, several random cases of ruptured intracranial aneurysms (IAs) have been treated in the HR. This study aims to compare the clinical and radiological outcomes of these cases with cases treated conventionally using a matched pair analysis. METHODS: Twenty (20%) consecutive patients with ruptured IA treated by microsurgical clipping in the HR between 2009 and 2015 were retrospectively matched with "conventionally" (C) treated patients (overall n = 101). Clinical and radiological outcome variables were assessed and compared. RESULTS: Despite a trend in favor of the HR group, no significant difference between both matched groups (HR vs. C) could be demonstrated regarding the functional outcome (upper/lower good recovery 16/20 vs. 17/20, p > 0.05), frequency of clipping-related vascular insults on CT scans (0/20 vs. 3/20, p > 0.05), aneurysm remnant rate on postoperative angiography (1/20 vs. 4/20, p > 0.05) and retreatment rate (0/20 vs. 1/20, p > 0.05). When cumulating all outcome events by a scoring system, however, the HR cohort showed a significantly lower occurrence of events (p < 0.05). In three cases co-treatment by an endovascular approach was performed in the HR cohort. CONCLUSION: In this relatively small cohort, a matched pair analysis revealed a discrete but not significant tendency toward a lower frequency of aneurysm remnants and clipping-related vascular insults in the HR cohort. However, HR cohort patients benefited from direct endovascular co-treatment in selected cases.

Unruptured intracranial aneurysm follow-up and treatment after morphological change is safe: observational study and systematic review.

BACKGROUND: The management of small unruptured incidentally discovered intracranial aneurysms (SUIAs) is still controversial. The aim of this study is to assess the safety of a management protocol of SUIAs, where selected cases with SUIAs are observed and secured only if signs of instability (growth) are documented. METHODS: A prospective consecutive cohort of 292 patients (2006-2014) and 368 SUIAs (anterior circulation aneurysms (ACs) smaller than 7 mm and posterior circulation aneurysms smaller than 4 mm without previous subarachnoid haemorrhage) was observed (mean follow-up time of 3.2 years and 1177.6 aneurysm years). Factors associated with aneurysm growth were systematically reviewed from the literature. RESULTS: The aneurysm growth probability was 2.6±0.1% per year. The rate of unexpected aneurysm rupture before treatment was 0.24% per year (95% CI 0.17% to 2.40%). The calculated rate of aneurysm rupture after growth was 6.3% per aneurysm-year (95% CI 1% to 22%). Aneurysms located in the posterior circulation and aneurysms with lobulation were more likely to grow. Females or patients suffering hypertension were more likely to have an aneurysm growing. The probability of aneurysms growth increased with the size of the dome and was proportional to the number of aneurysms diagnosed in a patient. CONCLUSIONS: It is safe to observe patients diagnosed with SUIAs using periodic imaging. Intervention to secure the aneurysm should be performed after growth is observed.

Evolving patterns of intracranial hemorrhage in advanced therapies in patients with acute pulmonary embolism.

BACKGROUND: Dissecting trends and contributing risk factors for intracranial hemorrhage (ICH) in patients treated for acute pulmonary embolism (PE) may allow for a better patient selection for existing and emerging treatment options. METHODS: The German nationwide inpatient sample was screened for patients admitted due to PE 2005-2020. Hospitalizations were stratified for the occurrence of ICH; risk factors for ICH and temporal trends were investigated. RESULTS: Overall, 816,653 hospitalizations due to acute PE in the period 2005-2020 were analyzed in the study. ICH was reported in 2516 (0.3 %) hospitalizations, and time trend analysis revealed a fluctuating but overall, largely unchanged annual incidence. There was an increase of ICH with age. Patients with ICH had a higher comorbidity burden (Charlson-Comorbidity-Index [CCI], 5.0 [4.0-7.0] vs. 4.0 [2.0-5.0]; P < 0.001), and higher CCI was associated with an OR of 1.26 (95%CI 1.24-1.27) for ICH. Further independent risk factors for ICH were age ≥ 70 years (OR 1.23 [1.12-1.34]), severe (versus low-risk) PE (OR 3.09 [2.84-3.35]), surgery (OR 1.59 [1.47-1.72]), acute kidney injury (OR 3.60 [3.09-4.18]), and ischemic stroke (OR 14.64 [12.61-17.00]). The identified risk factors for ICH varied among different reperfusion treatment groups. As expected, ICH had a substantial impact on case-fatality of PE (OR 6.16 [5.64-6.72]; P < 0.001). CONCLUSIONS: Incidence of ICH in patients hospitalized for acute PE in Germany was overall low and depended on the patients' comorbidity burden. Identifying patients at risk for ICH allows tailored patient selection for the different reperfusion treatments and might prevent ICH.

