Diagnostic yield of computed tomography angiography and magnetic resonance angiography in patients with catheter angiography-negative subarachnoid hemorrhage

OBJECT

The yield of CT angiography (CTA) and MR angiography (MRA) in patients with subarachnoid hemorrhage (SAH) who have a negative initial catheter angiogram is currently not well understood. This study aims to determine the yield of CTA and MRA in a prospective cohort of patients with SAH and a negative initial catheter angiogram.

METHODS

From January 1, 2005, until September 1, 2010, the authors instituted a prospective protocol in which patients with SAH-as documented by noncontrast CT or CSF xanthochromia and a negative initial catheter angiogram- were evaluated using CTA and MRA to assess for causative cerebral aneurysms. Two neuroradiologists independently evaluated the noncontrast CT scans to determine the SAH pattern (perimesencephalic or not) and the CT and MR angiograms to assess for causative cerebral aneurysms.

RESULTS

Seventy-seven patients were included, with a mean age of 52.8 years (median 54 years, range 19-88 years). Fifty patients were female (64.9%) and 27 male (35.1%). Forty-three patients had nonperimesencephalic SAH (55.8%), 29 patients had perimesencephalic SAH (37.7%), and 5 patients had CSF xanthochromia (6.5%). Computed tomography angiography demonstrated a causative cerebral aneurysm in 4 patients (5.2% yield), all of whom had nonperimesencephalic SAH (9.3% yield). Mean aneurysm size was 2.6 mm (range 2.1-3.3 mm). Magnetic resonance angiography demonstrated only 1 of these aneurysms. No causative cerebral aneurysms were found in patients with perimesencephalic SAH or CSF xanthochromia.

CONCLUSIONS

Computed tomography angiography is a valuable adjunct in the evaluation of patients with nonperimesencephalic SAH who have a negative initial catheter angiogram, demonstrating a causative cerebral aneurysm in 9.3% of patients.

Diagnostic yield of repeat catheter angiography in patients with catheter and computed tomography angiography negative subarachnoid hemorrhage

BACKGROUND

The yield of repeat catheter angiography in patients with subarachnoid hemorrhage (SAH) who have negative initial catheter and computed tomography (CT) angiograms is not well understood.

OBJECTIVE

To determine the yield of repeat catheter angiography in a prospective cohort of patients with SAH and negative initial catheter and CT angiograms.

METHODS

From January 1, 2005, until September 1, 2010, we instituted a prospective protocol in which patients with SAH documented by noncontrast CT (NCCT) or cerebrospinal fluid (CSF) xanthochromia and negative initial catheter and CT angiograms were evaluated with repeat catheter angiography 7 days and 3 months after presentation to assess for causative vascular abnormalities.

RESULTS

Seventy-two patients were included, with a mean age of 53.1 years (median, 53.5 years; range, 19-88 years). Forty-six patients were female (63.9%) and 26 male (36.1%). Thirty-nine patients had nonperimesencephalic SAH (54.2%), 29 patients had perimesencephalic SAH (40.3%), and 4 patients had CSF xanthochromia (5.5%). The first repeat catheter angiogram performed 7 days after presentation demonstrated a causative vascular abnormality in 3 patients (yield of 4.2%), 2 of which had nonperimesencephalic SAH (yield of 5.1%), and 1 had perimesencephalic SAH (yield of 3.4%). The second repeat catheter angiogram performed in 43 patients (59.7%) did not demonstrate any causative vascular abnormalities. No causative abnormalities were found in patients with CSF xanthochromia.

CONCLUSION

Repeat catheter angiography performed 7 days after presentation is valuable in the evaluation of patients with SAH who have negative initial catheter and CT angiograms, demonstrating a causative vascular abnormality in 4.2% of patients.

Effect of liquid embolic agents on Gamma Knife surgery dosimetry for arteriovenous malformations

Object

The effectiveness of Gamma Knife stereotactic surgery to obliterate brain arteriovenous malformations (AVMs) may be diminished by the preoperative adjunctive use of endovascular liquid embolic agents. The purpose of the present investigation was to determine if commercially available liquid embolic agents reduce the radiation dose to the target because of attenuation of the 60Co beam.

