Month: December 2017

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Early Postoperative Complications for Elderly Patients Undergoing Single-Level Decompression for Lumbar Disc Herniation, Ligamentous Hypertrophy, or Neuroforaminal Stenosis

Neurosurgery 81:1005–1010, 2017

Lumbar decompression for disc herniation is frequently performed on elderly patients, and this trend will continue as the population ages. Clinical reports on the complications of lumbar discectomy show good results and cost effectiveness in young or middle-aged patients.

OBJECTIVE: To assess and compare the morbidity of single-level lumbar disc surgery for radicular pain in a cohort of patients greater than 80 yr of age to that of a middle-aged cohort.

METHODS: A total of 9451 patients who received a single-level lumbar decompression procedure for disc displacement without myelopathy were retrospectively selected from a multicenter validated surgical database from the American College of Surgeons National Surgical Quality Improvement Program. A cohort with 485 patients greater than 80 yr of age (80+) was compared with a middle-aged cohort with 8966 patients between 45 and 65 yr. Preoperative comorbidity and postoperative outcome variables observed included mortality, myocardial infarction, return to the operating room, sepsis, deep vein thrombosis, transfusions, cardiac arrest necessitating cardiopulmonary resuscitation, coma greater than 24 h, urinary tract infection, acute renal failure, use of ventilator greater than 24 h, pulmonary embolism, pneumonia, wound dehiscence, and postoperative infection.

RESULTS: The preoperative comorbidities and characteristics were significantly different between the middle-aged and the 80+ cohorts, with the older cohort having many more preoperative comorbidities. There was statistically significantly greater postoperative morbidity among the 80+ cohort regarding pulmonary embolism (0.8% vs 0.2%, P = .037), intra/postoperative transfusion requirement (1.9% vs 0.7%, P = .01), urinary tract infection (1.2% vs 0.3%, P = .011), and 30-d mortality (0.4% vs 0.1%, P = .046).

CONCLUSION: In this large sample of patients who received a single-level lumbar decompression procedure for disc displacement without myelopathy, elderly patients, particularly with American Society of Anesthesiologists class 3 and 4, had a statistically significant increase in morbidity and mortality, but the overall risk of complications remains low.

 

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Clinical and radiological results of posterior cervical foraminotomy at two or three levels: a 3-year follow-up

Acta Neurochir (2017) 159:2369–2377

Single-level unilateral posterior cervical foraminotomy is regarded as a safe method. However, the outcomes of posterior cervical foraminotomy performed on two or three levels are uncertain and debated. We aimed to analyze the long-term clinical and radiological outcomes of posterior cervical foraminotomy at two or three levels.

Methods From September 2008 to December 2011, a total of 42 patients who underwent a posterior cervical foraminotomy at two or three levels and were followed for at least 3 years were analyzed with retrospective cohort study. Clinical assessments were performed using the visual analog scale (VAS), neck disability index (NDI) and modified MacNab criteria. Radiological evaluation included the assessment of static and dynamic lateral radiographs to identify instability, postlaminectomy kyphotic deformity, adjacent segmental degeneration (ASD), and focal degeneration.

Results The mean VAS improved from preoperative score 8.5 ± 0.3 to postoperative score 1.8 ± 0.5 significantly. The mean presenting NDI score was 32.9 ± 2.0 and the mean postoperative NDI score was 14.2 ± 1.3. Improvement of radiculopathy was displayed in 39 patients (92.9%). During radiological evaluation, no significant change in disc height related to ASD and focal degeneration was noted. However, we confirmed one patient with radiological instability and one patient with radiological postlaminectomy kyphotic deformity.

Conclusions Posterior cervical foraminotomy at two or three levels is fairly effective for treating patients with cervical radiculopathy, and results in long-lasting pain relief and improved quality of life in nearly all patients. However, further studies of three levels that include more patients are needed.

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Symmetry of the arcuate fasciculus and its impact on language performance of patients with brain tumors in the language-dominant hemisphere

J Neurosurg 127:1407–1416, 2017

Cerebral damage in frontal, parietal, and temporal brain areas and, probably more importantly, their interconnections can lead to deficits in language. However, neural plasticity and repair allow the brain to partly compensate for neural injury, mediated by both functional and structural changes. In this study, the authors sought to systematically investigate the relationship between language performance in brain tumor patients and structural perisylvian pathways (i.e., the arcuate fasciculus [AF]) using probabilistic fiber tracking on diffusion tensor imaging. The authors used a previously proposed model in which the AF is divided into anterior, long, and posterior segments. The authors hypothesized that right-handed patients with gliomas in the language-dominant (left) hemisphere would benefit from a more symmetrical or right-lateralized language pathway in terms of better preservation of language abilities. Furthermore, they investigated to what extent specific tumor characteristics, including proximity to the AF, affect language outcome in such patients.

