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Surgical assessment of the insula. Part 2: validation of the Berger-Sanai zone classification system for predicting extent of glioma resection

Insular glioma zone classification

J Neurosurg 124:482–488, 2016

Though challenging, maximal safe resection of insular gliomas enhances overall and progression-free survival and deters malignant transformation. Previously published reports have shown that surgery can be performed with low morbidity. The authors previously described a Berger-Sanai zone classification system for insular gliomas. Using a subsequent dataset, they undertook this study to validate this zone classification system for predictability of extent of resection (EOR) in patients with insular gliomas.

Methods The study population included adults who had undergone resection of WHO Grade II, III, or IV insular gliomas. In accordance with our prior published report, tumor location was classified according to the Berger-Sanai quadrant- style classification system into Zones I through IV. Interobserver variability was analyzed using a cohort of newly diagnosed insular gliomas and independent classification scores given by 3 neurosurgeons at various career stages. Glioma volumes were analyzed using FLAIR and T1-weighted contrast-enhanced MR images.

Results One hundred twenty-nine procedures involving 114 consecutive patients were identified. The study population from the authors’ previously published experience included 115 procedures involving 104 patients. Thus, the total experience included 244 procedures involving 218 patients with insular gliomas treated at the authors’ institution. The most common presenting symptoms were seizure (68.2%) and asymptomatic recurrence (17.8%). WHO Grade II glioma histology was the most common (54.3%), followed by Grades III (34.1%) and IV (11.6%). The median tumor volume was 48.5 cm3. The majority of insular gliomas were located in the anterior portion of the insula with 31.0% in Zone I, 10.9% in Zone IV, and 16.3% in Zones I+IV. The Berger-Sanai zone classification system was highly reliable, with a kappa coefficient of 0.857. The median EOR for all zones was 85%. Comparison of EOR between the current and prior series showed no change and Zone I gliomas continue to have the highest median EOR. Short- and long-term neurological complications remain low, and zone classification correlated with short-term complications, which were highest in Zone I and in Giant insular gliomas.

Conclusions The previously proposed Berger-Sanai classification system is highly reliable and predictive of insular glioma EOR and morbidity.

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Incidence of Adjacent Segment Disease Requiring Reoperation After Lumbar Laminectomy Without Fusion

ADJACENT SEGMENT DISEASE AFTER LUMBAR LAMINECTOMY

Neurosurgery 78:192–199, 2016

Adjacent segment disease (ASD) has not been described after laminectomy without fusion.

OBJECTIVE: To determine the incidence of ASD after a 1- or 2-level lumbar laminectomy.

METHODS: We retrospectively reviewed medical records of all patients who underwent 1- or 2-level, bilateral lumbar laminectomy without fusion for degenerative spinal disease (all follow-up $1 year). ASD was defined as clinical and/or radiographic evidence of degenerative spinal disease that required reoperation at the level above or below the index laminectomy.

RESULTS: Of the 398 patients, the incidence of ASD requiring reoperation was 10%. The 39 ASD cases were almost equally distributed at L2-L3 (31%), L3-L4 (26%), and L5-S1 (31%), and to a lesser extent at L4-L5 (15%) (P = .51). The ASD incidences of 10% and 9% were equivalent after a 1- and 2-level laminectomy, respectively (P = .76). Rostral ASD was statistically more common than caudal ASD after both the 1- (P , .001) and 2- (P , .001) level laminectomy. Of the 39 ASD cases, 95% required laminectomy, 26% discectomy, and 49% fusion. Average time to ASD was 4 years. After a Kaplan-Meier analysis, time to reoperation for ASD was equivalent among the 1- and 2-level laminectomy cohorts (log-rank test, P = .13).

CONCLUSION: The cumulative incidence of ASD requiring reoperation was 10% over a mean of 4 years. Both the 1- and 2-level laminectomy cohorts experienced equivalent incidences and rates of ASD. Of the 39 operations for ASD, about half required a fusion.

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Endoscopic endonasal clip ligation of cerebral aneurysms

Endoscopic endonasal clip ligation of cerebral aneurysms

J Neurosurg 124:463–468, 2016

The expansion of endovascular procedures for obliteration of cerebral aneurysms highlights one of the drawbacks of clip ligation through the transcranial route, namely brain retraction or brain transgression. Sporadic case reports have emerged over the past 10 years describing endonasal endoscopic clip ligation of cerebral aneurysms. The authors present a detailed anatomical study to evaluate the feasibility of an endoscopic endonasal approach for application of aneurysm clips.

Methods Nine human cadaveric head specimens were used to evaluate operative exposures for clip ligation of aneurysms in feasible anterior and posterior circulation locations. Measurements of trajectories were completed using a navigation system to calculate skull base craniectomy size, corridor space, and the surgeon’s ability to gain proximal and distal control of parent vessels.

