Author: cba

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Intraoperative Magnetic Resonance Ventriculography During Endoscopic Third Ventriculostomy

Usefulness of Intraoperative Magnetic Resonance Ventriculography During Endoscopic Third Ventriculostomy

Neurosurgery 73:730–738, 2013

Endoscopic third ventriculostomy (ETV) is the preferred method for the treatment of noncommunicating hydrocephalus. The different success rates of ETV indicate the difficulties in predicting the success of this procedure.

OBJECTIVE: To show the usefulness of intraoperative ventriculography performed by the low-field 0.15-T magnetic resonance imager Polestar N20 during ETV.

METHODS: The study was conducted in 11 patients with noncommunicating hydrocephalus caused by tumors or cysts of the third ventricle (n = 5), nontumoral stenosis of the sylvian aqueduct (n = 3), and fourth ventricle outlet obstruction (n = 3). Intraoperative magnetic resonance (iMR) ventriculography was performed before and after the ETV.

RESULTS: In each case, iMR-ventriculography was a safe procedure and determined the exact site of obstruction of cerebrospinal fluid flow. In all cases, iMR-ventriculography performed after ETV showed with the greatest accuracy the patency of the performed fenestrations, demonstrating in 9 patients good flow of the contrast from the third ventricle to the basal cisterns, restricted flow in 1 patient, and no flow in 1 patient. The results of ventriculography were consistent with the postoperative neurological status of operated-on patients. In 3 patients, the opinion of the surgeons about the patency of endoscopic fenestration, based on intraoperative observation of the third ventricle floor, was inconsistent with the results from iMR-ventriculography.

CONCLUSION: Low-field iMR-ventriculography is a safe procedure that can be successfully applied during ETV to determine the site of obstruction in hydrocephalus and the patency of performed ventricle fenestration.

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Low-pressure hydrocephalus: indication for custom-made catheters?

Low-pressure hydrocephalus- indication for custom-made catheters?

Acta Neurochir (2013) 155:1981–1985

Low-pressure hydrocephalus (LPH) is characterized by ventriculomegaly with persistent low intracranial pressure (ICP). Sub-zero drainage is needed for its management and multiple solutions have been described. Our aim is to report our experience with custom-made peritoneal catheters with larger inner diameter as an alternative treatment option.

Methods We made a retrospective review of all patients diagnosed with LPH and treated with custom-made peritoneal catheters at the Virgen del Rocío Pediatric Neurosurgical Unit. Catheters were coated with antibiotic or silver. The inner diameter of ventricular catheters was 1.4 mm; peritoneal catheters were larger than usual (1.9 mm inner diameter).

Results We identified four patients in whom five custommade peritoneal catheters were used over a 3-year period. There were two males and the mean age was 10 years (6 months–17 years). In all patients, placement of an EVD was necessary for sub-zero drainage, with maximum negative pressure of −8 cm H20. The mean time of maintenance of EVD was 102 days (10 days–1 year). Finally, three ventriculoperitoneal (VP) valveless systems, one with antigravitation device, and one Pro-GAV VP shunt were placed, all of them with larger custom-made peritoneal catheters. After a mean follow-up period of 2.3 years (6 months– 3 years), two patients are completely recovered, one patient is partially dependent for daily activities with good cognitive status, and the last one is a child who died due to his brain tumor.

Conclusion The custom-made peritoneal catheters with larger inner diameter could be a good option for the management of this complex pathology.

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Novel augmented reality–assisted percutaneous vertebroplasty

A novel 3D guidance system using augmented reality for percutaneous vertebroplasty

J Neurosurg Spine 19:492–501, 2013

Augmented reality (AR) is an imaging technology by which virtual objects are overlaid onto images of real objects captured in real time by a tracking camera. This study aimed to introduce a novel AR guidance system called virtual protractor with augmented reality (VIPAR) to visualize a needle trajectory in 3D space during percutaneous vertebroplasty (PVP). The AR system used for this study comprised a head-mount display (HMD) with a tracking camera and a marker sheet. An augmented scene was created by overlaying the preoperatively generated needle trajectory path onto a marker detected on the patient using AR software, thereby providing the surgeon with augmented views in real time through the HMD. The accuracy of the system was evaluated by using a computer-generated simulation model in a spine phantom and also evaluated clinically in 5 patients.

In the 40 spine phantom trials, the error of the insertion angle (EIA), defined as the difference between the attempted angle and the insertion angle, was evaluated using 3D CT scanning. Computed tomography analysis of the 40 spine phantom trials showed that the EIA in the axial plane significantly improved when VIPAR was used compared with when it was not used (0.96° ± 0.61° vs 4.34° ± 2.36°, respectively). The same held true for EIA in the sagittal plane (0.61° ± 0.70° vs 2.55° ± 1.93°, respectively). In the clinical evaluation of the AR system, 5 patients with osteoporotic vertebral fractures underwent VIPARguided PVP from October 2011 to May 2012. The postoperative EIA was evaluated using CT.

