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Daily bibliographic review of the Neurosurgery Department. La Fe University Hospital. Valencia, Spain

The predictive value of T-tau and AB1-42 levels in idiopathic normal pressure hydrocephalus

Acta Neurochir (2017) 159:2293–2300

Idiopathic normal pressure hydrocephalus (INPH) has no reliable biomarker to assist in the selection of patients who could benefit from ventriculo-peritoneal (VP) shunt insertion. The neurodegenerative markers Ttau and Aβ1-42 have been found to successfully differentiate between Alzheimer’s disease (AD) and INPH and therefore are candidate biomarkers for prognosis and shunt response in INPH. The aim of this study was to test the predictive value of cerebrospinal fluid (CSF) T-tau and Aβ1-42 for shunt responsiveness. In particular, we pay attention to the subset of INPH patients with raised T-tau, who are often expected to be poor surgical candidates.

Methods: Single-centre retrospective analysis of probable INPH patients with CSF samples collected from 2006 to 2016. Index test: CSF levels of T-tau and Aβ1-42. Reference standard: postoperative outcome. ROC analysis assessed the predictive value.

Results: A total of 144 CSF samples from INPH patients were analysed. Lumbar T-tau was a good predictor of postoperative mobility (AUROC 0.80). The majority of patients with a co-existing neurodegenerative disease responded well, including those with high T-tau levels.

Conclusion: INPH patients tended to exhibit low levels of CSF T-tau, and this can be a good predictor outcome. However levels are highly variable between individuals. Raised T-tau and being shunt-responsive are not mutually exclusive, and such patients ought not necessarily be excluded from having a VP shunt.A combined panel of markers may be a more specific method for aiding selection of patients for VP shunt insertion. This is the most comprehensive presentation of CSF samples from INPH patients to date, thus providing further reference values to the current literature.

Interactive iBook-Based Patient Education in a NeuroTrauma Clinic

Neurosurgery 81:787–794, 2017

Traumatic brain injury (TBI) is a leading cause of death and disability in the United States. Educational interventions may alleviate the burden of TBI for patients and their families. Interactive modalities that involve engagement with the educational material may enhance patient knowledge acquisition when compared to static text-based educational material.

OBJECTIVE: To determine the effects of educational interventions in the outpatient setting on self-reported patient knowledge, with a focus on iPad-based (Apple, Cupertino, California) interactive modules.

METHODS: Patients and family members presenting to a NeuroTrauma clinic at a tertiary care academic medical center completed a presurvey assessing baseline knowledge of TBI or concussion, depending on the diagnosis. Subjects then received either an interactive iBook (Apple) on TBI or concussion, or an informative pamphlet with identical information in text format. Subjects then completed a postsurvey prior to seeing the neurosurgeon.

RESULTS: All subjects (n = 152) significantly improved on self-reported knowledge measures following administration of either an iBook (Apple) or pamphlet (P < .01, 95% confidence interval [CI]). Subjects receiving the iBook (n = 122) performed significantly better on the postsurvey (P < .01, 95% CI), despite equivalent presurvey scores, when compared to those receiving pamphlets (n = 30). Lastly, patients preferred the iBook to pamphlets (P < .01, 95% CI).

CONCLUSION: Educational interventions in the outpatient NeuroTrauma setting led to significant improvement in self-reported measures of patient and family knowledge. This improved understanding may increase compliance with the neurosurgeon’s recommendations and may help reduce the potential anxiety and complications that arise following a TBI.

Microvascular Decompression for Trigeminal Neuralgia Using a Novel Fenestrated Clip and Tentorial Flap Technique

WORLD NEUROSURGERY 106: 775-784, 2017

Microvascular decompression (MVD) for neurovascular compression syndromes, such as trigeminal neuralgia and hemifacial spasm, has been traditionally described as an interposing technique using Teflon. Some alternative interposing materials have been proposed. In addition, transposing techniques have been increasingly reported as an alternative with a potentially lower recurrence rate and fewer complications.

OBJECTIVE: To describe our experience with a technique consisting of transposition of the superior cerebellar artery using a fenestrated clip and a tentorial flap in patients with trigeminal neuralgia.