Methods

The apparent linear attenuation coefficients for 120- to 140-keV radiographs in embolized regions were retrieved from CT scans for several patients with AVMs who had undergone embolization procedures with liquid embolic agents to reduce nidal volumes. Based on these coefficients and a virtual model of Gamma Knife surgery (GKS) with basic ray tracing, the authors obtained the path lengths and densities of the embolized regions. The attenuation of 60Co beams was then calculated for various sizes and positions of embolized AVM regions and for the number of beams used for treatment. Published experiments for several high-atomic-number materials were used to estimate the effective 60Co beam attenuation coefficients for the N-butyl cyanoacrylate (NBCA, suspended in ethiodized oil) and ethylene vinyl alcohol copolymer (EVOH, with suspended micronized tantalum powder, Onyx) used in the AVM embolizations. Dose reductions during GKS were calculated for a theoretical model based on the CT-documented apparent linear attenuation coefficients and for the 60Co energy attenuation coefficient. Dose measurements were obtained in a phantom study with EVOH for comparison with the estimates generated from the two attenuation coefficients.

Results

Based on CT (keV) apparent attenuation coefficients, the authors' theoretical model predicted that the cumulative effect of either of the embolic agents decreased the number of kilovoltage photons in an embolized nidus by −8% to −15% because of the increased atomic number and density of NBCA and Onyx. However, in using the effective attenuation coefficient for the 60Co energies as is used in GKS, the authors' theoretical model yielded only a 0.2% dose reduction per beam and a < 0.01%–0.2% dose reduction in total. These theoretical results were validated by measurements in a head phantom containing Onyx.

Conclusions

Dose reduction due to attenuation of the 60Co beam by the AVM embolization material was negligible for both NBCA and EVOH because of the high-energy 60Co beam.

Combined endovascular embolization and stereotactic radiosurgery in the treatment of large arteriovenous malformations

Object

Large cerebral arteriovenous malformations (AVMs) are often not amenable to direct resection or stereotactic radiosurgery (SRS) treatment. An alternative treatment strategy is staged endovascular embolization followed by SRS (Embo/SRS). The object of this study was to examine the experience at Washington University in St. Louis with Embo/SRS for large AVMs and review the results in earlier case series.

Methods

Twenty-one cases involving patients with large AVMs treated with Embo/SRS between 1994 and 2006 were retrospectively evaluated. The AVM size (before and after embolization), procedural complications, radiological outcome, and neurological outcome were examined. Radiological success was defined as AVM obliteration as demonstrated by catheter angiography, CT angiography, or MR angiography. Radiological failure was defined as residual AVM as demonstrated by catheter angiography, CT angiography, or MR angiography performed at least 3 years after SRS.

Results

The maximum diameter of all AVMs in this series was > 3 cm (mean 4.2 cm); 12 (57%) were Spetzler-Martin Grade IV or V. Clinical follow-up was available in 20 of 21 cases; radiological follow-up was available in 19 of 21 cases (mean duration of follow-up 3.6 years). Forty-three embolization procedures were performed; 8 embolization-related complications occurred, leading to transient neurological deficits in 5 patients (24%), minor permanent neurological deficits in 3 patients (14%), and major permanent neurological deficits in none (0%). Twenty-one SRS procedures were performed; 1 radiation-induced complication occurred (5%), leading to a permanent minor neurological deficit. Of the 20 patients with clinical follow-up, none experienced cerebral hemorrhage. In the 19 patients with radiological follow-up, AVM obliteration was confirmed by catheter angiography in 13, MR angiography in 2, and CT angiography in 1. Residual nidus was found in 3 patients. In patients with follow-up catheter angiography, the AVM obliteration rate was 81% (13 of 16 cases).

Conclusions

Staged endovascular embolization followed by SRS provides an effective means of treating large AVMs not amenable to standard surgical or SRS treatment. The outcomes and complication rates reported in this series compare favorably to the results of other reported therapeutic strategies for this very challenging patient population.

Use of Movable High-Field-Strength Intraoperative Magnetic Resonance Imaging With Awake Craniotomies for Resection of Gliomas: Preliminary Experience

BACKGROUND:

Awake craniotomy with electrocortical mapping and intraoperative magnetic resonance imaging (iMRI) are established techniques for maximizing tumor resection and preserving function, but there has been little experience combining these methodologies.

OBJECTIVE:

To report our experience of combining awake craniotomy and iMRI with a 1.5-T movable iMRI for resection of gliomas in close proximity to eloquent cortex.