The clinical results of the 5 patients showed that the EIA in all 10 needle insertions was 2.09° ± 1.3° in the axial plane and 1.98° ± 1.8° in the sagittal plane. There was no pedicle breach or leakage of polymethylmethacrylate.

VIPAR was successfully used to assist in needle insertion during PVP by providing the surgeon with an ideal insertion point and needle trajectory through the HMD. The findings indicate that AR guidance technology can become a useful assistive device during spine surgeries requiring percutaneous procedures.

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Orthotic (helmet) therapy in the treatment of plagiocephaly

Type IV plagio

Neurosurg Focus 35 (4):E2, 2013

The goal of this study was to review the current literature on orthotic (helmet) therapy use in the treatment of deformational plagiocephaly. Methods. PubMed was used to search English articles using the medical subject headings “deformational plagiocephaly” and “orthosis,” and “deformational plagiocephaly” and “helmet.”

Results. Forty-two articles were found. There were no Class I studies, 7 Class II studies, 1 Class III study, and 13 Class IV studies. Cranial orthoses have been shown to be effective in treating deformational plagiocephaly. It continues to be debated as to whether the statistical significance of treatment with cranial orthoses compared with conservative therapies is clinically significant. Children older than 12 months of age with deformational plagiocephaly may still benefit from orthotic therapy. The long-term effects of orthotic therapy are controversial.

Conclusions. There is a lack of Class I literature evidence supporting the use of helmet therapy in deformational plagiocephaly. There are controversies surrounding the use of orthotic therapy such as appropriate use, cost, use in older children, and long-term outcomes. Clinical indications for orthotic therapy need to be better defined with further research studies.

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Solitary clival plasmocytomas

Solitary clival plasmocytomas

Acta Neurochir (2013) 155:1849–1856

Tumours of the clivus are exceptionally rare, representing a diagnostic and a therapeutic challenge. Clival solitary plasmocytomas have been described only as single case reports or included in small clinical series with other intracranial location.

Methods Authors report clinical, radiological, and survival data of four patients, who underwent surgery for clival plasmocytomas between 1989 and 2012 in a single centre. Current knowledge about solitary plasmocytomas of the clivus are reviewed.

Results Follow-up time was 54 months (range: 9–165). Mean age of patient was 57 years, no gender predilection was observed. Main symptoms were headache (75 %) and double vision (75 %), due to third or sixth cranial nerve palsy. Mean time to diagnosis was 8.2 months. All patients underwent surgery as primary treatment, through either a transsphenoidal (75 %) or a transmaxillary approach (25 %). In all cases adjuvant conventional radiotherapy was performed with a median delivered dose of 45 Gy. Only one case of progression into multiple myeloma was observed 13 months after surgery, and the patient died 9 months later. No other recurrences or progression were observed. Mean overall survival and progression free survival time were, respectively, 54 and 51.7 months.

Conclusions Although extremely rare, clival plasmocytomas have to be considered in the differential diagnosis of a solitary clival lesion. Biological and clinical features of these tumours strongly differ from those of similar lesions in other part of the body. Early diagnosis, extensive tumour removal, opportune indication of adjuvant treatment with radiotherapy and chemotherapy are the keys to manage these cases.

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Hypoglossal canal dural arteriovenous fistula

Hypoglossal canal dural arteriovenous fistula

J Neurosurg 119:955–960, 2013

The purpose of this study was to evaluate the incidence, radiographic findings, relationship between presenting symptoms for treatment and drainage pattern, and treatment outcomes of hypoglossal canal dural arteriovenous fistula (HC-dAVF).

Methods. During a 16-year period, 238 patients underwent endovascular treatment for cranial dAVF at a single center. The incidence, radiographic findings, relationship between presenting symptoms for treatment and drainage pattern, and treatment outcomes of HC-dAVF were retrospectively evaluated.

