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Microneurosurgical Management Of Ophthalmic Segment Aneurysms

Ophthalmic segment aneurysms

Acta Neurochir (2013) 155:1025–1029

Power drilling commonly used for anterior clinoidectomy and optic canal unroofing can result in thermal injury to the optic nerve.

Methods The authors describe an intradural “limited drill” technique of anterior clinoidectomy and optic canal unroofing for microneurosurgical management of ophthalmic segment aneurysms, where optic canal unroofing is done with 1 mm Kerrison punch and the use of the power drill is restricted to anterior clinoidectomy to avoid thermal injury to the optic nerve. The optic nerve, internal carotid artery (ICA), and aneurysm are covered with wet gelfoam pieces to prevent any inadvertent contact with the drill.

Conclusion “Limited drill technique” is a safe and effective technique of anterior clinoidectomy and optic canal unroofing. Key points • Anterior clinoidectomy and optic canal unroofing is an important skull base technique required for safe clipping of the majority of ophthalmic segment aneurysms • Power drilling commonly used for optic canal unroofing can cause thermal injury to optic nerve • More than 2 mm free space is available around the optic nerve in the optic canal • Foot plate of 1 mm Kerrison punch can be safely introduced within a normal optic canal without causing mechanical injury to the optic nerve • Reflection of posteriorly based dural flap acts as a dural barrier, preventing direct contact of drill bit to optic nerve, internal carotid artery and aneurysm during drilling • Entanglement of cottonoids to rotating drill bit is a major problem in intradural anterior clinoidectomy • Wet gelfoam pieces do not get entangled to the rotating drill bit • Structures surrounding the area of drilling can be covered with wet gel foam pieces to prevent direct contact of the drill to neurovascular structures • Opened cisterns can be covered with wet gelfoam pieces during drilling to prevent deposition of bone dust in the subarachnoid space • “Limited drill technique” of anterior clinoidectomy and optic canal unroofing is a safe and effective technique for the exposure of ophthalmic segment aneurysms.

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Stereotactic Biopsy for Brainstem Tumors

stereotactic biopsy for brainstem tumors

Neurosurgery 72:873–882, 2013

The feasibility and safety of stereotactic biopsy for brainstem tumors (BSTs) are controversial. Although magnetic resonance imaging (MRI) has been reported as the preferred diagnostic tool, histopathological analysis is frequently necessary to establish a definitive diagnosis. Recent advances in molecular characterization of brainstem gliomas—accounting for the majority of BSTs—have revealed several potential targets for molecular-based therapies. Hence, a molecular stereotactic biopsy that combines histopathological diagnosis withmolecular-genetic analysis will become increasingly important for patients with BSTs.

OBJECTIVE: We conducted a systemic review and meta-analysis to determine the risks and benefits of stereotactic biopsy for BSTs.

METHODS: A systematic search in PubMed, Embase, and the Web of Science yielded 3766 potentially eligible abstracts. Meta-analysis was conducted on 38 studies describing 1480 biopsy procedures for BSTs. Primary outcome measures were diagnostic success and procedure-related complications. Data were analyzed according to standard meta-analytic techniques.

RESULTS: The weighted average proportions across the analyzed studies were: 96.2% (95% confidence interval [CI]: 94.5%-97.6%) for diagnostic success, 7.8% (95% CI: 5.6%- 10.2%) for overall morbidity, 1.7% (95% CI: 0.9%-2.7%) for permanent morbidity, and 0.9% (95% CI: 0.5%-1.4%) for mortality. Meta-regression revealed a significant correlation between diagnostic success rates and the number of biopsy procedures performed annually in each center (P = .011). Other factors did not affect the outcome measures.

CONCLUSION: Stereotactic biopsy of BSTs is safe. It allows exact histopathological diagnosis as a prerequisite for adequate treatment and opens new perspectives for the molecular characterization of these tumors as a crucial first step toward more individualized treatment concepts.

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Results of the NeuroBlate System first-in-humans Phase I clinical trial for recurrent glioblastoma

 

NeuroBlate

J Neurosurg 118:1202–1219, 2013

Laser interstitial thermal therapy has been used as an ablative treatment for glioma; however, its development was limited due to technical issues. The NeuroBlate System incorporates several technological advances to overcome these drawbacks. The authors report a Phase I, thermal dose–escalation trial assessing the safety and efficacy of NeuroBlate in recurrent glioblastoma multiforme (rGBM).