Results In each of the 9 cadaveric heads, excellent exposure of the target vessels was achieved. The transplanum, transtuberculum, and transcavernous approaches were used to explore the feasibility of anterior circulation access. Application of aneurysm clips was readily possible to the ophthalmic artery, A1 and A2 segments of the anterior cerebral artery, anterior communicating artery complex, and the paraclinoid and paraclival internal carotid artery. The transclival approach was explored, and clips were successfully deployed along the proximal branches of the vertebrobasilar system and basilar trunk and bifurcation. The median sizes of skull base craniectomy necessary for exposure of the anterior communicating artery complex and basilar tip were 3.24 cm2 and 4.62 cm2, respectively. The mean angles of surgical corridors to the anterior communicating artery complex and basilar tip were 11.4° and 14°, respectively. Although clip placement was feasible on the basilar artery and its branches, the associated perforating arteries were difficult to visualize, posing unexpected difficulty for safe clip application, with the exception of ventrolateral-pointing aneurysms.

Conclusions The authors characterize the feasibility of endonasal endoscopic clip ligation of aneurysms involving the paraclinoid, anterior communicating, and basilar arteries and proximal control of the paraclival internal carotid artery. The endoscopic approach should be initially considered for nonruptured aneurysms involving the paraclinoid and anterior communicating arteries, as well as ventrolateral basilar trunk aneurysms. Clinical experience will be mandatory to determine the applicability of this approach in practice.

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Predictors of Poor Quality of Life 1 Year After Subarachnoid Hemorrhage

A Simple and Quantitative Method to Predict Symptomatic Vasospasm After Subarachnoid Hemorrhage Based on Computed Tomography- Beyond the Fisher Scale

Neurosurgery 78:256–264, 2016

Risk factors for poor quality of life (QOL) after subarachnoid hemorrhage (SAH) remain poorly described.

OBJECTIVE: To identify the frequency and predictors of poor QOL 1 year after SAH.

METHODS: We studied 1-year QOL in a prospectively collected cohort of 1181 consecutively admitted SAH survivors between July 1996 and May 2013. Patient clinical, radiographic, surgical, and acute clinical course information was recorded. Reduced QOL (overall, physical, and psychosocial) at 1 year was assessed with the Sickness Impact Profile and defined as 2 SD below population-based normative Sickness Impact Profile values. Logistic regression leveraging multiple imputation to handle missing data was used to evaluate reduced QOL.

RESULTS: Poor overall QOL was observed in 35% of patients. Multivariable analysis revealed that nonwhite ethnicity, high school education or less, history of depression, poor clinical grade (Hunt-Hess Grade $3), and delayed infarction were predictors of poor overall and psychosocial QOL. Poor physical QOL was additionally associated with older age, hydrocephalus, pneumonia, and sepsis. At 1 year, patients with poor QOL had increased difficulty concentrating, cognitive dysfunction, depression, and reduced activities of daily living. More than 91% of patients with poor QOL failed to fully return to work. These patients frequently received physical rehabilitation, but few received cognitive rehabilitation or emotional-behavioral support.

CONCLUSION: Reduced QOL affects as many as one-third of SAH survivors 1 year after SAH. Delayed infarction is the most important in-hospital modifiable factor that affects QOL. Increased attention to cognitive and emotional difficulties after hospital discharge may help patients achieve greater QOL.

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Treatment of isolated cervical facet fractures

cervical facet fracture

J Neurosurg Spine 24:347–354, 2016

In this clinically based systematic review of cervical facet fractures, the authors’ aim was to determine the optimal clinical care for patients with isolated fractures of the cervical facets through a systematic review.

Methods A systematic review of nonoperative and operative treatment methods of cervical facet fractures was performed. Reduction and stabilization treatments were compared, and analysis of postoperative outcomes was performed. MEDLINE and Scopus databases were used. This work was supported through support received from the Association for Collaborative Spine Research and AOSpine North America.

Results Eleven studies with 368 patients met the inclusion criteria. Forty-six patients had bilateral isolated cervical facet fractures and 322 had unilateral isolated cervical facet fractures. Closed reduction was successful in 56.4% (39 patients) and 63.8% (94 patients) of patients using a halo vest and Gardner-Wells tongs, respectively. Comparatively, open reduction was successful in 94.9% of patients (successful reduction of open to closed reduction OR 12.8 [95% CI 6.1–26.9], p < 0.0001); 183 patients underwent internal fixation, with an 87.2% success rate in maintaining anatomical alignment. When comparing the success of patients who underwent anterior versus posterior procedures, anterior approaches showed a 90.5% rate of maintenance of reduction, compared with a 75.6% rate for the posterior approach (anterior vs posterior OR 3.1 [95% CI 1.0–9.4], p = 0.05).

