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Background and Purpose: Thrombolytic therapy represented the gold standard for the treatment of ischemic stroke. Its drawbacks include increased bleeding risk and low recanalization rates. Mechanical thrombectomy is a new promising therapy option. Devices used for this procedure were substantially improved during recent years. New devices require extensive preclinical invivo testing. We therefore sought to translate the commonly used pig model to a simplified and cheaper rabbit model., Materials and Methods: We performed thromboembolisation in eight intubated and sedated adult female New Zealand white rabbits. The thrombus was created by careful rotation of autologous blood in a silicone tube and addition of barium sulfate for radiopacity. We injected the artificial thrombus via a catheter through the cannulated femoral artery. After thromboembolisation, 2D-DSA was performed to evaluate location and thrombus dimensions., Comparison With Exisiting Method(s): None., Results: No complications or mortality were observed in our series. In seven cases (87.5%) the location of the thromboembolism was the maxillary artery and in one case (12.5%) the thrombus reached the occipital artery. The radiopaque thrombus had a length of 7.0±4.55mm invivo. Vessel diameters in angiographic evaluation were 2.44±0.21mm for the common carotid artery and 2.1±0.16mm for the maxillary artery., Conclusions: The novel small animal model for mechanical thrombectomy in rabbit is technically feasible and cheap. It offers comparable vessel diameters to cranial arteries and closely mimics human coagulation system., (Copyright © 2016. Published by Elsevier B.V.)

Background: Giant aneurysms are challenging lesions with unacceptable high rates of aneurysm recanalization and rerupture following embolization. Reliable in vivo models are urgently needed to test the performance of new more efficient endovascular devices., Materials and Methods: Aneurysms were created in 11 New Zealand white rabbits (4.5-5.5kg): A long venous pouch (length 25-30mm) mimicking the aneurysm sac was derived from the external jugular vein and sutured into a microsurgically created bifurcation between both common carotid arteries. After 4 weeks the rabbits underwent 3T Magnetic resonance angiography (3T-MRA). Exemplary computational fluid dynamics (CFD) simulations were performed to compare the flow conditions of giant rabbit and human aneurysms. We used species-related boundary conditions, in particular, we measured blood viscosity values. Biaxial mechanical tests were performed for the mechanical characterization and comparison., Comparison With Exisiting Method(s): None., Results: No peri- or postoperative mortality was observed. 3T-MRA showed aneurysm patency in 10 out of 11 aneurysms (90.9%). Aneurysm lengths ranged from 21.5-25.6mm and aneurysm necks from 7.3-9.8mm. CFD showed complex flow profiles with multiple vortices in both, rabbit and human aneurysms. Lower blood viscosity values of the rabbit (3.92mPas vs. human 5.34mPas) resulted in considerable lower wall shear stress rates (rabbit 0.38Pa vs. human 1.66Pa). Mechanical tests showed lower stiffness of rabbit aneurysms compared to unruptured human aneurysms., Conclusions: The proposed model showed favorable aneurysm patency rates, low morbidity and good hemodynamic comparability with complex flow patterns. Biomechanical testing suggests that experimental aneurysms might be even more fragile compared to human aneurysms., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Delayed vasospasm (VSP) following aneurysmal subarachnoid hemorrhage (aSAH) remains a major source of morbidity. Milrinone was recently suggested as an invasive VSP treatment option. It is a phosphodiesterase III inhibitor with vasodilating and additional positive inotrope and anti-inflammatory effects., Methods: In this preliminary series, we included patients with severe VSP and unsuccessful maximum conservative therapy. Inclusion criteria were (1) transcranial Doppler (TCD) mean >180 cm/s; (2) increase of >50 % of TCD mean values within 6 h to values >150 cm/s; and/or (3) neurological deterioration (after exclusion of hemorrhage, hydrocephalus, and other systemic reasons). Patients received endovascular therapy with nimodipine 2 mg followed by milrinone 4-8 mg. Reinterventions were indicated aggressively in cases of persistent neurological deficits or persistent high mean TCD >180 cm/s., Results: Of 121 consecutive aSAH patients, 16 (13.2 %) received endovascular VSP therapy. Of these, 11 patients (68.5 %) received ≥ 3 interventions (median 4; maximum 9); 14 (87.5 %) showed postinterventional angiographic improvement of vessel diameters; and 11 (68.5 %) showed improvement of their neurological deficits after a mean follow-up time of 4.5 months. No cardiovascular adverse events attributed to milrinone were observed., Conclusions: Milrinone may be a useful supplementary substance for endovascular VSP therapy. Aggressive reintervention indications did not cause additional adverse events.

