Neurosurgery Blog

31/10/201327/10/2013

Who Should Undergo Surgery for Degenerative Spondylolisthesis?

Spine 2013;38:1799–1811

Combined prospective randomized controlled trial and observational cohort study of degenerative spondylolisthesis (DS) with an as-treated analysis.

Objective. To determine modifi ers of the treatment effect (TE) of surgery (the difference between surgical and nonoperative outcomes) for DS using subgroup analysis. Summary of Background Data. Spine Patient Outcomes Research Trial demonstrated a positive surgical TE for DS at the group level. However, individual characteristics may affect TE.

Methods. Patients with DS were treated with either surgery (n = 395) or nonoperative care (n = 210) and were analyzed according to treatment received. Fifty-fi ve baseline variables were used to defi ne subgroups for calculating the time-weighted average TE for the Oswestry Disability Index during 4 years (TE = Δ Oswestry Disability Index surgery − Δ Oswestry Disability Index nonoperative ). Variables with signifi cant subgroup-by-treatment interactions ( P < 0.05) were simultaneously entered into a multivariate model to select independent TE predictors.

Results. All analyzed subgroups that included at least 50 patients improved signifi cantly more with surgery than with nonoperative treatment ( P < 0.05). Multivariate analyses demonstrated that age 67 years or less (TE − 15.7 vs. − 11.8 for age > 67, P = 0.014); female sex (TE − 15.6 vs. − 11.2 for males, P = 0.01); the absence of stomach problems (TE − 15.2 vs. − 11.3 for those with stomach problems, P = 0.035); neurogenic claudication (TE − 15.3 vs. − 9.0 for those without claudication, P = 0.004); refl ex asymmetry (TE − 17.3 vs. − 13.0 for those without asymmetry, P = 0.016); opioid use (TE − 18.4 vs. − 11.7 for those not using opioids, P < 0.001); not taking antidepressants (TE − 14.5 vs. − 5.4 for those on antidepressants, P = 0.014); dissatisfaction with symptoms (TE − 14.5 vs. − 8.3 for those satisfi ed or neutral, P = 0.039); and anticipating a high likelihood of improvement with surgery (TE − 14.8 vs. − 5.1 for anticipating a low likelihood of improvement with surgery, P = 0.019) were independently associated with greater TE.

Conclusion. Patients who met strict inclusion criteria improved more with surgery than with nonoperative treatment, regardless of other specific characteristics. However, TE varied signifi cantly across certain subgroups.

Level of Evidence: 3

30/10/201327/10/2013

Impact on Seizure Control of Surgical Resection or Radiosurgery for Cerebral Arteriovenous Malformations

Neurosurgery 73:648–656, 2013

Seizures are a common presenting symptom of arteriovenous malformations (AVMs). However, the impact of treatment modality on seizure control remains unclear.

OBJECTIVE: To compare seizure control after surgical resection or radiosurgery for AVMs.

METHODS: We analyzed retrospectively collected information for 378 patients with cerebral AVMs treated at our institution from 1990 to 2010. The application of strict inclusion criteria resulted in a study population of 164 patients.

RESULTS: In our cohort, 31 patients (20.7%) had Spetzler-Martin grade I AVMs, 51 (34.0%) grade II, 47 (31.3%) grade III, 20 (13.3%) grade IV, and 1 (0.7%) grade V. Of the 49 patients (30%) presenting with seizures, 60.4% experienced seizure persistence after treatment. For these patients, radiosurgery was associated with seizure recurrence (odds ratio: 4.32, 95% confidence interval: 1.24-15.02, P = .021). AVM obliteration was predictive of seizure freedom at last follow-up (P = .002). In contrast, for patients presenting without seizures, 18.4% experienced de novo seizures after treatment, for which surgical resection was identified as an independent risk factor (hazard ratio: 8.65, 95% confidence interval: 3.05-24.5, P < .001).

CONCLUSION: Although our data suggest that achieving seizure freedom should not be the primary goal of AVM treatment, surgical resection may result in improved seizure control compared with radiosurgery for patients who present with seizures. Conversely, in patients without presenting seizures, surgical resection increases the risk of newonset seizures compared with radiosurgery, but primarily within the early posttreatment period. Surgical resection and radiosurgery result in divergent seizure control rates depending on seizure presentation.

