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Aspirin is associated with an increased risk of subdural hematoma in normal-pressure hydrocephalus patients following shunt implantation

Subdural Hematoma

J Neurosurg 123:423–426, 2015

In this paper the authors investigate whether shunt-treated patients with normal-pressure hydrocephalus receiving aspirin therapy are at increased risk of developing subdural hematoma (SDH).

Methods Records from 80 consecutive patients who had undergone implantation of a cerebrospinal fluid shunt for the treatment of normal-pressure hydrocephalus were retrospectively reviewed.

Results Eleven cases of symptomatic SDH occurred, all among patients receiving aspirin or clopidogrel. The 5-year survival estimate was 0.3 (p < 0.0001) for users of aspirin and the hazard ratio was 12.8 (95% CI 3.1–53).

Conclusions Patients on an aspirin therapy regimen have a markedly increased risk of SDH after a shunt has been implanted for the treatment of normal-pressure hydrocephalus. Users of clopidogrel may have an even greater risk.

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Pericallosal aneurysm: A difficult challenge for microsurgery and endovascular treatment

PAA

Neurochirurgie 61 (2015) 244–249

Pericallosal artery aneurysms (PAA) represent 2 to 9% of intracranial aneurysms and their management remains difficult.

Objective. We aimed to report our experience to evaluate the outcome of patients with ruptured and unruptured PAA, when the treatment modality is decided in a multidisciplinary fashion.

Materials and methods. In this retrospective study, we included 28 patients (8 men and 20 women) treated for a PAA in our institution between 2002 and 2012, among the 2430 patients who underwent the treatment of an intracranial aneurysm in the same period. Fifteen patients harbored a ruptured aneurysm while 13 benefited from a prophylactic treatment. The mean age at diagnosis was 52 years (range 37 to 75 SD: ±5) in patients with ruptured aneurysm and 54.2 years (range 35 to 66 SD: ±5) in patients with unruptured aneurysm. Endovascular treatment has been performed in 9 patients while 19 patients underwent a microsurgical treatment. Clinical outcome has been assessed using the modified Rankin scale (mRS) at 3 months. Long-term imaging follow-up included a CT angiography at 36 months for clipped aneurysms and MR angiography at 6, 18 and 36 months for coiled aneurysms.

Results. The median follow-up was 3.4 years (range 2.8 to 4.2). The mRS was ≤ 2 in all patients with unruptured aneurysms. In patients with ruptured aneurysm, the mRS was ≤ 2 at 3 months in 13 patients (87%). Persistent cognitive disorders were noted in 8 patients with ruptured aneurysm, 2 of them were considered as possibly related to the treatment. Aneurysm recurrence has been depicted in 4 patients (at 6 months in 3 patients and 1 year in 1 patient) requiring further treatment in all cases; all of them had an aneurysm remnant on immediate conventional angiography. No recurrence was noted in patients without remnant on immediate post-treatment angiography.

Conclusion. Both endovascular and microsurgical treatment are challenged in this location. Multidisciplinary discussion is essential to optimize the management of patients with PAA

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Comparative effectiveness and safety of image guidance systems in neurosurgery

AR

J Neurosurg 123:307–313, 2015

Over the last decade, image guidance systems have been widely adopted in neurosurgery. Nonetheless, the evidence supporting the use of these systems in surgery remains limited. The aim of this study was to compare simultaneously the effectiveness and safety of various image guidance systems against that of standard surgery.

Methods In this preclinical, randomized study, 50 novice surgeons were allocated to one of the following groups: 1) no image guidance, 2) triplanar display, 3) always-on solid overlay, 4) always-on wire mesh overlay, and 5) on-demand inverse realism overlay. Each participant was asked to identify a basilar tip aneurysm in a validated model head. The primary outcomes were time to task completion (in seconds) and tool path length (in mm). The secondary outcomes were recognition of an unexpected finding (i.e., a surgical clip) and subjective depth perception using a Likert scale.

Results The time to task completion and tool path length were significantly lower when using any form of image guidance compared with no image guidance (p < 0.001 and p = 0.003, respectively). The tool path distance was also lower in groups using augmented reality compared with triplanar display (p = 0.010). Always-on solid overlay resulted in the greatest inattentional blindness (20% recognition of unexpected finding). Wire mesh and on-demand overlays mitigated, but did not negate, inattentional blindness and were comparable to triplanar display (40% recognition of unexpected finding in all groups). Wire mesh and inverse realism overlays also resulted in better subjective depth perception than always-on solid overlay (p = 0.031 and p = 0.008, respectively).

Conclusions New augmented reality platforms may improve performance in less-experienced surgeons. However, all image display modalities, including existing triplanar displays, carry a risk of inattentional blindness.