Conclusions In comparison with nonoperative treatments, operative treatments provided a more successful outcome in terms of failure of treatment to maintain reduction for patients with cervical facet fractures. Operative treatment appears to provide superior results to the nonoperative treatments assessed.

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Hemodynamic response during aneurysm clipping surgery among experienced neurosurgeons

surgery_aneurysm

Acta Neurochir (2016) 158:221–227

Neurosurgery is a challenging field associated with high levels of mental stress. The goal of this study was to investigate the hemodynamic response of experienced neurosurgeons during aneurysm clipping surgery and to evaluate whether neurosurgeons’ hemodynamic responses are associated with patients’ clinical statuses.

Methods Four vascular neurosurgeons (all male; mean age 51 ± 10 years; post-residency experience ≥7 years) were studied during 42 aneurysm clipping procedures. Blood pressure (BP) and heart rate (HR) were assessed at rest and during seven phases of surgery: before the skin incision, after craniotomy, after dural opening, after aneurysm neck dissection, after aneurysm clipping, after dural closure and after skin closure.

Results HR and BP were significantly greater during surgery relative to the rest situation (p≤ 0.03). There was a statistically significant increase in neurosurgeons’ HR (F [6, 41] = 10.88, p <0.001), systolic BP (F [6, 41] =2.97, p =0.01), diastolic BP (F [6, 41] = 2.49, p = 0.02) and mean BP (F [6, 41] = 3.36, p = 0.003) during surgery. The greatest mean HR was after aneurysm clipping, and the greatest BP was after aneurysm neck dissection. Systolic, diastolic and mean BPs were significantly greater during surgical clipping for unruptured aneurysms compared to ruptured aneurysms across all stages of surgery (p ≤ 0.002); however, after adjusting for neurosurgeon experience, the difference in BP as a function of aneurysm rupture was not significant (p>0.08). Aneurysm location, intraoperative aneurysm rupture, admission WFNS score, admission Glasgow Coma Scale scores and Fisher grade were not associated with neurosurgeons’ intraoperative HR and BP (all p > 0.07).

Conclusions Aneurysm clipping surgery is associated with significant hemodynamic system activation among experienced neurosurgeons. The greatest HR and BP were after aneurysm neck dissection and clipping. Aneurysm location and patient clinical status were not associated with intraoperative changes of neurosurgeons’ HR and BP.

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Venous preservation in the anterior transpetrosal approach

Venous preservation in the anterior transpetrosal approach

J Neurosurg 124:432–439, 2016

The drainage of the superficial middle cerebral vein (SMCV) has previously been classified into 4 subtypes. Extradural procedures and dural incisions during the anterior transpetrosal approach (ATPA) may interrupt the route of drainage from the SMCV. In this study, the authors examined the relationship between anatomical variations in the SMCV and the corresponding surgical modifications to the ATPA that are necessary for venous preservation.

Methods This study included 48 patients treated via the ATPA in whom the SMCV was examined using 3D CT venography. The drainage patterns of the SMCV were classified into 3 types: cavernous or absent (Type 1), sphenobasal (Type 2), and sphenopetrosal (Type 3). Type 2 was subdivided into medial (Type 2a) and lateral (Type 2b), and Type 3 was subdivided into vein (Type 3a), vein and sinus (Type 3b), and sinus (Type 3c). The authors performed 3 ATPA modifications to preserve the SMCV: epidural anterior petrosectomy with subdural visualization of the sphenobasal vein (SBV), modification of the dural incision, and subdural anterior petrosectomy. Standard ATPA can be performed with Type 1, Type 2a, and Type 3a drainage. With Type 2b drainage, an epidural anterior petrosectomy with subdural SBV visualization is appropriate. The dural incision should be modified in Type 3b. With Type 3c, a subdural anterior petrosectomy is required.

Results The frequency of each type was 68.7% (33/48) in Type 1, 8.3% (4/48) in Type 2a, 4.2% (2/48) in Type 2b, 14.6% (7/48) in Type 3a, 2.1% (1/48) in Type 3b, and 2.1% (1/48) in Type 3c. No venous complications were found.

Conclusions The authors propose an SMCV modified classification based on ATPA modifications required for venous preservation.

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A Reappraisal of Anterior Communicating Artery Aneurysms: A Case for Stent-Assisted Embolization

Anterior Communicating Artery Aneurysms- A Case for Stent-Assisted Embolization

Neurosurgery 78:200–207, 2016

Wide-necked anterior communicating artery aneurysms represent a subset of lesions with challenging endovascular treatment despite new endoluminal and intrasaccular devices.

