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Wolfgang Dietrich, Andrea Reinprecht, Andreas Gruber, and Thomas Czech

✓ An azygos pericallosal artery (APCA) aneurysm is a rare anomaly that is closely associated with saccular aneurysms. This is the earliest report to document de novo formation and rupture of an aneurysm at the bifurcation of an unpaired pericallosal trunk. The authors report the case of a woman who presented at the age of 52 years with subarachnoid hemorrhage (SAH) from the rupture of a newly formed APCA bifurcation aneurysm, 7 years after she had undergone surgery to clip a ruptured anterior cerebral artery aneurysm. De novo formation of aneurysms after SAH rarely occurs and certain risk factors like multiple and familial aneurysms, arterial hypertension, or smoking have been postulated. Late follow-up examination with angiography to detect de novo aneurysms should be considered in patients with this vascular anomaly after SAH.

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Gerhard Bavinzski, Monika Killer, Andreas Gruber, Andrea Reinprecht, Cordell E. Gross, and Bernd Richling

Object. The authors retrospectively analyzed the results of their 6-year experience in the treatment of basilar artery (BA) bifurcation aneurysms by using Guglielmi detachable coils (GDCs).

Methods. This analysis involved 45 BA tip aneurysms in 16 men and 29 women who ranged in age from 23 to 78 years (mean 50 years). Seventy-five percent of the aneurysms had ruptured and 25% remained unruptured. Of the group whose aneurysms hemorrhaged, 14 patients were Hunt and Hess Grade I or II and 20 were Hunt and Hess Grades III to V; 32 patients were treated within 2 weeks of their subarachnoid hemorrhage (SAH). Initially, treatment with GDCs was limited to poor-grade high-risk patients who refused surgery or patients in whom surgery proved unsuccessful. Later in the study, good-grade patients with narrow-necked aneurysms were also treated using GDCs.

The length of clinical follow up ranged from 1 to 72 months (average 27.4 months) in the 37 surviving patients. In 33 of the 45 aneurysms treated with coil placement, good to excellent results were achieved. There were 12 poor results (27%) including one in a patient from the non-SAH group who suffered a thrombotic complication due to an underlying vasculitis. Eight deaths were recorded in this group of 45 patients. One of these deaths was caused by a complication related to anesthesia, one by unknown causes, and six resulted from complications of the disease. One patient rebled on the 2nd day after the endovascular procedure. The mortality and permanent morbidity rates directly related to the intervention were 2.2% and 4.4%, respectively.

Angiographic studies obtained immediately postintervention demonstrated 99 to 100% occlusion in 30 (67%) of the aneurysms; nine (20%) were more than 90% occluded; and six (13%) were less than 90% occluded by the GDCs. Follow-up angiograms were obtained in 31 patients between 2 and 72 months after coil placement. Nineteen (61%) of the follow-up angiograms revealed stable results (that is, no change from initial treatment). Twelve of the 31 showed coil compaction, but only eight of these lesions could accept additional coils.

In large aneurysms recanalization was seen in 57%, and some of the larger lesions required as many as four embolizations (mean 1.7) to achieve optimal occlusion. When small-necked aneurysms were analyzed as a subset, a stable angiographic result was seen in 92%.

Conclusions. Use of GDCs led to excellent clinical and angiographic results in the majority of patients with BA tip aneurysms included in this limited follow-up study. Rebleeding was encountered in one of the 34 previously ruptured BA aneurysms treated with GDCs, and no hemorrhages have been documented in the 11 unruptured aneurysms treated with GDCs in this series. Long-term follow-up studies are necessary before it is possible to compare adequately the treatment of aneurysms with coil placement to the gold standard of aneurysm clipping.

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Andreas Stadlbauer, Ewald Moser, Stephan Gruber, Christopher Nimsky, Rudolf Fahlbusch, and Oliver Ganslandt

Object. It is often difficult to delineate the extent of invasion of high- and low-grade gliomas into normal brain tissue by using conventional T1- and T2-weighted magnetic resonance (MR) imaging. Knowledge of the relationship between the tumor infiltration zone and normal brain, however, is one of the prerequisites for performing as radical a tumor resection as possible. Proton MR spectroscopy allows noninvasive measurements of the concentrations and spatial distributions of brain metabolites and, therefore, may provide biochemical information in vivo, that is useful in distinguishing pathological from normal areas of the brain.

The authors have developed a method to use the properties of MR spectroscopy to investigate intraoperatively pathological changes in the spatial distribution of choline (Cho)-containing compounds, total creatine, and N-acetylaspartate (NAA) in brain tumors with the aid of frameless stereotaxy.

Methods. Maps of the Cho/NAA ratio were calculated and automatic segmentation of the tumors was performed. Spectroscopic images of the segmented tumor were matched to an anatomical three-dimensional (3D) MR imaging set by applying a fully automated mutual-information algorithm. The resulting 3D MR image can be used subsequently for neurosurgical planning, transfer to a frameless stereotactic system, and display in the navigation microscope during surgery leading to 1H-MR spectroscopy-guided navigation.