METHODS: We describe a novel transposing technique using a fenestrated clip and a tentorial flap in patients with neurovascular compression. An illustrative case is provided of an 83-year-old female patient who complained of a 4-year history of left trigeminal neuralgia caused by compression by the superior cerebellar artery who was treated with this technique. Furthermore, a thorough review of the literature is presented. –

RESULTS: The patient underwent the procedure with the proposed technique without complication. Both the surgery and the postoperative course were uneventful. The patient remains asymptomatic 1 year after the procedure.

CONCLUSION: We propose a novel technique for the treatment of trigeminal neuralgia, eliminating the need for padding the vessel with a foreign body. This technique can be applied successfully in selected cases of neurovascular compression syndromes.

Complex Internal Carotid Artery Aneurysm Treated by Extracranial to Intracranial Bypass Using High-Flow Grafts with Therapeutic Internal Carotid Artery Occlusion

Neurosurgery 81:672–679, 2017

Although the extracranial-to-intracranial high-flow bypass (EC-IC HFB) continues to be indispensable for complex aneurysms, the risk factors for the graft occlusion and whether the graft size changes after the bypass have not been well established.

OBJECTIVE: To evaluate the risk factors for the graft occlusion and to confirm whether graft diameters changed over time.

METHODS: The data of 75 patients who suffered from complex internal carotid artery (ICA) aneurysms and were treated by EC-IC HFB using radial artery graft (RAG) or saphenous vein graft (SVG) with therapeutic ICA occlusion were evaluated. Clinical and radiological characteristics were compared in patients with and without the graft occlusion by the logrank test. Graft diameters measured preoperatively, postoperatively, at 6 months, and at 1 year were compared by paired t-test.

RESULTS: During a follow-up period (median 26.2 months), graft occlusions were seen in 4 patients (5.3%), and these were the SVGs. Only SVG was related to graft occlusion (P<.001). There was a significant increase with time in RAG diameters (preoperative, 3.1 ± 0.41 mm; postoperative, 3.6 ± 0.65 mm; 6 months, 4.3 ± 1.0 mm; 1 year, 4.4 ± 1.0 mm), while there were no significant diameter changes in SVGs.

CONCLUSION: The present study showed that the SVG was related to the graft occlusion and RAGs gradually enlarged. Unless Allen test is negative, RAG may be better to be used as a graft in EC-IC HFB if therapeutic ICA occlusion is needed.

Stereoelectroencephalography Using Magnetic Resonance Angiography for Avascular Trajectory Planning

Neurosurgery 81:688–695, 2017

Stereoelectroencephalography (SEEG) requires high-quality angiographic studies because avascular trajectory planning is a prerequisite for the safety of this procedure. Some epilepsy surgery groups have begun to use computed tomography angiography and magnetic resonance T1-weighted sequence with contrast enhancement for this purpose.

OBJECTIVE: To present the first series of patients with avascular trajectory planning of SEEG based on magnetic resonance angiography (MRA).

METHODS: Thirty-six SEEG explorations for drug-resistant focal epilepsy were performed from January 2013 to December 2015. A retrospective analysis of this consecutive surgical series was then performed. Magnetic resonance imaging included MRA with a modified contrast-enhanced magnetic resonance venography (MRV) protocol with a short acquisition delay, which allowed simultaneous arterial and venous visualization. Our criteria for satisfactoryMRAwere the visualization of at least first-order branches of the angular artery, paracentral and calcarine artery, and third-order tributaries of the superficial Sylvian vein, vein of Labbe, and vein of Trolard.

RESULTS: Thirty-four patients underwent 36 SEEG explorations with 369 electrodes carrying 4321 contacts. Contrast-enhanced MRA using the MRV protocol was judged satisfactory for SEEG planning in all explorations. Postoperative complications were not observed in our series of 36 SEEG explorations, which included 50 transopercular insular trajectories.

CONCLUSION: MRA using an MRV protocol may be applied for avascular trajectory planning during SEEG procedures. This technique provides a simultaneous visualization of cortical arteries and veins without the need for additional radiation exposure or intraarterial catheter placement.

 

Multimodality Treatment of Skull Base Chondrosarcomas

Neurosurgery 81:520–530, 2017

Limited data exist to guide the multimodality management of chondrosarcomas (CSAs) arising in the skull base.

OBJECTIVE : To determine the impact of histological subtype/grade on progression-free survival (PFS) and the indications for surgery, radiation, and chemotherapy based on histology.