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Validation of a System to Predict Recanalization After Endovascular Treatment of Intracranial Aneurysms

Recanalization-for-Patients-With-Endovascular-Treatment-of-Intracranial-Aneurysms-e1429712894823

Neurosurgery 77:168–174, 2015

With increasing use of endovascular techniques in the treatment of ruptured and unruptured aneurysms, the issue of obliteration efficacy has become increasingly important. We have previously reported the Aneurysm Recanalization Stratification Scale, which uses accessible predictors including aneurysm-specific factors (size, rupture, and intraluminal thrombosis) and treatment-related features (treatment modality and immediate angiographic result) to predict retreatment risk after endovascular therapy.

OBJECTIVE: To assess the external validity of the Aneurysm Recanalization Stratification Scale.

METHODS: External validity was assessed in independent cohorts from 4 centers in the United States and Canada where endovascular and open neurovascular procedures are performed, and in a multicenter cohort of 1543 patients. Probability of retreatment stratified by risk score was derived for each center and the combined multicenter cohort.

RESULTS: Despite moderate variability in retreatment rate among centers (29.5%, 9.9%, 9.6%, 26.3%, 19.7%, and 18.3%), the Aneurysm Recanalization Stratification Scale demonstrated good predictive value with C-statistics of 0.799, 0.943, 0.780, 0.695, 0.755, and 0.719 for each center and the combined cohort, respectively. Probability of retreatment stratified by risk score for the combined cohort is as follows: -2, 4.9%; -1, 5.7%; 0, 5.8%; 1, 13.1%; 2, 19.2%; 3, 34.9%; 4, 32.7%; 5, 73.2%; 6, 89.5%; and 7, 100.0%.

CONCLUSION: Surgical decision-making and patient-centered informed consent require comprehensive and accessible information on treatment efficacy. The Aneurysm Recanalization Stratification Scale is a valid prognostic index. This is the first comprehensive model that has been developed to quantitatively predict retreatment risk following endovascular therapy.

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The Mechanism of Ligamentum Flavum Hypertrophy

Ligamentum Flavum Hypertrophy

Neurosurgery 77:274–282, 2015

Biochemical alterations associated with mechanical stress have been explored as an initiating step in the pathological progression of ligamentum flavum hypertrophy (LFH); however, this mechanism remains poorly understood. Recently, the inflammation induced after mechanical stress and the subsequent response of ligamentum flavum (LF) cells have been implicated in LFH pathology.

OBJECTIVE: To investigate the hypothesis that angiogenesis may be a critical link between hypertrophy and a series of stimulating events, including mechanical stress.

METHODS: LF from 20 lumbar spinal canal stenosis (LSCS) patients and 16 non-LSCS patients (control group) were collected during surgery. Patient demographic and radiographic data were obtained. The levels of angiogenic factors (vascular endothelial growth factor [VEGF], angiopoietin-1, vascular cell adhesion molecule, and basic fibroblast growth factor) in the LF were investigated by using an enzyme-linked immunosorbent assay. Angiogenesis was also quantified by immunohistochemical detection of CD34-positive capillaries. The correlations among clinical factors, including radiographic factors, angiogenic factors, and angiogenesis, were statistically analyzed.

RESULTS: The LSCS group was older and exhibited a longer symptom duration, wider segmental motion, and thicker LF than the control group. The LSCS group showed significantly higher tissue concentrations of VEGF (P , .001) that positively correlated with LF thickness (r = 0.557, P , .001) and segmental motion (r = 0.586, P , .001). The LSCS group showed significantly more CD34-positive capillaries than the control group (P = .004).

CONCLUSION: The LSCS group showed greater segmental motion, higher VEGF concentrations, and more CD34-positive capillaries than the control group. These data indicate that VEGF-mediated angiogenesis following mechanical stress may be a critical step within the series of pathological events in LFH.

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Outcomes in Reoperated Low-Grade Gliomas

OUTCOMES IN REOPERATED LOW-GRADE GLIOMAS

Neurosurgery 77:175–184, 2015

Low-grade gliomas (LGGs) comprise a diverse set of intrinsic brain tumors that correlate strongly with survival. Data on the effect of reoperation are sparse.

OBJECTIVE: To evaluate the effect of reoperation on patients with LGG.

METHODS: Fifty-two consecutive patients with reoperated LGGs treated at the University of Washington between 1986 and 2004 were identified and evaluated in a retrospective analysis.

RESULTS: The average overall survival (OS) for this cohort was 12.95 ± 0.96 years. The overall 10-year survival rate was 57%. The absence of any residual tumor at either the first or second operation was associated with significantly increased OS. Negative prognostic variables for OS included the use of upfront radiation and pathology at recurrence. The average overall progression-free survival to the first recurrence (PFS1) was 6.23 ± 0.51 years. Positive prognostic factors for improved PFS1 included the use of upfront radiation therapy. Variables not associated with differences in PFS1 included the use of upfront chemotherapy, enhancement, pathology, extent of resection, the presence of residual tumor, and Karnofsky Performance Scale score <80. The average overall progression-free survival to the second recurrence was 2.73 ± 0.39 years. Pathology at recurrence was associated with significant differences in progression-free survival to the second recurrence, as was extent of resection at time of first recurrence, and Karnofsky Performance Scale score <80.

