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Editorial

Vertebrobasilar dissections

Giuseppe Lanzino

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Kenichi Sato, Karel G. TerBrugge and Timo Krings

Object

Spinal dural arteriovenous fistulas (SDAVFs) consist of a shunt with converging feeding vessels arising from radiculomeningeal arteries and draining retrogradely via a radicular vein into the perimedullary veins, thereby causing progressive myelopathy due to venous hypertension in the spinal cord. The purpose of this study was to evaluate the hypothesis that the obstruction of radicular venous outlets could be an additional factor inducing symptomatic venous hypertension due to a decreased outflow in SDAVFs.

Methods

The authors compared the clinical and imaging findings in patients with asymptomatic SDAVFs identified incidentally at the upper thoracic region with the findings in symptomatic patients who harbored SDAVFs at the same level.

Results

All symptomatic patients presented with medullary dysfunction. The mean age of patients with asymptomatic SDAVF was 51.5 years, approximately 10 years younger than the patients with symptomatic SDAVF (64.1 years old). Despite the existence of dilated perimedullary vessels in the dorsal side of the spinal cord in all patients, the spinal cord edema seen in symptomatic patients was not detected on the MR images obtained in patients with asymptomatic SDAVF. The spinal angiograms of the asymptomatic patients distinctively demonstrated early radicular venous outflow from affected perimedullary veins to the extradural venous plexus as a potential alternate route for the venous hypertension to be released.

Conclusions

Obstruction of the radicular venous outflow could be an important factor in inducing spinal congestive edema due to venous hypertension, as well as subsequent clinical symptoms of SDAVFs.

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Daipayan Guha, Tim-Rasmus Kiehl, Timo Krings and Taufik A. Valiante

Schwannomas of the brain parenchyma are extremely rare, occurring mostly in children and young adults. Fewer than 50 cases have been reported in the English-language literature. Isolated temporal lobe epilepsy is a rare presentation of intracerebral schwannomas, with only 2 reported cases. The authors present the case of a 51-year-old woman with a 4-year history of medication-refractory seizures, which were localized on electroencephalography to the right temporal lobe. Magnetic resonance imaging identified a mildly space-occupying, T2 hyperintense, and inhomogeneously enhancing mass in her left mesial temporal lobe. Histological, immunohistochemical, and electron microscopy examinations of the surgical specimen established a diagnosis of intracerebral schwannoma. Accurate diagnosis of intracerebral schwannomas is essential, particularly in younger patients, given the lesions' nature, amenity to resection, favorable long-term prognosis, and broad radiological differential. The etiology of these lesions remains unknown, and multiple proposed theories are reviewed.

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Juan Pablo Cruz, Rene van Dijk, Timo Krings and Ronit Agid

Dural arteriovenous fistulas (DAVFs) of the cavernous sinus are acquired arteriovenous shunts between the dural branches of the internal and external carotid arteries and the cavernous sinus. These fistulas may present with cortical venous reflux, but more commonly drain antegradely toward the superior ophthalmic vein (SOV). Transvenous embolization is the most common endovascular treatment, but in some cases transvenous access to the compartment of the shunt may not be possible. In cases with no corticovenous reflux, manual compression of the SOV is an excellent alternative treatment, which is well known but rarely reported in the literature. The authors describe a series of 3 cavernous DAVFs with anterior drainage treated successfully by intermittent manual compression of the SOV.

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Jai Jai Shiva Shankar, Karel terBrugge and Timo Krings

Synchronous multiplicity of cranial and spinal dural arteriovenous fistulas (DAVFs) is known but uncommon. The authors report on a patient with the unusual finding of multiple cranial and multiple separate spinal DAVFs. The patient initially presented with vague visual symptoms in 2004. A cranial DAVF was identified along the left transverse sinus with cortical venous reflux and another DAVF was identified along the posterior part of the superior sagittal sinus with no cortical venous reflux. The first DAVF was treated both endovascularly and surgically and the second was left untreated. The follow-up angiogram showed multiple spinal DAVFs at the levels of C-1, C-2, and C-6 on the left side and at the C-3 level on the right side along with another cranial DAVF along the anterior part of the superior sagittal sinus with cortical venous reflux. A retrospective analysis of the digital subtraction angiogram and MR images suggested that the cervical spinal DAVFs were already present in 2004 (6 years previously). Multiple DAVFs, although rare, do exist and it is important to look for any evidence of their presence when evaluating patients with symptoms suggestive of arteriovenous fistulas.