METHODS: A retrospective review was performed of 37 patients (conventional type: 81%, mesenchymal: 16.2%, dedifferentiated: 2.7%) treated at The University of Texas M.D. Anderson Cancer Center. Of the conventional subtype, 23% were grade 1, 63% were grade 2, and 14% were grade 3. In addition to surgery, mesenchymal/dedifferentiated CSAs (18% of the cohort) underwent neoadjuvant chemotherapy and 48.6% of the overall cohort received adjuvant radiotherapy. Histological grade/subtype and treatment factors were assessed for impact on median PFS (primary outcome).

RESULTS: Conventional subtype vs mesenchymal/dedifferentiated was positively associated with median PFS (166 vs 24 months, P < .05). Increasing conventional grade inversely correlated with median PFS (P < .05). Gross total resection positively impacted PFS in conventionalCSAs (111.8 vs 42.9months, P=.201) and mesenchymal/dedifferentiated CSAs (58.2 vs 1.0 month, P < .05). Adjuvant radiotherapy significantly impacted PFS in conventional grades 2 and 3 (182 vs 79 months, P < .05) and a positive trend with mesenchymal/dedifferentiated CSAs (43.5 vs 22.0 months). Chemotherapy improved PFS for mesenchymal/dedifferentiated CSAs (50 vs 9 months, P = .089).

CONCLUSION: There is a potential need for histological subtype/grade specific treatment protocols. For conventional CSAs, surgery alone provides optimal results grade 1 CSAs, while resection with adjuvant radiotherapy yields the best outcomefor grade 2 and 3 CSAs. Improvements in PFS seen with neoadjuvant therapy in mesenchymal/dedifferentiated CSAs indicate a potential role for systemic therapies. Larger studies are necessary to confirm the proposed treatment protocols.

Pelvic retroversion: a compensatory mechanism for lumbar stenosis

J Neurosurg Spine 27:137–144, 2017

The flexed posture of the proximal (L1–3) or distal (L4–S1) lumbar spine increases the diameter of the spinal canal and neuroforamina and can relieve symptoms of neurogenic claudication. Distal lumbar flexion can result in pelvic retroversion; therefore, in cases of flexible sagittal imbalance, pelvic retroversion may be compensatory for lumbar stenosis and not solely compensatory for the sagittal imbalance as previously thought. The authors investigate underlying causes for pelvic retroversion in patients with flexible sagittal imbalance.

METHODS One hundred thirty-eight patients with sagittal imbalance who underwent a total of 148 fusion procedures of the thoracolumbar spine were identified from a prospective clinical database. Radiographic parameters were obtained from images preoperatively, intraoperatively, and at 6-month and 2-year follow-up. A cohort of 24 patients with flexible sagittal imbalance was identified and individually matched with a control cohort of 23 patients with fixed deformities. Flexible deformities were defined as a 10° change in lumbar lordosis between weight-bearing and non–weight-bearing images. Pelvic retroversion was quantified as the ratio of pelvic tilt (PT) to pelvic incidence (PI).

RESULTS The average difference between lumbar lordosis on supine MR images and standing radiographs was 15° in the flexible cohort. Sixty-eight percent of the patients in the flexible cohort were diagnosed preoperatively with lumbar stenosis compared with only 22% in the fixed sagittal imbalance cohort (p = 0.0032). There was no difference between the flexible and fixed cohorts with regard to C-2 sagittal vertical axis (SVA) (p = 0.95) or C-7 SVA (p = 0.43). When assessing for postural compensation by pelvic retroversion in the stenotic patients and nonstenotic patients, the PT/PI ratio was found to be significantly greater in the patients with stenosis (p = 0.019).

CONCLUSIONS For flexible sagittal imbalance, preoperative attention should be given to the root cause of the sagittal misalignment, which could be compensation for lumbar stenosis. Pelvic retroversion can be compensatory for both the lumbar stenosis as well as for sagittal imbalance.

 

The paramedian supracerebellar infratentorial approach

Acta Neurochir (2017) 159:1529–1532

Lesions of the superior cerebellar surface, pineal region, lateral and dorsal midbrain and mesial temporal lobe are challenging to treat and often require neurosurgical intervention.

Methods The paramedian variation of the supracerebellar infratentorial approach utilizes the downward slope of the cerebellum to facilitate exposure and the lower density of cerebellar bridging veins away from the midline decreases the need to sacrifice larger venous channels. We also discuss our experiences with the approach, and some of the drawbacks and nuances that we have encountered as it has evolved over the years.