OBJECTIVE: To assess the long-term clinical and angiographic outcomes of stentassisted embolization for wide-necked anterior communicating artery aneurysms.

METHODS: Between March 2008 and March 2014, 32 patients with unruptured widenecked AComm aneurysms were treated using stent-assisted embolization. The Glasgow Outcome Scale was reviewed at the time of discharge and at latest follow-up. Ischemic and hemorrhagic events were also recorded and analyzed. Aneurysm occlusion was evaluated post-intervention and on subsequent follow-up evaluations.

RESULTS: Successful stent deployment was achieved in all cases, but in 1 patient the coils could not be contained inside the aneurysm, and the procedure was aborted without complications. The distal segment of the stent was positioned in the ipsilateral A2 in 16 patients, in the contralateral A2 in 15 patients, and in the contralateral A1 in 1 patient. There were no periprocedural thromboembolic or hemorrhagic complications. The rate of major complications was 6%. One patient developed intracranial hemorrhage related to antiplatelet therapy and another had ischemic events due to in-stent stenosis. Angiographic follow-up was available for 26 aneurysms and during a mean follow-up of 22 months, 81% of the lesions were completely occluded and 8% had a small residual neck. The retreatment rate for residual aneurysms was 3%.

CONCLUSION: Our long-term results suggest that stent-assisted embolization for anterior communicating artery aneurysms may be considered an excellent treatment option with an adequate combination of safety profile and effectiveness.

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Perioperative monitoring of pulsatile and static intracranial pressure in patients with Chiari malformation type 1

Natural history of Chiari malformation Type I following decision for conservative treatment

Acta Neurochir (2016) 158:341–347

Patients with Chiari malformation type 1 (CMI) often present with elevated pulsatile and static intracranial pressure (ICP). The preferred treatment of CMI, foramen magnum decompression (FMD), is assumed to normalise ICP and craniospinal pressure dissociation. In order to further explore the mechanisms behind FMD, the present study investigated whether or not pulsatile and static ICP normalises immediately after FMD.

Method The study included CMI patients undergoing FMD with perioperative ICP monitoring as a part of clinical management. The pulsatile and static ICP scores were retrieved from the department’s ICP database, and the clinical and radiological data from the patient records.

Results Eleven patients were included in the study. During the first 3 days following FMD, mixed model analysis revealed no significant time-dependent differences of preoperatively elevated either pulsatile (mean wave amplitude,MWA; p=0.85) and/or static (mean ICP, p = 0.90) ICP. Percentage of mean ICP >15 mmHg increased during days 2 and 3 after FMD. Two patients from the present series had to receive ventriculoperitoneal shunt after FMD in the early postoperative period.

Conclusions The present observations suggest that anatomical restoration of cerebrospinal fluid pathways by FMD does not lead to immediate normalisation of preoperatively altered pulsatile and static ICP in patients withCMI. This finding may explain persistent symptoms during the early period after FMD.

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Default mode network connectivity in patients with idiopathic normal pressure hydrocephalus

iNPH

J Neurosurg 124:350–358, 2016

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder characterized by gait disturbance, cognitive impairment, and incontinence. It is unclear whether the pathophysiology of iNPH is associated with alterations in the default mode network (DMN). The authors investigated alterations in the DMN of patients with iNPH and sought to determine whether a relationship exists between the resting-state functional connectivity of the DMN and a patient’s clinical symptoms.

Methods Resting-state functional MRI (rs-fMRI) was performed in 16 preoperative patients with iNPH and 15 neurologically healthy control subjects of a similar age. Independent component and dual-regression analyses were used to quantify DMN connectivity. The patients’ clinical symptoms were rated according to the iNPH grading scale (iNPHGS). Each of their specific clinical symptoms were rated according to the cognitive, gait, and urinary continence domains of iNPHGS, and neurocognitive status was assessed using the Mini-Mental State Examination, Frontal Assessment Battery (FAB), and Trail Making Test Part A. The strength of DMN connectivity was compared between patients and controls, and the correlation between DMN connectivity and iNPHGS was examined using both region of interest (ROI)–based analysis and voxel-based analysis. The correlation between DMN connectivity and each of the specific clinical symptoms, as well as neurocognitive status, was examined using voxel-based analysis.

Results Both ROI-based and voxel-based analyses revealed reduced DMN connectivity in patients with iNPH. ROI-based analysis showed increased DMN connectivity with worsening clinical symptoms of iNPH. Consistently, voxelbased analyses revealed that DMN connectivity correlated positively with the iNPHGS score, as well as the cognitive and urinary continence domain scores, and negatively with the FAB score. The significant peak in correlation in each case was localized to the precuneus.