METHODS Twenty-seven right-handed patients (12 males and 15 females; mean age 52 ± 16 years) with 11 low-grade and 16 high-grade gliomas of the left hemisphere underwent 3-T diffusion-weighted MRI (30 directions) and language assessment as part of presurgical planning. For a systematic quantitative evaluation of the AF, probabilistic fiber tracking with a 2 regions of interest approach was carried out. Volumes of the 3 segments of both hemispheric AFs were evaluated by quantifying normalized and thresholded pathways. Resulting values served to generate the laterality index of the AFs.

RESULTS Patients without language deficits tended to have an AF that was symmetric or lateralized to the right, whereas patients with deficits in language significantly more often demonstrated a left-lateralized posterior segment of the AF. Patients with high-grade gliomas had more severe language deficits than those with low-grade gliomas. Backward logistic regression revealed the laterality index of the posterior AF segment and tumor grade as the only independent statistically significant predictors for language deficits in this cohort.

CONCLUSIONS In addition to the well-known fact that tumor entity influences behavioral outcome, the authors’ findings suggest that the right homologs of structural language-associated pathways could be supportive for language function and facilitate compensation mechanisms after brain damage in functionally eloquent areas. This further indicates that knowledge about preoperative functional redistribution (identified by neurofunctional imaging) increases the chance for total or near-total resections of tumors in eloquent areas. In the future, longitudinal studies with larger groups are mandatory to overcome the methodological limitations of this cross-sectional study and to map neuroplastic changes associated with language performance and rehabilitation in brain tumor patients.

 

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Magnetic resonance imaging characteristics and the prediction of outcome of vestibular schwannomas following Gamma Knife radiosurgery

J Neurosurg 127:1384–1391, 2017

Gamma Knife surgery (GKS) is a promising treatment modality for patients with vestibular schwannomas (VSs), but a small percentage of patients have persistent postradiosurgical tumor growth. The aim of this study was to determine the clinical and quantitative MRI features of VS as predictors of long-term tumor control after GKS.

METHODS The authors performed a retrospective study of all patients with VS treated with GKS using the Leksell Gamma Knife Unit between 2005 and 2013 at their institution. A total of 187 patients who had a minimum of 24 months of clinical and radiological assessment after radiosurgery were included in this study. Those who underwent a craniotomy with tumor removal before and after GKS were excluded. Study patients comprised 85 (45.5%) males and 102 (54.5%) females, with a median age of 52.2 years (range 20.4–82.3 years). Tumor volumes, enhancing patterns, and apparent diffusion coefficient (ADC) values were measured by region of interest (ROI) analysis of the whole tumor by serial MRI before and after GKS.

RESULTS The median follow-up period was 60.8 months (range 24–128.9 months), and the median treated tumor volume was 3.54 cm3 (0.1–16.2 cm3). At last follow-up, imaging studies indicated that 150 tumors (80.2%) showed decreased tumor volume, 20 (10.7%) had stabilized, and 17 (9.1%) continued to grow following radiosurgery. The postradiosurgical outcome was not significantly correlated with pretreatment volumes or postradiosurgical enhancing patterns. Tumors that showed regression within the initial 12 months following radiosurgery were more likely to have a larger volume reduction ratio at last follow-up than those that did not (volume reduction ratio 55% vs 23.6%, respectively; p < 0.001). Compared with solid VSs, cystic VSs were more likely to regress or stabilize in the initial postradiosurgical 6–12-month period and during extended follow-up. Cystic VSs exhibited a greater volume reduction ratio at last follow-up (cystic vs solid: 67.6% ± 24.1% vs 31.8% ± 51.9%; p < 0.001). The mean preradiosurgical maximum ADC (ADCmax) values of all VSs were significantly higher for those with tumor regression or stabilization at last follow-up compared with those with progression (2.391 vs 1.826 × 10-3 mm2/sec; p = 0.010).

CONCLUSIONS Loss of central enhancement after radiosurgery was a common phenomenon, but it did not correlate with tumor volume outcome. Preradiosurgical MRI features including cystic components and ADCmax values can be helpful as predictors of treatment outcome.