The Oswestry Spinal Risk Index (OSRI) in assessing prognosis of patients with spinal metastases.

Introduction: The Oswestry Spinal Risk Index (OSRI) was designed to predict life expectancy of patients presenting with spinal metastases. It integrates the most predictive items of existing scores and is calculated using not more than two items: General condition and primary tumor. Research question: The purpose of this study was to externally validate the OSRI in a large cohort and to compare it with the established scores. Material and methods: We retrospectively identified 211 consecutive surgical patients with symptomatic spinal metastases. We collected clinical and radiographic data, such as Karnofsky Performance Score (KPS), Frankel Status, primary tumor pathology and metastatic spread to calculate the Tokuhashi score, Tomita score, modified Bauer score and the OSRI. Logistic regression models, Kaplan-Meyer-curves, discriminant power and variance analyses were applied using Harrell's C-index and Cox and Snell's Pseudo R². Results: Predicted and actual survival of our cohort's patients correlated significantly in each investigated scoring systems (p < 0.001). In test quality measurements Tokuhashi score performed best (C = 0.7204; R² = 0.3619), followed by OSRI (C = 0.7023; R² = 0.2612), Tomita (C = 0.6748; R² = 0.2818) and modified Bauer score (C = 0.6653; R² = 0.2486). Accuracy of predicted life expectancy was highest in modified Bauer score and OSRI. Discussion and conclusion: Compared to the original scores, the OSRI provided equal or even superior results in assessing our study population's life expectancy. Its particular advantage lies in the simplicity of its application, which well meets the demands of surgical decision-making in daily practice.

Caliper navigation for craniotomy planning of convexity targets.

INTRODUCTION: A technique to localize a radiological target on the head convexity fast and with acceptable precision is sufficient for surgeries of superficial intracranial lesions, and of help in the setting of emergency surgery, computer navigation breakdown, limited resources and education. We present a caliper technique based on fundamental geometry, with inexpensive and globally available tools (conventional CT or MRI image viewer, calculator, caliper). METHODS: The distances of the radiological target from two landmarks (nasion and porus acusticus externus) are assessed with an image viewer and Pythagoras' theorem. The two distances are then marked around the landmarks onto the head of the patient with help of a caliper. The intersection defines the target. We tested the technique in a saw bone skull model and afterwards in the operating room. Convexity targets were localized with the caliper navigation technique and then with computer navigation as ground truth. RESULTS: In the saw bone model, the mean offset between the caliper navigated target and the real target was 2.9 ± 2.8 mm, 95% CI (1.6 mm; 4.2 mm). The mean offset between computer navigated target and real target was 1.6 ± 0.9 mm, 95% CI (1.2 mm; 2 mm) (ns). In 15 patients undergoing navigated cranial procedures, 100 targets were assessed in reference to computer navigation. The mean offset of the caliper navigation was 11 ± 5.2 mm, 95% CI (9.9 mm; 12 mm). CONCLUSION: This is a low-tech approach for translation of a radiological target to the patient's head in short time and with globally available inexpensive tools, with satisfying precision for many procedures.

Quantitative assessment and localization of the hollowing of the temple after craniectomy and cranioplasty-The frontozygomatic shadow.