Conclusions This approach is versatile and effective and the authors’ surgical approach of choice for resecting these challenging lesions.

 

Clinical Experience and Results of Microsurgical Resection of Arteriovenous Malformation in the Presence of Space-Occupying Intracerebral Hematoma

Neurosurgery 81:75–86, 2017

Management of ruptured arteriovenous malformations (AVMs) with a mass-producing intracerebral hematoma (ICH) represents a surgical dilemma.

OBJECTIVE: To evaluate the clinical outcome and obliteration rates of microsurgical resection of AVM when performed concomitantly with evacuation of an associated spaceoccupying ICH.

METHODS: Data of patients with AVMwere collected prospectively. Cases were identified in which an AVM was resected and an associated space-occupying ICH was evacuated at the same time, and divided into “group 1,” in which the surgery was performed acutely within 48 h of presentation (secondary to elevated intracranial pressure); and “group 2,” in which selected patients were operated upon in the presence of a liquefying ICH in the “subacute”stage. Clinical outcomes were assessed using themodified Rankin Scale, with a score of 0 to 2 considered a good outcome. Obliteration rateswere assessed using postoperative angiography.

RESULTS: From 2001 to 2015, 131 patients underwent microsurgical resection of an AVM, of which 65 cases were included. In “group 1” (n = 21; Spetzler-Ponce class A = 13, class B = 5, and class C = 3), 11 of 21 (52%) had a good outcome and in 18 of 19 (95%) of those who had a postoperative angiogramthe AVMswere completely obliterated. In “group 2”(n=44; Spetzler-Ponce class A=33, class B=9, and class C=2), 31 of 44 (93%) had a good outcome and 42 of 44 (95%) were obliterated with a single procedure. For supratentorial AVMs, the ICH cavity was utilized to provide an operative trajectory to a deep AVM in 11 cases, and in 26 cases the ICH cavity was deep to the AVM and hence facilitated the deep dissection of the nidus.

CONCLUSION: In selected patients the presence of a liquefying ICH cavity may facilitate the resection of AVMs when performed in the subacute stage resulting in a good neurological outcome and high obliteration rate.

Perpetuation of errors in illustrations of cranial nerve anatomy

J Neurosurg 127:192–198, 2017

For more than 230 years, anatomical illustrations have faithfully reproduced the German medical student Thomas Soemmerring’s cranial nerve (CN) arrangement. Virtually all contemporary atlases show the abducens, facial, and vestibulocochlear nerves (CNs VI–VIII) all emerging from the pontomedullary groove, as originally depicted by Soemmerring in 1778.

Direct observation at microsurgery of the cerebellopontine angle reveals that CN VII emerges caudal to the CN VIII root from the lower lateral pons rather than the pontomedullary groove. Additionally, the CN VI root lies in the pontomedullary groove caudal to both CN VII and VIII in the vast majority of cases.

In this high-resolution 3D MRI study, the exit location of CN VI was caudal to the CN VII/VIII complex in 93% of the cases. Clearly, Soemmerring’s rostrocaudal numbering system of CN VI-VII-VIII (abducens-facial-vestibulocochlear CNs) should instead be VIII-VII-VI (vestibulocochlear- facial-abducens CNs). While the inaccuracy of the CN numbering system is of note, what is remarkable is that generations of authors have almost universally chosen to perpetuate this ancient error. No doubt some did this through faithful copying of their predecessors. Others, it could be speculated, chose to depict the CN relationships incorrectly rather than run contrary to long-established dogma.

This study is not advocating that a universally recognized numbering scheme be revised, as this would certainly create confusion. The authors do advocate that future depictions of the anatomical arrangements of the brainstem roots of CNs VI, VII, and VIII ought to reflect actual anatomy, rather than be contorted to conform with the classical CN numbering system.

 

I can hear my shunt—audible noises associated with CSF shunts in hydrocephalic patients

Acta Neurochir (2017) 159:981–986

Cerebrospinal fluid (CSF) shunts are life-long implants, and patients have reported anecdotally on noises associated with their shunts. There is, however, a marked lack of information regarding acoustic phenomena related to CSF shunts.

Methods We identified all patients who had been treated or followed in our neurosurgical department within a 15-year period from January 2000 up to the end of 2014. After approval of the local ethics committee all patients who were cognitively intact were explored by a questionnaire and by personal interview about acoustic phenomena related to their shunts.