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Intrawound Vancomycin Decreases the Risk of Surgical Site Infection After Posterior Spine Surgery: A Multicenter Analysis

Spine 2018;43:65–71

Study Design. Secondary analysis of data from a prospective multicenter observational study.

Objective. The aim of this study was to evaluate the occurrence of surgical site infection (SSI) in patients with and without intrawound vancomycin application controlling for confounding factors associated with higher SSI after elective spine surgery.

Summary of Background Data. SSI is a morbid and expensive complication associated with spine surgery. The application of intrawound vancomycin is rapidly emerging as a solution to reduce SSI following spine surgery. The impact of intrawound vancomycin has not been systematically studied in a welldesigned multicenter study.

Methods. Patients undergoing elective spine surgery over a period of 4 years at seven spine surgery centers across the United States were included in the study. Patients were dichotomized on the basis of whether intrawound vancomycin was applied. Outcomes were occurrence of SSI within postoperative 30 days and SSI that required return to the operating room (OR). Multivariable random-effect log-binomial regression analyses were conducted to determine the relative risk of having an SSI and an SSI with return to OR.

Results. A total of 2056 patients were included in the analysis. Intrawound vancomycin was utilized in 47% (n=966) of patients. The prevalence of SSI was higher in patients with no vancomycin use (5.1%) than those with use of intrawound vancomycin (2.2%). The risk of SSI was higher in patients in whom intrawound vancomycin was not used (relative risk (RR) – 2.5, P<0.001), increased number of levels exposed (RR -1.1, P=0.01), and those admitted postoperatively to intensive care unit (ICU) (RR -2.1, P=0.005). Patients in whom intrawound vancomycin was not used (RR -5.9, P<0.001), increased number of levels were exposed (RR-1.1, P=0.001), and postoperative ICU admission (RR -3.3, P<0.001) were significant risk factors for SSI requiring a return to the OR.

Conclusion. The intrawound application of vancomycin after posterior approach spine surgery was associated with a reduced risk of SSI and return to OR associated with SSI.

Level of Evidence: 2

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Relative lumbar lordosis and lordosis distribution index

Neurosurg Focus 43 (6):E5, 2017

The subtraction of lumbar lordosis (LL) from the pelvic incidence (PI) offers an estimate of the LL required for a given PI value. Relative LL (RLL) and the lordosis distribution index (LDI) are PI-based individualized measures. RLL quantifies the magnitude of lordosis relative to the ideal lordosis as defined by the magnitude of PI. LDI defines the magnitude of lower arc lordosis in proportion to total lordosis. The aim of this study was to compare RLL and PI – LL for their ability to predict postoperative complications and their correlations with health-related quality of life (HRQOL) scores.
METHODS Inclusion criteria were ≥ 4 levels of fusion and ≥ 2 years of follow-up. Mechanical complications were proximal junctional kyphosis/proximal junctional failure, distal junctional kyphosis/distal junctional failure, rod breakage, and implant-related complications. Correlations between PI – LL, RLL, PI, and HRQOL were analyzed using the Pearson correlation coefficient. Mechanical complication rates in PI – LL, RLL, LDI, RLL, and LDI interpreted together, and RLL subgroups for each PI – LL category were compared using chi-square tests and the exact test. Predictive models for mechanical complications with RLL and PI – LL were analyzed using binomial logistic regressions.
RESULTS Two hundred twenty-two patients (168 women, 54 men) were included. The mean age was 52.2 ± 19.3 years (range 18–84 years). The mean follow-up was 28.8 ± 8.2 months (range 24–62 months). There was a significant correlation between PI – LL and PI (r = 0.441, p < 0.001), threatening the use of PI – LL to quantify spinopelvic mismatch for different PI values. RLL was not correlated with PI (r = -0.093, p > 0.05); therefore, it was able to quantify divergence from ideal lordosis for all PI values. Compared with PI – LL, RLL had stronger correlations with HRQOL scores (p < 0.05). Discrimination performance was better for the model with RLL than for PI – LL. The agreement between RLL and PI – LL was high (k = 0.943, p < 0.001), moderate (k = 0.455, p < 0.001), and poor (k = -0.154, p = 0.343), respectively, for large, average, and small PI sizes. When analyzed by RLL, each PI – LL category was further divided into distinct groups of patients who had different mechanical complication rates (p < 0.001).
CONCLUSIONS Using the formula of PI – LL may be insufficient to quantify normolordosis for the whole spectrum of PI values when applied as an absolute numeric value in conjunction with previously reported population-based average thresholds of 10° and 20°. Schwab PI – LL groups were found to constitute an inhomogeneous group of patients. RLL offers an individualized quantification of LL for all PI sizes. Compared with PI – LL, RLL showed a greater association with both mechanical complications and HRQOL. The use of RLL and LDI together, instead of PI – LL, for surgical planning may result in lower mechanical complication rates and better long-term HRQOL.