BACKGROUND: After cranioplasty, in many cases a not negligible soft tissue defect remains in the temporozygomatical area, also referred to as a hollowing defect of the temple. OBJECTIVE: To assess the precise localization and volume of the hollowing defect, to optimize future cranioplasties. METHODS: CT data of patients who received craniectomy and conventional CAD cranioplasty in our institution between 2012 and 2018 were analyzed. CT datasets prior to craniectomy and after cranioplasty were subtracted to quantify the volume and localization of the defect. RESULTS: Out of 91 patients, 21 had suitable datasets. Five cases had good cosmetic results with no defect visible, 16 patients had an apparent hollowing defect. Their average defect volume was 5.0 cm3 ± 4.5 cm3. The defect localizations were in the area behind the zygomatic process and just below the superior temporal line, covering an area of app. 3x3 cm2. Surgical attempts of temporal muscle restoration were more often found in reports of good results (p<0.01), but also in 50% of reports, whose surgeries resulted in hollowing of the temple. Mean time between the two surgeries was 112 ± 43 days. No significant differences between patients with and without hollowing defect were detected regarding time between the two surgeries, age or performing surgeon. CONCLUSION: This work supplies evidence for the indication of a surgical corrective during cranioplasty in the small but cosmetically relevant area of the "frontozygomatic shadow". Based on our 3D data analysis, future focused surgical strategies may obtain better aesthetical results here.

Future directions of postoperative spinal implant infections.

This article outlines some promising future concepts against postoperative spinal implant infections on the basis of today available literature. The ever-adapting bacteria causing this common complication compel a corresponding continuous research about best effective treatment. The aim is to give a perspective on several future attack-points: surgical infection prevention strategies such as technical optimization of implants and surgical technique; faster diagnostic tools to detect infection, especially in the context of late infections with low-virulent germs and with regard to decision-making in the course of the surgical workflow; and combined surgical and medical treatment options against implant infections. The surgical treatment section will also state open issues concerning implant removal, and the medical treatment section will give an outlook to promising medical alternatives in a post-antibiotic era. To keep up in this field will be important to retain spine surgery in the future as the state-of-the-art treatment option for mandatory spinal interventions in the presence of tumor or trauma and even more so as an attractive option for patients with degenerative spinal disorder for improvement of their life quality.

Endoscopic Transcranial Duraplasty for Rhinoliquorrhea: A Cadaveric Study.

BACKGROUND: Repair of the anterior skull base for cerebrospinal fluid leak requires either endoscopic endonasal approach or open transcranial approach. OBJECTIVE: To present a less invasive surgical procedure for sealing of the entire anterior fossa floor for traumatic rhinoliquorrhea. METHODS: Cadaver study in 3 head specimens. Endoscopic placement of a furled bovine pericardial patch bilaterally along the sphenoid ridge and planum in guidewire technique. Unfurling and spreading of the patch under endoscope assistance. RESULTS: Patch placement was feasible in all 3 specimens without visible injuries to the frontal lobes. Dissection and preservation of the olfactory tracts was only possible for 50% of olfactory tracts. CONCLUSION: Endoscopic transcranial keyhole duraplasty is a promising concept for traumatic rhinoliquorrhea.

Spinal ependymoma in adults: a multicenter investigation of surgical outcome and progression-free survival.

OBJECTIVE Spinal ependymomas are rare glial neoplasms. Because their incidence is low, only a few larger studies have investigated this condition. There are no clear data concerning prognosis and therapy. The aim of the study was to describe the natural history, perioperative clinical course, and local tumor control of adult patients with spinal ependymomas who were surgically treated under modern treatment standards. METHODS The authors performed a multicenter retrospective study. They identified 158 adult patients with spinal ependymomas who had received surgical treatment between January 2006 and June 2013. The authors analyzed the clinical and histological aspects of these cases to identify the predictive factors for postoperative morbidity, tumor resectability, and recurrence. RESULTS Gross-total resection (GTR) was achieved in 80% of cases. At discharge, 37% of the patients showed a neurological decline. During follow-up the majority recovered, whereas 76% showed at least preoperative status. Permanent functional deterioration remained in 2% of the patients. Transient deficits were more frequent in patients with cervically located ependymomas (p = 0.004) and in older patients (p = 0.002). Permanent deficits were independently predicted only by older age (p = 0.026). Tumor progression was observed in 15 cases. The 5-year progression-free survival (PFS) rate was 80%, and GTR (p = 0.037), WHO grade II (p = 0.009), and low Ki-67 index (p = 0.005) were independent prognostic factors for PFS. Adjuvant radiation therapy was performed in 15 cases. No statistically relevant effects of radiation therapy were observed among patients with incompletely resected ependymomas (p = 0.079). CONCLUSIONS Due to its beneficial value for PFS, GTR is important in the treatment of spinal ependymoma. Gross-total resection is feasible in the majority of cases, with acceptable rates of permanent deficits. Also, Ki-67 appears to be an important prognostic factor and should be included in a grading scheme for spinal ependymomas.