METHODS:

Twelve patients (9 male and 3 female patients; age, 32-60 years; mean, 41 years) undergoing awake craniotomy and iMRI for glioma resections were identified from a prospective database. Assessments were made of how these 2 modalities were integrated and what impact this strategy had on safety, surgical decision making, workflow, operative time, extent of tumor resection, and outcome.

RESULTS:

Twelve craniotomies were safely performed in an operating room equipped with a movable 1.5-T iMRI. The extent of resection was limited because of proximity to eloquent areas in 5 cases: language areas in 3 patients and motor areas in 2 patients. Additional tumor was identified and resected after iMRI in 6 patients. Average operating room time was 7.9 hours (range, 5.9-9.7 hours). Compared with preoperative neurological function, immediate postoperative function was stable/improved in 7 and worse in 5; after 30 days, it was stable/improved in 11 and worse in 1.

CONCLUSION:

Awake craniotomy and iMRI with a movable high-field-strength device can be performed safely to maximize resection of tumors near eloquent language areas.

Implementation and preliminary clinical experience with the use of ceiling mounted mobile high field intraoperative magnetic resonance imaging between two operating rooms

OBJECTIVE

Intraoperative magnetic resonance imaging (ioMRI) provides immediate feedback and quality assurance enabling the neurosurgeon to improve the quality of a range of neurosurgical procedures. Implementation of ioMRI is a complex and costly process. We describe our preliminary 16 months experience with the integration of an IMRIS movable ceiling mounted high field (1.5 T) ioMRI setup with two operating rooms.

METHODS

Aspects of implementation of our ioMRI and our initial 16 months of clinical experience in 180 consecutive patients were reviewed.

RESULTS

The installation of a ceiling mounted movable ioMRI between two operating rooms was completed in April 2008 at Barnes-Jewish Hospital in St. Louis. Experience with 180 neurosurgical cases (M:F-100:80, age range 1-79 years, 71 gliomas, 57 pituitary adenomas, 9 metastases, 11 other tumor cases, 4 Chiari decompressions, 6 epilepsy resections and 22 other miscellaneous procedures) demonstrated that this device effectively provided high quality real-time intraoperative imaging. In 74 of all 180 cases (41%) and in 54% of glioma resections, the surgeon modified the procedure based upon the ioMRI. Ninety-three percent of ioMRI glioma cases achieved gross/near total resection compared to 65% of non ioMRI glioma cases in this time frame.

CONCLUSION

A movable high field strength ioMRI can be safely integrated between two neurosurgical operating rooms. This strategy leads to modification of the surgical procedure in a significant number of cases, particularly for glioma surgery. Long-term follow up is needed to evaluate the clinical and financial impact of this technology in the field of neurosurgery.

Clinical features and outcome in North American adults with idiopathic basal arterial occlusive disease without moyamoya collaterals

OBJECTIVE

To define the clinical characteristics and outcome of patients with idiopathic stenosis or occlusion of the basal arteries, without moyamoya collateral vessel formation.

METHODS

We identified patients who presented to our institution from 1996 to 2005 with occlusive disease of the distal internal carotid artery or the proximal middle or anterior cerebral arteries demonstrated by digital subtraction cerebral angiography. We excluded those with evidence of atherosclerotic disease, systemic vasculitis, moyamoya phenomenon, or any other condition that could otherwise explain their arterial occlusive disease. Medical records were reviewed for presenting symptoms and clinical characteristics. Outcome was determined from chart review and phone interviews.

RESULTS

Twelve patients were identified. All presented with transient ischemic attack or stroke. Eleven were women. Age at presentation ranged from 34 to 71 years. Nine had a history of hypertension; 5 had unilateral intracranial disease. Recurrent stroke on medical therapy occurred in none of the 5 during an average follow-up of 29 months. Seven had bilateral disease. Ischemic stroke occurred between 2 and 107 months after the initial event in 5 of 8 medically treated hemispheres. Moyamoya collateral vessels developed in 1 patient as shown on follow-up angiography.

CONCLUSION

The clinical features and outcome of these patients are similar to those reported in large case series of North American patients with moyamoya phenomenon. These data suggest a common etiology for the basal arterial occlusive process and a variable ability to form moyamoya collateral vessels.