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Guillaume Saliou, Peter Dirks, Lee-Anne Slater and Timo Krings

OBJECTIVE

The etiology of jugular bulb stenosis (JBS) or occlusion in the context of vein of Galen aneurysmal malformations (VGAMs) is unknown. It can lead to decompensation of a lesion that was previously clinically stable. The aim of this study was to describe the natural history of JBS or occlusion in VGAM and to determine whether there is an association with bony remodeling of the jugular foramina.

METHODS

The authors identified all cases of JBS greater than 70% bilaterally involving patients seen at The Hospital for Sick Children between January 2007 and June 2014. The foramen diameters were measured on sagittal CT imaging, on a slice passing at the level of the jugular vein. The jugular foramen diameters were also compared to measurements obtained in a matched population of the same age group who had no VGAM and had undergone cerebral CT for a reason other than vascular disease.

RESULTS

Eight patients (6 male and 2 female) with bilateral JBS were included in this series. The median duration of clinical follow-up was 2.5 years (IQR 1.7–4.2 years). JBS was associated with bony narrowing the jugular foramina in 7 of the 8 patients over time. Between 1 and 2 years of age, patients with a VGAM demonstrated jugular foramen narrowing in comparison with a matched population (p = 0.015).

CONCLUSIONS

Jugular bulb stenosis or occlusion in VGAM may be associated with narrowing of the jugular foramina. These conditions seem to have a male predominance. If treatment is required, bony narrowing of the jugular foramina should be taken into account when deciding whether angioplasty and stent placement or surgical bypass might be appropriate therapeutic options.

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Sasikhan Geibprasert, Sirintara Pongpech, Pakorn Jiarakongmun and Timo Krings

Spinal dural arteriovenous fistulas (DAVFs) are the spinal vascular malformations that are encountered most often, and they are usually encountered in the lower thoracic region. Cervical spine DAVFs are exceedingly rare and may be difficult to differentiate from radicular arteriovenous malformations, epidural arteriovenous shunts, or perimedullary AVFs. Typical angiographic findings in spinal DAVFs include a slow-flow shunt with converging feeding vessels from radiculomeningeal arteries draining via a radicular vein centripetally into perimedullary veins. The MR imaging findings such as spinal cord edema and perimedullary dilated vessels may be used to direct the spinal angiography that is needed to localize and classify the shunt. When the shunt is distant from the pathological imaging findings, the diagnosis may be difficult to establish, especially when the shunt is present at an atypical location such as the cervical spine. The authors present the case of a 51-year-old man presenting with lower thoracic and conus medullaris congestive edema due to a cervical spine DAVF that was located at the C-5 level. Transarterial embolization with N-butyl cyanoacrylate closed the proximal vein and completely obliterated the fistula. Clinical and imaging follow-up confirmed occlusion of the fistula, with improvement in clinical symptoms.

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Timo Krings, Marcus H. T. Reinges, Ruth Thiex, Joachim M. Gilsbach and Armin Thron

Object. During neurosurgical interventions, preservation of subcortical axons is as important as preservation of cortical neurons. The goal of this study was to assess the combined use of functional (f) and diffusion-weighted (DW) magnetic resonance (MR) imaging to assist in the preservation of the structure and function of the motor system.

Methods. The authors evaluated the combination of fMR imaging and DW MR imaging to detect cortical motor areas with their corresponding pyramidal tracts in 12 healthy volunteers and in 10 consecutive patients with various space-occupying lesions affecting the central motor system.

Activation within the primary motor cortex (M1) and white matter bundles originating from this cortical region was demonstrated in 21 of the 22 individuals examined. Additional activation was exhibited along the course of white matter tracts at the level of the pons and, in the contralateral hemisphere, in the M1. Fiber tract displacement was visualized in all patients in white matter that had appeared normal on routine T1- and T2-weighted MR images.