CONCLUSION: This is among the largest studies to assess variables associated with outcome in patients with reoperated LGG. Reresection appears to provide significant benefit, and extent of resection remains the strongest predictor of OS.

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Posterior thoracic corpectomy with cage reconstruction for metastatic spinal tumors

mini-open and open transpedicular corpectomy

J Neurosurg Spine 23:217–227, 2015

Spinal metastases most commonly affect the vertebral bodies of the spinal column, and spinal cord compression is an indication for surgery. Commonly, an open posterior approach is employed to perform a transpedicular costotransversectomy or lateral extracavitary corpectomy. Because of the short life expectancies in patients with metastatic spinal disease, decreasing the morbidity of surgical treatment and recovery time is critical. One potential approach to decreasing morbidity is utilizing minimally invasive surgery (MIS). Although significant advances have been made in MIS of the spine, data supporting the utility of MIS are still emerging. This study compared outcomes of patients who underwent mini-open versus traditional open transpedicular corpectomy for spinal metastases in the thoracic spine.

Methods A consecutive cohort from 2006 to 2013 of 49 adult patients who underwent thoracic transpedicular corpectomies for spinal metastases was retrospectively identified. Patients were categorized into one of 2 groups: open surgery and mini-open surgery. Mini-open transpedicular corpectomy was performed with a midline fascial incision over only the corpectomy level of interest and percutaneous instrumentation above and below that level. The open procedure consisted of a traditional posterior transpedicular corpectomy. Chi-square test, 2-tailed t-test, and ANOVA models were employed to compare perioperative and follow-up outcomes between the 2 groups.

Results In the analysis, there were 21 patients who had mini-open surgery and 28 patients who had open surgery. The mean age was 57.9 years, and 59.2% were male. The tumor types encountered were lung (18.3%), renal/bladder (16.3%), breast (14.3%), hematological (14.3%), gastrointestinal tract (10.2%), prostate (8.2%), melanoma (4.1%), and other/unknown (14.3%). There were no significant intergroup differences in demographics, comorbidities, neurological status (American Spinal Injury Association [ASIA] grade), number of corpectomies performed, and number of levels instrumented. The open group had a mean operative time of 413.6 minutes, and the mini-open group had a mean operative time of 452.4 minutes (p = 0.329). Compared with the open group, the mini-open group had significantly less blood loss (917.7 ml vs 1697.3 ml, p = 0.019) and a significantly shorter hospital stay (7.4 days vs 11.4 days, p = 0.001). There was a trend toward a lower perioperative complication rate in the mini-open group (9.5%) compared with the open group (21.4%), but this was not statistically significant (p = 0.265). At follow-up, there were no significant differences in ASIA grade (p = 0.342), complication rate after the 30-day postoperative period (p = 0.999), or need for surgical revision (p = 0.803). The open approach had a higher overall infection rate of 17.9% compared with that in the mini-open approach of 9.5%, but this was not statistically significant (p = 0.409).

Conclusions The mini-open transpedicular corpectomy is associated with less blood loss and shorter hospital stay compared with open transpedicular corpectomy. The mini-open corpectomy also trended toward lower infection and complication rates, but these did not reach statistical significance.

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Continuous subcortical motor evoked potential stimulation using the tip of an ultrasonic aspirator for the resection of motor eloquent lesions

Continuous subcortical motor evoked potential stimulation

J Neurosurg 123:301–306, 2015

Resection of a motor eloquent lesion has become safer because of intraoperative neurophysiological monitoring (IOM). Stimulation of subcortical motor evoked potentials (scMEPs) is increasingly used to optimize patient safety. So far, scMEP stimulation has been performed intermittently during resection of eloquently located lesions. Authors of the present study assessed the possibility of using a resection instrument for continuous stimulation of scMEPs.

Methods An ultrasonic surgical aspirator was attached to an IOM stimulator and was used as a monopolar subcortical stimulation probe. The effect of the aspirator’s use at different ultrasound power levels (0%, 25%, 50%, 75%, and 100%) on stimulation intensity was examined in a saline bath. Afterward monopolar stimulation with the surgical aspirator was used during the resection of subcortical lesions in the vicinity of the corticospinal tract in 14 patients in comparison with scMEP stimulation via a standard stimulation electrode. During resection, the stimulation current at which an MEP response was still measurable with subcortical stimulation using the surgical aspirator was compared with the corresponding stimulation current needed using a standard monopolar subcortical stimulation probe at the same location.