Methods. Adults with suspected supratentorial rGBM of 15- to 40-mm dimension and a Karnofsky Performance Status score of ≥ 60 were eligible. After confirmatory biopsy, treatment was delivered using a rigid, gas-cooled, sidefiring laser probe. Treatment was monitored using real-time MRI thermometry, and proprietary software providing predictive thermal damage feedback was used by the surgeon, along with control of probe rotation and depth, to tailor tissue coagulation. An external data safety monitoring board determined if toxicity at lower levels justified dose escalation.

Results. Ten patients were treated at the Case Comprehensive Cancer Center (Cleveland Clinic and University Hospitals–Case Medical Center). Their average age was 55 years (range 34–69 years) and the median preoperative Karnofsky Performance Status score was 80 (range 70–90). The mean tumor volume was 6.8 ± 5 cm3 (range 2.6–19 cm3), the percentage of tumor treated was 78% ± 12% (range 57%–90%), and the conformality index was 1.21 ± 0.33 (range 1.00–2.04). Treatment-related necrosis was evident on MRI studies at 24 and 48 hours. The median survival was 316 days (range 62–767 days). Three patients improved neurologically, 6 remained stable, and 1 worsened. Steroid-responsive treatment-related edema occurred in all patients but one. Three had Grade 3 adverse events at the highest dose.

Conclusions. NeuroBlate represents new technology for delivering laser interstitial thermal therapy, allowing controlled thermal ablation of deep hemispheric rGBM. Clinical trial registration no.: NCT00747253 (ClinicalTrials. gov).

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A Simple Protocol to Prevent External Ventricular Drain Infections

A_Simple_Protocol_to_Prevent_External_Ventricular

Neurosurgery 72:993–999, 201

External ventricular drains (EVDs) are associated with high rates of infection, and EVD infections cause substantial morbidity and mortality.

OBJECTIVE: To determine whether the introduction of an evidence-based EVD infection control protocol could reduce the rate of EVD infections.

METHODS: This was a retrospective analysis of an EVD infection control protocol introduced in a tertiary care neurointensive care unit. We compared rates of cerebrospinal fluid culture positivity and ventriculitis for the 3 years before and 3 years after the introduction of an evidence-based EVD infection control protocol. A total of 262 EVD placements were analyzed, with a total of 2499 catheter-days.

RESULTS: The rate of cerebrospinal fluid culture positivity decreased from 9.8% (14 of 143; 11.43 per 1000 catheter-days) at baseline to 0.8% (1 of 119; 0.79 per 1000 catheterdays) in the EVD infection control protocol period (P = .001). The rate of ventriculitis decreased from 6.3% (9 of 143; 7.35 per 1000 catheter-days) to 0.8% (1 of 119; 0.79 per 1000 catheter-days; P = .02).

CONCLUSION: The introduction of a simple, evidence-based infection control protocol was associated with a dramatic reduction in the risk of EVD infection.

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Intra-arterial Injection Fluorescein Videoangiography in Aneurysm Surgery

Intra_arterial_Injection_Fluorescein

Neurosurgery 72[ONS Suppl 2]:ons141–ons150, 2013

To visualize blood flow in the arteries and aneurysm during surgery, intravenous fluorescence videoangiography has been used. However, the image contrast with this procedure is diminished by repeated study because the dye remains for about 10 minutes after injection.

OBJECTIVE: To determine the optimal dye concentration and to clarify the usefulness of fluorescein videoangiography by intra-arterial dye injection.

METHODS: In the pilot study, fluorescein sodium dissolved at various concentrations was illuminated with excitation light, and fluorescence was detected by cameras. The fluorescence of 0.001% fluorescein sodium solution mixed with plasma at various concentrations was then examined. In 13 aneurysm patients, dye solution was administered through the catheter for intraoperative digital subtraction angiography. The intravenous injection method was also performed, and the findings were compared.

RESULTS: Dye was clinically used at a concentration of 0.005% to 0.1% on the basis of the results of the pilot study. Fluorescence emission from the vessels and aneurysms was clearly observed by both methods; however, arterial injection provided brighter emission, resulting in clearer demonstration of the bloodstream than venous injection. Dye clearance was also quicker, which allowed repeat injections without delay. Dye filling in the aneurysm indicating incomplete occlusion was detected in 2 cases, and occlusion of the perforating artery was observed in 2 cases.