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Differentiating brain radionecrosis from tumour recurrence: a role for contrast-enhanced ultrasound?

Acta Neurochir (2017) 159:2405–2408

Differentiating radionecrosis from tumour recurrence is a major issue in neuro-oncology. Conventional imaging is far from being validated as an alternative to histologicalassessment.

We report the case of a patient operated on for suspected recurrence of brain metastasis 9 months after cyberknife radiosurgery. While magnetic resonance imaging showed strong enhancement of the lesion, intraoperative contrast-enhanced ultrasonography (CEUS) surprisingly did
not—different from what is expected for brain metastases.

Histopathological examination documented radionecrosis. For the first time, we describe radionecrosis with CEUS; further investigation is needed; however, the lack of enhancement could represent an important hallmark in differential diagnosis with neoplastic tissue.

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What Is the Fate of Pseudarthrosis Detected 1 Year After Anterior Cervical Discectomy and Fusion?

Spine 2018;43:E23–E28

Objective. To investigate the consequences and appropriate management of pseudarthrosis after anterior cervical discectomy and fusion (ACDF).

Summary of Background Data. Pseudarthrosis is a frequent complication of ACDF and causes unsatisfactory results. Little is known about long-term prognosis of detecting pseudarthrosis 1 year after ACDF.

Methods. Eighty-nine patients with a minimum 2-year followup were included. ACDF surgery using allograft and plating was performed: single-level in 51 patients, two-level in 26 patients, and three-level in 12 patients. Presence of pseudarthrosis was evaluated 1 year postoperatively and then the nonunion segments were re-evaluated 2 years postoperatively. Demographic data were assessed to identify the risk factors associated with pseudarthrosis. A visual analogue scale for neck/arm pain and the Neck Disability Index were analyzed preoperatively and at 1 and 2 years postoperatively.

Results. Pseudarthrosis was detected in 29 patients (32.6%) 1 year postoperatively: 15of 51 patients after single-level surgery, 9 of 26 patients after two-level surgery, and 5 of 12 patients after three-level surgery. Only eight patients showed persistent nonunion at 2 years: 3 of 15 patients after single-level surgery, 3 of 9 after two-level surgery, and 2 of 5 after three-level surgery. The remaining 21 patients (72.4%) achieved bony fusion 2 years postoperatively without any intervention. Patients who underwent two-level or three-level ACDF had a significantly higher pseudarthrosis rate than those who underwent single-level ACDF, with odds ratios of 1.844 and 3.147, respectively. The improvements in visual analogue scale for neck pain and Neck Disability Index scores in the persistent nonunion group were significantly lower than those in the final union group at 2 years.

Conclusion. Patients with pseudarthrosis detected 1 year postoperatively may be observed without any intervention because approximately 70% of them will eventually fuse by the 2-year point. Early revision could, however, be considered if the pseudarthrosis is associated with considerable neck pain after multilevel ACDF.

Level of Evidence: 3

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Comparison of endovascular and microsurgical management of 208 basilar apex aneurysms

J Neurosurg 127:1342–1352, 2017

The deep and difficult-to-reach location of basilar apex aneurysms, along with their location near critical adjacent perforating arteries, has rendered the perception that microsurgical treatment of these aneurysms is risky. As a result, these aneurysms are considered more suitable for treatment by endovascular intervention. The authors attempt to compare the immediate and long-term outcomes of microsurgery versus endovascular therapy for this aneurysm subtype.

METHODS A prospectively maintained database of 208 consecutive patients treated for basilar apex aneurysms between 2000 and 2012 was reviewed. In this group, 161 patients underwent endovascular treatment and 47 were managed microsurgically. The corresponding records were analyzed for presenting characteristics, postoperative complications, discharge status, and Glasgow Outcome Scale (GOS) scores up to 1 year after treatment and compared using chi-square and Student t-tests.