Results Three hundred forty-seven patients were eligible for the survey, and 260 patients completed the questionnaire. Twenty-nine patients (11.2%) reported on noises raised by their shunts. All of them experienced short-lasting noises while changing body posture, mainly from a horizontal to an upright position, or while reclining the head. Most of the patients reported on soft sounds, but loud and even very loud noises occurred in some patients. Seventy-six percent of the patients were not bothered by these noises as they considered it as a normal part of the therapy or as proof that the shunt device was functioning. Modern valves with gravitational units are prone to produce noises in young adults, but nearly all valve types can evoke noises.

Conclusions Noises caused by a shunt do occur in a considerable number of patients with shunts. One should be aware of this phenomenon, and these patients must be taken seriously.

Intraoperative image updating for brain shift following dural opening

J Neurosurg 126:1924–1933, 2017

Preoperative magnetic resonance images (pMR) are typically coregistered to provide intraoperative navigation, the accuracy of which can be significantly compromised by brain deformation. In this study, the authors generated updated MR images (uMR) in the operating room (OR) to compensate for brain shift due to dural opening, and evaluated the accuracy and computational efficiency of the process.

METHODS: In 20 open cranial neurosurgical cases, a pair of intraoperative stereovision (iSV) images was acquired after dural opening to reconstruct a 3D profile of the exposed cortical surface. The iSV surface was registered with pMR to detect cortical displacements that were assimilated by a biomechanical model to estimate whole-brain nonrigid deformation and produce uMR in the OR. The uMR views were displayed on a commercial navigation system and compared side by side with the corresponding coregistered pMR. A tracked stylus was used to acquire coordinate locations of features on the cortical surface that served as independent positions for calculating target registration errors (TREs) for the coregistered uMR and pMR image volumes.

RESULTS: The uMR views were visually more accurate and well aligned with the iSV surface in terms of both geometry and texture compared with pMR where misalignment was evident. The average misfit between model estimates and measured displacements was 1.80 ± 0.35 mm, compared with the average initial misfit of 7.10 ± 2.78 mm between iSV and pMR, and the average TRE was 1.60 ± 0.43 mm across the 20 patients in the uMR image volume, compared with 7.31 ± 2.82 mm on average in the pMR cases. The iSV also proved to be accurate with an average error of 1.20 ± 0.37 mm. The overall computational time required to generate the uMR views was 7–8 minutes.

CONCLUSIONS: This study compensated for brain deformation caused by intraoperative dural opening using computational model–based assimilation of iSV cortical surface displacements. The uMR proved to be more accurate in terms of model-data misfit and TRE in the 20 patient cases evaluated relative to pMR. The computational time was acceptable (7–8 minutes) and the process caused minimal interruption of surgical workflow.

Safety of Superior Petrosal Vein Sacrifice During Microvascular Decompression of the Trigeminal Nerve

WORLD NEUROSURGERY 103: 84-87, 2017

Microvascular decompression (MVD) is a safe and effective treatment for trigeminal neuralgia. Cerebellar venous infarction is a complication associated with surgical sacrifice of the superior petrosal vein (SPV). The SPV intervenes between the trigeminal nerve and the surgeon. Optimal exposure of the cisternal trigeminal nerve, particularly at the brainstem, can be achieved by sacrificing the SPV. We analyzed a cohort of 224 patients to determine the frequency of cerebellar venous infarction.

METHODS: Retrospective analysis of records and neuroradiology for patients undergoing trigeminal MVD at the Manchester Skull Base Unit between August 1st 2008 and July 31st 2015.

RESULTS: A total of 184 of 224 (82%) patients had coagulation and division of the main stem of the SPV. There were no cases of venous infarction. There was one case of mild, transient, cerebellar symptoms and signs, with no radiologic evidence of venous infarction. This patient had SPV sacrifice at surgery but also had postoperative thrombosis of the transverse sinus. Venous sinus thrombosis affected 5 of 184 (2.7%) patients. A total of 208 of 224 (93%) patients had a good outcome with improvement or resolution of their trigeminal neuralgia at 3 months.

CONCLUSIONS: The overall rate of venous complications in this study was 2.7%; however, we had no cases of venous infarction in 184 patients who had sacrifice of the SPV. The incidence of venous infarction associated with SPV obliteration during MVD surgery is therefore <0.5%. SPV sacrifice may be used where necessary to optimize visualization of the root entry zone and maximize the chance of effective decompression of the trigeminal nerve.