Conclusions This is the first study to establish alterations in the DMN of patients with iNPH. DMN connectivity may be a useful indicator of the severity of clinical symptoms in patients with iNPH.

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Outcome of Transsphenoidal Surgery for Cushing Disease

Cushing's disease

Neurosurgery 78:216–223, 2016

Transsphenoidal surgery is the standard approach for treating Cushing disease. Evidence is needed to document effectiveness.

OBJECTIVE: To analyze results of transsphenoidal surgery in 276 consecutive patients, including 19 children.

METHODS: Medical records were reviewed for patients treated initially with surgery for Cushing disease from 1980 to 2012. Radiographic features, pathology, remissions, recurrences, and complications were recorded. Patients were categorized for statistical analysis based on tumor size (microadenomas, macroadenomas, and negative imaging) and remission type (type 1 = morning cortisol ≤3 mg/dL; type 2 = morning cortisol normal).

RESULTS: Females comprised 78% of patients and were older than men. Imaging showed 50% microadenomas, 13% macroadenomas, and 37% negative for tumor. Remission rates for microadenomas, macroadenomas, and negative imaging were 89%, 66%, and 71%, respectively. Patients with microadenomas were more likely to have type 1 remission. Pathology showed adrenocorticotropic hormone-secreting adenomas in 82% of microadenomas, in 100% of macroadenomas, and in 43% of negative imaging. The incidence of hyperplasia was 8%. The finding of hyperplasia or no tumor on pathology predicted treatment failure. The recurrence rate was 17%, with an average time to recurrence of 4.0 years. Patients with type 1 remission had a lower rate of recurrence (13% type 1 vs 50% type 2) and a longer time to recurrence. Children had similar imaging findings, remission rates, and pathology. There were no operative deaths.

CONCLUSION: Transsphenoidal surgery provides a safe and effective treatment for Cushing disease. For both adults and children, the best outcomes occurred in patients with microadenomas and/or those with type 1 remission.

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Patients with incidental WHO grade II glioma frequently suffer from neuropsychological disturbances

Plastic relocation of motor cortex in a patient with LGG (low grade glioma) confirmed by NBS (navigated brain stimulation)

Acta Neurochir (2016) 158:305–312

WHO grade II gliomas (low-grade glioma, LGG) are increasingly diagnosed in patients undergoing MRI for many conditions. These patients are classically considered asymptomatic because they do not experience seizures. Although it was previously demonstrated that symptomatic LGG patients frequently have neurocognitive disorders, the literature does not provide data on the neuropsychological status of patients with incidental LGG (iLGG).

Objective Our aim is to investigate whether neurocognitive impairments exist in a homogeneous iLGG population.

Methods We conducted an analysis of pretreatment neuropsychological assessments of patients with iLGG (histologically proven) admitted to our center from 2007 to 2014. We also obtained data on subjective complaints, tumor size and location.

Results Our study focused on 15 iLGG patients. Two thirds reported subjective complaints, mainly tiredness (40 %) and attentional impairment (33 %). Neurocognitive functions were disturbed in 60 % of patients; 53 % had altered executive functions, 20 % had working memory impairment, and 6 % had attentional disturbances. Only one patient with normal preoperative neuropsychological assessment experienced a deficit at the 3-month postoperative examination.

Conclusions For the first time to our knowledge, we suggest that numerous iLGG patients have neuropsychological impairments. Therefore, greater attention should be paid to objective neuropsychological assessment in iLGG because of the high prevalence of insidious cognitive deficits. Moreover, our original findings bring into question the traditional wait-andsee attitude in iLGG, mainly based on the erroneous dogma that these patients have no functional disturbances. Neuropsychological assessment is mandatory to select the best individualized therapeutic management with preservation of quality of life.

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Delayed Facial Palsy After Vestibular Schwannoma Resection

vestibular-schwannoma

Neurosurgery 78:251–255, 2016

Preservation of facial nerve function following vestibular schwannoma surgery is a high priority. Even those patients with normal to near-normal function in the early postoperative period remain at risk for delayed facial palsy (DFP).

OBJECTIVE: To evaluate the incidence and prognosis of DFP and to identify risk factors for its occurrence.

METHODS: A retrospective cohort study of 489 patients who underwent vestibular schwannoma resection at our institution between 2000 and 2014. Delayed facial palsy was defined as deterioration in facial function of at least 2 House-Brackmann (HB) grades between postoperative days 5 to 30. Only patients with a HB grade of I to III by postoperative day 5 were eligible for study inclusion.

