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Acute posttraumatic spinal cord herniation

Case report and review of the literature

Gerhard Marquardt, Stefan Weidauer, Friedhelm E. Zanella and Volker Seifert

✓ Transdural herniations of the spinal cord are rare, and those occurring acutely after a spinal cord injury (SCI) are particularly unusual. In this report, the authors present the case of acute posttraumatic spinal cord herniation in a patient who sustained severe polytraumatic injuries. The clinical manifestations were acute flaccid paralysis of the right leg and rapidly progressive sensorimotor deficits of the contralateral leg. The herniation was surgically reduced. Postoperatively left leg paralysis was completely resolved. The authors review the pertinent literature, and suggest that, with regard to another underlying pathophysiological mechanism, cases of acute posttraumatic spinal cord herniation should be differentiated from those “posttraumatic” cases in which herniation of the spinal cord occurs years or even decades after the traumatic event. To the best of the authors' knowledge, only one similar case has been previously reported. They conclude that acute posttraumatic spinal cord herniation should be included in the differential diagnosis of acute neurological deterioration after SCI.

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Gerhard Marquardt, Soledad M. Barduzal Angles, Fouad D. Leheta and Volker Seifert

✓ A rare case of peripheral-nerve compression in the upper arm caused by a spontaneous venous aneurysm is reported. The apparent dysfunction of the median nerve led to various vain surgical explorations of the nerve at different levels. The real localization of nerve entrapment was identified by a thorough clinical examination, and sonography yielded a correct diagnosis. Surgical resection of the venous aneurysm resulted in complete relief of pain. To the authors' knowledge, this is the first report of a spontaneous venous malformation in the upper arm causing focal neuropathy.

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Rüdiger Gerlach, Gerhard Marquardt, Heimo Wissing, Inge Scharrer, Andreas Raabe and Volker Seifert

✓ The authors report on a 64-year-old woman with a huge recurrent skull base hemangiopericytoma, in whom they encountered severe difficulty in attaining intraoperative hemostasis. Standard surgical hemostatic methods and the administration of fresh-frozen plasma and prothrombin complex concentrates failed to stop diffuse bleeding from an inoperable tumor remnant. At a critical point during the operation, the intravenous administration of recombinant activated factor VII, combined with mechanical compression, finally led to satisfactory hemostasis. The rationale for using recombinant activated factor VII in situations of uncontrolled bleeding during neurosurgical procedures is discussed, along with the literature in which the use of recombinant activated factor VII as a maneuver of last resort is reported for hemostasis in other surgical fields.

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Christian Foerch, Josef M. Lang, Jochen Krause, Andreas Raabe, Matthias Sitzer, Volker Seifert, Helmuth Steinmetz and Kirn R. Kessler

Object. Whether decompressive hemicraniectomy is an appropriate treatment for space-occupying middle cerebral artery (MCA) infarction is still a controversial issue. Previous studies are in agreement on a reduction of the mortality rate, but the reported functional outcome was highly variable. The authors sought to determine functional impairment, disability, and health-related quality of life (QOL) outcome in long-term survivors who had undergone this procedure, and tried to identify factors related to functional outcome.

Methods. The study included 36 consecutive patients (mean age 58.8 ± 12.7 years, 20 men and 16 women) who underwent decompressive hemicraniectomy for treatment of malignant MCA infarction (29 on the right and seven on the left side; mean time to surgery 37.8 ± 20 hours). The survival rate was determined at 6 months: 13.7 ± 6.7 months after the stroke, a cross-sectional personal investigation of survivors was performed to assess functional impairment, disability, and health-related QOL.

Survival rates were 78% at 6 months and 64% at the time of the follow-up investigation; one patient was lost to follow up. Sixteen of 22 long-term survivors lived at home. The median Barthel Index (BI) was 45 (25th and 75th percentile 19 and 71) and the BI correlated negatively with patient age (r = −0.58, p = 0.005). Three patients reached a BI of at least 90. Older age, more severe neurological deficit on admission, and longer duration of intensive care treatment and mechanical ventilation were significantly associated with worse disability (BI < 50). The health-related QOL was considerably impaired in the subscales of mobility, household management, and body care.

Conclusions. Decompressive hemicraniectomy improves survival in patients with malignant MCA infarction when compared with earlier reports of conservative treatment alone. Functional outcome and QOL remain markedly impaired, especially among elderly patients and in those with a severe neurological deficit at admission.

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Andreas Mack, Robert Wolff, Stefan Scheib, Marcus Rieker, Dirk Weltz, G. Mack, Hans-Jürg Kreiner, Ulrich Pilatus, Friedhelm E. Zanella, Heinz D. Böttcher and Volker Seifert

Object. The limiting factor affecting accuracy during gamma knife surgery is image quality. The new generation of magnetic resonance (MR) imaging units with field strength up to 3 teslas promise superior image quality for anatomical resolution and contrast. There are, however, questions about chemical shifts or susceptibility effects, which are the subject of this paper.