Results The use of ultrasound at different energy levels did result in a slight but irrelevant increase in stimulation energy via the tip of the surgical aspirator in the saline bath. Stimulation of scMEPs using the surgical aspirator or monopolar probe was successful and almost identical in all patients. One patient developed a new permanent neurological deficit. Transient new postoperative paresis was observed in 28% (4 of 14) of cases. Gross-total resection was achieved in 64% (9 of 14) cases and subtotal resection (> 80% of tumor mass) in 35% (5 of 14).

Conclusions Continuous motor mapping using subcortical stimulation via a surgical aspirator, in comparison with the sequential use of a standard monopolar stimulation probe, is a feasible and safe method without any disadvantages. Compared with the standard probe, the aspirator offers continuous information on the distance to the corticospinal tract.

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Diagnostic Value and Safety of Brain Biopsy in Patients With Cryptogenic Neurological Disease: A Systematic Review and Meta-analysis of 831 Cases

Brain_biopsy_under_stereotaxy

Neurosurgery 77:283–295, 2015

The role of brain biopsy in patients with cryptogenic neurological disease is uncertain.

OBJECTIVE: To determine the risks and benefits of diagnostic brain biopsy for nonneoplastic indications in immunocompetent patients.

METHODS: Appropriate studies were identified by searching electronic databases.

RESULTS: We screened 3645 abstracts and included 20 studies with a total of 831 patients. Indications for biopsy were: (1a) severe neurological disease of unknown etiology in adults (n = 7) and (1b) in children (n = 2); (2) suspected primary angiitis of the central nervous system (PACNS) (n = 3); (3) chronic meningitis of unknown cause (n = 3); (4) atypical dementia (n = 4); and (5) nonneoplastic disease (n = 1). Diagnostic success rates calculated for subgroups were 51.3% (34.5-68.1) for 1a, 53.8% (42.9-64.5) for 1b, 74.7% (64.0-84.1) for 2, 30.3% (17.2-45.4) for 3, and 60.8% (41.2-78.8) for 4. Clinical impact rates were 30.5% (13.6-50.6) for 1a (n = 6), 67.1% (42.8-87.3) for 1b (n = 2), 8.3% (2.3-20.0) for 3 (n = 1), and 14.2% (6.5-24.3) for 4 (n = 2). Lymphoma (n = 32) and Creutzfeldt-Jakob disease (n = 30) were the most common diagnoses on the final histopathology reports of positive brain biopsies in 1a. In 1b, encephalitis (n = 7), PACNS (n = 6), and demyelination (n = 6) were the most common. The odds ratio for achieving a diagnostic biopsy when there was a radiological target was 3.70 (P = .014, 95% confidence interval, 1.31-10.42).

CONCLUSION: Brain biopsy in cryptogenic neurological disease was associated with the highest diagnostic yield in patients with suspected PACNS. The greatest clinical impact was seen in children with cryptogenic neurological disease. The presence of a radiological target was associated with a higher diagnostic yield.

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Complications following cranioplasty: incidence and predictors in 348 cases

cranioplasty

J Neurosurg 123:182–188, 2015

The factors that contribute to periprocedural complications following cranioplasty, including patient-specific and surgery-specific factors, need to be thoroughly assessed. The aim of this study was to evaluate risk factors that predispose patients to an increased risk of cranioplasty complications and death.

Methods The authors conducted a retrospective review of all patients at their institution who underwent cranioplasty following craniectomy for stroke, subarachnoid hemorrhage, epidural hematoma, subdural hematoma, and trauma between January 2000 and December 2011. The following predictors were tested: age, sex, race, diabetic status, hypertensive status, tobacco use, reason for craniectomy, urgency status of the craniectomy, graft material, and location of cranioplasty. The cranioplasty complications included reoperation for hematoma, hydrocephalus postcranioplasty, postcranioplasty seizures, and cranioplasty graft infection. A multivariate logistic regression analysis was performed. Confidence intervals were calculated as the 95% CI.

Results Three hundred forty-eight patients were included in the study. The overall complication rate was 31.32% (109 of 348). The mortality rate was 3.16%. Predictors of overall complications in multivariate analysis were hypertension (OR 1.92, CI 1.22–3.02), increasing age (OR 1.02, CI 1.00–1.04), and hemorrhagic stroke (OR 3.84, CI 1.93–7.63). Predictors of mortality in multivariate analysis were diabetes mellitus (OR 7.56, CI 1.56–36.58), seizures (OR 7.25, CI 1.238–42.79), bifrontal cranioplasty (OR 5.40, CI 1.20–24.27), and repeated surgery for hematoma evacuation (OR 13.00, CI 1.51–112.02). Multivariate analysis was also applied to identify the variables that affect the development of seizures, the need for reoperation for hematoma evacuation, the development of hydrocephalus, and the development of infections.