RESULTS Among these 208 aneurysms, 116 (56%) were ruptured, including 92 (57%) and 24 (51%) of the endovascularly and microsurgically managed aneurysms, respectively. The average Hunt and Hess grade was 2.4 (2.4 in the endovascular group and 2.2 in the microsurgical group; p = 0.472). Postoperative complications of cranial nerve deficits and hemiparesis were more common in patients treated microsurgically than endovascularly (55.3% vs 16.2%, p < 0.05; and 27.7% vs 10.6%, p < 0.05, respectively). However, aneurysm remnants and need for retreatment were more common in the endovascular than the microsurgical group (41.3% vs 2.3%, p < 0.05; and 10.6% vs 0.0%, p < 0.05, respectively). Stent placement significantly reduced the need for retreatment. Rehemorrhage rates and average GOS score at discharge and 1 year after treatment were not statistically different between the two treatment groups.

CONCLUSIONS Patients with basilar apex aneurysms were significantly more likely to be treated via endovascular management, but compared with those treated microsurgically, they had higher rates of recurrence and need for retreatment. The current study did not detect an overall difference in outcomes at discharge and 1 year after either treatment modality. Therefore, in a select group of patients, microsurgical treatment continues to play an important role.

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Minimally Invasive Transforaminal Lumbar Interbody Fusion: Meta-analysis of the Fusion Rates. What is the Optimal Graft Material?

Neurosurgery 81:958–971, 2017

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is an increasingly popular procedure with several potential advantages over traditional open TLIF.

OBJECTIVE: The current study aimed to compare fusion rates of different graft materials used in MIS-TLIF, via meta-analysis of the published literature.

METHODS: A Medline search was performed and a database was created including patient’s type of graft, clinical outcome, fusion rate, fusion assessment modality, and duration of follow-up. Meta-analysis of the fusion rate was performed using StatsDirect software (StatsDirect Ltd, Cheshire, United Kingdom).

RESULTS: A total of 1533 patients from 40 series were included. Fusion rates were high, ranging from 91.8% to 99%. The imaging modalities used to assess fusion were computed tomography scans (30%) and X-rays (70%). Comparison of all recombinant human bone morphogenetic protein (rhBMP) series with all non-rhBMP series showed fusion rates of 96.6% and 92.5%, respectively. The lowest fusion rate was seen with isolated use of autologous local bone (91.8%). The highest fusion ratewas observed with combination of autologous local bone with bone extender and rhBMP (99.1%). The highest fusion rate without the use ofBMPwas seen with autologous local bone+bone extender (93.1%). The reported complication rate ranged from 0% to 35.71%. Clinical improvement was observed in all studies.

CONCLUSION: Fusion rates are generally high with MIS-TLIF regardless of the graft material used. Given the potential complications of iliac bone harvesting and rhBMP, use of other bone graft options for MIS-TLIF is reasonable. The highest fusion rate without the use of rhBMP was seen with autologous local bone plus bone extender (93.1%).

 

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Clinical features and surgical outcomes of patients with skull base chordoma

J Neurosurg 127:1257–1267, 2017

Skull base chordoma is relatively rare, and a limited number of reports have been published regarding its clinical features. Moreover, the factors associated with extent of resection, as well as the value of marginal resection for long-term survival, are still in question for this disease. The objective of this study was to investigate these factors by evaluating their clinical features and surgical outcomes.

METHODS A retrospective analysis of 238 patients with skull base chordomas, who met the inclusion criteria, was performed. This study summarized the clinical features, selection of approaches, degree of resection, and postoperative complications by statistical description analyses; proposed modified classifications of tumor location and bone invasion; studied the contributions of the clinical and radiological factors to the extent of resection by Pearson c2, ANOVA, rank test, and binary logistic regression analysis; and estimated the differences in overall survival and progression-free survival rates with respect to therapeutic history, classification of tumor location, extent of bone invasion, and extent of tumor resection by the Kaplan-Meier method. A p value < 0.05 was considered statistically significant.

RESULTS The study included 140 male and 98 female patients with a mean age of 38.1 years. Headache and neck pain (33.2%) and diplopia (29%) were the most common initial symptoms. Sphenoclival type accounted for the largest proportion of tumor location (59.2%); endophytic chordoma was the more common type of bone invasion (81.5%). Lateral open approaches were performed in two-thirds of the study population (78.6%). The rate of marginal resection was 66%, composed of gross-total resection (11.8%) and near-total resection (54.2%). Meningitis (8%) and CSF leakage (3.8%) were the most frequent complications. The mean follow-up period was 43.7 months. The overall survival and progression-free survival rates at 5 years were 76% and 45%, respectively. Recurrent tumor and larger tumor volume (≥ 40 cm3) were identified as risk factors of marginal resection. Patients who presented with recurrent tumor and underwent intralesional resection had a worse long-term outcome.