CONCLUSION: Intra-arterial fluorescein videoangiography provides brighter and clearer imaging of blood flow with a smaller dose of dye than intravenous videoangiography. It can be repeated within a short time and is useful for detecting incomplete clipping or unexpected obstruction of arteries.

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The “onco-functional balance” in surgery for diffuse low-grade glioma

LGG

Acta Neurochir (2013) 155:951–957

Diffuse low-grade glioma (DLGG) is a growing pre-cancerous tumor, often diagnosed in patients with no or only mild deficit. Maximal and early surgical resection is currently the first therapeutic option, in order to delay the malignant transformation and thus increase the overall survival. Preserving the quality of life (QoL) is nonetheless another priority. Here, our purpose is to weight the value of the extent of resection versus the neurological worsening that could be voluntarily generated by a radical resection; that is, to study the “onco-functional balance” at the individual level.

To this end, we will examine DLGG involving the supplementary motor area and DLGG involving visual pathways. We will consider the benefit-risk ratio of different strategies of resection, according to the brain structures actually invaded and their plastic potential. The aim is to increase both the quantity of life and the time with a normal QoL, on the basis of strong interactions between the tumor course, brain reorganization and multistage surgical approach adapted to each patient over time.

To this end, beyond the conceptual and technical issues, the most important point remains the honest and unique relationship between the surgical oncologist and the patient, based on clear and complete information about the behavior of DLGG versus the expected medical and social consequences of a resection over years. In other words, in the era of “evidence-based medicine”, it is crucial to not forget “individual-based medicine” by offering tailored resections adapted to each patient.

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Prognostic factors of Grade II gliomas

neuronBig

J Neurosurg 118:1157–1168, 2013

The spontaneous prognostic factors and optimal therapeutic strategy for WHO Grade II gliomas (GIIGs) have yet to be unanimously defined. Specifically, the role of resection is still debated, most notably because the actual amount of resection has seldom been assessed.

Methods. Cases of GIIGs treated before December 2007 were extracted from a multicenter database retrospectively collected since January 1985 and prospectively collected since 1996. Inclusion criteria were a patient age ≥ 18 years at diagnosis, histological diagnosis of WHO GIIG, and MRI evaluation of tumor volume at diagnosis and after initial surgery. One thousand ninety-seven lesions were included in the analysis. The mean follow-up was 7.4 years since radiological diagnosis. Factors significant in a univariate analysis (with a p value ≤ 0.1) were included in the multivariate Cox proportional hazard regression model analysis.

Results. At the time of radiological diagnosis, independent spontaneous factors of a poor prognosis were an age ≥ 55 years, an impaired functional status, a tumor location in a nonfrontal area, and, most of all, a larger tumor size. When the study starting point was set at the time of first treatment, independent favorable prognostic factors were limited to a smaller tumor size, an epileptic symptomatology, and a greater extent of resection.

Conclusions. This large series with its volumetric assessment refines the prognostic value of previously stressed clinical and radiological parameters and highlights the importance of tumor size and location. The results support additional arguments in favor of the predominant role of resection, in accordance with recently reported experiences.

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Dura Splitting Decompression for Chiari I Malformation in Pediatric Patients

Dura_Splitting_Decompression_for_Chiari_I

Neurosurgery 72:922–929, 2013

Dural splitting decompression may be an effective and safe treatment for Chiari I malformation.

OBJECTIVE: To compare clinical outcomes, complications, and resource utilization for patients undergoing Chiari I decompression with or without duraplasty.

METHODS: Between 2000 and 2009, the senior author performed 113 Chiari I decompression operations with dural splitting or duraplasty in children less than 18 years of age; 110 were included in a retrospective cohort analysis of safety, efficacy, and treatment cost. Patients without significant syringomyelia underwent dural splitting decompression, and patients with syringomyelia underwent duraplasty.

RESULTS: Sixty-three patients without significant syringomyelia (57%) underwent dural splitting decompression. They were significantly younger than patients undergoing duraplasty (8.3 ± 4.9 years vs 10.4 ± 4.4 years; P < .05). Headaches improved or resolved in most patients in both groups (90.5% vs 93.6%; P = .59). Dysphagia, long tract signs, cranial nerve, and bulbar symptoms also improved similarly in both groups. Three duraplasty patients were treated medically for aseptic meningitis; one underwent reoperation for a symptomatic pseudomeningocele. No patient undergoing dural splitting decompression experienced a cerebrospinal fluid-related complication. Extradural decompression required less operative time than duraplasty (105.5 vs 168.9 minutes, P < .001), a shorter length of stay (2.4 vs 2.8 days, P = .011), and lower total cost for the primary hospitalization ($26 837 vs $29 862, P = .015).