Correlating Clinical Risk Factors and Histological Features in Ruptured and Unruptured Human Intracranial Aneurysms: The Swiss AneuX Study.

Pathogenesis of intracranial aneurysm is complex and the precise biomechanical processes leading to their rupture are uncertain. The goal of our study was to characterize the aneurysmal wall histologically and to correlate histological characteristics with clinical and radiological factors used to estimate the risk of rupture. A new biobank of aneurysm domes resected at the Geneva University Hospitals (Switzerland) was used. Histological analysis revealed that unruptured aneurysms have a higher smooth muscle cell (SMC) content and a lower macrophage content than ruptured domes. These differences were associated with more collagen in unruptured samples, whereas the elastin content was not affected. Collagen content and type distribution were different between thick and thin walls of unruptured aneurysms. Classification of aneurysm domes based on histological characteristics showed that unruptured samples present organized wall rich in endothelial and SMCs compared with ruptured samples. Finally, aneurysm wall composition was altered in unruptured domes of patients presenting specific clinical factors used to predict rupture such as large dome diameter, dome irregularities, and smoking. Our study shows that the wall of aneurysm suspected to be at risk for rupture undergoes structural alterations relatively well associated with clinical and radiological factors currently used to predict this risk.

Reliable? The Value of Early Postoperative Magnetic Resonance Imaging after Cerebral Cavernous Malformation Surgery.

BACKGROUND: Cerebral cavernous malformations (CCM) can cause intracerebral hemorrhage. The lesions themselves are frequently associated with perifocal hemosiderin deposits caused by repetitive microhemorrhages. Main indications for a surgical treatment are recurrent symptomatic hemorrhages or cavernoma-related epilepsy. After surgical resection, follow-up magnetic resonance imaging (MRI) is usually performed to confirm 1) the complete resection of the CCM and, especially in cases of cavernoma-related epilepsy, 2) the complete resection of the hemosiderin deposits. METHODS: This prospective study evaluates the value of early postoperative MRI (within 72 hours) regarding the detection of CCM or hemosiderin remnants compared with a standard 3-6 months postoperative MRI control in 61 CCM cases. RESULTS: Sensitivity of early postoperative MRI for CCM remnant detection was 66.67% (95% confidence interval [CI], 9.43%-99.16%), specificity was 76.74% (95% CI, 61.37%-88.24%), positive predictive value was 16.67% (95% CI, 2.09%-48.41%), and negative predictive value was 97.06% (95% CI, 84.67%-99.93%). Because of the high number of patients who could not be evaluated because of imaging artifacts, sensitivity and specificity analysis was not performed for early postoperative MRI using T2*/susceptibility-weighted imaging to assess hemosiderin remnants. Sensitivity of early postoperative MRI for hemosiderin remnant detection using T2-weighted sequences was 85.71% (95% CI, 63.66%-96.95%), specificity was 66.67% (95% CI, 44.68%-84.37%), positive predictive value was 69.23% (95% CI, 55.45%-80.27%), and negative predictive value was 84.21% (95% CI, 64.31%-94.04%). CONCLUSIONS: Our data suggest that early postoperative MRI after CCM surgery is often hampered by imaging artifacts creating false-positive results and therefore ineligible for a resection control. However, reliability of a negative result on early postoperative T2-weighted MRI is relatively high regarding both CCM and hemosiderin remnants.