Results. The incidence of HC-dAVF was 4.2% (n = 10). Initial symptoms were tinnitus with headache (n = 6), tinnitus only (n = 1), ocular symptoms (n = 1), otalgia (n = 1), and congestive myelopathy (n = 1). Presenting symptoms requiring treatment included ocular symptoms (n = 4), hypoglossal nerve palsy (n = 4), aggravation of myelopathy (n = 1), and aggravation of tinnitus with headache (n = 1). While the affected HC was widened in 4 of 10 patients, hypersignal intensity on source images was conspicuous in all 7 patients who underwent MR angiography (MRA). All ocular symptoms and congestive myelopathy were associated with predominant drainage to superior ophthalmic or perimedullary veins due to antegrade drainage restriction. All patients who underwent transvenous coil embolization (n = 8) or transarterial N-butyl cyanoacrylate (NBCA) embolization (n = 1) improved without recurrence. One patient who underwent transarterial particle embolization had a recurrence 12 months posttreatment and was retreated with transvenous embolization.

Conclusions. The incidence of HC-dAVF was 4.2% of all cranial dAVF patients who underwent endovascular treatment. Source images of MRA helped to accurately diagnose HC-dAVF. More aggressive symptoms may develop as a result of a change in the predominant drainage route due to the development of venous stenosis or obstruction over time. Transvenous coil embolization appears to be the first treatment of choice.

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Incidence and Risk Factors for Dysphagia After Anterior Cervical Fusion

ACDF

Spine 2013;38:1820–1825

Study Design. Retrospective database analysis.

Objective. To determine the national incidence, mortality, and risk factors for dysphagia associated with anterior cervical spinal fusion surgery in the United States.

Summary of Background Data. Dysphagia is a known complication associated with anterior cervical fusion (ACF). A population-based database was analyzed to characterize the incidence of dysphagia in terms of demographics, mortality, and risk factors associated with ACF.

Methods. Data from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project were obtained from 2002 to 2009. Patients undergoing ACF for cervical myelopathy and/ or radiculopathy were identifi ed and separated into cohorts (1- to 2-level and 3 + -level fusions), and incidences of dysphagia were identifi ed. Demographics, length of stay, costs, mortality, and use of bone morphogenetic proteins (BMPs) were assessed. Statistical data were analyzed in SPSS (version 20), using the Student t test for discrete variables and the χ 2 test for categorical data. Binomial logistic regression was used to identify independent predictors of dysphagia. A P value of less than 0.001 was used to denote signifi cance.

Results. A total of 159,590 ACF cases were identified of which 139,434 were 1- to 2-level ACF and 20,156 were 3 + -level ACF. The incidence of dysphagia in the 3 + -level ACF group was double that of the 1- to 2-level ACF group (44.8 vs . 22.4 per 1000; P < 0.001). Patients with dysphagia were significantly older than patients without dysphagia ( P < 0.001). Dysphagia was more common in males undergoing 1- to 2-level ACF ( P < 0.001). BMP was used more frequently for patients with dysphagia in the 1- to 2-level ACF group (9.4% vs . 7.2% of cases; P < 0.001). Logistic regression analysis demonstrated that independent predictors for dysphagia included age ( ≥ 65 yr), male sex, 3 + -level fusion, BMP use, and preoperative patient comorbidities.

Conclusion. Dysphagia occurs twice as often after 3 + -level ACF compared with 1- to 2-level ACF. Utilization of BMP was also linked to an increased incidence of dysphagia in the 1- to 2-level ACF group. Regardless of the number of levels fused, patients experiencing dysphagia had increased age, comorbid risk factors, hospitalizations, and costs.

Level of Evidence: 3

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Increased body mass index in CM-I and syringomyelia

Increased body mass index in CM-I and syringomyelia

J Neurosurg 119:1058–1067, 2013

In this paper the authors describe an association between increased body mass index (BMI) and Chiari malformation Type I (CM-I) in adults, as well as its relationship to the development of syringomyelia.

Methods. In the period between January 2004 and December 2011, the senior author reviewed the data for all CM-I patients with or without syringomyelia and neurological deficit. Analyzed factors included clinical status (headaches and neurological signs), radiological characteristics of syringomyelia (diameter and vertical extent of syrinx), BMI, and relationship of age to BMI, syrinx diameter, and vertical extent of syrinx.

Results. Sixty consecutive adults had CM-I, 26 of whom also had syringomyelia. The mean BMI among all patients was 30.35 ± 7.65, which is Class I obesity (WHO), and was similar among patients with or without syringomyelia. Extension of the vertical syrinx was greater in overweight patients (p = 0.027) than in those with a normal body weight. Evidence of de novo syrinx formation was found in 2 patients who gained an average BMI of 10.8 points. After repeated decompression and no change in holocord syrinx width or vertical extent, a reduction in the syrinx was seen after BMI decreased 11.7 points in one individual. No correlation was found between patient age and BMI, age and vertical extension of the syrinx, and age and diameter of the syrinx.