29/10/201327/10/2013

Are readmission rates on a neurosurgical service indicators of quality of care?

J Neurosurg 119:1043–1049, 2013

The goal of this study was to examine the reasons for early readmissions within 30 days of discharge to a major academic neurosurgical service.

Methods. A database of readmissions within 30 days of discharge between April 2009 and September 2010 was retrospectively reviewed. Clinical and administrative variables associated with readmission were examined, including age, sex, race, days between discharge and readmission, and insurance type. The readmissions were then assigned independently by 2 neurosurgeons into 1 of 3 categories: scheduled, adverse event, and unrelated. The adverse event readmissions were further subcategorized into patients readmitted although best practices were followed, those readmitted due to progression of their underlying disease, and those readmitted for preventable causes. These variables were compared descriptively.

Results. A total of 348 patients with 407 readmissions were identified, comprising 11.5% of the total 3552 admissions. The median age of readmitted patients was 55 years (range 16–96 years) and patients older than 65 years totaled 31%. There were 216 readmissions (53% of 407) for management of an adverse event that was classified as either preventable (149 patients; 37%) or unpreventable (67 patients; 16%). There were 113 patients (28%) who met readmission criteria but who were having an electively scheduled neurosurgical procedure. Progression of disease (48 patients; 12%) and treatment unrelated to primary admission (30 patients; 7%) were additional causes for readmission. There was no significant difference in the proportion of early readmissions by payer status when comparing privately insured patients and those with public or no insurance (p = 0.09).

Conclusions. The majority of early readmissions within 30 days of discharge to the neurosurgical service were not preventable. Many of these readmissions were for adverse events that occurred even though best practices were followed, or for progression of the natural history of the neurosurgical disease requiring expected but unpredictably timed subsequent treatment. Judicious care often requires readmission to prevent further morbidity or death in neurosurgical patients, and penalties for readmission will not change these patient care obligations.

28/10/201327/10/2013

Suboccipital endoscopic management of the entrapped fourth ventricle

Acta Neurochir (2013) 155:1957–1963

Entrapped fourth ventricle is the result of both inlet aqueduct and outlet fourth ventricular midline and lateral foraminae obstruction. It occurs as a sequalae of intracranial hemorrhagic or inflammatory disease condition. Usually it presents after previous shunting for communicating hydrocephalus with a period of improvement, after which manifestations of posterior fossa expanding process appear. The diagnosis of this rare condition is easy considering the patient past history and the recent clinical state, together with the midline CSF density of the dilated fourth ventricle in either the CT or MR images. The treatment options for this condition include open and endoscopic approaches together with the traditional ventricular to extracranial CSF diversionary procedures.

Objective The aim of the study was to adopt a procedure for treatment of entrapped fourth ventricle that carries the advantage of the minimally invasive technique thus avoiding the complications of the traditional opened and shunt surgeries as well as decreasing multiple procedures due to aqueduct restenosis or stent fall.

Methods Thirteen patients with symptomatic entrapped fourth ventricle underwent suboccipital endoscopic trans–fourth ventricular aqueductoplasty from May 2007 till November 2011. The Gabb endoscopic system was used and aqueductoplasty was performed using 3F Fogarty balloon followed by stent placement. Nine patients were females. The mean age was 3.6 years and the mean follow up period was 23 months. All cases had a previous one or two supratentorial VP shunt placement.

Results Short stent was used in eight patients. During the follow up, stent migration occurred in five of them. Three of these five patients developed posterior fossa compression manifestations due to aqueduct restenosis. Long stent from the aqueduct till the bur hole site for these three patients and the following five patients was used. All cases showed both clinical and radiologic improvement. Apart from the stent migration, no procedure-related complications were encountered.

Conclusion Endoscopic suboccipital paramedian aqueductoplasty with the use of a stent is a safe and effective surgical option that—in our opinion—should stand as the first line treatment for the entrapped fourth ventricle. Long stent is better used after aqueductoplasty to avoid the restenosis if no stent is used or stent fall after short stents. However, good case selection, familiarity with this fairly common endoscopic approach and longer follow-up is needed for obtaining an optimal result.