CONCLUSIONS The classifications of both tumor location and bone invasion demonstrated clinical value. Marginal resection was more likely to be achieved for primary lesions with smaller volumes (< 40 cm3). The rate of CSF leakage declined due to improved dura mater repair with free fat grafts. Marginal resection, or gross-total resection when possible, should be performed in patients with primary chordomas to achieve better long-term survival.

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Surgical Treatment of Mesiotemporal Lobe Epilepsy: Which Approach is Favorable?

Neurosurgery 81:992–1004, 2017

Mesiotemporal lobe epilepsy is one of the most frequent causes for pharmacoresistant epilepsy. Different surgical approaches to the mesiotemporal area are used.

OBJECTIVE: To analyze epileptological and neuropsychological results as well as complications of different surgical strategies.

METHODS: This retrospective study is based on a consecutive series of 458 patients all harboring pharmacoresistant mesiotemporal lobe epilepsy. Following procedures were performed: standard anterior temporal lobectomy, anterior temporal or key-hole resection, extended lesionectomy, and transsylvian and subtemporal selective amygdalohippocampectomy. Postoperative outcome was evaluated according to different surgical procedures.

RESULTS: Overall, 1 yr after surgery 315 of 432 patients (72.9%) were classified Engel I; in particular, 72.8% were seizure-free after anterior temporal lobectomy, 76.9% after key-hole resection, 84.4% after extended lesionectomy, 70.3% after transylvian selective amygdalohippocampectomy, and 59.1% after subtemporal selective amygdalohippocampectomy. No significant differences in seizure outcome were found between different resective procedures, neither in short-term nor long-term follow-up. There was no perioperative mortality. Permanent morbidity was encountered in 4.4%. There were no significant differences in complications between different resection types. In the majority of patients, selective attention improved following surgery. Patients after left-sided operations performed significantly worse regarding verbal memory as compared to right-sided procedures. However, surgical approach had no significant effect on memory outcome.

CONCLUSION: Different surgical approaches for mesiotemporal epilepsy analyzed resulted in similar epileptological, neuropsychological results, and complication rates. Therefore, the approach for the individual patient does not only depend on the specific localization of the epileptogenic area, but also on the experience of the surgeon.

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Stereotactic Radiosurgery for Brainstem Arteriovenous Malformations

Neurosurgery 81:910–920, 2017

The management of brainstem arteriovenous malformations (bAVMs) is a formidable challenge. bAVMs harbor higher morbidity and mortality compared to other locations.

OBJECTIVE: To review the outcomes following stereotactic radiosurgery (SRS) of bAVMs in a multicenter study.

METHODS: Six medical centers contributed data from 205 patients through the International Gamma Knife Research Foundation. Median age was 32 yr (6-81). Median nidus volume was 1.4 mL (0.1-69 mL). Favorable outcome (FO) was defined as AVM obliteration and no post-treatment hemorrhage or permanent symptomatic radiation-induced complications.

RESULTS: Overall obliteration was reported in 65.4% (n = 134) at a mean follow-up of 69 mo. Obliteration was angiographically proven in 53.2% (n = 109) and on MRA in 12.2% (n=25). Actuarial rate of obliteration at 2, 3, 5, 7, and 10 yr after SRS was 24.5%, 43.3%, 62.3%, 73%, and 81.8% respectively. Patients treated with a margin dose >20 Gy were more likely to achieve obliteration (P = .001). Obliteration occurred earlier in patients who received a higher prescribed margin dose (P = .05) and maximum dose (P = .041). Post-SRS hemorrhage occurred in 8.8% (n = 18). Annual post gamma knife latency period hemorrhage was 1.5%. Radiation-induced complications were radiologically evident in 35.6% (n = 73), symptomatic in 14.6% (n=30), and permanent in 14.6% (n=30, which included long-tract signs and new cranial nerve deficits). FO was achieved in 64.4% (n = 132). Predictors of an FO were a higher Virginia radiosurgery AVM scale score (P = .003), prior hemorrhage (P = .045), and a lower prescribed maximum dose (P = .006).

CONCLUSION: SRS for bAVMs results in obliteration and avoids permanent complications in the majority of patients.

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Spine Navigation Based on 3-Dimensional Robotic Fluoroscopy for Accurate Percutaneous Pedicle Screw Placement

World Neurosurg. (2017) 108:76-83.