RESULTS: One hundred twenty-one patients with HB grade IV to VI facial weakness at postoperative day 5 were excluded from analysis. Of the remaining 368, 60 (16%) patients developed DFP (mean 12 days postoperatively, range: 5-25 days). All patients recovered function to HB grade I to II by a mean of 33 days (range: 7-86 days). Patients that developed DFP had higher rates of gross total resections (83% vs 71%, P = .05) and retrosigmoid approaches (72% vs 52%, P, .01). There was no difference in recovery time between patients who received treatment with steroids, steroids with antivirals, or no treatment at all (P = .530).

CONCLUSION: Patients with a gross total tumor resection or undergoing a retrosigmoid approach may be at higher risk of DFP. The prognosis is favorable, with patients likely recovering to normal or near-normal facial function within 1 month of onset.

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Delayed contrast-enhanced MRI for brain metastases

Delayed contrast-enhanced MRI for brain metastases

J Neurosurg 124:489–495, 2016

Contrast-enhanced MRI is the preeminent diagnostic test for brain metastasis (BM). Detection of BMs for stereotactic radiosurgery (SRS) planning may improve with a time delay following administration of a high-relaxivity agent for 1.5-T and 3-T imaging systems. Metastasis detection with time-delayed MRI was evaluated in this study.

Methods Fifty-three volumetric MRI studies from 38 patients undergoing SRS for BMs were evaluated. All studies used 0.1-mmol/kg gadobenate dimeglumine (MultiHance; Bracco Diagnostics) immediately after injection, followed by 2 more axial T1-weighted sequences after 5-minute intervals (final image acquisition commenced 15 minutes after contrast injection). Two studies were motion limited and excluded. Two hundred eighty-seven BMs were identified. The studies were randomized and examined separately by 3 radiologists, who were blinded to the temporal sequence. Each radiologist recorded the number of BMs detected per scan. A Wilcoxon signed-rank test compared BM numbers between scans. One radiologist determined the scan on which BMs were best defined. All confirmed, visible tumors were contoured using iPlan RT treatment planning software on each of the 3 MRI data sets. A linear mixed model was used to analyze volume changes.

Results The interclass correlations for Scans 1, 2, and 3 were 0.7392, 0.7951, and 0.7290, respectively, demonstrating excellent interrater reliability. At least 1 new lesion was detected in the second scan as compared with the first in 35.3% of subjects (95% CI 22.4%–49.9%). The increase in BM numbers between Scans 1 and 2 ranged from 1 to 10. At least 1 new lesion was detected in the third scan as compared with the second in 21.6% of subjects (95% CI 11.3%–35.3%). The increase in BM numbers between Scans 2 and 3 ranged from 1 to 9. Between Scans 1 and 3, additional tumors were seen on 43.1% of scans (increase ranged from 1 to 14). The median increase in tumor number for all comparisons was 1. There was a significant increase in number of BMs detected from Scan 1 to Scan 2 (p < 0.0367) and from Scan 1 to Scan 3 (p < 0.0264). In 34 of the 51 subjects (66.7%), the radiologist selected the third scan as the one providing the clearest tumor definition. There was an average 25.4% increase in BM volume between Scans 1 and 2 (p < 0.0001) and a 9% increase in BM volume between Scans 2 and 3 (p = 0.0001).

Conclusions In patients who are being prepared for SRS of BMs, delayed MRI after contrast injection revealed more targets that needed treatment. In addition, apparent treatment volumes increased with a time delay. To avoid missing tumors that could be treated at the time of planned SRS and resultant “treatment failures,” the authors recommend that postcontrast MR images be acquired between 10 and 15 minutes after injection in patients undergoing SRS for treatment of BMs.

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Predictors of Outcome Following Cerebral Aqueductoplasty

Cerebral Aqueductoplasty

Neurosurgery 78:285–296, 2016

The evidence supporting the efficacy and safety of cerebral aqueductoplasty (CA) is limited to small surgical series.

OBJECTIVE: To perform an individual participant data meta-analysis to determine the efficacy and safety of CA and to determine the effect of patient’s age, etiology, surgical approach, and use of stent on success.

METHODS: Electronic databases (MEDLINE, EMBASE, and CINAHL) were searched with no language or date restrictions to identify cohort studies of consecutive participants undergoing CA (without concomitant endoscopic third ventriculostomy or cerebrospinal fluid [CSF] shunt) that reported outcome. Outcome was defined as the time elapsed from the index operation until a second procedure was performed for CSF diversion.

RESULTS: Of 146 citations, 14 articles reporting on 137 participants were eligible. One hundred three participants (75%) did not require a second CSF diversion procedure. The mean duration until repeat CSF diversion procedure was 121.6 months (95% confidence interval [CI], 102.2-141.0). In multivariate analysis, older age at surgery (hazard ratio [HR], 0.43; 95% CI, 0.21-0.88; P = .020), congenital etiology (HR, 0.18; 95% CI, 0.04-0.85; P = .030), and use of stent (HR, 0.30; 95% CI, 0.13-0.70; P = .006) were independent predictors of good outcome. Morbidity, mainly ophthalmoparesis and hemorrhage, was experienced in 22% of participants.