Background: Thin cerebral aneurysm wall thickness (AWT) is connected to high aneurysm rupture risk. MR imaging of AWT leads to overestimations. The aim of the present study was to quantify MR inaccuracy by comparison with accurate light microscopic measurements., Methods: In 13 experimental microsurgical bifurcation aneurysms in rabbits, 3 Tesla (3 T)-MR imaging using contrast-enhanced T1 Flash sequences (resolution: 0.4 × 0.4 × 1.5 mm³) was performed. The aneurysms were retrieved immediately after MR acquisition, cut longitudinally, and calibrated photographs were obtained. AWT (dome, neck) and parent vessel thickness (PVT) were measured on the MR images and microscopic photographs by independent investigators. All parameters were statistically compared (Wilcoxon test, Spearman correlation)., Results: AWT and PVT could be imaged and measured in all aneurysms with good quality. Comparison with the "real" light microscopic measurements showed a progressive tendency of MR AWT overestimation with smaller AWT: AWT at the dome (0.24 ± 0.06 mm vs. MR 0.30 ± 0.08 mm; p = 0.0078; R = 0.6125), AWT at the neck (0.25 ± 0.07 mm vs. MR 0.29 ± 0.07 mm; p = 0.0469; R = 0.7451), and PVT (0.46 ± 0.06 mm vs. MR 0.48 ± 0.06 mm; p = 0.5; R = 0.8568)., Conclusion: In this experimental setting, 3 T-MR imaging of cerebral AWT showed unacceptable inaccuracies only below the image resolution threshold. Theoretically, AWT for clinical usage could be classified in ranges, defined by the maximum image resolution.

Background: Thin aneurysm wall thickness (AWT) is thought to portend an elevated risk of intracranial aneurysm rupture. Magnetic resonance imaging (MRI) is biased by AWT overestimations. Previously, this suspected bias has been qualitatively described but never quantified. We aimed to quantify the overestimation of AWT by MRI when compared to the gold standard of AWT as measured by light microscopy of fresh aneurysm specimens (without any embedding procedure). This analysis should help to define the clinical potential of MRI estimates of AWT., Methods: 3-Tesla (3T) MRI (contrast-enhanced T1 Flash sequences; resolution: 0.4 x 0.4 x 1.5 mm(3)) was performed in 13 experimental aneurysms. After MR acquisition, the aneurysms were retrieved, longitudinally sectioned and calibrated micrographs were obtained immediately. AWT at the dome, AWT at the neck and parent vessel wall thickness (PVT) were measured on precisely correlated MR-images and histologic micrographs by blinded independent investigators. Parameters were statistically compared (Wilcoxon test, Spearman's correlation)., Results: AWT was assessed and reliably measured using MRI. Interobserver variability was not significant for either method. MR overestimation was only significant below the image resolution threshold: AWT at the dome (0.24 ± 0.06 mm vs. MR 0.30 ± 0.08 mm; p = 0.0078; R = 0.6125), AWT at the neck (0.25 ± 0.07 mm vs. MR 0.29 ± 0.07 mm; p = 0.0469; R = 0.7451), PVT (0.46 ± 0.06 mm vs. MR 0.48 ± 0.06 mm; p = 0.5; R = 0.8568)., Conclusion: In this experimental setting, MR overestimations were minimal (mean 0.02 mm) above the image resolution threshold. When AWT is classified in ranges defined by the MR resolution threshold, clinical usage may be beneficial. Further quantitative and comparative experimental and human studies are warranted to confirm these findings.

For ruptured human cerebral aneurysms endovascular embolization has become an equivalent alternative to aneurysm clipping.(1) However, large clinical trials have shown disappointing long-term results with unacceptable high rates of aneurysm recanalization and delayed aneurysm rupture.(2) To overcome these problems, animal experimental studies are crucial for the development of better endovascular devices.(3-5) Several animal models in rats, rabbits, canines and swine are available.(6-8) Comparisons of the different animal models showed the superiority of the rabbit model with regard to hemodynamics and comparability of the coagulation system and cost-effectiveness.(9-11) The venous pouch arterial bifurcation model in rabbits is formed by a venous pouch sutured into an artificially created true bifurcation of both common carotid arteries (CCA). The main advantage of this model are true bifurcational hemodynamics.(12) The major drawbacks are the sofar high microsurgical technical demands and high morbidity and mortality rates of up to 50%.(13) These limitations have resulted in less frequent use of this aneurysm model in the recent years. These shortcomings could be overcome with improved surgical procedures and modified peri- and postoperative analgetic management and anticoagulation.(14-16) Our techniques reported in this paper demonstrate this optimized technique for microsurgical creation of arterial bifurcation aneurysms.