CONCLUSION: In this retrospective cohort study, dural splitting decompression was equally effective, safer, and lower cost for treatment of Chiari I malformation without syringomyelia. A multicenter trial with groups balanced for the presence of syringomyelia is necessary to determine whether these results are generalizable.

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Foramen magnum meningiomas: To drill or not to drill the occipital condyle?

FMM

Surg Neurol Int 2013;4:73

Despite the development of microsurgery and cranial base techniques, the surgical management of Foramen Magnum Meningiomas (FMM) continues to be a technical challenge to neurosurgeons. Controversy concerning the utility of systematic condyle drilling for approaching FMM has been raised. Our aim was to describe the surgical technique, analyze its safety, and the postoperative outcome in 12 consecutive FMM patients.

Methods: From 1986 to 2011,12 patients with FMM underwent operations in the Department of Neurosurgery at Servidores do Estado Hospital and in a private clinic. All patients were operated using a standard suboccipital craniectomy, preserving the occipital condyle, opening of the Foramen Magnum, and ipsilateral removal of the posterior arch of C1.

Results: There was no operative mortality, nine patients achieved Glasgow Outcome Scale 4 or 5. Condylar resection was not deemed necessary in any case. Gross total resection was achieved in nine patients. After surgery, four patients developed lower cranial nerve weakness. There was no significant postoperative complication in the remaining patients. The average follow-up is 8.2 years.

Conclusion: The vast majority of FMM can be safely removed with a retrocondylar lateral suboccipital approach without condylar resection, using meticulous microsurgical techniques.

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The high-risk discectomy patient: prevention of reherniation in patients with large anular defects using an anular closure device

Barricaid

Eur Spine J (2013) 22:1030–1036

With lumbar discectomy for disc herniation, surgeons must choose between limited nucleus removal associated with higher reherniation risk or more aggressive nucleus removal associated with increased back pain and disc degeneration. This trade-off is particularly challenging in patients with large anular defects, which carry the highest risk of reherniation. We examined the effect of an anular closure device on reherniation and clinical outcomes.

Methods Seventy-five primary discectomy patients had a limited discectomy followed by implantation of an anular closure device and were followed-up to 2 years. Anular defect size and volume of removed nucleus was recorded at surgery. Reherniations were reported, pain and function were monitored throughout, and imaging was performed at annual visits.

Results The overall symptomatic reherniation rate was 1.4 %, and the asymptomatic reherniation rate was 1.5 % at 12 months and 5.1 % at 24 months. Both rates compare favorably with literature reports which include symptomatic rates ranging between 2 and 18 % (up to 27 % for patients with large anular defects) and an asymptomatic rate of 13 %.

Conclusions The low reherniation rate in patients at highrisk of reherniation based on anular defect size, despite discectomy being only limited, suggests that an anular closure device may reduce reherniation risk. Clinical outcomes for pain and function at 1 and 2 years post-operatively compared favorably with literature reports. Further study in a randomized controlled trial is required to confirm these results.

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Modern intraoperative imaging modalities for the vascular neurosurgeon treating intracerebral hemorrhage

modern OR

Neurosurg Focus 34 (5):E2, 2013

This paper reviews the current intraoperative imaging tools that are available to assist neurosurgeons in the treatment of intracerebral hemorrhage (ICH). This review shares the authors’ experience with each modality and discusses the advantages, potential limitations, and disadvantages of each.

Surgery for ICH is directed at blood clot removal, reduction of intracranial pressure, and minimization of secondary damage associated with hematoma breakdown products. For effective occlusion and safe obliteration of vascular anomalies associated with ICH, vascular neurosurgeons today require a thorough understanding of the various intraoperative imaging modalities available for obtaining real-time information. Use of one or more of these modalities may improve the surgeon’s confidence during the procedure, the patient’s safety during surgery, and surgical outcome.