Minimally invasive spine surgery is associated with obstructed visibility of anatomic landmarks and increased radiation exposure, leading to higher incidence of pedicle screw mispositioning. To address these drawbacks, intraoperative 3-dimensional fluoroscopy (io3DF) and navigation are being increasingly used. We aimed to present our dedicated multifunctional hybrid operating room (HyOR) setup and evaluate the accuracy and safety of io3DF image-guided spinal navigation in transforaminal lumbar interbody fusion with percutaneous pedicle screw (PPS) placement.

METHODS: The HyOR includes a fixed 3D multiaxis robotic fluoroscopy arm that moves automatically to the preprogrammed position when needed. An initial io3DF assessment is performed to collect intraoperative images, which are automatically transferred into the navigation system. These data are used to calibrate the PPSs and insert them under computer-assisted navigation. A second io3DF is performed for verifying PPS position.

RESULTS: Between January 2014 and December 2016, 66 consecutive patients (age, 58.6  14.1 years) were treated for refractory lumbar degenerative pain. Seventy-three spinal levels were treated, and 276 screws were placed, with 4.2 ± 0.76 screws per patient. There was no measurable radiation to the HyOR staff, whereas the mean radiation dose per patient was 378.3  uGym2. The overall accuracy rate of PPS placement was 99.6%. There were no significant procedure-related complications.

CONCLUSIONS: Spine navigation based on io3DF images enabled us to avoid radiation exposure to the operating room team while delivering minimal but sufficient radiation doses to our patients. This approach achieved an accuracy rate of 99.6% for PPS placement in the safe zone, without significant complications.

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Anatomic Features of Paraclinoid Aneurysms

Neurosurgery 81:949–957, 2017

Paraclinoid aneurysms are among the most challenging aneurysms to treat. Computed tomography (CT) angiography helps in evaluating the radiological characteristics of these aneurysms next to bony structures.

OBJECTIVE: To present the CT angiography characteristics of paraclinoid aneurysms in order to better understand such pathology.

METHODS: The study examined CT angiography-based anatomical characteristics obtained retrospectively from 136 patients with 144 paraclinoid aneurysms selected from single-defined catchment populations in Finland. We examined the diameters of the parent artery (internal carotid artery), the location of the aneurysm, its dimensions (width, height, neck), and aneurysm wall irregularity.

RESULTS:We analyzed 144 paraclinoid aneurysms in 136 patients admitted to the hospital during 2000-2014.Multivariable analysis reveals that rupture aneurysms have the following radiological features: aneurysm larger than 5 mm in diameter (P = .006), irregular wall (P = .046), superior location, larger aspect ratio (P = .039), and neck wider than parent artery (P < .001).

CONCLUSION: Smaller diameter of the internal carotid artery and superior location, as well as a large and irregular aneurysm wall, are radiological characteristics of ruptured paraclinoid aneurysms, which CT angiography can measure easily.

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Cervical Spine Deformity—Part 3: Posterior Techniques, Clinical Outcome, and Complications

Neurosurgery 81:893–898, 2017

The goals of cervical deformity surgery include deformity correction, restoration of horizontal gaze, decompression of neural elements, spinal stabilization with a biomechanically sound construct, and meticulous arthrodesis technique to prevent pseudoarthrosis and minimizing surgical complications.

Many different surgical options exist, but selecting the correct approach that ensures the optimal clinical outcome can be challenging and often controversial. In this last part of the cervical deformity review series, various posterior deformity correction techniques are discussed in detail, along with an overview of surgical outcome and postoperative complications.

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Efficacy and outcomes of facial nerve–sparing treatment approach to cerebellopontine angle meningiomas

J Neurosurg 127:1231–1241, 2017

Advanced microsurgical techniques contribute to reduced morbidity and improved surgical management of meningiomas arising within the cerebellopontine angle (CPA). However, the goal of surgery has evolved to preserve the quality of the patient’s life, even if it means leaving residual tumor. Concurrently, Gamma Knife radiosurgery (GKRS) has become an acceptable and effective treatment modality for newly diagnosed, recurrent, or progressive meningiomas of the CPA. The authors review their institutional experience with CPA meningiomas treated with GKRS, surgery, or a combination of surgery and GKRS. They specifically focus on rates of facial nerve preservation and characterize specific anatomical features of tumor location with respect to the internal auditory canal (IAC).

METHODS Medical records of 76 patients with radiographic evidence or a postoperative diagnosis of CPA meningioma, treated by a single surgeon between 1992 and 2016, were retrospectively reviewed. Patients with CPA meningiomas smaller than 2.5 cm in greatest dimension were treated with GKRS, while patients with tumors 2.5 cm or larger underwent facial nerve–sparing microsurgical resection where appropriate. Various patient, clinical, and tumor data were gathered. Anatomical features of the tumor origin as seen on preoperative imaging confirmed by intraoperative investigation were evaluated for prognostic significance. Facial nerve preservation rates were evaluated.