Conclusions. An association between increased BMI and CM-I in adults was recognized. Gaining weight may influence the de novo creation of a syrinx in adults who previously had minimally symptomatic or asymptomatic CM-I, and reducing weight can improve a syrinx after unsuccessful surgical decompression. Therefore, a reduction in body weight should be recommended for all overweight and obese patients with CM-I.

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Gravity assisted vs. medium pressure valves for communicating hydrocephalus show similar valve-revision rates

Gravity assisted vs. medium pressure valves for communicating hydrocephalus show similar valve-revision rates

Acta Neurochir (2013) 155:1987–1991

Two common valve types used to treat hydrocephalus include gravity assisted valves (GAV) and medium pressure valves (MPV). Despite their different mechanism of action, differentiated surgical indications per type are not well defined. One could assume that due to a higher complexity of the GAV system, it may be more prone to valve-related malfunction. The purpose of this retrospective study was to compare the valve-related complication rates of GAV and MPV in patients with communicating hydrocephalus.

Method Patients aged 16 years or older undergoing their first shunt implantation using GAV or MPV were included. We recorded demographic data, implantation diagnosis, outcome, complications, valve type and valve adjustments. Symptoms were documented at discharge and follow-up. Valve-related malfunctions were distinguished from other shunt complications.

Results N =252 patients (range 16.6–88.4, mean 65.0 years, 116 male and 136 female) underwent shunt placement for the first time. N =122 GAV (48.4 %) and n =130 MPV were implanted (51.6 %) over a period of 5 years. The most frequent diagnoses were normal pressure hydrocephalus (NPH) in 86 cases (34.1 %) and posthemorrhagic hydrocephalus in 114 cases (45.2 %). About two thirds of patients were free of hydrocephalus-related symptoms at follow-up. N =66 subjects (26.2 %) underwent at least one shunt revision. N =29 revisions (11.5 %) were due to valve-related malfunction. Valve-related revisions were the main cause for revision in 18/37 cases (48.6 %) in the GAV group and in 11/29 (37.9 %) in the MPV group. Neither clinical improvement nor valve-related malfunctions were found to be statistically different among groups.

Conclusions Despite their technical differences, GAV and MPV show similar valve-related revision rates in the treatment of communicating hydrocephalus.

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Hemorrhage risk, surgical management, and functional outcome of brainstem cavernous malformations

Cavernous_angioma_T2

J Neurosurg 119:996–1008, 2013

The aim of this study was to evaluate the pre- and postoperative rehemorrhage risk, neurological function outcome, and prognostic factors of surgically treated brainstem cavernous malformations (CMs) with long-term follow-up.

Methods. The authors conducted a retrospective review of the clinical data from 242 patients with brainstem CMs that were surgically treated between 1999 and 2010. Patient charts, imaging findings, and outcomes were examined.

Results. The study included 242 patients, with a male-to-female ratio of 1.3 and mean age of 32.6 years. The mean modified Rankin Scale scores on admission, at discharge, at 3 and 6 months after surgery, and at recent evaluation were 2.2, 2.6, 2.3, 1.8, and 1.5, respectively. The preoperative calculated annual hemorrhage and rehemorrhage rates were 5.0% and 60.9%, respectively. The complete resection rate was 95%. Surgical morbidity occurred in 112 patients (46.3%). Eighty-five patients (35.1%) demonstrated worsened condition immediately after surgery; 34 (41.0%) and 51 (61.4%) of these patients recovered to their baseline level within 3 and 6 months after surgery, respectively. At a mean follow-up of 89.4 months, the patients’ condition had improved in 147 cases (60.7%), was unchanged in 70 cases (28.9%), and had worsened in 25 cases (10.3%). A total of 8 hemorrhages occurred in 6 patients, and the postoperative annual hemorrhage rate was 0.4%. Permanent morbidity remained in 65 patients (26.9%). The adverse factors for preoperative rehemorrhage were age ≥ 50 years, size ≥ 2 cm, and perilesional edema. The risk factors for postoperative hemorrhage were developmental venous anomaly and incomplete resection. The independent adverse factors for long-term outcome were increased age, multiple hemorrhages, ventral-seated lesions, and poor preoperative status. Favorable, complete improvement in the postoperative deficits over time was correlated with good preoperative neurological function and continuing improvement thereafter.

Conclusions. Favorable long-term outcomes and significantly low postoperative annual hemorrhage rates were achieved via surgery. Total resection should be attempted with an aim of minimal injury to neurological function; however, postoperative deficits can improve during the postoperative course. Close follow-up with radiological examination is proposed for patients with adverse factors predictive of rehemorrhage.