Rapidly Growing Pulmonary Metastasis from Anaplastic Meningioma with Lethal Outcome: A Case Report.

Anaplastic meningioma is seldom encountered. Moreover, distant metastasis is extremely rare, with only a handful cases reported. Here, we report the case of a 74-year-old female patient who underwent a combined cranial and endonasal approach for an extensive spheno-orbital anaplastic meningioma (WHO grade III), followed by adjuvant radiotherapy. Although local tumor control was achieved, she presented with lung metastasis 2 years later. The patient then died from pulmonary complications related to chest metastasis. On the basis of this case, we discuss the available literature on metastatic meningiomas and radiologic follow-up strategies.

The Extended Lateral Supraorbital Approach and Extradural Anterior Clinoidectomy Through a Frontopterio-Orbital Window: Technical Note and Pilot Surgical Series.

BACKGROUND: Lateral approaches to treat anterior cranial fossa lesions have evolved since the first frontotemporal approach described by Dandy in 1918. We describe a less invasive approach to perform extradural anterior clinoidectomy through a lateral supraorbital (LSO) approach for anterior circulation aneurysms and anterolateral skull base lesions. METHODS: The extended LSO approach involves performing a standard lateral supraorbital craniotomy followed by drilling of the sphenoid wing and lateral wall of the orbit through the frontal bony opening of the LSO approach, without any temporal extension of the craniotomy. This creates a frontopterio-orbital window exposing the periorbita; superior, medial, and anterior aspect of the temporal dura mater; and superior orbital fissure. After unroofing the superior orbital fissure, the meningo-orbital fold is cut, and the temporal dura mater is peeled from the lateral wall of the cavernous sinus to expose the anterior clinoid process allowing a standard opening of the optic canal and anterior clinoidectomy. RESULTS: The extended LSO approach and extradural anterior clinoidectomy allowed access to 4 sphenoid wing/anterior clinoidal meningiomas, 5 anterior circulation aneurysms, 2 temporomesial lesions, and 1 orbital/cavernous sinus abscess. Postoperatively, 2 patients had transient hemiparesis, 2 patients had transient third nerve palsy, and 1 patient had minimal visual field deterioration. All patients had a modified Rankin Scale score ≤1 at 8-week follow-up. CONCLUSION: The extended LSO approach opens a new route (frontopterio-orbital window) to perform extradural anterior clinoidectomy safely and increases surgical exposure, angles, and operability of a less invasive keyhole craniotomy (LSO approach) to treat anterior cranial fossa lesions.

Quantification of Working Volumes, Exposure, and Target-Specific Maneuverability of the Pterional Craniotomy and Its Minimally Invasive Variants.

OBJECTIVE: Quantitative comparison of minimally invasive and standard cranial approaches remains a methodologic challenge. The aim of this study was to apply a new digital, navigation-based method to quantify multiple parameters of the pterional, supraorbital, lateral supraorbital and mini-pterional approaches and to describe a target-specific maneuverability score. METHODS: Supraorbital, lateral supraorbital, mini-pterional, and standard pterional craniotomies were performed on 8 sides in 4 cadaver heads. The limits of superficial and deep exposure and surgical target points were registered with image-guidance (Medtronic Stealth). A custom software (Guided Therapeutics Eyes II Software [GTxEyesII]) calculated superficial and deep surface areas, working volumes, and target distances. Volumes were reconstructed digitally and visualized with GTxEyesII. Finally, we defined for each approach a target-specific maneuverability score based on surface exposure, target distance, target position, and anatomical obstacles. RESULTS: Surface exposure and volumes were significantly smaller for keyhole approaches compared with standard pterional craniotomy (P < 0.01). Maneuverability index scores showed the greatest values for standard pterional craniotomies, but nearly equally high scores could be achieved by one or several of the less-invasive approaches for most of the targets. CONCLUSIONS: The combination of a navigation-based measurement method with custom software (GTxEyesII) provides a powerful tool for visualization and quantification of surgical approaches. Compared with standard pterional craniotomy, alternative keyhole craniotomies offer comparable deep exposure with smaller working volumes and relatively high maneuverability for specific targets.