The modern techniques discussed include 1) indocyanine green–based video angiography, which provides realtime information based on high-quality images showing the residual filling of vascular pathological entities and the patency of blood vessels of any size in the surgical field; and 2) intraoperative angiography, which remains the gold standard intraoperative diagnostic test in the surgical management of cerebral aneurysms and arteriovenous malformations. Hybrid procedures, providing multimodality image-guided surgeries and combining endovascular with microsurgical strategies within the same surgical session, have become feasible and safe. Microdoppler is a safe, noninvasive, and reliable technique for evaluation of hemodynamics of vessels in the surgical field, with the advantage of ease of use. Intraoperative MRI provides an effective navigation tool for cavernoma surgery, in addition to assessing the extent of resection during the procedure. Intraoperative CT scanning has the advantage of very high sensitivity to acute bleeding, thereby assisting in the confirmation of the extent of hematoma evacuation and the extent of vascular anomaly resection. Intraoperative ultrasound aids navigation and evacuation assessment during intracerebral hematoma evacuation surgeries. It supports the concept of minimally invasive surgery and has undergone extensive development in recent years, with the quality of ultrasound imaging having improved considerably.

Image-guided therapy, combined with modern intraoperative imaging modalities, has changed the fundamentals of conventional vascular neurosurgery by presenting real-time visualization of both normal tissue and pathological entities. These imaging techniques are important adjuncts to the surgeon’s standard surgical armamentarium. Familiarity with these imaging modalities may help the surgeon complete procedures with improved safety, efficiency, and clinical outcome

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Morphological and clinical risk factors for the rupture of anterior communicating artery aneurysms

Anterior communicating artery aneurysm rupture

J Neurosurg 118:978–983, 2013

Patients with ruptured anterior communicating artery (ACoA) aneurysms have historically been observed to have poor neuropsychological outcomes, and ACoA aneurysms have accounted for a higher proportion of ruptured than unruptured aneurysms. Authors of this study aimed to investigate the morphological and clinical characteristics predisposing to ACoA aneurysm rupture.

Methods. Data from 140 consecutive patients with ACoA aneurysms managed at the authors’ facility between July 2003 and November 2011 were retrospectively reviewed. Patients with (78) and without (62) aneurysm rupture were divided into groups, and morphological and clinical characteristics were compared. Morphological characteristics were evaluated based on 3D CT angiography and included aneurysm location, dominance of the A1 portion of the anterior cerebral artery, direction of the aneurysm dome around the ACoA, aneurysm bleb(s), size of the aneurysm and its neck, aneurysm–parent artery angle, and existence of other intracranial unruptured aneurysms.

Results. Patients with ruptured ACoA aneurysms were significantly younger (a higher proportion were younger than 60 years of age) than those with unruptured lesions, and a significantly smaller proportion had hypercholesterolemia. A significantly larger proportion of patients with ruptured aneurysms showed an anterior direction of the aneurysm dome around the ACoA, had a bleb(s), and/or had an aneurysm size ≥ 5 mm. Multivariate logistic regression analysis showed that an anterior direction of the aneurysm dome around the ACoA (OR 6.0, p = 0.0012), the presence of a bleb(s) (OR 22, p < 0.0001), and an aneurysm size ≥ 5 mm (OR 3.16, p = 0.035) were significantly associated with ACoA aneurysm rupture.

Conclusions. Findings in the present study demonstrated that the anterior projection of an ACoA aneurysm may be related to rupturing. The authors would perhaps recommend treatment to patients with unruptured ACoA aneurysms that have an anterior dome projection, a bleb(s), and a size ≥ 5 mm.

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Endoscopic transnasal odontoidectomy to treat basilar invagination with congenital osseous malformations

Basilar invagination

Eur Spine J (2013) 22:1127–1136

Transoral resection of the odontoid has been accepted as a standard procedure to decompress the cervicomedullary junction during the past several decades. The endoscopic transnasal odontoidectomy is emerging as a feasible surgical alternative to conventional microscopic transoral approach. In this article, we describe several operative nuances and pearls from our experience about this approach, which provided successful decompression.

Methods From September 2009 to April 2010, three consecutive patients with basilar invagination, of which the etiology was congenital osseous malformations, underwent endoscopic transnasal odontoidectomy. All patients presented with myelopathy. The last two cases also received occipitocervical fixation and bone fusion during the same surgical episode to ensure stability.

Results All the patients were extubated after recovery from anesthesia and allowed oral food intake the next day. Cerebrospinal fluid rhinorrhea was found in the second case and cured by continuous lumber drainage of cerebrospinal fluid. No infection was noted. The average follow- up time was more than 24 months. Remarkable neurological recovery was observed postoperative in all patients.