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A surgical technique to expand the operative corridor for supracerebellar infratentorial approaches

Supracerebellar corridor

Acta Neurochir (2013) 155:1895–1900

The supracerebellar infratentorial approach is a commonly used route in neurosurgery. It provides a narrow and deep corridor to the dorsal midbrain and pineal region. The authors describe a surgical technique to expand the operative corridor and the surgeon’s working angles during this approach.

Methods Thirteen cases of patients who underwent resection of their lesions using this extended approach were reviewed. During their suboccipital craniotomy, additional bone over the transverse sinus (paramedian approach) and the confluence of the sinuses (midline approach) were removed. Two sutures (tentorial stay sutures) were anchored to the tentorium anterior to the transverse sinus and tension was applied. A video narrated by the senior author describes the details of technique.

Results This additional bone removal and tentorial stay sutures led to gentle elevation of the tentorium and partial mobilization of the dural venous sinuses superiorly. This technique enhanced operative viewing through improved illumination and expanded working angles for microsurgical instruments while minimizing the need for fixed retractors and extensive cerebellar retraction. All patients underwent satisfactory removal of their lesions. No patient suffered from any related complication.

Conclusion The use of stay sutures anchored on the tentorium is a simple and effective technique that expands the surgical corridor during supracerebellar infratentorial approaches.

Keywords Supracerebellar infratentorial approach . Stay sutures . Retraction . Operative corridor . Surgical procedures . Operative

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Intraoperative optical imaging for functional mapping

Intraoperative optical imaging for functional mapping

J Neurosurg 119:853–863, 2013

Intraoperative optical imaging (IOI) is an experimental technique used for visualizing functional brain areas after surgical exposure of the cerebral cortex. This technique identifies areas of local changes in blood volume and oxygenation caused by stimulation of specific brain functions. The authors describe a new IOI method, including innovative data analysis, that can facilitate intraoperative functional imaging on a routine basis. To evaluate the reliability and validity of this approach, they used the new IOI method to demonstrate visualization of the median nerve area of the somatosensory cortex.

Methods. In 41 patients with tumor lesions adjacent to the postcentral gyrus, lesions were surgically removed by using IOI during stimulation of the contralateral median nerve. Optical properties of the cortical tissue were measured with a sensitive camera system connected to a surgical microscope. Imaging was performed by using 9 cycles of alternating prolonged stimulation and rest periods of 30 seconds. Intraoperative optical imaging was based on blood volume changes detected by using a filter at an isosbestic wavelength (delta = 568 nm). A spectral analysis algorithm was used to improve computation of the activity maps. Movement artifacts were compensated for by an elastic registration algorithm. For validation, intraoperative conduction of the phase reversal over the central sulcus and postoperative evaluation of the craniotomy site were used.

Results. The new method and analysis enabled significant differentiation (p < 0.005) between functional and nonfunctional tissue. The identification and visualization of functionally intact somatosensory cortex was highly reliable; sensitivity was 94.4% and specificity was almost 100%. The surgeon was provided with a 2D high-resolution activity map within 12 minutes. No method-related side effects occurred in any of the 41 patients.

Conclusions. The authors’ new approach makes IOI a contact-free and label-free optical technique that can be used safely in a routine clinical setup. Intraoperative optical imaging can be used as an alternative to other methods for the identification of sensory cortex areas and offers the added benefit of a high-resolution map of functional activity. It has great potential for visualizing and monitoring additional specific functional brain areas such as the visual, motor, and speech cortex. A prospective national multicenter clinical trial is currently being planned.

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Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas

Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas

Acta Neurochir (2013) 155:1871–187

No systematic study is yet available that focuses on the surgical anatomy of the superior petrosal vein and its significance during surgery for cerebellopontine angle meningiomas. The aim of the present study was to examine the variation of the superior petrosal vein via the retrosigmoid suboccipital approach in relation to the tumor attachment of cerebellopontine angle meningiomas as well as postoperative complications related to venous occlusion.

Forty-three patients with cerebellopontine angle meningiomas were analyzed retrospectively. Based on the operative findings, the tumors were classified into four subtypes: the petroclival type, tentorial type, anterior petrous type, and posterior petrous type. According to a previous anatomical report, the superior petrosal veins were divided into three groups: Type I which emptied into the superior petrosal sinus above and lateral to the internal acoustic meatus, Type II which emptied between the lateral limit of the trigeminal nerve at Meckel’s cave and the medial limit of the facial nerve at the internal acoustic meatus, and Type III which emptied into the superior petrosal sinus above and medial to Meckel’s cave.

In both the petroclival and anterior petrous types, the most common vein was Type III which is the ideal vein for a retrosigmoid approach. In contrast, the Type II vein which is at high risk of being sacrificed during a suprameatal approach procedure was most frequent in posterior petrous type, in which the superior petrosal vein was not largely an obstacle. Intraoperative sacrificing of veins was associated with a significantly higher rate of venous-related phenomena, while venous complications occurred even in cases where the superior petrosal vein was absent or compressed by the tumor.