Complete cage migration/subsidence into the adjacent vertebral body after posterior lumbar interbody fusion.

A variety of implant-related short and long-term complications after lumbar fusion surgery are recognized. Mid to long-term complications due to cage migration and/or cage subsidence are less frequently reported. Here, we report a patient with a complete cage migration into the superior adjacent vertebral body almost 20 years after the initial posterior lumbar interbody fusion procedure. In this patient, the cage migration/subsidence was clinically silent, but a selective decompression for adjacent segment degenerative lumbar spinal stenosis was performed. We discuss the risk factors for cage migration/subsidence in view of the current literature.

Cerebral blood flow reactivity in patients undergoing selective amygdalohippocampectomy for epilepsy of mesial temporal origin. A prospective randomized comparison of the trans-Sylvian and the transcortical approach.

OBJECTIVE: The aim of this study was to assess (1) whether vasoreactivity is altered in patients with epilepsy and (2) whether the two most commonly used approaches, the trans-Sylvian (TS) and the trans-cortical (TC) route, differ in their impact on cortical blood flow. METHODS: Patients were randomized to undergo selective amygdalohippocampectomy (selAH) through a TC or TS route. Before and after selAH, we recorded microcirculation parameters on the superficial cortex surrounding the surgical corridor. Blood flow and velocity were measured using laser Doppler flowmetry and micro-Doppler, respectively. Cortical oxygen saturation (SO2) was measured using remission spectrophotometry under hypocapnic and normocapnic conditions. RESULTS: Ten patients were operated using the TS approach, and eight were operated via the TC approach. Vasomotor reactivity patterns measured with micro-Doppler were physiologically prior to selAH in both groups. After completion of surgery, a significant increase in SO2-values occurred in the TS group (before: 56.7 ± 2.2, after: 65.5 ± 3.0%SO2), but not in the TC group (before: 52.9 ± 5.2, after: 53.0 ± 3.7%SO2). The rate of critical SO2 values below 25% was significantly higher after the TC approach (12.3%) compared to the TS approach (5.2%; p < 0.05). DISCUSSION: Our findings provide the first invasively measured evidence that patients with mesial temporal lobe epilepsy have preserved cerebral blood flow responses to alterations in CO2. In addition, local cortical SO2 was higher in the TS group than in the TC group after selAH. This may be a sign of reactive cortical vessel dilation after proximal vessel manipulation associated with the TS approach. In contrast, the lower values of SO2 after the TC approach indicate tissue ischaemia surrounding the surgical corridor surrounding the corticotomy.

ALIF versus TLIF for post-discectomy syndrome.

OBJECTIVE: To evaluate whether anterior lumbar interbody fusion (ALIF) is superior to transforaminal lumbar interbody fusion (TLIF) in cases of post-discectomy syndrome (PDS). METHODS: In this retrospective study, we analyzed the consecutive results of 83 patients operated for PDS refractory to conservative treatment. A total of 46 patients underwent ALIF via a retroperitoneal approach; 37 patients underwent TLIF. Both fusion types were augmented by means of pedicle screw instrumentation. Early and delayed complications were registered within the course of hospitalization or outpatient clinical follow-up, respectively. Parameters such as patient satisfaction, current pain levels, pain medication, and change in work ability were obtained via telephone follow-up. RESULTS: Overall, 81.9% of patients were available for follow-up. Both ALIF and TLIF significantly improved back and leg pain (p < 0.01) and were described as satisfying operations by 75.8% and 73.3% of the patients, respectively. No significant difference between ALIF and TLIF results could be observed. Complications included dural tears, screw malposition, bleeding from major vessels (ALIF), abdominal wall insufficiency (ALIF), and nerve root injury (TLIF). One patient in the ALIF group and seven patients in the TLIF group required fusion extensions to adjacent levels within the observation period (observation period was 34 and 71 months, respectively). CONCLUSIONS: Both ALIF and TLIF techniques can be applied for PDS with equally good results. The technical advantages of ALIF have to be balanced with the additional morbidity and operation time owed to the additional approach. ALIF might be associated with a lower incidence of adjacent level disease compared with TLIF.