RESULTS According to our treatment paradigm, 51 (67.1%) patients underwent microsurgical resection and 25 (32.9%) patients underwent GKRS. Gross-total resection (GTR) was achieved in 34 (66.7%) patients, and subtotal resection (STR) in 17 (33.3%) patients. Tumors recurred in 12 (23.5%) patients initially treated surgically, requiring additional surgery and/or GKRS. Facial nerve function was unchanged or improved in 68 (89.5%) patients. Worsening facial nerve function occurred in 8 (10.5%) patients, all of whom had undergone microsurgical resection. Upfront treatment with GKRS for CPA meningiomas smaller than 2.5 cm was associated with preservation of facial nerve function in all patients over a median follow-up of 46 months, regardless of IAC invasion and tumor origin. Anatomical origin was associated with extent of resection but did not correlate with postoperative facial nerve function. Tumor size, extent of resection, and the presence of an arachnoid plane separating the tumor and the contents of the IAC were associated with postoperative facial nerve outcomes.

CONCLUSIONS CPA meningiomas remain challenging lesions to treat, given their proximity to critical neurovascular structures. GKRS is a safe and effective option for managing CPA meningiomas smaller than 2.5 cm without associated mass effect or acute neurological symptoms. Maximal safe resection with preservation of neurological function can be performed for tumors 2.5 cm or larger without significant risk of facial nerve dysfunction, and, when combined with GKRS for recurrence and/or progression, provides excellent disease control. Anatomical features of the tumor origin offer critical insights for optimizing facial nerve preservation in this cohort.

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Endoscopic treatment of middle fossa arachnoid cysts

Acta Neurochir (2017) 159:2313–2317

Endoscopic treatment of middle fossa arachnoid cysts is an alternative option to microsurgical fenestration and shunting procedures. The procedure is minimally invasive and obviates the morbidity of craniotomy and shunting.

Methods Operative charts and videos of patients undergoing endoscopic fenestration of middle fossa arachnoid cysts were retrieved from the senior author’s database of endoscopic procedures and reviewed. Description of the surgical techniques was then formulated.

Conclusions Endoscopic fenestration of middle fossa arachnoid cysts entails communicating the cyst cavity to the basal cisterns via multiple fenestrations that should be made as large as possible with care to avoid injury of the juxtaposed neurovascular structures.

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Outcomes After Endoscopic Endonasal Resection of Craniopharyngiomas in the Pediatric Population

World Neurosurg. (2017) 108:6-14.

Craniopharyngiomas have traditionally been treated via open transcranial approaches. More recently, endoscopic transsphenoidal approaches have been increasingly used; however, few case series exist in the pediatric population.

METHODS: A retrospective review of patients (aged <18 years) undergoing endoscopic transsphenoidal resection of craniopharyngiomas between 1995 and 2016 was performed. Preoperative data included presenting symptoms, tumor size, location, and components. Postoperative outcomes included symptom resolution, visual outcomes, endocrine outcomes, disease recurrence, and major complications.

RESULTS: Sixteen pediatric patients with mean age of 11.0 years (range, 5-15 years) were included. The median follow-up time was 56.2 months. Mean maximal tumor diameter was 3.98 cm. Most of the tumors had suprasellar (93.8%) and intrasellar (68.8%) components. The gross total resection rate was 93.8%. The most common presenting symptoms were vision changes (81.3%) and increased intracranial pressure (56.3%). Most patients (66.7%) had their presenting symptoms resolved by their first postoperative visit. Vision improved or remained normal in 69.2% of patients. Postoperatively, new incidence of panhypopituitarism or diabetes insipidus developed in 63.6% and 46.7% of patients, respectively. New hypothalamic obesity developed in 28.6% of patients. The postoperative cerebrospinal fluid leak rate was 18.8%. One patient died of intraventricular hemorrhage postoperatively. The major complication rate was 12.5%. Disease recurrence occurred in 1 patient with gross total resection (6.3%).

CONCLUSIONS: Endoscopic transsphenoidal resection for craniopharyngiomas can achieve high rates of total resection with low rates of disease recurrence in larger tumors than previously described. However, hypothalamic-pituitary dysfunction and cerebrospinal fluid leak remain significant postoperative morbidities

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