Conclusions The authors’ goal was to provide the neurosurgeon with predictors of morbidity and mortality that could be incorporated in the clinical decision-making algorithm. Control of a patient’s risk factors and early recognition of complications may help practitioners avoid the exhaustive list of complications.

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Venous organization in the transverse foramen

Venous organization in the transverse foramen

J Neurosurg 123:118–125, 2015

The anatomical arrangement of the venous system within the transverse foramen is controversial; there is disagreement whether the anatomy consists of a single vertebral vein or a confluence of venous plexus. Precise knowledge of this arrangement is necessary in imaging when vertebral artery dissection is suspected, as well as in surgical approaches for the cervical spine. This study aimed to better explain anatomical organization of the venous system within the transverse foramen according to the Trolard hypothesis of a transverse vertebral sinus.

Methods This was an anatomical and radiological study. For the anatomical study, 10 specimens were analyzed after vascular injection. After dissection, histological cuts were prepared. For the radiological study, a high-resolution MRI study with 2D time-of-flight segment MR venography sequences was performed on 10 healthy volunteers.

Results Vertebral veins are arranged in a plexiform manner within the transverse canal. This arrangement begins at the upper part of the transverse canal before the vertebral vein turns into a single vein along with the vertebral artery running from the transverse foramen of the C-6. This venous system runs somewhat ventrolaterally to the vertebral artery. In most cases, this arrangement is symmetrical and facilitates radiological readings. The anastomoses between vertebral veins and ventral longitudinal veins are uniform and arranged segmentally at each vertebra.

Conclusions These findings confirm recent or previous anatomical descriptions and invalidate others. It is hard to come up with a common description of the arrangement of vertebral veins. The authors suggest providing clinicians as well as anatomists with a well-detailed description of components essential to the understanding of this organization.

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Augmented reality–guided neurosurgery: accuracy and intraoperative application of an image projection technique

Augmented reality–guided neurosurgery- accuracy and intraoperative application of an image projection technique

J Neurosurg 123:206–211, 2015

An augmented reality system has been developed for image-guided neurosurgery to project images with regions of interest onto the patient’s head, skull, or brain surface in real time. The aim of this study was to evaluate system accuracy and to perform the first intraoperative application.

Methods Images of segmented brain tumors in different localizations and sizes were created in 10 cases and were projected to a head phantom using a video projector. Registration was performed using 5 fiducial markers. After each registration, the distance of the 5 fiducial markers from the visualized tumor borders was measured on the virtual image and on the phantom. The difference was considered a projection error. Moreover, the image projection technique was intraoperatively applied in 5 patients and was compared with a standard navigation system.

Results Augmented reality visualization of the tumors succeeded in all cases. The mean time for registration was 3.8 minutes (range 2–7 minutes). The mean projection error was 0.8 ± 0.25 mm. There were no significant differences in accuracy according to the localization and size of the tumor. Clinical feasibility and reliability of the augmented reality system could be proved intraoperatively in 5 patients (projection error 1.2 ± 0.54 mm).

Conclusions The augmented reality system is accurate and reliable for the intraoperative projection of images to the head, skull, and brain surface. The ergonomic advantage of this technique improves the planning of neurosurgical procedures and enables the surgeon to use direct visualization for image-guided neurosurgery.

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Serial Imaging Surveillance for Patients With a History of Intracranial Aneurysm: Risk of De Novo Aneurysm Formation

De Novo Aneurysm Formation

Neurosurgery 77:32–43, 2015

Although rare, de novo intracranial aneurysms (DNIAs) may develop in patients with a history of intracranial aneurysms (IAs).

OBJECTIVE: To evaluate the benefit of routine radiographic screening for DNIAs.

METHODS: Data for 2153 patients with IAs were retrospectively analyzed. A total of 185 patients underwent screening for DNIAs at frequent intervals.

RESULTS: Overall, DNIAs were detected in 26 patients (1.2%). Of the 185 patients with surveillance, DNIAs developed in 9 (4.9%). The risk of DNIA detection was 1.14% per person-year of follow-up (95% confidence interval: 0.6%-2.2%). Patients with imaging follow-up had a significantly higher rate of DNIA detection compared with patients without regular imaging surveillance (4.9% vs 0.86%; P , .001), but surveillance was associated with smaller lesions (with surveillance: 3.8 6 1.8 mm, without: 7.0 6 4.4 mm, mean 6 standard deviation; P = .026). A unimodal distribution of time to detection was found in those with surveillance, with a peak between 0 and 2 years. There was a trend toward an association of cigarette smoking and DNIA detection within 10 years (P = .06); 6 of the 26 patients (23.1%) with DNIAs had a history of cigarette smoking, with all 6 patients continuing to smoke up to the detection of the DNIAs, which were detected in 2.5 6 1.8 years.