Conclusion The endoscopic transnasal odontoidectomy is a feasible approach for anterior decompression of pathology at the cervicomedullary junction. The advantages over the standard transoral odontoidectomy include elimination of risk of tongue swelling and teeth damaging, improvement of visualization, alleviation of prolonged intubation, reduction of need for enteral tube feeding and less risk of affecting phonation. The minimally invasive access and faster recovery associated with this technique make it a valid alternative for decompression of the ventral side of the cervicomedullary junction

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The failure of preoperative ethylene-vinyl alcohol copolymer embolization to improve outcomes in arteriovenous malformation management: case series

AVM-before

J Neurosurg 118:969–977, 2013

Ethylene-vinyl alcohol copolymer embolization is increasingly used preoperatively in the resection of brain arteriovenous malformations (AVMs). However, the case for embolization improving the outcome of resection has not been evaluated. In this paper the authors set out to compare outcomes after surgery for brain AVMs in 2 consecutive periods of practice. In the first period, selective embolization was used without the use of ethylene-vinyl alcohol copolymer. In the second period, selective embolization with ethylene-vinyl alcohol copolymer was performed.

Methods. A consecutive case series (prospectively collected data) was retrospectively analyzed. Adverse outcomes were considered to be an outcome modified Rankin Scale score greater than 2 due to embolization or surgery.

Results. A total of 538 surgical cases were included. The percentages of adverse outcomes were as follows: 0.34% for Spetzler-Martin AVMs less than Grade III (1 of 297 cases); 5.23% (95% CI 2.64%–9.78%) for Grade III AVMs (9 of 172 cases); and 17% (95% CI 10%–28%) for AVMs greater than Grade III (12 of 69 cases). There was no improvement in outcomes from the first period to the second period. The adverse outcome for Grade III brain AVMs in the first period was 5.2% (7 of 135 cases) and in the second period (after ethylene-vinyl alcohol copolymer was introduced) it was 5.4% (2 of 37 cases). For AVMs greater than Grade III, the adverse outcome was 12% (6 of 49 cases) in the first period and 30% (6 of 20 cases) in the second period.

Conclusions. Outcomes for brain AVM surgery were not improved by ethylene-vinyl alcohol copolymer embolization. Preoperative embolization of high-grade AVMs with an ethylene-vinyl alcohol copolymer did not prevent those hemorrhagic complications which embolization is hypothesized to prevent based on theoretical speculations but not demonstrated in practice.

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Use of microscope-integrated near-infrared indocyanine green videoangiography in the surgical treatment of intramedullary cavernous malformations

ICG video intram. cavernomas

J Neurosurg Spine 18:443–449, 2013

The characteristics and efficacy of indocyanine green (ICG) videoangiography in cavernous malformation (CM) have not been fully elucidated. The purpose of this paper is to examine the potential utility of ICG videoangiography in the surgical treatment of intramedullary CMs.

METHODS
The authors conducted a retrospective review of 8 cases involving 5 men and 3 women who had undergone surgery for intramedullary CM between January 2008 and July 2011. All patients were evaluated by means of MRI. The MRI findings and clinical history in all cases suggested intramedullary CM as a preoperative diagnosis. In 2 of 8 cases, dilated venous structures associated with CMs were demonstrated. In one of these cases, there were coexisting extramedullary CMs. Intraoperatively, ICG fluorescence was observed for 5 minutes using microscope-integrated videoangiography.

RESULTS
In all 8 cases, intra- and extramedullary CMs were seen as avascular areas on ICG videoangiography. Indocyanine green videoangiography helped surgeons to localize and predict margins of the lesions before performing myelotomy. Importantly, in the cases with associated venous anomalies, ICG videoangiography was useful in delineating and preserving the venous structures. In extramedullary CMs located dorsal to the spinal cord, gradual ICG infiltration was seen, starting at 110 seconds and maximal at 210 seconds after injection. Postoperative MRI confirmed total removal of the lesions in all cases, and subsequent recovery of all patients was uneventful.

CONCLUSIONS
Indocyanine green videoangiography provided useful information with regard to the detection of lesion margins by demonstrating intramedullary CMs as avascular areas. In cases associated with venous anomalies, ICG contributed to safe and complete removal of the CMs by visualizing the venous structure. In extramedullary CMs, ICG videoangiography demonstrated the characteristic of slow blood flow within CMs.