A Simple and Reliable Method for the Diagnosis of Ventriculoperitoneal Shunt Malfunction

OBJECTIVE: To provide a simple and reliable method for the diagnosis of ventriculoperitoneal shunt malfunction.

METHODS: A total of 14 participants were enrolled in this study, consisting of 7 patients with suspected shunt malfunction and 7 control cases with apparent normal drainage. In all cases, 0.1 mL of 5% glucose solution was injected into the reservoir and 0.1 mL of cerebrospinal fluid was withdrawn from the reservoir 20 minutes later to measure glucose concentration.

RESULTS: The glucose concentration in cerebrospinal fluid of the shunt malfunction group was greater than that of the control group (P < 0.05).

CONCLUSIONS: The proposed method is reliable, safe, and relatively simple for the diagnosis of ventriculoperitoneal shunt malfunction and provides a reference for treatment.

Cerebral Revascularization for Aneurysms in the Flow-Diverter Era

Neurosurgery 80:759–768, 2017

Cerebral bypass has been an important tool in the treatment of complex intracranial aneurysms. The recent advent of flow-diverting stents (FDS) has expanded the capacity for endovascular arterial reconstruction.

OBJECTIVE: We investigated how the advent of FDS has impacted the application and outcomes of cerebral bypass in the treatment of intracranial aneurysms.

METHODS: We reviewed a consecutive series of cerebral bypasses during aneurysm surgery over the course of 10 years. FDS were in active use during the last 5 years of this series. We compared the clinical characteristics, surgical technique, and outcomes of patients who required cerebral bypass for aneurysm treatment during the preflow diversion era (PreFD) with those of the postflow diversion era (PostFD).

RESULTS: We treated 1061 aneurysms in the PreFD era (from July 2005 through June 2010) and 1348 in the PostFD era (from July 2010 through June 2015). Eighty-five PreFD patients (8%) and 45 PostFD patients (3%) were treated with cerebral bypass. PreFD patients had better baseline functional status compared to PostFD patients with average preoperative modified Rankin Scale score of 0.55 in PreFDand 1.18 in PostFD.

CONCLUSION: After the introduction of FDS, cerebral bypass was performed in a lower proportion of patients with aneurysms. Patients selected for bypass in the flow-diverter era had worse preoperative modified Rankin Scale scores indicating a greater complexity of the patients. Cerebral bypass in well-selected patients and revascularization remains an important technique in vascular neurosurgery. It is also useful as a rescue technique after failed FDS treatment of aneurysms.

Is lumbar facet fusion biomechanically equivalent to lumbar posterolateral onlay fusion?

J Neurosurg Spine 26:586–593, 2017

This study was designed with the following research objectives: 1) to determine the efficacy of facet fusion with recombinant human bone morphogenetic protein–2 (rhBMP-2) on an absorbable collagen sponge (ACS) in an ovine lumbar facet fusion model; 2) to radiographically and histologically compare the efficacy of lumbar facet fusion with rhBMP-2/ACS to facet fusion with an iliac crest bone graft (ICBG); and 3) to biomechanically compare lumbar facet fusion with rhBMP-2/ACS to lumbar posterolateral fusion (PLF) with ICBG.

METHODS The efficacies of the 3 treatments to induce fusion were evaluated in an instrumented ovine lumbar fusion model. Eight sheep had 10 cm3/side ICBG placed as an onlay graft for PLF at L2–3. At the adjacent L3–4 level, 0.5 cm3/ side ICBG was placed for facet fusion. Finally, 0.5 cm3/side rhBMP-2/ACS (0.43 mg/ml) was placed for facet fusion at L4–5. CT scans were obtained at 2, 4, and 6 months postoperatively with 2 reviewers conducting an evaluation of the 6-month results for all treated spinal levels. All 8 sheep were killed at 6 months, and all posterolateral instrumentation was removed at this time. The spines were then sectioned through L3–4 to allow for nondestructive unconstrained bio- mechanical testing of the L2–3 and L4–5 segments. All treated spinal levels were analyzed using undecalcified histology with corresponding microradiography. Statistical comparisons were made between the treatment groups.