CONCLUSION: The low 1.14% per-person year risk of DNIA detection and small DNIA size at detection cannot justify routine screening for DNIAs in all patients with a personal history of IAs. If imaging follow-up is considered for selected patients, early screening will likely yield the most benefit in patients who continue to smoke cigarettes.

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A single-stage posterior approach with open reduction and pedicle screw fixation in subaxial cervical facet dislocations

A single-stage posterior approach with open reduction and pedicle screw fixation in subaxial cervical facet dislocations

J Neurosurg Spine 23:35–41, 2015

The optimal treatment for cervical facet dislocations is controversial, but the generally accepted process recommends an initial closed reduction with the next step determined according to the success of the closed reduction and the presence of traumatic disc herniation. This study aimed to show the efficacy of a posterior approach performed with an open reduction and pedicle screw fixation with removal of disc particles, if required, in the management of subaxial cervical dislocations.

Methods Between March 2012 and September 2013, 21 consecutive patients with cervical facet dislocations were enrolled. The affected levels were as follows: 4 at C3–4; 2 at C4–5; 5 at C5–6; and 10 at the C6–7 level. Seven patients had traumatic disc herniations. Closed reduction was not attempted; a prompt posterior cervical surgery was performed instead. After open reduction, pedicle screw fixation was performed. In cases with traumatic disc herniation, herniated disc fragments were excised via a posterolateral approach and successful decompressions were determined by postoperative MRI studies. Clinical outcomes were assessed using the American Spinal Injury Association (ASIA) grading system. Radiological outcomes were assessed by comparing the degree of subluxation and the angle of segmental lordosis between pre- and postoperative CT scans.

Results All patients improved neurologically. The mean segmental angles improved from 7.3° ± 8.68° to -5.9° ± 4.85°. The mean subluxation improved from 23.4% ± 16.52% to 2.6% ± 7.19%. Disc fragments were successfully removed from the 7 patients with herniated discs, as shown on MRI.

Conclusions Open reduction followed by pedicle screw fixation or posterolateral removal of herniated disc fragments is a good treatment option for cervical facet dislocations.

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Spinal sagittal balance and microendoscopic laminotomy

Spinal sagittal balance and microendoscopic laminotomy

J Neurosurg Spine 23:49–54, 2015

More information about the association between preoperative anterior translation of the C-7 plumb line and clinical outcomes after decompression surgery in patients with lumbar spinal canal stenosis (LSS) would help resolve problems for patients with sagittal imbalance. The authors evaluated whether preoperative sagittal alignment of the spine affects low-back pain and clinical outcomes after microendoscopic laminotomy.

Methods This study was a retrospective review of prospectively collected surgical data. The study comprised 88 patients with LSS (47 men and 41 women) who ranged in age from 39 to 86 years (mean age 68.7 years). All patients had undergone microendoscopic laminotomy at Osaka City University Graduate School of Medicine from May 2008 through October 2012. The minimum duration of clinical and radiological follow-up was 6 months. All patients were evaluated by Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores for low-back pain, leg pain, and leg numbness before and after surgery. The distance between the C-7 plumb line and the posterior corner of the sacrum (sagittal vertical axis [SVA]) was measured on lateral standing radiographs of the entire spine obtained before surgery. Radiological factors and clinical outcomes were compared between patients with a preoperative SVA ≥ 50 mm (forwardbending trunk [F] group) and patients with a preoperative SVA < 50 mm (control [C] group). A total of 35 patients were allocated to the F group (19 male and 16 female) and 53 to the C group (28 male and 25 female).

Results The mean SVA was 81.0 mm for patients in the F group and 22.0 mm for those in the C group. At final followup evaluation, no significant differences between the groups were found for the JOA score improvement ratio (73.3% vs 77.1%) or the VAS score for leg numbness (23.6 vs 24.0 mm); the VAS score for low-back pain was significantly higher for those in the F group (21.1 mm) than for those in the C group (11.0 mm); and the VAS score for leg pain tended to be higher for those in the F group (18.9 ± 29.1 mm) than for those in the C group (9.4 ± 16.0 mm).

Conclusions Preoperative alignment of the spine in the sagittal plane did not affect JOA scores after microendoscopic laminotomy in patients with LSS. However, low-back pain was worse for patients with preoperative anterior translation of the C-7 plumb line than for those without.

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Prognostic Significance of Peritumoral Edema in Patients With Vestibular Schwannomas

Prognostic Significance of Peritumoral Edema in Patients With Vestibular Schwannomas

Neurosurgery 77:81–86, 2015

Peritumoral edema (PTE) in skull base meningiomas correlates to the absence of an arachnoid plane and difference in outcome. In vestibular schwannomas (VS), PTE and its significance for microsurgery and outcome have never been systematically evaluated.

OBJECTIVE: To evaluate whether PTE correlates with tumor characteristics, the presence of an arachnoid plane, and outcome.