The variation in the superior petrosal vein appeared to differ among the tumor attachment subtypes, which could permit a satisfactory surgical exposure without dividing the superior petrosal vein. In cases where the superior petrosal vein was previously occluded, other bridging veins could correspond with implications for the crucial venous drainage system, and should thus be identified and protected whenever possible.

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Postoperative Displacement of Deep Brain Stimulation Electrodes Related to Lead-Anchoring Technique

Postoperative Displacement of Deep Brain Stimulation Electrodes Related to Lead-Anchoring Technique-1

Neurosurgery 73:681–688, 2013

Displacement of deep brain stimulation (DBS) electrodes may occur after surgery, especially due to large subdural air collections, but other factors might contribute.

OBJECTIVE: To investigate factors potentially contributing to postoperative electrode displacement, in particular, different lead-anchoring techniques.

METHODS: We retrospectively analyzed 55 patients (106 electrodes) with Parkinson disease, dystonia, tremor, and obsessive-compulsive disorder in whom early postoperative and long-term follow-up computed tomography (CT) was performed. Electrodes were anchored with a titanium microplate or with a commercially available plastic cap system. Two independent examiners determined the stereotactic coordinates of the deepest DBS contact on early postoperative and long-term follow-up CT. The influence of age, surgery duration, subdural air volume, use of microrecordings, fixation method, follow-up time, and side operated on first was assessed.

RESULTS: Subdural air collections measured on average 4.36±6.2 cm3. Three-dimensional (3-D) electrode displacement and displacement in the X, Y, and Z axes significantly correlated only with the anchoring method, with larger displacement for microplate-anchored electrodes. The average 3-D displacement for microplate-anchored electrodes was 2.3 ± 2.0 mm vs 1.5 ± 0.6 mm for electrodes anchored with the plastic cap (P = .030). Fifty percent of the microplate-anchored electrodes showed 2-mm or greater (potentially relevant) 3-D displacement vs only 25% of the plastic cap–anchored electrodes (P < .01).

CONCLUSION: The commercially available plastic cap system is more efficient in preventing postoperative DBS electrode displacement than titanium microplates. A reliability analysis of the electrode fixation is warranted when alternative anchoring methods are used.

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Pathophysiology of shunt dysfunction in shunt treated hydrocephalus

Pathophysiology of shunt dysfunction in shunt

Acta Neurochir (2013) 155:1763–1772

We hypothesized that shunt dysfunction in the ventricular catheter and the shunt valve is caused by different cellular responses. We also hypothesized that the cellular responses depend on different pathophysiological mechanisms.

Methods Removed shunt material was collected. Macroscopic tissue in the catheters was paraffin-embedded and HE-stained. Valves were incubated with trypsin-EDTA in order to detach macroscopically invisible biomaterial, which was then cytospinned and HE-stained. Associated aetiological and surgical data were collected by reviewing patient files, and ventricular catheter position was examined using preoperative radiology (CT scans).

Results We examined eleven ventricular catheters and ten shunt valves. Catheters: 6/11 catheters contained intraluminal tissue consisting of vascularised glial tissue and inflammatory cells (macrophages/giant cells and a few eosinophils). Catheter adherence correlated with the presence of intraluminal tissue, and all tissue containing catheters had some degree of ventricle wall contact. All obstructed catheters contained intraluminal tissue, except one catheter that was dysfunctional because of lost ventricular contact. Valves: Regardless of intraoperative confirmation of valve obstruction, all ten valves contained an almost uniform cellular response of glial cells (most likely ependymal cells), macrophages/giant cells, and lymphomonocytic cells. Some degree of ventricle wall catheter contact was present in all examined valves with available radiology (9/10).

Conclusions The same cellular responses (i.e., glial cells and inflammatory cells) cause both catheter obstruction and valve obstruction. We propose two synergistic pathophysiological mechanisms. (1) Ventricle wall/parenchymal contact by the catheter causesmechanical irritation of the parenchyma including ependymal exfoliation. (2) The shunt material provokes an inflammatory reaction, either nonspecific or specific. In combination, these mechanisms cause obstructive tissue ingrowth (glial and inflammatory) in the catheter and clogging of the valve by exfoliated glial cells and reactive inflammatory cells.