Conclusions. The combination of DW MR and fMR imaging allows visualization of the origin, direction, and functionality of large white matter tracts. This will prove helpful for imaging structural connectivity within the brain during functional imaging. Moreover, local relationships of cerebral tumors that encroach upon M1 and subcortical fiber tracts can be defined. This promises to decrease patient morbidity and to broaden the clinical applications of functional imaging.

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Ruth Thiex, Joachim Weis, Timo Krings, Sonia Barreiro, Funda Yakisikli-Alemi, Joachim M. Gilsbach and Veit Rohde

Object

Fibrinolytic therapy with recombinant tissue plasminogen activator (rtPA) is considered a treatment option in patients with deep-seated intracerebral hemorrhage (ICH). Nevertheless, the results of animal experiments have shown that tPA exerts pleiotropic actions in the brain, including regulation of vasoactivity, amplification of calcium conductance by cleavage of the N-methyl-D-aspartate (NMDA) receptor subunit, and activation of metalloproteinases, which increase excitotoxicity, damage the blood–brain barrier, and worsen edema. The authors investigated whether the noncompetitive NMDA receptor antagonist MK801 can be used as an adjuvant therapy in combination with rtPA to attenuate the unfavorable delayed edema formation and inflammation observed following rtPA therapy in an experimental porcine model of ICH.

Methods

Twenty pigs were used in this study; MK801 (0.3 mg/kg) was administered to each pig intravenously immediately after hematoma induction and on the 1st and 3rd day after hematoma induction. Ten of the 20 pigs were randomly assigned to fibrinolytic therapy with rtPA (MK801–tPA group), whereas in the remaining 10 control animals (MK801 group) the hematomas were allowed to follow their natural courses of resorption. The extent of edema formation was evaluated using magnetic resonance (MR) imaging volumetry on Days 0, 4, and 10 after hematoma induction and was compared with histopathological changes found at necropsy. The mean edema volumes in these two groups were also compared with that in the group of nine pigs examined in a preceding experimental series, in which the animals’ hematomas were only treated with rtPA (tPA group).

In the 10 animals in the MK801–tPA group, the mean perihematoma edema volume on MR images had not significantly increased by Day 4 (p < 0.08) or Day 10 (p < 0.35) after hematoma induction. In the 10 animals in the MK801 group, the increase in mean perifocal edema size was significant after 4 days (p < 0.001) and nonsignificant after 10 days (p < 0.09). In the nine animals in the tPA group, the mean edema volume significantly increased by Days 4 (p < 0.002) and 10 (p < 0.03).

Conclusions

As suggested by the reduction in delayed edema volume and the inflammatory response, MK801 modifies the neurotoxic properties of rtPA but not those of blood degradation products. Possibly, fibrinolytic therapy of ICH is more beneficial if combined with agents such as MK801.

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Dittapong Songsaeng, Sasikhan Geibprasert, Karel G. ter Brugge, Robert Willinsky, Michael Tymianski and Timo Krings

Object

The goal was to investigate whether morphological features of aneurysms can be identified that determine initial success and recurrence rates of coiled aneurysms of the basilar artery tip, the posterior communicating artery (PCoA), and the anterior communicating artery.

Methods

The authors evaluated 202 aneurysms in connection with their pretreatment morphological features including size, neck-to-dome ratio, angulation of the aneurysm in relation to the parent artery, orientation of the aneurysm dome, and associated anatomical variations. The mean follow-up was 19 months (range 6–96 months) after endovascular coil occlusion. Using multivariate logistic regression, probabilities for initial complete occlusion and long-term stability of the treatment were calculated.

Results

Recanalization occurred in 49 of 202 cases. Favorable factors for long-term stability included small aneurysms with small necks. However, additional factors related to local hemodynamic forces could be identified for the different aneurysm locations, which may influence initial success rates and long-term stability of aneurysm treatment with endovascular coiling. These factors were a medial dome orientation and a symmetrical disposition of both A1 segments (for the anterior communicating artery), a posteroinferior dome orientation and a small-size PCoA (for the PCoA), and a cranial symmetrical fusion (for the basilar artery tip).

Conclusions

A detailed pretreatment analysis of morphological features of aneurysms may help to determine those aneurysms that are more prone to recurrence, which could add to the treatment decision and the follow-up algorithm.