METHODS: A retrospective study of the institutional database. PTE was evaluated on fluid-attenuated inversion recovery magnetic resonance images. Preoperative patient data and intraoperative tumor features (presence of tumor pseudocapsule, vascularity, degree of adhesion/invasion of the arachnoid) were noted. Outcome measures were completeness of removal, neurological outcome, and complication rate. These parameters in patients with PTE (group A) were correlated to those in matched series without edema (group B).

RESULTS: Thirty patients presented with PTE (5%). The mean VS size was 3.4 cm. No major differences in the degree of adhesion or presence of an arachnoid plane were found. VS with PTE were more frequently hypervascular (26.7% in group A vs 6.7% in group B). The presence of PTE in VS was not related to surgical radicality. VS with PTE had worse early postoperative facial nerve function, but at 12 months, there was no major difference. VS with PTE were prone to cause postoperative hemorrhages in the tumor bed.

CONCLUSION: PTE in VS does not correlate with the degree of tumor adhesion and the presence of an arachnoid dissection plane. The radicality of tumor removal and longterm functional outcome in patients with and without PTE was similar. VS with PTE are more vascular and prone to cause postoperative hemorrhages. Therefore, meticulous hemostasis is advisable.

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Decreased Probability of Initial Pain Cessation in Classic Trigeminal Neuralgia Treated With Gamma Knife Surgery in Case of Previous Microvascular Decompression

TN and radiosurgery

Neurosurgery 77:87–95, 2015

Microvascular decompression (MVD) is the reference technique for pharmacoresistant trigeminal neuralgia (TN).

OBJECTIVE: To establish whether the safety and efficacy of Gamma Knife surgery for recurrent TN are influenced by prior MVD.

METHODS: Between July 1992 and November 2010, 54 of 737 patients (45 of 497 with .1 year of follow-up) had a history of MVD (approximately half also with previous ablative procedure) and were operated on with Gamma Knife surgery for TN in the Timone University Hospital. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.6 mm (range, 3.9-11.9 mm) anterior to the emergence of the nerve. A median maximum dose of 85 Gy (range, 70-90 Gy) was delivered.

RESULTS: The median follow-up time was 39.5 months (range, 14.1-144.6 months). Thirty-five patients (77.8%) were initially pain free in a median time of 14 days (range, 0- 180 days), much lower compared with our global population of classic TN (P = .01). Their actuarial probabilities of remaining pain-free without medication at 3, 5, 7, and 10 years were 66.5%, 59.1%, 59.1%, and 44.3%. The hypoesthesia actuarial rate at 1 year was 9.1% and remained stable until 12 years (median, 8 months).

CONCLUSION: Patients with previous MVD showed a significantly lower probability of initial pain cessation compared with our global population with classic TN (P = .01). The toxicity was low (only 9.1% hypoesthesia); furthermore, no patient reported bothersome hypoesthesia. However, the probability of maintaining pain relief without medication was 44.3% at 10 years, similar to our global series of classic TN (P = .85).

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Retrospective Analysis of Interobserver Spatial Variability in the Localization of Broca’s and Wernicke’s Areas Using Three Different fMRI Language Paradigms

Brocas'area

J Neuroimaging 2015;25:626-633

To determine interobserver spatial variability in language area localization using three commonly employed language tasks.

MATERIALS AND METHODS With institutional review board approval, 125 fMRI time series from 50 different clinical language cases were retrospectively reviewed by three blinded readers who selected 3- dimensional points representing the perceived center of Wernicke’s and Broca’s areas using three language tasks (semantic decision, SD; sentence comprehension, SC; and silent word generation, WG). Point dispersion values were then calculated using the perimeter of the 3-dimensional triangle defined by the three readers’ selections.

RESULTS After resolving interobserver laterality disagreements, there was no difference in spatial variability between the three tasks (P = .069). The SD task had the fewest interobserver laterality disagreements (P = .028) and the SC task had fewer failed localizations for Broca’s area (P = .050) and Wernicke’s area (P = .013).

CONCLUSION While there were no differences between interobserver spatial variability in language area localization between the three tasks, language task choice impacts the accuracy of fMRI language area identification because tasks vary in their rates of interobserver laterality disagreements and failed localizations. A combination of tasks including one with low laterality disagreements (eg, SD) and one with few failed localizations (eg, SC) may offer the best combination.

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Cervical laminoplasty developments and trends, 2003–2013: a systematic review

Laminoplasty

J Neurosurg Spine 23:24–34, 2015

Despite extensive clinical experience with laminoplasty, the efficacy of the procedure and its advantages over laminectomy remain unclear. Specific clinical elements, such as incidence or progression of kyphosis, incidence of axial neck pain, postoperative cervical range of motion, and incidence of postoperative C-5 palsies, are of concern. The authors sought to comprehensively review the laminoplasty literature over the past 10 years while focusing on these clinical elements.