CONCLUSION: Small retrospective cohort studies are inherently prone to biases, some of which are overcome through the use of individual participant data. The best available evidence suggests that CA is an effective procedure with a moderate morbidity profile. Older age at surgery, congenital etiology, and use of stent predict a good outcome with respect to delaying the requirement for a second CSF diversion procedure.

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Morphometric analysis of the medial opticocarotid recess and its anatomical relations relevant to the transsphenoidal endoscopic endonasal approaches

Morphometric analysis of the medial opticocarotid recess

Acta Neurochir (2016) 158:319–324

The medial opticocarotid recess (MOCR) is located in the posterior wall of the sphenoid sinus, medial to the junction of the optic canal (OC) and the carotid prominence (CP). There is controversy in the literature in relation to the presence of the MOCR and its constancy, which is relevant when approaching the skull base through an endoscopic route.

Methods The morphometric relations of the MOCR with the surrounding structures were studied in 18 cadaveric specimens after endoscopic endonasal approach (EEA).

Results The distance between both MOCR was 11.06± 1.14 mm; the distance between the MOCR and the lateral opticocarotid (LOCR) recess was 5.56 ± 0.85 mm; the distance between the MOCR and the suprasellar recess was 3.72±0.49 mm; the angle between the MOCR plane and the OC 13.32±2.30°; the angle between the MOCR plane and the CP 13.50±2.68° and; the angle between the OC and the CP 26.81±4.26°. All measurements showed low variability, with low standard deviation and interquartile range. No relations were found between any of the measurements.

Conclusions The MOCR may be used as a reference point for precise location of structures during EEA. Objective measurements may be especially useful in cases with distorted sphenoid bone anatomy.

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Microvascular anatomy of the cerebellar parafloccular perforating space

Microvascular anatomy of parafloccular perforating space

J Neurosurg 124:440–449, 2016

The cerebellopontine angle is a common site for tumor growth and vascular pathologies requiring surgical manipulations that jeopardize cranial nerve integrity and cerebellar and brainstem perfusion. To date, a detailed study of vessels perforating the cisternal surface of the middle cerebellar peduncle—namely, the paraflocculus or parafloccular perforating space—has yet to be published. In this report, the perforating vessels of the anterior inferior cerebellar artery (AICA) in the parafloccular space, or on the cisternal surface of the middle cerebellar peduncle, are described to elucidate their relevance pertaining to microsurgery and the different pathologies that occur at the cerebellopontine angle.

Methods Fourteen cadaveric cerebellopontine cisterns (CPCs) were studied. Anatomical dissections and analysis of the perforating arteries of the AICA and posterior inferior cerebellar artery at the parafloccular space were recorded using direct visualization by surgical microscope, optical histology, and scanning electron microscope. A comprehensive review of the English-language and Spanish-language literature was also performed, and findings related to anatomy, histology, physiology, neurology, neuroradiology, microsurgery, and endovascular surgery pertaining to the cerebellar flocculus or parafloccular spaces are summarized.

Results A total of 298 perforating arteries were found in the dissected specimens, with a minimum of 15 to a maximum of 26 vessels per parafloccular perforating space. The average outer diameter of the cisternal portion of the perforating arteries was 0.11 ± 0.042 mm (mean ± SD) and the average length was 2.84 ± 1.2 mm. Detailed schematics and the surgical anatomy of the perforating vessels at the CPC and their clinical relevance are reported.

Conclusions The parafloccular space is a key entry point for many perforating vessels toward the middle cerebellar peduncle and lateral brainstem, and it must be respected and protected during surgical approaches to the cerebellopontine angle.

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Determining Surgical Approaches to Basilar Bifurcation Aneurysms

Determining Surgical Approaches to Basilar Bifurcation Aneurysms

Neurosurgery 78:181–191, 2016

The basilar bifurcation aneurysm (BBA) is still considered to be one of the most challenging aneurysms for micro- and endovascular surgery. Classic surgical approaches, such as subtemporal, lateral supraorbital (LSO), and modified presigmoid, are still reliable and effective.

OBJECTIVE: To analyze the clinical and radiological factors that affect the selection of these classic surgical approaches and their outcomes.

METHODS: A retrospective analysis was conducted on the clinical and radiological data from computed tomographic angiography of BBA that have been clipped in the Department of Neurosurgery of Helsinki University Central Hospital between 2004 and 2014. Statistical analyses were performed using parametric and nonparametric tests where values were considered significant below P = .05.