Methods. The 3-tesla MR imaging unit (Siemens Trio) was analyzed and compared with a 1-tesla unit (Siemens Magnetom Expert) and to a 1.5-tesla unit (Philips Gyroscan). Evaluation of the magnitude of error was performed within transverse slices in two orientations (axial/coronal) by using a cylindrical phantom with an embedded grid. Deviations were determined for 21 targets in a slab phantom with known geometrical positions within the stereotactic frame. Distortions caused by chemical shift and/or susceptibility effects were analyzed in a head phantom. Inhouse software was used for data analyses.

The mean deviation was less than 0.3 mm in axial and less than 0.4 mm in coronal orientations. For the known targets the maximum deviation was 1.16 mm. By optimizing these parameters in the protocol these inaccuracies could be reduced to less than 1.1 mm. Due to inhomogeneities a shift in the z direction of up to 1.5 mm was observed for a dataset, which was shown to be compressed by 1.2 mm.

Conclusions. The 3-tesla imaging unit showed superior anatomical contrast and resolution in comparison with the established 1-tesla and 1.5-tesla units; however, due to the high field strength the field within the head coil is very sensitive to inhomogeneities and therefore 3-tesla imaging data will have be handled with care.

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Elke Hattingen, Catriona Good, Stefan Weidauer, Sebastian Herminghaus, Peter Raab, Gerhard Marquardt, Andreas Raabe, Volker Seifert and Friedhelm E. Zanella

Object. The goal of this study was to evaluate a novel form of brain surface representation that allows simple, reliable mapping of the surface neuroanatomy for the preoperative evaluation of the spatial relationship between a focal lesion and the precentral gyrus.

Methods. High-resolution three-dimensional (3D) magnetic resonance (MR) imaging data sets were postprocessed using a curved multiplanar reformatting technique to create brain surface reformatted (BSR) images. These BSR images were reconstructed in less than 5 minutes and demonstrated the entire central sulcus with adjacent surface structures in one view. Two experienced neuroradiologists determined the localization of lesions near the central sulcus in 27 patients on standard MR images in three orthogonal planes and on BSR images. In addition, these observers judged whether the lesions were easy or difficult to localize on standard MR and BSR images, and whether diagnoses based on these methods were certain or doubtful. Anatomical localization based on BSR images was compared with that based on functional MR (fMR) images or intraoperative mapping of motor function. The BSR images yielded a perfect concordance with the fMR images and intraoperative mapping (Cohen κ 1.0) and optimal diagnostic accuracy in localizing perirolandic lesions (both sensitivity and specificity were 100%). Localization was judged to be easy for 48 of 54 diagnoses based on BSR images compared with 26 of 54 based on standard MR images. Diagnoses were assessed as certain for 52 cases based on BSR images and 34 cases based on standard MR images.

Conclusions. Brain surface reformatted imaging improves the diagnostic accuracy of standard anatomical MR imaging for localizing superficial brain lesions in relation to the precentral gyrus. The complementary use of this technique with standard two-dimensional imaging is supported by the fast and simple postprocessing technique and may provide useful information for preoperative surgical planning.

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Gerhard Marquardt, Matthias Setzer, Alf Theisen, Edgar Dettmann and Volker Seifert

Object. The goal of this study was to develop a novel dynamic model for experimental spinal cord compression that closely approximates neoplastic epidural compression of the spinal cord in humans.

Methods. In 30 New Zealand white rabbits, the thoracic spine was exposed via a posterior approach. On each side of one vertebral lamina a small hole was drilled caudal to the articular process. A silicone band was passed through these holes, forming a loop. The spinal dura mater was exposed via an interlaminar approach. The loop was brought into contact with the dura mater and fixed in its position encircling 270° of the circumference of the spinal cord. Thereafter, the loop was gradually tightened at set times by pulling at the ends of the band and fixing them again in their new position. The spinal cord was thus increasingly compressed in a circular and dynamic manner.

Neurological deficits of various degrees were created in all animals in the compression group, and the compressive effect of the loop was reliably demonstrated on MR imaging. After decompression of the spinal cord, the neurological deficits were reversible in the majority of animals, and MR imaging revealed either no signal changes or only circumscribed ones within the cord. In contrast, MR images obtained in animals that did not recover revealed the occurrence of extensive chronic myelopathy.

Conclusions. This novel model features reproducibility of paresis and neurological recovery. It is a dynamic model simulating circular tumor growth and is characterized by its easy, straightforward, and cost-saving applicability.

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Hartmut Vatter, Michael Zimmermann, Veronika Tesanovic, Andreas Raabe, Lothar Schilling and Volker Seifert

Object. The central role of endothelin (ET)—1 in the development of cerebral vasospasm after subarachnoid hemorrhage is indicated by the successful treatment of this vasospasm in several animal models by using selective ETA receptor antagonists. Clazosentan is a selective ETA receptor antagonist that provides for the first time clinical proof that ET-1 is involved in the pathogenesis of cerebral vasospasm. The aim of the present investigation was, therefore, to define the pharmacological properties of clazosentan that affect ETA receptor—mediated contraction in the cerebrovasculature.