Time-of-flight magnetic resonance angiography imaging of a residual arteriovenous malformation nidus after Onyx embolization for stereotactic radiosurgery planning. Technical note

This report demonstrates that time-of-flight (TOF) MR angiography is a useful adjunct for planning stereotactic radiosurgery (SRS) of large arteriovenous malformations (AVMs) after staged embolization with Onyx. Onyx (ethylene vinyl copolymer), a recently approved liquid embolic agent, has been increasingly used to exclude portions of large AVMs from the parent circulation prior to SRS. Limiting SRS to regions of persistent arteriovenous shunting and excluding regions eliminated by embolization may reduce unnecessary radiation doses to eloquent brain structures. However, SRS dosimetry planning presents unique challenges after Onyx embolization because it creates extensive artifacts on CT scans, and it cannot be delineated from untreated nidus on standard MR sequences. During the radiosurgery procedure, MR images were obtained using a GE Signa 1.5-T unit. Standard axial T2 fast spin echo high-resolution images (TR 3000 msec, TE 108 msec, slice thickness 2.5 mm) were generated for optimal visualization of brain tissue and AVM flow voids. The 3D TOF MR angiography images of the circle of Willis and vertebral arteries were subsequently obtained to visualize AVM regions embolized with Onyx (TR 37 msec, TE 6.9 msec, flip angle 20 degrees). Adjunct TOF MR angiography images demonstrated excellent contrast between nidus embolized with Onyx and regions of persistent arteriovenous shunting within a large AVM prior to SRS. Additional information derived from these sequences resulted in substantial adjustments to the treatment plan and an overall reduction in the treated tissue volume.

Incidence of deep venous thrombosis after subarachnoid hemorrhage

Object

The aim of this study was to determine the efficacy of venous ultrasonography in screening for deep venous thrombosis (DVT) after subarachnoid hemorrhage (SAH). A large cohort of patients who had suffered SAH was evaluated with the primary end points of ascertaining the incidence of asymptomatic DVT with venous Doppler ultrasonography screening and of identifying risk factors for the development of DVT and subsequent pulmonary embolism.

Methods

Data from patients with aneurysmal SAH who had been admitted to the neurosurgical intensive care unit (ICU) between December 2002 and October 2006 were retrospectively evaluated. Patients who had undergone surgical or endovascular treatment of an aneurysm following SAH and survived ≥ 15 days were included in the study.

Results

The overall incidence of DVT among the entire study cohort was 18%. A subgroup analysis identified all patients, with or without symptoms for DVT, who had undergone venous Doppler ultrasonography screening. The incidence of asymptomatic DVT was 24%. Univariate analysis of all patients revealed a significant correlation between the risk of DVT and Hunt and Hess grade (r = 0.38, p < 0.0001), Fisher grade (r = 0.31, p < 0.0001), total hospital stay (r = 0.49, p < 0.0001), and number of days in the ICU (r = 0.48, p < 0.0001). Multivariate analysis demonstrated that the total hospital stay and number of days in the ICU were significant predictors of DVT in all patients (p < 0.0001 and p < 0.0002, respectively). In the subgroup of screened patients, Hunt and Hess grade, total hospital stay, and number of days in the ICU were significant predictors of DVT. Although screened patients were more likely to have DVT (χ2 = 6.0976, p < 0.02), there was no significant difference in the incidence of DVT or pulmonary embolism between patients who did and those who did not undergo routine lower-extremity Doppler ultrasonography screening.

Conclusions

Routine compressive venous Doppler ultrasonography is an efficient, noninvasive means of identifying DVT as a screening modality in both symptomatic and asymptomatic patients following aneurysmal SAH. The ability to confirm or deny the presence of DVT in this patient population allows one to better identify the indications for chemoprophylaxis. Prophylaxis for venous thromboembolism in neurosurgical patients is common. Emerging literature and anecdotal experience have exposed risks of complications with prophylactic anticoagulation protocols. The identification of patients at high risk—for example, those with asymptomatic DVT—will allow physicians to better assess the role of prophylactic anticoagulation.

CRANIAL DURAL ARTERIOVENOUS FISTULAE

OBJECTIVE

Cranial dural arteriovenous fistulae (dAVF) with cortical venous drainage (CVD) (Borden Types 2 and 3) are reported to carry a 15% annual risk of intracranial hemorrhage (ICH) or nonhemorrhagic neurological deficit (NHND). The purpose of this study was to compare the clinical course of Type 2 and 3 dAVFs that present with ICH or NHND with those that do not.