RESULTS: One hundred four patients with BBA underwent surgical clipping in our department between 2004 and 2014. Eight patients were excluded from the study because of incomplete preoperative radiological evaluations, leaving 96 patients for further analysis. Multiple aneurysm clipping, mean basilar bifurcation angle, and aneurysm neck distance from posterior clinoid process were shown to be factors that determine the surgical approach. Unfavorable outcome is strongly associated with poor Hunt-Hess grade on admission, distance from aneurysm neck (the posterior clinoid process), thrombosis, and dome size.

CONCLUSION: Microsurgery for BBA clipping can be performed safely with simple surgical approaches: subtemporal and LSO. There are several factors determining the approach selected. Poor patient outcome in BBA was highly associated with poor preoperative clinical grade and large size of aneurysm dome.

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The value of multimodality intraoperative neurophysiological monitoring in treating pediatric Chiari malformation type I

CMI

Acta Neurochir (2016) 158:335–340

Chiari malformation type I is defined as a descent of cerebellar tonsils below the level of the foramen magnum. The traditional treatment for symptomatic patients is foramen magnum decompression (FMD) surgery. Intraoperative neurophysiological monitoring (INM) is an established surgical adjunct, which is proposed to reduce the potential risk of various surgical procedures. Though INM has been suggested as being helpful in patient positioning and in determining the optimal surgical extent of FMD (i.e., duroplasty, laminectomy, tonsillectomy), its shortcomings include prolongation of anesthesia and surgery as well as monetary costs. Multimodality INM including transcranial-electric motor evoked potential (TcMEP) is not routinely employed in most practices. This study evaluates efficacy of multimodality INM during FMD.

Methods This work is a retrospective analysis of prospectively collected data. Twenty-two FMD surgeries in 21 pediatric patients (aged 1–18 years) were performed at our center utilizing multimodality INM. All patients presented Chiari malformation type I, 18 of which had presented with syringomyelia, underwent posterior fossa decompression (FMD+ C1 laminectomy), accompanied in some with additional cervical laminectomies, duroplasty, and partial tonsillectomies. TcMEP and somatosensory evoked potentials (SSEP) were monitored throughout the procedure including before and after positioning. INM alarms were correlated with perioperative and long-term patient outcomes.

Results INM data remained stable during 19 operations. Three cases displayed significant attenuation in the monitoring signals, all concomitant with patient positioning on the surgical table. One case showed attenuation in SSEP data only, which remained attenuated following repositioning. Another displayed altered TcMEP concomitant with positioning which partially stabilized following repositioning and resolved following bony decompression. The third case showed unilateral attenuation of both TcMEP and SSEP data, which did not rectify until closure. In each of these three cases, no new neurological deficits were observed post operatively.

Conclusions Multimodality INM can be useful in FMD surgery, particularly during patient positioning. TcMEP attenuations may occur independent of SSEPs. The clinical implications of these monitoring alerts have yet to be defined. There is a need to establish an optimal, cost-effective monitoring protocol for FMD.

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Clinical effect of different shunt valve settings in iNPH

Hydrocephalus

J Neurosurg 124:359–367, 2016

The study aim was to examine the effect of gradually reducing the opening pressure on symptoms and signs in the shunt treatment of idiopathic normal pressure hydrocephalus (iNPH).

Methods In this prospective double-blinded, randomized, controlled, double-center study on patients with iNPH, a ventriculoperitoneal shunt with an adjustable Codman Medos Valve was implanted in 68 patients randomized into 2 groups. In 1 group (the 20–4 group) the valve setting was initially set to 20 cm H2O and gradually reduced to 4 cm H2O over the course of the 6-month study period. In the other group (the 12 group), the valve was kept at a medium level of 12 cm H2O during the whole study period. All patients were clinically evaluated using 4 tests preoperatively as well as postoperatively at 1, 2, 3, 4, and 6 months. The test scores between the 2 groups (20–4 and 12) were compared for each clinical evaluation.

Results Fifty-five patients (81%) were able to complete the study. There were no significant differences between the 2 groups (20–4 and 12) preoperatively or at any time postoperatively. Both groups exhibited significant clinical improvement after shunt insertion at all valve settings compared with the preoperative score, with the greatest improvement observed at the first postoperative evaluation. The clinical improvement was significant within the first 3 months, and thereafter no significant improvement was seen in either group.

Conclusions Gradual reduction of the valve setting from 20 to 4 cm H2O did not improve outcome compared with a fixed valve setting of 12 cm H2O. Improvement after shunt surgery in iNPH patients was evident within 3 months, irrespective of valve setting.

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