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Optimizing Contrast-Enhanced Magnetic Resonance Imaging Characterization of Brain Metastases: Relevance to Stereotactic Radiosurgery

Optimizing_Contrast_Enhanced_Magnetic_Resonance

Neurosurgery 72:691–701, 2013

Intracranial metastases are the most common form of intra-axial brain tumor. Management approaches to brain metastases include surgical resection, whole-brain radiotherapy, and stereotactic radiosurgery (SRS). The management approach that is selected is based typically on algorithms that incorporate the number, size, and location of lesions.

SRS is the treatment of choice when metastases detected on imaging are few (maximum, 3-5) and/or of small size (#30 mm) and offers the advantages of noninvasiveness and the ability to treat inaccessible lesions compared with surgical resection.

Contrast-enhanced magnetic resonance imaging (MRI) is the standard imaging technique for determining the number, size, and location of metastatic lesions. In SRS, the capability of MRI to delineate lesion borders precisely in 3 dimensions helps reduce recurrence rates and minimize radiation necrosis in surrounding tissue.

Optimization of the MRI protocol, including selection of the appropriate gadolinium-based contrast agent (GBCA), is paramount for accurate lesion imaging. GBCAs differ in their safety, tolerability, and efficacy because of their diverse physicochemical properties. Gadobutrol and gadobenate dimeglumine are high-relaxivity GBCAs that demonstrate superior efficacy for imaging metastatic lesions compared with other GBCAs, whereas gadobutrol additionally provides macrocyclic stability.

This article reviews recent comparative trials of GBCAs and discusses their relevance for optimizing MRI protocols in the management of brain metastases, with particular relevance to SRS.

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Superior cerebellar artery–posterior cerebral artery bypass

Superior cerebellar artery–posterior cerebral artery bypass

J Neurosurg 118:1053–1057, 2013

Iatrogenic pseudoaneurysms are rare but serious complications of transsphenoidal surgery, and an iatrogenic pseudoaneurysm of the posterior cerebral artery (PCA) has been reported just once in the literature.

The authors encountered such a case with a new P1 segment PCA pseudoaneurysm after endoscopic transsphenoidal resection of a pituitary adenoma. The aneurysm proved ideal for a novel intracranial–intracranial bypass in which the superior cerebellar artery (SCA) was used as an in situ donor artery to revascularize the recipient P2 segment. The bypass allowed aneurysm trapping without causing ischemic stroke or neurological morbidity.

This case represents the first reported surgical treatment of an iatrogenic PCA pseudoaneurysm. Endovascular occlusion with coils was an option, but dolichoectatic morphology requires sacrifice of the P1 segment, with associated risks to the thalamoperforators and circumflex perforators. The SCA-PCA bypass was ideal because of low-flow demands. Like other in situ bypasses, it requires no dissection of extracranial arteries, no second incision for harvesting interposition grafts, and has a high likelihood of long-term patency. The SCA-PCA bypass is also applicable to fusiform SCA aneurysms requiring revascularization with trapping.

This case demonstrates a dangerous complication that results from the limited view of the posterolateral surgical field through the endoscope and the imprecision of endoscopic instruments.

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Accuracy of stimulating electrode placement in paediatric pallidal deep brain stimulation for primary and secondary dystonia

DBS in pediatric dystonia

Acta Neurochir (2013) 155:823–836

Accuracy of electrode placement is an important determinant of outcome following deep brain stimulation (DBS) surgery. Data on accuracy of electrode placement into the globus pallidum interna (GPi) in paediatric patients is limited, particularly those with non-primary dystonia who often have smaller GPi. Pallidal DBS is known to bemore effective in the treatment of primary dystonia compared with secondary dystonia.

Objectives We aimed to determine if accuracy of pallidal electrode placement differed between primary, secondary and NBIA (neuronal degeneration and brain iron accumulation) associated dystonia and how this related to motor outcome following surgery.

Methods A retrospective review of a consecutive cohort of children and young people undergoing DBS surgery in a single centre. Fused in frame preoperative planning magnetic resonance imaging (MRI) and postoperative computed tomography (CT) brain scans were used to determine the accuracy of placement of DBS electrode tip in Leskell stereotactic system compared with the planned target. The differences along X, Y, and Z coordinates were calculated, as was the Euclidean distance of electrode tip from the target. The relationship between proximity to target and change in Burke-Fahn-Marsden Dystonia Rating Scale at 1 year was also measured.