METHODS

Twenty-eight patients with Type 2 or 3 dAVFs were retrospectively evaluated. CVD was classified as asymptomatic (aCVD) if patients presented incidentally or with pulsatile tinnitus or orbital phenomena. CVD was classified as symptomatic (sCVD) if patients presented with ICH or NHND. Occurrence of new ICH or new or worsening NHND between diagnosis and disconnection of CVD or last follow-up (if not disconnected) was noted. Overall frequency of events was compared using Fisher's exact test. Cumulative, event-free survival was compared using Kaplan-Meier analysis with log-rank testing.

RESULTS

Of 17 patients with aCVD, 1 (5.9%) developed ICH and none experienced NHND or death during the median 31.4-month follow-up period. Of 11 patients with sCVD, 2 (18.2%) developed ICH and 3 (27.3%) experienced new or worsened NHND over the median 9.7-month follow-up period. One of these patients subsequently died. Overall frequency of ICH or NHND was significantly lower in patients with aCVD versus sCVD (P = 0.022). Respective annual event rates were 1.4 versus 19.0%. aCVD patients had significantly higher cumulative event-free survival (P = 0.0016).

CONCLUSION

Cranial dAVFs with aCVD may have a less aggressive clinical course than those with sCVD.

Randomized Phase II Study of Cilengitide, an Integrin-Targeting Arginine-Glycine-Aspartic Acid Peptide, in Recurrent Glioblastoma Multiforme

Purpose

Cilengitide, an inhibitor of αvβ3 and αvβ5 integrin receptors, demonstrated minimal toxicity and durable activity across a wide range of doses administered to adults with recurrent glioblastoma multiforme (GBM) in a prior phase I study. The current multicenter phase II study was conducted to evaluate the activity and safety of cilengitide in GBM patients at first recurrence.

Patients and Methods

Eligible patients were randomly assigned to receive either 500 or 2,000 mg of cilengitide twice weekly on a continuous basis. Patients were assessed every 4 weeks. The primary end point was 6-month progression-free survival (PFS) rate. Secondary end points included PFS, overall survival (OS), and radiographic response, as well as quality-of-life and pharmacokinetic assessments.

Results

Eighty-one patients were enrolled, including 41 on the 500-mg arm and 40 on the 2,000-mg arm. The safety profile of cilengitide was excellent, with no significant reproducible toxicities observed on either arm. Antitumor activity was observed in both treatment cohorts but trended more favorably among patients treated with 2,000 mg, including a 6-month PFS of 15% and a median OS of 9.9 months.

Conclusion

Cilengitide monotherapy is well tolerated and exhibits modest antitumor activity among recurrent GBM patients. Additional studies integrating cilengitide into combinatorial regimens for GBM are warranted.

Clinical management of frequently encountered brain tumors

This overview of commonly encountered brain tumors will concentrate on the three most common neoplasms that occur in adult medicine, e.g., gliomas, metastatic lesions, and meningiomas.

Tissue transgluaminase 2 expression in meningiomas

Meningiomas are common intracranial tumors that occur in extra-axial locations, most often over the cerebral convexities or along the skull-base. Although often histologically benign these tumors frequently present challenging clinical problems. Primary clinical management of patients with symptomatic tumors is surgical resection. Radiation treatment may arrest growth or delay recurrence of these tumors, however, meningioma cells are generally resistant to apoptosis after treatment with radiation. Tumor cells are known to alter their expression of proteins that interact in the ECM to provide signals important in tumor progression. One such protein, fibronectin, is expressed in elevated levels in the ECM in a number of tumors including meningiomas. We recently reported that levels of both extracellular fibronectin and tissue transglutaminase 2 (TG2) were increased in glioblastomas. We examined the expression of fibronectin and its association TG2 in meningiomas. Both fibronectin and TG2 were strongly expressed in all meningiomas studied. TG2 activity was markedly elevated in meningiomas, and TG2 was found to co-localize with fibronectin. Treatment of meningiomas with the small molecule TG2 inhibitor, KCC009, inhibited the binding of TG2 to fibronectin and blocked disposition of linear strands of fibronectin in the ECM. KCC009 treatment promoted apoptosis and enhanced radiation sensitivity both in cultured IOMM-Lee meningioma cells and in meningioma tumor explants. These findings support a potential protective role for TG2 in meningiomas.