25/10/201325/10/2013

Reoperation for Refractory Epilepsy in Childhood: A Second Chance for Selected Patients

Neurosurgery 73:695–704, 2013

Reoperations account for 10% in pediatric epilepsy surgery cohorts, and they are especially relevant in young children with catastrophic epilepsy. OBJECTIVE: To determine surgical outcomes and their predictive factors in reoperations for refractory epilepsy in childhood.

METHODS: We retrospectively analyzed presurgical findings, resections, and outcomes of 23 consecutive children who underwent reoperations from 2000 to 2011.

RESULTS: Etiology included cortical dysplasia with/without glioneuronal tumor in 19 patients (83%), sole glioneuronal tumor in 2, and tuberous sclerosis and Rasmussen encephalitis in 1 each. The reasons for the failure of the initial surgery were functional considerations in 8 (35%), incorrect delineation of the epileptogenic zone in 8 (35%), and resection not performed as initially planned in 7 (30%) cases. Final procedures included 8 (35%) intralobar, 8 (35%) multilobar resections, and 7 (30%) hemispherotomies. Following reoperations, 14 (61%) patients were seizure free, 6 (26%) showed significant or worthwhile improvement, and 3 (13%) did not respond to surgery. Six of 8 patients who underwent the first resection before the age of 3 years, 6 of 8 whose first resection was limited by functional considerations, and all 7 with hemispherotomy as the final resection achieved seizure freedom after reoperation.

CONCLUSION: Reoperation is particularly beneficial for selected children with refractory epilepsy associated with cortical dysplasia that did not respond to an initial limited and/or early resection but achieved seizure freedom after extensive procedures. When indicated, reoperation should be performed at the youngest possible age to profit from higher functional plasticity in compensating for neurological deficit.

24/10/201324/10/2013

The preoperative use of navigated transcranial magnetic stimulation facilitates early resection of suspected low-grade gliomas in the motor cortex

Acta Neurochir (2013) 155:1813–1821

Resection is recommended for low-grade gliomas, but often it is not performed if the tumor is suspected of invading the primary motor cortex. The study aim is to assess what influence preoperative navigated transcranial magnetic stimulation (nTMS) has on the treatment strategy and clinical outcome for suspected low-grade gliomas in presumed motor eloquent location.

Methods This paper reports on all our patients with gliomas in the primary motor cortex that were non-enhancing on MRI, since we began using nTMS (n=11). For the comparison group, we identified the 11 most recent such patients just before we started using nTMS.

Results Exact delineation of motor functional versus nonfunctional cortical tissue was provided by nTMS in all cases, also within the area of altered FLAIR signal. In 6 out of 11 cases, the nTMS mapping result changed the treatment plan towards early and more extensive resection. Only one nTMS patient had another seizure within the follow-up period, whereas four patients in the comparison group had further seizures. In the nTMS group, 1 of 4 patients with pre-op neurological deficits improved by one year; whereas the comparison group had increased neurological deficits in 3 of the 8 patients not having surgery. The median (range) change of tumor volume from baseline to 1 year was −83 % (−67 % to −100 %) in the nTMS group, but +12 % (+40 % to −56 %) in the comparison group (p<0.001).

Conclusions nTMS provides accurate motor mapping results also in infiltrative gliomas and enables more frequent and more extensive surgical resection of non-enhancing gliomas in or near the primary motor cortex. The substantial differences observed here in neurological and oncological outcomes suggest that further comparative research is warranted.

23/10/201319/10/2013

De Novo Formation of a Cavernoma in a Thrombosed Developmental Venous Anomaly

Neurosurgery 73:E739–E745, 2013

Mechanisms that lead to de novo formations of nonfamilial-type cavernomas are not well understood. One of the interesting hypotheses is the causative relationship between developmental venous anomaly (DVA) and cavernoma formation. We report a unique case in which serial imaging demonstrated the evolution of de novo formation of a cavernoma in association with a thrombosed DVA. A detailed review of the causal hypothesis between a DVA and cavernoma is also provided.