Methods The authors conducted a literature search of articles in the Medline database published between 2003 and 2013, in which the terms “laminoplasty,” “laminectomy,” and “posterior cervical spine procedures” were used as key words. Included was every single case series in which patient outcomes after a laminoplasty procedure were reported. Excluded were studies that did not report on at least one of the above-mentioned items.

Results A total of 103 studies, the results of which contained at least 1 of the prespecified outcome variables, were identified. These studies reported 130 patient groups comprising 8949 patients. There were 3 prospective randomized studies, 1 prospective nonrandomized alternating study, 15 prospective nonrandomized data collections, and 84 retrospective reviews. The review revealed a trend for the use of miniplates or hydroxyapatite spacers on the open side in Hirabayashi-type laminoplasty or on the open side in a Kurokawa-type laminoplasty. Japanese Orthopaedic Association (JOA) scoring was reported most commonly; in the 4949 patients for whom a JOA score was reported, there was improvement from a mean (± SD) score of 9.91 (± 1.65) to a score of 13.68 (± 1.05) after a mean follow-up of 44.18 months (± 35.1 months). The mean preoperative and postoperative C2–7 angles (available for 2470 patients) remained stable from 14.17° (± 0.19°) to 13.98° (± 0.19°) of lordosis (average follow-up 39 months). The authors found significantly decreased kyphosis when muscle/posterior element–sparing techniques were used (p = 0.02). The use of hardware in the form of hydroxyapatite spacers or miniplates did not influence the progression of deformity (p = 0.889). An overall mean (calculated from 2390 patients) of 47.3% loss of range of motion was reported. For the studies that used a visual analog scale score (totaling 986 patients), the mean (cohort size–adjusted) postoperative pain level at a mean follow-up of 29 months was 2.78. For the studies that used percentages of patients who complained of postoperative axial neck pain (totaling 1249 patients), the mean patient number–adjusted percentage was 30% at a mean follow-up of 51 months. The authors found that 16% of the studies that were published in the last 10 years reported a C-5 palsy rate of more than 10% (534 patients), 41% of the studies reported a rate of 5%–10% (n = 1006), 23% of the studies reported a rate of 1%–5% (n = 857), and 12.5% reported a rate of 0% (n = 168).

Conclusions Laminoplasty remains a valid option for decompression of the spinal cord. An understanding of the importance of the muscle-ligament complex, plus the introduction of hardware, has led to progress in this type of surgery. Reporting of outcome metrics remains variable, which makes comparisons among the techniques difficult.

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Imaging-Based Features of Headaches in Chiari Malformation Type I

Imaging-Based Features of Headaches in Chiari Malformation Type I

Neurosurgery 77:96–103, 2015

Suboccipital cough-induced headaches are considered a hallmark symptom of Chiari malformation type I (CMI). However, non–Valsalva-related suboccipital headaches and headaches in other locations are also common in CMI. The diagnostic significance and the underlying factors associated with these different headaches types are not well understood.

OBJECTIVE: To compare cranial morphology and hydrodynamics in 3 types of headaches in CMI to better understand the pathophysiological basis for the different headache characteristics.

METHODS: Twenty-two cranial physiological and morphological measures were obtained with specialized magnetic resonance imaging scans from 63 symptomatic pretreated CMI patients, 40 with suboccipital headaches induced by Valsalva maneuvers (34 women; age, 36 6 10 years), 15 with non–Valsalva-related suboccipital headaches (10 women; age, 33 6 9 years), 8 with nonsuboccipital non–Valsalva-induced headaches (8 women; age, 39 6 13 years), and 37 control subjects (24 women; age, 36 6 12 years). Group differences were identified with the use of the 2-tailed Student t test. RESULTS: Posterior cranial fossa markers of CMI were similar among the 3 headache subtypes. However, the Valsalva-related suboccipital headaches cohort demonstrated a significantly lower intracranial compliance index than the non–Valsalva-related suboccipital headaches cohort (7.5 6 3.4 vs 10.9 6 4.9), lower intracranial volume change during the cardiac cycle (0.48 6 0.19 vs 0.61 6 0.16 mL), and higher magnetic resonance imaging–derived intracranial pressure (11.1 6 4.3 vs 7.7 6 2.8 mm Hg; P = .02). The Valsalva-related suboccipital headaches cohort had smaller intracranial and lateral ventricular volumes compared with the healthy cohort. The non–Valsalva-related suboccipital headaches cohort had reduced venous drainage through the jugular veins.

CONCLUSION: Valsalva-induced worsening of occipital headaches appears to be related to a small intracranial volume rather than the smaller posterior cranial fossa. This explains the reduced intracranial compliance and corresponding higher pressure measured in CMI patients with headaches affected by Valsalva maneuvers.

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