Conclusions. This method may allow better intraoperative identification of tumor border zones based on metabolic changes due to tumor infiltration.

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Andreas Gruber, Andrea Reinprecht, Harald Görzer, Peter Fridrich, Thomas Czech, Udo M. Illievich, and Bernd Richling

Object. This observational study is based on a consecutive series of 207 patients with aneurysmal subarachnoid hemorrhage who were treated within 7 days of their most recent bleed. The purpose of the study was to evaluate the effect of respiratory failure on neurological outcome.

Methods. Pulmonary function was assessed by determination of parameters describing pulmonary oxygen transport and exchange, by using composite scores for quantification of lung injury (lung injury score [LIS]) and mechanical ventilator settings (PIF score). Pulmonary function was related to the Hunt and Hess (H & H) grade assigned to the patient at hospital admission (p < 0.001). The pattern and time course of lung injury differed significantly between patients with H & H Grade I or II, Grade III, and Grade IV or V. Hunt and Hess grade, Fisher computerized tomography grade, intracranial pressure, cerebral perfusion pressure, LIS, ratio of PaO2 to the fraction of inspired oxygen (FiO2), and the ratio of the alveolar-minus-arterial oxygen tension difference (AaDO2) to FiO2 were related to neurological outcome (p < 0.001). The LIS on the day of maximum lung injury remained an independent predictor of outcome (p = 0.01) in a stepwise logistic regression analysis. The probability of poor neurological outcome significantly increased with both decreasing cerebral perfusion pressure and increasing severity of lung injury.

Conclusions. The overall mortality rate was 22.2% (46 of 207 patients). Subarachnoid hemorrhage and its neurological sequelae accounted for the principal mortality in this series. Medical (nonneurological and nontreatment-related) complications accounted for 37% of all deaths. Systemic inflammatory response syndrome with associated multiple organ dysfunction syndrome was the leading cause of death from medical complications. The authors conclude that respiratory failure is related to neurological outcome, although it is not commonly the primary cause of death from medical complications.

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Arthur Hosmann, Carmen Angelmayr, Andreas Hopf, Steffen Rauscher, Jonas Brugger, Lavinia Ritscher, Isabelle Bohl, Philipp Schnackenburg, Adrian Engel, Walter Plöchl, Markus Zeitlinger, Andrea Reinprecht, Karl Rössler, and Andreas Gruber

OBJECTIVE

Intrahospital transport for CT scans is routinely performed for neurosurgical patients. Particularly in the sedated and mechanically ventilated patient, intracranial hypertension and blood pressure fluctuations that might impair cerebral perfusion are frequently observed during these interventions. This study quantifies the impact of intrahospital patient transport on multimodality monitoring measurements, with a particular focus on cerebral metabolism.

METHODS

Forty intrahospital transports in 20 consecutive patients suffering severe aneurysmal subarachnoid hemorrhage (SAH) under continuous intracranial pressure (ICP), brain tissue oxygen tension (pbtO2), and cerebral microdialysis monitoring were prospectively included. Changes in multimodality neuromonitoring data during intrahospital transport to the CT scanner and the subsequent 10 hours were evaluated using linear mixed models. Furthermore, the impact of risk factors at transportation, such as cerebral vasospasm, cerebral hypoxia (pbtO2 < 15 mm Hg), metabolic crisis (lactate-pyruvate ratio [LPR] > 40), and transport duration on cerebral metabolism, was analyzed.

RESULTS

During the transport, the mean ICP significantly increased from 7.1 ± 3.9 mm Hg to 13.5 ± 6.0 mm Hg (p < 0.001). The ICP exceeded 20 mm Hg in 92.5% of patients; pbtO2 showed a parallel rise from 23.1 ± 13.3 mm Hg to 28.5 ± 23.6 mm Hg (p = 0.02) due to an increase in the fraction of inspired oxygen during the transport. Both ICP and pbtO2 returned to baseline values thereafter. Cerebral glycerol significantly increased from 71.0 ± 54.9 µmol/L to 75.3 ± 56.0 µmol/L during the transport (p = 0.01) and remained elevated for the following 9 hours. In contrast, cerebral pyruvate and lactate levels were stable during the transport but showed a significant secondary increase 1–8 hours and 2–9 hours, respectively, thereafter (p < 0.05). However, the LPR remained stable over the entire observation period. Patients with extended transport duration (more than 25 minutes) were found to have significantly higher levels of cerebral pyruvate and lactate as well as lower glutamate concentrations in the posttransport period.

CONCLUSIONS

Intrahospital transport and horizontal positioning during CT scans induce immediate intracranial hypertension and an increase in cerebral glycerol, suggesting neuronal injury. Afterward, sustained impairment of neuronal metabolism for several hours could be observed, which might increase the risk of secondary ischemic events. Therefore, intrahospital transport for neuroradiological imaging should be strongly reconsidered and only indicated if the expected benefit of imaging results outweighs the risks of transportation.