CLINICAL PRESENTATION: We report a 37-year-old female patient in whom a cavernoma-like lesion arose 1 year after the progressive thrombosis of a medullary (or caput medusa) vein of a DVA. The presence of an acute angulation in the draining vein may have prompted an intrinsic outflow restriction. Possible worsening of venous disequilibrium led to subsequent thrombus progression, venous congestion, and occlusion of the vein with venous dilation and signs of stasis on follow-up magnetic resonance imaging. Finally, this developed into a lobulated lesion with salt-and-pepper appearance at the converging region of medullary tributaries, which typified the classic features of a cavernoma.

CONCLUSION: Compared with other published cases of de novo cavernoma formation in relation to a DVA, our case, for the first time, allows us to witness the temporal evolution from a thrombosed DVA to the birth of a cavernoma around it. This supports the hypothesis that the cavernoma can be an acquired disease that arises from a DVA.

22/10/201319/10/2013

Sagittal plane correction in pedicle subtraction osteotomy

J Neurosurg Spine 19:507–514, 2013

The Xia 3 SUK Direct Vertebral Rotation (DVR) System was developed for performing the vertebral derotation maneuver in scoliosis surgery. The author applied this device to sagittal plane correction in pedicle subtraction osteotomy for adult spinal deformity.

The surgical procedure included 1) preparing secure proximal and distal foundations for correction using mutisegmental pedicle screw-rod fixation (to avoid stress concentration to a specific screw-bone interface), 2) decancellating only the posterior two-thirds of the vertebral column, 3) providing supplemental interbody fusion above and below the osteotomy site (the anterior one-third of the vertebral column and interbody cages serve as an anterior column support and a pivot of correction), 4) closing the osteotomy by gradual approximation of SUK tubes secured to the proximal- and distal-most screw heads, and 5) connecting rods between the proximal and distal screw-rod constructs.

Eight consecutive patients with fixed sagittal imbalance were treated using this surgical procedure. No patient required distal fixation points extending to the sacrum and/or pelvis. The sagittal plane correction was 43°. The mean anterior deviation of the C-7 plumb line was improved from 12.7 cm to 4.0 cm immediately after surgery, and it was 6.0 cm at the final follow-up.

A pedicle subtraction osteotomy using the Xia 3 SUK DVR System ensures a safe and secure sagittal plane correction in adult spinal deformity.

21/10/201319/10/2013

Surgical consideration of cervical dumbbell tumors

Acta Neurochir (2013) 155:1907–1910

Nineteen patients with cervical dumbbell tumors treated surgically were analyzed retrospectively.

Methods Surgical strategies for dumbbell tumor were discussed from the perspective of safe, less-invasive surgery.

Results Patients included 6 men and 13 women, with a mean age at the time of surgery of 48.3 years (range, 25–70 years). Underlying pathologies included 16 schwannomas, 2 neurofibromas, and 1 double tumor (schwannoma and meningioma). According to Eden’s classification, one patient was classified as Type 1, 5 as Type 2, 8 as Type 3, and 5 as Type 4. In 13 cases, tumors were excised through the posterior approach alone, compared to five cases using the anterior approach. One case was excised using combined anterior and posterior approaches. Facetectomy was not performed in 18 cases. In one case, the facet joint on one side had already destroyed and needed instrumentation. Tumors were totally excised in all cases. Postoperatively, the patients did not display any further neurological deficit, with the exception of transient radiculopathy in two patients. Major surgical complications and cerebrospinal fluid leakage were not seen. Tumor recurrence and spinal segmental instability were not found during follow-up period (mean, 41.6 months).

Conclusions Dumbbell tumor surgery requires sufficient debulking of the epidural and paravertebral mass, using intraoperative nerve stimulation and Doppler ultrasonography to detect the vertebral artery. When using a posterior approach, recapping laminoplasty using an ultrasonic bone curette is very useful to remove tumor without sacrificing facet joints.

18/10/201316/10/2013

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.

17/10/201316/10/2013

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.

16/10/201313/10/2013

Novel augmented reality–assisted 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.

15/10/201313/10/2013

Orthotic (helmet) therapy in the treatment of plagiocephaly

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.

14/10/201313/10/2013

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.

11/10/201309/10/2013

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.

10/10/201310/10/2013

Incidence and Risk Factors for Dysphagia After Anterior Cervical Fusion

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

09/10/201305/10/2013

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.

08/10/201306/10/2013

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.

07/10/201305/10/2013

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

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.

04/10/201303/10/2013

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

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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