Combined surgical resection and stereotactic radiosurgery for treatment of cerebral metastases

BACKGROUND

Patients with limited intracranial metastatic disease traditionally have been treated with surgery followed by WBRT. However, there is growing concern for the debilitating cognitive effects after WBRT in long-term survivors. We present a series of patients treated with surgery followed by SRS, while reserving WBRT as a salvage therapy for disease progression.

METHODS

Medical records from 15 patients with 1 to 2 cerebral metastases who underwent both resection and SRS were reviewed. Outcome measures included overall survival, survival by RPA class, EOR, local tumor control, progression of intracranial disease, need for WBRT salvage therapy, and COD.

RESULTS

Fifteen patients with cerebral metastases were treated with the combined surgery-SRS paradigm. Eight of the 15 patients (53.3%) were designated RPA class 1, with 6 of 15 (40.0%) in class 2 and 1 of 15 (6.7%) in class 3. Gross total resection was achieved in 12 cases (80.0%). Overall median survival was 20.0 months, with values of 22.0 and 13.0 months for RPA classes 1 and 2, respectively. Local recurrence occurred in 16.7% of those patients with GTR. Six patients (40.0%) went on to receive WBRT at a median of 8.0 months from initial presentation. Twelve patients (80.0%) had died at the completion of the study, and the COD was CNS progression in 33.3%.

CONCLUSIONS

Surgical resection combined with SRS is an effective treatment for selected patients with limited cerebral metastatic disease. Survival using this combined treatment was equivalent to or greater than that reported by other studies using surgery + WBRT or SRS + WBRT.

Safety and efficacy of subthalamic nucleus deep brain stimulation performed with limited intraoperative mapping for treatment of Parkinson's disease

OBJECTIVE

The aim of this study is to establish the safety and efficacy of bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson's disease (PD) patients with disabling motor fluctuations performed with an expedient procedure with limited intraoperative mapping.

METHODS

Bilateral STN DBS systems were implanted in 110 PD patients. Targeting of STN was achieved with T2-weighted magnetic resonance imaging guidance and a stereotactic navigation system confirmed by limited electrophysiological mapping. The safety of the procedure was analyzed in all 110 patients. The efficacy of the procedure was assessed in the practically-defined off medication state in the 72 patients who underwent evaluations 3 to 12 months after electrode implantation.

RESULTS

Adverse effects were infrequent and transient with no incidence of death, hemiparesis, or seizure. In the 72 patients, STN DBS reduced total Unified Parkinson's Disease Rating Scale motor scores at the time of the follow-up evaluation by 47% from 43.4 +/- 16.1 with stimulators off to 22.8 +/- 11.6 with stimulators on (P < 0.001). The changes in Unified Parkinson's Disease Rating Scale motor subscores improved as follows: rest tremor, 74% (P < 0.001); rigidity, 58% (P < 0.001); bradykinesia, 37% (P < 0.001); pull test, 35% (P < 0.001); gait, 44% (P < 0.001); axial signs, 42% (P < 0.001); and speech, 13% (P = 0.002). The prescribed total daily levodopa-equivalent dose decreased 45 +/- 32%. We averaged 1.3 +/- 0.9 electrodes passes per lead implantation. The mean operating time from the mounting of the stereotactic frame to its removal was 5 hours 42 minutes (median, 5 h 25 min; standard deviation, 1 h 12 min).

CONCLUSION

This STN DBS surgical technique for PD is expedient with effective outcomes and low complication rates.

In vivo imaging in a murine model of glioblastoma

OBJECTIVE

To use in vivo imaging methods in mice to quantify intracranial glioma growth, to correlate images and histopathological findings, to explore tumor marker specificity, to assess effects on cortical function, and to monitor effects of chemotherapy.

METHODS

Mice with DBT glioma cell tumors implanted intracranially were imaged serially with a 4.7-T small-animal magnetic resonance imaging (MRI) scanner. MRI tumor volumes were measured and correlated with postmortem histological findings. Different nonspecific and specific positron emission tomography radiopharmaceuticals, [18F]2-fluoro-2-deoxy-d-glucose, [18F]3'-deoxy-3'-fluorothymidine, or [11C]RHM-I, a sigma2-receptor ligand, were visualized with microPET (CTI-Concorde MicroSystems LLC, Knoxville, TN). Intrinsic optical signals were imaged serially during contralateral whisker stimulation to study the impact of tumor growth on cortical function. Other groups of mice were imaged serially with MRI after one or two doses of the antimitotic N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU).