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Matthias Millesi, Engelbert Knosp, Georg Mach, Johannes A. Hainfellner, Gerda Ricken, Siegfried Trattnig, and Andreas Gruber

OBJECTIVE

In the last several decades, various factors have been studied for a better evaluation of the risk of rupture in incidentally discovered intracranial aneurysms (IAs). With advanced MRI, attempts were made to delineate the wall of IAs to identify weak areas prone to rupture. However, the field strength of the MRI investigations was insufficient for reasonable image resolution in many of these studies. Therefore, the aim of this study was to analyze findings of IAs in ultra–high field MRI at 7 Tesla (7 T).

METHODS

Patients with incidentally found IAs of at least 5 mm in diameter were included in this study and underwent MRI investigations at 7 T. At this field strength a hyperintense intravascular signal can be observed on nonenhanced images with a brighter “rim effect” along the vessel wall. Properties of this rim effect were evaluated and compared with computational fluid dynamics (CFD) analyses.

RESULTS

Overall, 23 aneurysms showed sufficient image quality for further evaluation. In 22 aneurysms focal irregularities were identified within this rim effect. Areas of such irregularities showed significantly higher values in wall shear stress and vorticity compared to areas with a clearly visible rim effect (p = 0.043 in both).

CONCLUSIONS

A hyperintense rim effect along the vessel wall was observed in most cases. Focal irregularities within this rim effect showed higher values of the mean wall shear stress and vorticity when compared by CFD analyses. Therefore, these findings indicate alterations in blood flow in IAs within these areas.

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Gerhard Bavinzski, Volkan Talazoglu, Monika Killer, Bernd Richling, Andreas Gruber, Cordell E. Gross, and Hanns Plenk Jr.

Object. The histopathological characteristics of aneurysms obtained at autopsy or surgery 3 days to 54 months after being treated with Guglielmi detachable coils (GDCs) were assessed.

Methods. Seventeen aneurysms were obtained at autopsy and one was removed at surgery. Fourteen were examined histologically with the coils in situ. Naked coils embedded in an unorganized thrombus were found in those aneurysms that had been treated with coils within 1 week earlier. An incomplete replacement of the intraluminal blood clot by fibrous tissue and a partial membranous covering at the aneurysm orifice were observed in those aneurysms that had been treated with coils between 2 and 3 weeks prior to examination. One small aneurysm treated 6 weeks before harvesting showed formation of an endothelium-lined layer of connective tissue at the orifice. Collagen-rich vascularized tissue surrounding the coils was found in an aneurysm removed at surgery 54 months after coil implantation. Interestingly, six (50%) of 12 aneurysms (two small, three large, and one giant) that had been deemed 100% occluded on initial angiography showed tiny open spaces between the coils at the neck on gross examination.

Conclusions. Endothelialization of the aneurysm orifice following placement of GDCs can occur; however, it appears to be the exception rather than the rule. In large aneurysms the process of intraaneurysm clot organization seems to be delayed and incomplete; tiny open spaces between the coils and an incomplete membranous covering in the region of the neck are frequently encountered. Further longitudinal studies are required to establish the spectrum of healing profiles that may direct our efforts in modifying the GDC system to produce a more stable long-term result.

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Andreas Gruber, Karl Roessler, Apostolos Georgopoulos, Albert Mißbichler, Raphael Bonelli, Bernd Richling, Gerhard Bavinzski, and Thomas Czech

Object

Whereas the removal of subarachnoid blood is possible during early-stage aneurysm surgery, this cannot be achieved in aneurysms treated by endovascular means. The levels of potential spasmogens in the cerebrospinal fluid (CSF) in patients receiving endovascular treatment might therefore be higher, with the potential for more severe post–subarachnoid hemorrhage (SAH) vasospasm.

Methods

Serum and CSF concentrations of big endothelin (ET)–1 were serially measured in patients with SAH receiving one of the following treatments: 1) early (within 72 hours of SAH) aneurysm surgical treatment (15 patients), 2) early endovascular treatment (17 patients), or 3) no intervention in the acute phase (12 patients). In patients suffering delayed infarctions higher levels of big ET–1 CSF were demonstrated than in those without infarctions (p = 0.01). In patients in whom surgery was performed in the acute phase lower big ET–1 CSF concentrations were demonstrated than in those who received embolization treatment or no treatment (p = 0.02). Subgroup analysis demonstrated that in patients receiving early endovascular treatment, higher big ET–1 CSF concentrations were revealed than in those undergoing early aneurysm surgery; this was true for patients with (microsurgery-treated, 1.84 ± 0.83 pg/ml; and embolization-treated 2.19 & plusmn; 0.54 pg/ml) and without (microsurgery-treated 1.76 & plusmn; 0.61 pg/ml; and embolization-treated 2.01 ± 0.48 pg/ml) delayed infarctions.

Conclusions

Among patients with SAH who received treatment during the acute phase, those undergoing early aneurysm surgery were shown to have lower big ET–1 CSF levels than those receiving embolization and no treatment (that is, the nonsurgical treatment groups). The clinical significance of this finding remains to be established in future clinical trials, because in the present study the trend toward lower levels of big ET–1 CSF in the microsurgically treated group was not paralleled by a lower delayed stroke rate or an improvement in neurological outcome.