Results Data were collected from 88 electrodes placed in 42 patients (14 primary dystonia, 18 secondary dystonia and 10 NBIA associated dystonia). Median differences between planned target and actual position were: left-side X-axis 1.05 mm, Y-axis 0.85 mm, Z-axis 0.94 mm and Euclidean difference 2.04 mm; right-side X-axis 1.28 mm, Y-axis 0.70 mm, Z-axis 0.70 mm and Euclidean difference 2.45 mm. Accuracy did not differ between left and right-sided electrodes. No difference in accuracy was seen between primary, secondary or NBIA associated dystonia. Dystonia reduction at 1 year post surgery did not appear to relate to proximity of implanted electrode to surgical target across the cohort.

Conclusions Accuracy of surgical placement did not differ between primary, secondary or NBIA associated dystonia. Decreased efficacy of pallidal DBS in secondary and NBIA associated dystonia is unlikely to be related to difficulties in achieving the planned electrode placement.

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Amygdalohippocampotomy: surgical technique and clinical results

Amygdalohippocampotomy

J Neurosurg 118:1107–1113, 2013

The removal of mesial temporal structures, namely amygdalohippocampectomy, is the most efficient surgical procedure for the treatment of epilepsy. However, disconnection of the epileptogenic zones, as in temporal lobotomy or, for different purposes, hemispherotomy, have shown equivalent results with less morbidity. Thus, authors of the present study began performing selective amygdalohippocampotomy in cases of refractory mesial temporal lobe epilepsy (TLE) to treat mesial temporal lobe sclerosis (MTLS).

Method. The authors conducted a retrospective analysis of all cases of amygdalohippocampotomy collected in a database between November 2007 and March 2011.

Results. Since 2007, 21 patients (14 males and 7 females), ages 20–58 years (mean 41 years), all with TLE due to MTLS, were treated with selective ablation of the lateral amygdala plus perihippocampal disconnection (anterior one-half to two-thirds in dominant hemisphere), the left side in 11 cases and the right in 10. In 20 patients the followup was 2 or more years (range 24–44 months, average 32 months). Clinical outcome for epilepsy 2 years after surgery (20 patients) was good/very good in 19 patients (95%) with an Engel Class I (15 patients [75%]) or II outcome (4 patients [20%]) and bad in 1 patient (5%) with an Engel Class IV outcome (extratemporal focus and later reoperation). Surgical morbidity included hemiparesis (capsular hypertensive hemorrhage 24 hours after surgery, 1 patient), verbal memory worsening (2 patients), and quadrantanopia (permanent in 2 patients, transient in 1). Late psychiatric depression developed in 3 cases. Operative time was reduced by about 30 minutes (15%) on average with this technique.

Conclusions. Amygdalohippocampotomy is as effective as amygdalohippocampectomy to treat MTLS and is a potentially safer, time-saving procedure.

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A Comparison of Language Mapping by Preoperative Navigated Transcranial Magnetic Stimulation and Direct Cortical Stimulation During Awake Surgery

A_Comparison_of_Language_Mapping_by_Preoperative

Neurosurgery 72:808–819, 2013

Navigated transcranial magnetic stimulation (nTMS) is increasingly used in presurgical brain mapping. Preoperative nTMS results correlate well with direct cortical stimulation (DCS) data in the identification of the primary motor cortex. Repetitive nTMS can also be used for mapping of speech-sensitive cortical areas.

OBJECTIVE: The current cohort study compares the safety and effectiveness of preoperative nTMS with DCS mapping during awake surgery for the identification of language areas in patients with left-sided cerebral lesions.

METHODS: Twenty patients with tumors in or close to left-sided language eloquent regions were examined by repetitive nTMS before surgery. During awake surgery, language-eloquent cortex was identified by DCS. nTMS results were compared for accuracy and reliability with regard to DCS by projecting both results into the cortical parcellation system.

RESULTS: Presurgical nTMS maps showed an overall sensitivity of 90.2%, specificity of 23.8%, positive predictive value of 35.6%, and negative predictive value of 83.9% compared with DCS. For the anatomic Broca’s area, the corresponding values were a sensitivity of 100%, specificity of 13.0%, positive predictive value of 56.5%, and negative predictive value of 100%, respectively.

CONCLUSION: Good overall correlation between repetitive nTMS and DCS was observed, particularly with regard to negatively mapped regions. Noninvasive inhibition mapping with nTMS is evolving as a valuable tool for preoperative mapping of language areas. Yet its low specificity in posterior language areas in the current study necessitates further research to refine the methodology.

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