RESULTS

MRI and histological tumor volumes were highly correlated (r2 = 0.85). Significant binding of [11C]RHM-I was observed in growing tumors. Over time, tumors reduced and displaced (P # 0.001) whisker-activated intrinsic optical signals but did not change intrinsic optical signals in the contralateral hemisphere. Tumor growth was delayed 7 days after a single dose of BCNU and 18 days after two doses of BCNU. Mean tumor volume 15 days after DBT implantation was significantly smaller for treated mice (1- and 2-dose BCNU) compared with controls (P = 0.0026).

CONCLUSION

Mouse MRI, positron emission tomography, and optical imaging provide quantitative and qualitative in vivo assessments of intracranial tumors that correlate directly with tumor histological findings. The combined imaging approach provides powerful multimodality assessments of tumor progression, effects on brain function, and responses to therapy.

Poverty impacts of foot-and-mouth disease and the poverty reduction implications of its control

Foot-and-mouth disease (FMD) remains one of the most important livestock diseases of the world, given its highly infectious nature, its broad economic impacts on animal wellbeing and productivity, and its implications for successful access to domestic and export markets for livestock and products. The impacts of the disease vary markedly between developed and developing countries, and also within many developing countries. These differences in impact shape some markedly heterogeneous incentives for FMD control and eradication, which become of particular importance when setting priorities for poverty reduction in developing countries. Some consider that the benefits from FMD control accrue only to the better off in such societies and, as such, may not be a priority for investments targeted at poverty reduction. But is that view justified? Others see the control of FMD as a major development opportunity in a globalised environment. In this paper, Brian Perry and Karl Rich summarise the differential impacts of FMD and its control, and link these findings with the growing understanding of how the control of this globally important disease may contribute to the processes of pro-poor growth in certain countries of the developing world.

Postural tremor suppression is dependent on thalamic stimulation frequency

Deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) reduces tremor in people with essential tremor (ET), yet the dependence of tremor suppression on stimulation frequency remains unclear. To address this issue, we tested tremor suppression for three 15-second measurements during a variety of stimulation frequencies in 11 ET patients treated with VIM DBS. Stimulation frequencies at or above 100 Hz produced maximal benefit; higher frequencies provided no additional benefit. If this short-term measure predicts long-term response in routine activities at home, then this stimulation frequency setting will prolong battery half-life compared to higher frequency settings. These findings suggest that ET patients treated with VIM DBS may receive adequate benefit from stimulation frequencies about 100 Hz and this setting compared to commonly used higher settings will prolong battery life of surgically implanted pulse generators.

Transglutaminase 2 inhibitor, KCC009, disrupts fibronectin assembly in the extracellular matrix and sensitizes orthotopic glioblastomas to chemotherapy

Transglutaminase 2 (TG2, a.k.a. tissue transglutaminase) belongs to a family of transglutaminase enzymes that stabilize proteins by affecting covalent crosslinking via formation of amide bonds. Cell surface TG2 is directly involved as an adhesive receptor in cell-extracellular matrix (ECM) interactions. Here, we show that TG2 activity is elevated in glioblastomas compared with non-neoplastic brain. Immunofluorescent studies showed increased staining of fibronectin colocalized with TG2 in the ECM in glioblastomas. In addition, small clusters of invading human glioblastoma cells present in non-neoplastic brain parenchyma secrete high levels of TG2 and fibronectin that distinguish them from normal brain stroma. Downregulation of TG2 in U87MG glioblastoma cells with RNAi demonstrated decreased assembly of fibronectin in the ECM. Treatment with KCC009 blocked the remodeling of fibronectin in the ECM in glioblastomas in both in vitro and in vivo studies. KCC009 treatment in mice harboring orthotopic glioblastomas (DBT-FG) sensitized the tumors to N,N'-bis(2-chloroethyl)-N-nitrosourea chemotherapy, as measured by reduced bioluminescence, increased apoptosis and prolonged survival. The ability of KCC009 to interfere with the permissive remodeling of fibronectin in the ECM in glioblastomas suggests a novel target to enhance sensitivity to chemotherapy directed not only at the tumor mass, but also invading glioblastoma cells.