Methods. Isometric force measurements were performed in rat basilar artery (BA) ring segments with (E+) and without (E−) endothelial function. Concentration effect curves (CECs) were constructed by cumulative application of ET-1 or big ET-1 in the absence or presence of clazosentan (10−9, 10−8, and 10−7 M). The inhibitory potency of clazosentan was determined by the value of the affinity constant (pA2).

The CECs for contraction induced by ET-1 and big ET-1 were shifted to the right in the presence of clazosentan in a parallel dose-dependent manner, which indicates competitive antagonism. The pA2 values for ET-1 were 7.8 (E+) and 8.6 (E−) and the corresponding values for big ET-1 were 8.6 (E+) and 8.3 (E−).

Conclusions. The present data characterize clazosentan as a potent competitive antagonist of ETA receptor—mediated constriction of the cerebrovasculature by ET-1 and its precursor big ET-1. These functional data may also be used to define an in vitro profile of an ET receptor antagonist with a high probability of clinical efficacy.

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Hartmut Vatter, Michael Zimmermann, Veronika Tesanovic, Andreas Raabe, Volker Seifert and Lothar Schilling

Object. The disturbed balance between nitric oxide and endothelin (ET)—1 in the cerebrovasculature seems to play a major role in the development of cerebral vasospasm after subarachnoid hemorrhage. Endothelin-1 represents the contractile part in this balance. In addition to the prevailing ETA receptor—dependent contractile effect, ET-1 also has ETB receptor—mediated vasodilatory attributes. The aim of the present study was to define the actual selectivity of clazosentan, the first putative highly ETA receptor—selective antagonist clinically proven to be effective in the treatment of vasospasm in the cerebrovasculature.

Methods. Rat basilar artery ring segments with endothelial function were used for the measurement of isometric force. Concentration effect curves were constructed by cumulative application of sarafotoxin S6c, ET-1, or big ET-1 in the presence or absence of clazosentan (10−9 to 10−6 M) after a precontraction was induced by prostaglandin F. The inhibition by clazosentan was estimated by the value of the affinity constant (pA2).

The relaxation induced by sarafotoxin S6c, ET-1, and big ET-1 was inhibited in a competitive manner by clazosentan, yielding pA2 values of 7.1, 6.7, and 6.5, respectively. The selectivity to the ETA receptor in the cerebrovascular system was approximately two logarithmic units.

Conclusions. The present investigation shows a competitive inhibition of ETB receptor—mediated relaxation in cerebral vessels by clazosentan in therapeutically relevant concentrations. Thus, additional clinical trials should be undertaken to evaluate clazosentan concentrations in cerebrospinal fluid. Furthermore, the present data may be taken to describe the pharmacological properties for an ET receptor antagonist specifically tailored for the treatment of pathological conditions of impaired cerebral blood flow.

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Andreas Raabe, Peter Nakaji, Jürgen Beck, Louis J. Kim, Frank P. K. Hsu, Jonathan D. Kamerman, Volker Seifert and Robert F. Spetzler

Object. The authors prospectively compared a new technique of surgical microscope-based indocyanine green (ICG) videoangiography with intraoperative or postoperative digital subtraction (DS) angiography.

Method. The technique was performed during 187 surgical procedures in which 124 aneurysms in 114 patients were clipped. Using a newly developed setup, the ICG technique has been integrated into an operating microscope (Carl Zeiss Co., Oberkochen, Germany). A microscope-integrated light source containing infrared excitation light illuminates the operating field. The dye is injected intravenously into the patient, and intravascular fluorescence from within the blood vessels is imaged using a video camera attached to the microscope. The patency of parent, branching, and perforating arteries and documentation of clip occlusion of the aneurysm as shown by ICG videoangiography were compared with intraoperative or postoperative findings on DS angiography.

The results of ICG videoangiography corresponded with intra- or postoperative DS angiography in 90% of cases. The ICG technique missed mild but hemodynamically irrelevant stenosis that was evident on DS angiography in 7.3% of cases. The ICG technique missed angiographically relevant findings in three cases (one hemodynamically relevant stenosis and two residual aneurysm necks [2.7% of cases]). In two cases the missed findings were clinically and surgically inconsequential; in the third case, a 4-mm residual neck may require a second procedure. Indocyanine green videoangiography provided significant information for the surgeon in 9% of cases, most of which led to clip correction.

Conclusions. Microscope-based ICG videoangiography is simple and provides real-time information about the patency of vessels of all sizes and about the aneurysm sac. This technique may be useful during routine aneurysm surgery as an independent form of angiography or as an adjunct to intra- or postoperative DS angiography.