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Role of endoscopy in the microvascular decompression for neurovascular conflicts in the cerebello-pontine angle

neurovascular conflict

Acta Neurochir (2013) 155:1709–1716

Microvascular decompression (MVD) is the surgical intervention designed to resolve neurovascular conflicts (NCs) in the cerebellopontine angle (CPA). Today, endoscopy is commonly used in many neurosurgical procedures. This study aims to retrospectively assess the usefulness of endoscopy during MVD, focusing on microscopic endoscopic-assisted (MEA) MVD.

Methods Between January 2010 and December 2012, 141 patients underwent MVD procedures: 119 (84.5 %) were affected by idiopathic trigeminal neuralgia (TN), 20 (14 %) by hemifacial spasm (HFS), 1 by glossopharyngeal neuralgia (GN) and 1 by TN and GN simultaneously; 128 (91 %) MVD were first time procedures, while 13 (9 %) were recurrences (10 TN, 3 HFS). Visualization techniques used were: pure microscopic in 89 (63 %) cases, fully endoscopic in 12 (8.5 %) and MEA in 40 (28.5 %). The MEA technique was used when the conflict was not clearly identified under microscopic view or it was not certainly resolved.

Results Overall, a NC was found in 130 (92 %) cases, while 11 patients had no intraoperative evidence of NC. Considering specifically the 40 MEA cases, 12 (8.5 % overall) conflicts not clearly visible with the microscope were revealed and solved, a complete conflict resolution was confirmed in 13 (9 % overall) cases, while an incomplete conflict resolution was shown in four cases (3 % overall).

Conclusion Pure microscopic MVD remains the technique of choice. The endoscope is a useful adjunctive imaging tool in confirming NCs identified by the microscope, revealing conflicts missed by the microscopic survey alone and verifying adequate nerve decompression.

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Fenestration of the lamina terminalis during aneurysm surgery

Lamina terminalis fenestration

J Neurosurg 119:629–633, 2013

Fenestration of the lamina terminalis (FLT) during aneurysm surgery for subarachnoid hemorrhage can, in theory, improve CSF circulation from the lateral and third ventricles to the cortical subarachnoid space, which may, in turn, decrease the incidence of hydrocephalus and vasospasm. However, the actual effects of FLT on CSF circulation have been difficult to determine, due to confounding factors. In addition, it is unclear whether the lamina terminalis remains functionally patent when the brain resumes its normal position. The goal of this study was to assess the functional patency of the fenestrated lamina terminalis in patients who underwent surgery for ruptured aneurysms.

Methods. This prospective study included 15 patients who underwent surgical clipping of ruptured anterior circulation aneurysms, with FLT performed during surgery. On postoperative Day 1, the external ventricular drain of each patient was closed, and 1 ml of Omnipaque 300, an iodine-based contrast agent, was injected intraventricularly, accompanied by cranial maneuvering designed to position the contrast agent adjacent to the lamina terminalis. Three to 5 minutes after cranial maneuvering, the flow of contrast agent into the basal cisterns was assessed with CT imaging. Flow was verified by an increase in Hounsfield units in a prespecified “region of interest” within the basal cisterns on the CT scan. This procedure was performed using a standardized protocol designed in consultation with the Department of Radiology and approved by the institutional review board. One patient who underwent endoscopic third ventriculostomy was recruited as a positive control to validate the technique, and 1 patient who underwent aneurysm clipping but not FLT was recruited as a negative control.

Results. Seventeen patients consented to study participation. In the 15 patients who underwent aneurysm clipping and FLT, and the negative control patient who underwent aneurysm clipping but not FLT, the contrast agent followed the normal ventricular pathway from the lateral ventricles into the fourth ventricle, and did not appear in the basal cisterns. In the positive control patient, the contrast agent robustly and immediately filled the basal cisterns.

Conclusions. Fenestration of the lamina terminalis did not result in functional patency of the lamina terminalis when performed as part of surgical clipping for ruptured aneurysms.

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Outcome After Suboccipital Decompression for Chiari Malformation I in Adults

Assessment_of_1_Year_Outcomes_and

Neurosurgery 73:569–581, 2013

To date, there has been no study to comprehensively assess the effectiveness of suboccipital craniectomy (SOC) for Chiari malformation I (CMI) using validated patient-reported outcome measures.

OBJECTIVE: To determine the effectiveness and minimum clinically important difference thresholds of SOC for the treatment of adult patients with CMI using patientreported outcome metrics.

METHODS: Fifty patients undergoing first-time SOC and C1 laminectomy for CMI at a single institution were followed up for 1 year. Baseline and 1-year postoperative pain, disability, quality of life, patient satisfaction, and return to work were assessed. Minimum clinically important difference thresholds were calculated with 2 anchors: the Health Transition Index and North American Spine Society satisfaction questionnaire.