RESULTS The PLF with ICBG (ICBG PLF group) and the rhBMP-2 facet fusion (rhBMP-2 Facet group) treatment groups demonstrated similar levels of stiffness, with the rhBMP-2 Facet group having on average slightly higher stiffness in all 6 loading directions. All 8 levels in the autograft facet fusion treatment group demonstrated CT radiographic and histological fusion. All 8 levels in the rhBMP-2 Facet group showed bilateral CT radiographic and histological fusion. Six of 16 rhBMP-2/ACS-treated facet defects demonstrated small intraosseous hematomas or seromas. Four of the 8 levels (50%) in the ICBG PLF treatment group demonstrated bilateral histological fusion. Three of 8 levels in the ICBG PLF treatment group showed unilateral fusion. One of the 8 levels in the ICBG PLF treatment group demonstrated bilateral histological nonfusion.

CONCLUSIONS Both rhBMP-2/ACS and autograft demonstrated 100% efficacy when used for facet fusion in the instrumented ovine model. However, the ICBG PLF treatment group only demonstrated a 50% bilateral fusion rate. Biomechanically, the ICBG PLF and rhBMP-2 Facet groups demonstrated similar stiffness in all 6 loading directions, with the rhBMP-2 Facet group having on average slightly higher stiffness in all directions.

Reappearance of arteriovenous malformations after complete resection of ruptured arteriovenous malformations

J Neurosurg 126:1088–1093, 2017

Ruptured arteriovenous malformations (AVMs) are often obliterated after emergency microsurgical treatment. However, some studies have reported AVM recurrence after the obliteration of ruptured AVMs. The authors report their experience with AVM recurrence after successful microsurgical treatment of ruptured AVMs.

METHODS The authors reviewed the medical data of 139 consecutive patients who underwent microsurgery at the authors’ institution for ruptured AVM between 2002 and 2012. Each patient underwent a conventional cerebral angiography examination immediately after the surgery. Subsequent follow-ups were performed with MR angiography after 6 months, and, if there was no indication of AVM recurrence, patients were followed up with conventional cerebral angiography between 1 and 2 years after the treatment; pediatric patients were followed up until age 18 years. Recurrence was defined as new radiological evidence of an AVM at the site of a ruptured AVM or a new hemorrhage in patients with angiographically documented AVM obliteration on postoperative angiograms.

RESULTS The mean age of the patients at the time of ruptured AVM diagnosis was 30.8 years (SD ± 5, range 4–69 years), and 44 of the patients were younger than 18 years (the mean age at diagnosis in this pediatric subgroup was 11.4 years [range 4–17.9 years]). Complete AVM obliteration after the initial microsurgery was observed in 123 patients (89.5%). Reappearance of an AVM was noted in 7 patients between 12 and 42 months after the treatment, and all of these patients were younger than 18 years. The recurrent AVM was located in an eloquent zone in 4 patients, and deep venous drainage was noted in 3 patients. Radiosurgery was performed in 6 of these patients, and 1 patient underwent another microsurgical procedure. The authors noted only one rebleeding due to an AVM recurrence during the latency period after radiosurgery.

CONCLUSIONS The recurrence of an AVM is fairly rare and affects mostly pediatric patients. Therefore, especially in children, long-term angiographic follow-up is required to detect AVM recurrence or an AVM remnant. The authors stress the need for discussion involving a multidisciplinary neurosurgical team to decide on treatment in cases of any AVM recurrence or remnant.

Surgery for meningioma in the elderly and long-term survival

J Neurosurg 126:1201–1211, 2017

The purpose of this study was to compare long-term prognosis after meningioma surgery in elderly and younger patients as well as to compare survival of elderly patients with surgically treated meningioma to survival rates for the general population.

METHODS Five hundred meningioma patients (median follow-up 90 months) who underwent surgery between 1994 and 2009 were subdivided into “elderly” (age ≥ 65 years, n = 162) and “younger” (age < 65 years, n = 338) groups for uni- and multivariate analyses. Mortality was compared with rates for the age- and sex-matched general population.