Percutaneous transvenous embolization of a dural arteriovenous fistula through a mastoid emissary vein

✓ Definitive endovascular treatment of dural arteriovenous fistulas (DAVFs) requires obliteration of the site of the fistula: either the diseased dural sinus or the pial vein. Access to this site is often limited by occlusion of the sinus proximal and distal to the segment containing the fistula. The authors describe a technique in which the mastoid emissary vein is used to gain access to a Borden–Shucart Type II DAVF in the transverse–sigmoid sinus. Recognition of this route of access, if present, may facilitate endovascular treatment of these lesions. Access to the transverse sinus via this approach can be straightforward and may be underused.

Clinical Features and Outcome in North American Adults With Moyamoya Phenomenon

Background and Purpose— To describe baseline clinical features and outcomes of adults with moyamoya phenomenon treated at a single North American institution.

Methods— We identified 34 adults with moyamoya phenomenon by review of angiographic records. Clinical presentation and baseline stroke risk factors were obtained by chart review. Follow-up was obtained prospectively. A 5-year Kaplan-Meier stroke risk was calculated.

Results— The median age was 42 (range 20 to 79) years. Twenty-five were women. The initial symptom was ischemia, hemorrhage, or asymptomatic in 24, 7, and 3 patients, respectively. Twenty-two had bilateral involvement and 12 had unilateral moyamoya vessels. Baseline stroke risk factors were similar between groups. The median follow-up in 31 living patients was 5.1 (range 0.2 to 19.6) years. Fourteen patients were treated with surgical revascularization (20 total hemispheres). In medically treated symptomatic hemispheres, the 5-year risk of recurrent ipsilateral stroke was 65% after the initial symptom and 27% after angiographic diagnosis. Patients with bilateral involvement presenting with ischemic symptoms were at the highest risk of subsequent stroke (n=17, 5-year risk of stroke with medical treatment after first symptom of 82%). In surgically treated hemispheres, the 5-year risk of perioperative or subsequent ipsilateral stroke or death was 17%. This was significantly different compared with medical treatment after first symptom ( P =0.02) but not after angiographic diagnosis.

Conclusion— Moyamoya phenomenon in North American adults is associated with a high risk of recurrent stroke, particularly those with bilateral involvement and ischemic symptoms. These data suggest a potential benefit with surgery if diagnosis could be made earlier.

Tissue transglutaminase 2 inhibition promotes cell death and chemosensitivity in glioblastomas

Tissue transglutaminase 2 belongs to a family of transglutaminase proteins that confers mechanical resistance from proteolysis and stabilizes proteins. Transglutaminase 2 promotes transamidation between glutamine and lysine residues with the formation of covalent linkages between proteins. Transglutaminase 2 also interacts and forms complexes with proteins important in extracellular matrix organization and cellular adhesion. We have identified the novel finding that treatment of glioblastoma cells with transglutaminase 2 inhibitors promotes cell death and enhances sensitivity to chemotherapy. Treatment with either the competitive transglutaminase 2 inhibitor, monodansylcadaverine, or with highly specific small-molecule transglutaminase 2 inhibitors, KCA075 or KCC009, results in induction of apoptosis in glioblastoma cells. Treatment with these transglutaminase 2 inhibitors resulted in markedly decreased levels of the prosurvival protein, phosphorylated Akt, and its downstream targets. These changes promote a proapoptotic profile with altered levels of multiple intracellular proteins that determine cell survival. These changes include decreased levels of the antiapoptotic proteins, survivin, phosphorylated Bad, and phosphorylated glycogen synthetase kinase 3beta (GSK-3beta), and increased levels of the proapoptotic BH3-only protein, Bim. In vivo studies with s.c. murine DBT glioblastoma tumors treated with transglutaminase 2 inhibitors combined with the chemotherapeutic agent, N-N'-bis (2-chloroethyl)-N-nitrosourea (BCNU), decreased tumor size based on weight by 50% compared with those treated with BCNU alone. Groups treated with transglutaminase 2 inhibitors showed an increased incidence of apoptosis determined with deoxynucleotidyl transferase-mediated biotin nick-end labeling staining. These studies identify inhibition of transglutaminase 2 as a potential target to enhance cell death and chemosensitivity in glioblastomas.