RESULTS: The severity of headaches improved in 37 patients (74%). Improvement in syrinx size was seen in 12 patients (63%) and myelopathy in 12 patients (60%). All patientreported outcomes showed significant improvement 1 year postoperatively (P,.05). Of the 38 patients (76%) employed preoperatively, 29 (76%) returned to work postoperatively at a median time of 6 weeks (interquartile range, 4-12 weeks). Minimum clinically important difference thresholds after SOC for CMI were 4.4 points for numeric rating scale for headache, 0.7 points for numeric rating scale for neck pain, 13.8 percentage points for Headache Disability Index, 14.2 percentage points for Neck Disability Index, 7.0 points for Short Form-12 Physical Component Summary, 6.1 points for Short Form-12 Mental Component Summary, 4.5 points for Zung depression, 1.7 points for modified Japanese Orthopaedic Association, and 0.34 quality-adjusted life-years for Euro-Qol-5D.

CONCLUSION: Surgical management of CMI in adults via SOC provides significant and sustained improvement in pain, disability, general health, and quality of life as assessed by patient-reported outcomes. This patient-centered assessment suggests that suboccipital decompression for CMI in adults is an effective treatment strategy.

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Deformable Anatomic Templates Improve Analysis of Gliomas With Minimal Mass Effect in Eloquent Areas

Deformable Anatomic Templates Improve Analysis of Gliomas With Minimal Mass Effect in Eloquent Areas

Neurosurgery 73:534–542, 2013

Despite improvements in advanced magnetic resonance imaging and intraoperative mapping, cases remain in which it is difficult to determine whether viable eloquent structures are involved by a glioma. A novel software program, deformable anatomic templates (DAT), rapidly embeds the normal location of eloquent cortex and functional tracts in the magnetic resonance images of glioma-bearing brain.

OBJECTIVE: To investigate the feasibility of the DAT technique in patients with gliomas related to eloquent brain.

METHODS: Forty cases of gliomas (grade II-IV) with minimal mass effect were referred for a prospective preoperative and postoperative DAT analysis. The DAT results were compared with the patient’s functional magnetic resonance imaging, diffusion tensor imaging, operative stimulation, and new postoperative clinical deficits.

RESULTS: Fifteen of the 40 glioma patients had overlap between tumor and eloquent structures. Immediate postoperative neurological deficits were seen in 9 cases in which the DAT showed the eloquent area both within the tumor and within or at the edge of the resection cavity. In 6 cases with no deficits, DAT placed the eloquent area in the tumor but outside the resection cavity.

CONCLUSION: This is proof of concept that DAT can improve the analysis of diffuse gliomas of any grade by efficiently alerting the surgeon to the possibility of eloquent area invasion. The technique is especially helpful in diffuse glioma because these tumors tend to infiltrate rather than displace eloquent structures. DAT is limited by tract displacement in gliomas that produces moderate to severe mass effect.

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Sphenoid sinus anatomy and suprasellar extension of pituitary tumors

Sphenoid sinus anatomy

J Neurosurg 119:669–674, 2013

As tumors enlarge, they generally grow along paths of least resistance. For pituitary macroadenomas, extrasellar extension into the suprasellar region, cavernous sinus, or sphenoid sinus may occur. The sphenoid sinus is known to have a variable anatomical configuration, and the authors hypothesize that certain anatomical factors may resist tumor expansion into the sphenoid sinus, thereby directing tumor growth into the suprasellar space. In this paper the authors’ goal was to determine if sphenoid anatomy influences pituitary tumor growth.

Methods. The authors conducted a retrospective analysis of 106 consecutive surgical cases of pituitary macroadenoma. Patient demographics, suprasellar extension, sellar width, and features of the sphenoid intersinus septum were recorded on radiographic review. The chi-square test, t-test, logistic regression, and classification and regression tree analysis were used for statistical analysis.

Results. Of the 106 patients included in the study, 71 (67%) demonstrated suprasellar extension of their tumor. Patients with suprasellar tumor extension had significantly greater intersinus septum width (width > 1.27 mm: OR = 14.32; p = 0.0012) and were significantly older (age > 54 yrs: OR = 3.33; p = 0.0176). They also tended to be male and to have two or more sphenoid partitions (OR = 6.58; p = 0.0306). While patients with suprasellar extension tended to be more likely to have a midline partition and a larger sellar width than their counterparts, these differences did not reach statistical significance.

Conclusions. Certain aspects of the sphenoid sinus anatomy may function to resist pituitary tumor growth into the sphenoid sinus. Progressive enlargement of pituitary macroadenomas may extend in a suprasellar direction, in part, as a consequence of the sphenoid sinus anatomy.

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