RESULTS The median age at diagnosis was 71 in the elderly group and 51 years in the younger group. Sex, intracranial tumor location, grade of resection, radiotherapy, and histopathological subtypes were similar in the 2 groups. Highgrade (WHO Grades II and III) and spinal tumors were more common in older patients than in younger patients (15% vs 8%, p = 0.017, and 12% vs 4%, p = 0.001, respectively). The progression-free interval (PFI) was similar in the 2 groups, whereas mortality at 3 months after surgery was higher and median overall survival (OS) was shorter in older patients (7%, 191 months) than in younger patients (1%, median not reached; HR 4.9, 95% CI 2.75–8.74; p < 0.001). Otherwise, the median OS in elderly patients did not differ from the anticipated general life expectancy (HR 1.03, 95% CI 0.70–1.50; p = 0.886). Within the older patient group, PFI was lower in patients with high-grade meningiomas (HR 24.74, 95% CI 4.23–144.66; p < 0.001) and after subtotal resection (HR 10.57, 95% CI 2.23–50.05; p = 0.003). Although extent of resection was independent of perioperative mortality, the median OS was longer after gross-total resection than after subtotal resection (HR 2.7, 95% CI 1.09–6.69; p = 0.032).

CONCLUSIONS Elderly patients with surgically treated meningioma do not suffer from impaired survival compared with the age-matched general population, and their PFI is similar to that of younger meningioma patients. These data help mitigate fears concerning surgical treatment of elderly patients in an aging society.

Intracranial pressure monitoring after primary decompressive craniectomy in traumatic brain injury

Acta Neurochir (2017) 159:615–622

Intracranial pressure (ICP) monitoring represents an important tool in the management of traumatic brain injury (TBI). Although current information exists regarding ICP monitoring in secondary decompressive craniectomy (DC), little is known after primary DC following emergency hematoma evacuation.

Methods: Retrospective analysis of prospectively collected data. Inclusion criteria were age ≥18 years and admission to the intensive care unit (ICU) for TBI and ICP monitoring after primary DC. Exclusion criteria were ICU length of stay (LOS) <1 day and pregnancy. Major objectives were: (1) to analyze changes in ICP/cerebral perfusion pressure (CPP) after primary DC, (2) to evaluate the relationship between ICP/CPP and neurological outcome and (3) to characterize and evaluate ICP-driven therapies after DC.

Results: A total of 34 patients were enrolled. Over 308 days of ICP/CPP monitoring, 130 days with at least one episode of intracranial hypertension (26 patients, 76.5%) and 57 days with at least one episode of CPP <60 mmHg (22 patients, 64.7%) were recorded. A statistically significant relationship was discovered between the Glasgow Outcome Scale (GOS) scores and mean post-decompression ICP (p < 0.04) andbetween GOS and CPP minimum (CPPmin) (p < 0.04). After DC, persisting intracranial hypertension was treated with: barbiturate coma (n = 7, 20.6%), external ventricular drain (EVD) (n = 4, 11.8%), DC diameter widening (n = 1, 2.9%) and removal of newly formed hematomas (n = 3, 8.8%).

Conclusion: Intracranial hypertension and/or low CPP occurs frequently after primary DC; their occurence is associated with an unfavorable neurological outcome. ICP monitoring appears useful in guiding therapy after primary DC.

 

The white matter tracts of the cerebrum in ventricular surgery and hydrocephalus

J Neurosurg 126:945–971, 2017

The relationship of the white matter tracts to the lateral ventricles is important when planning surgical approaches to the ventricles and in understanding the symptoms of hydrocephalus. The authors’ aim was to explore the relationship of the white matter tracts of the cerebrum to the lateral ventricles using fiber dissection technique and MR tractography and to discuss these findings in relation to approaches to ventricular lesions.

METHODS Forty adult human formalin-fixed cadaveric hemispheres (20 brains) and 3 whole heads were examined using fiber dissection technique. The dissections were performed from lateral to medial, medial to lateral, superior to inferior, and inferior to superior. MR tractography showing the lateral ventricles aided in the understanding of the 3D relationships of the white matter tracts with the lateral ventricles.

RESULTS The relationship between the lateral ventricles and the superior longitudinal I, II, and III, arcuate, vertical occipital, middle longitudinal, inferior longitudinal, inferior frontooccipital, uncinate, sledge runner, and lingular amygda-loidal fasciculi; and the anterior commissure fibers, optic radiations, internal capsule, corona radiata, thalamic radiations, cingulum, corpus callosum, fornix, caudate nucleus, thalamus, stria terminalis, and stria medullaris thalami were defined anatomically and radiologically. These fibers and structures have a consistent relationship to the lateral ventricles.

CONCLUSIONS Knowledge of the relationship of the white matter tracts of the cerebrum to the lateral ventricles should aid in planning more accurate surgery for lesions within the lateral ventricles.

Neurosurgery Department. “La Fe” University Hospital. Valencia, Spain

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