Objective: Spontaneous spinal epidural hematoma (SEH) has not been reported under anti-thrombotic therapy with acetyl-salicylic acid (ASA) in a dosage of 50 mg/d., Methods: Spinal MRI, emergency laminectomy., Results: A 77-yo, HIV-negative female under longterm treatment over three years with ASA 50 mg/d for varicositas, prescribed by her general practitioner, experienced sudden onset back pain with radiation towards both knees after getting up in the morning. One-and-a-half hours later she also developed ascending hypesthesia and weakness originating from both distal lower limbs. Three hours after onset, hypesthesia had reached the T10-level bilaterally and she had become paraplegic. There was reduced intestinal motility, stool incontinence, and urinary hesitancy. MRI of the thoraco-lumbar spine demonstrated a SEH T9-L1 indenting the dural sack and compressing the myelon. Immediately after emergency laminectomy T10-12 with micro-surgical evacuation of the clot, 12 h after onset, she could move both legs again and was able to walk with support 7 days after surgery., Conclusions: This case shows that SEH occurs under a minimal dose of ASA and that such patients rapidly recover upon immediate surgical decompression and evacuation of the hematoma.

Cells that are taken from the nucleus pulposus (NP) and that are allowed to proliferate in monolayer cultures often exhibit changes in their cell morphology and matrix-protein synthesis. However, whether concomitant alterations occur with respect to their mRNA levels for collagen I (CI), collagen II (CII) and aggrecan (AGG) is unclear. In this study, human NP cells from seven individuals were cultured in monolayers and specific mRNAs for CI, CII and AGG were quantified by real-time polymerase chain reaction in fresh NP tissue and during four passages of NP-cell culture. In addition, the presence of CI, CII and AGG protein was determined by immunofluorescence staining of NP cells. We found a significant reduction of CI, CII and AGG mRNA after the initiation of culture in DMEM compared with mRNA levels in fresh NP tissue. During passages 2--4, no further reduction of mRNA levels for CII and AGG was observed. The mRNA level for CI was reduced significantly with duration of culture. Immunofluorescence staining of cultured NP cells revealed expression of CI, CII and AGG protein during the whole culture period. Our data thus demonstrate a reduction of specific mRNA for matrix proteins during the initiation of NP-cell culture but the stable expression of the key matrix proteins, CII and AGG, during further expansion of the cells in monolayers, suggesting no functional changes occur in cultured NP cells.

Background: Aneurysms of the posterior inferior cerebellar artery (PICA) are rare lesions. The anatomical behaviour of the artery itself is complex and characterised by a multitude of variations. The same holds true for the aneurysms discovered there. Dissecting aneurysms can be found from the PICA origin to the distal artery berry. They have a wider range of clinical and radiographical presentations and their surgical treatment requires more than one standard approach., Methods: We encountered 14 patients with PICA aneurysms within two surgical series of a total of 1345 cerebral aneurysm patients (1 %). In this patient group of the last 27 years only 3 of the 14 were distal aneurysms ("true" PICA aneurysms), Results: The 14 patients harboured 15 aneurysms (9 right-sided and 6 left-sided). The female/male ratio of the patients was 9/5, the mean age 52.7 years. 13 of them had sustained an SAH. 7/14 patients were hypertensive, in 10 patients at least one of putative cerebrovascular risk factors was found. From the 15 aneurysms treated, 11 were typical berry aneurysms, 4 dissecting aneurysms. The aneurysms ranged in size from 5 to 20 mm (mean 9.1). 11 aneurysms were located within the anterior medullary segment, 1 in the tonsillomedullary and 2 in the telovelomedullary segments. All patients were surgically treated, 10 in a semi-sitting position via a suboccipital craniotomy, 4 in the prone position. 13 aneurysms were clipped, two were treated differently. Two patients died due to their bad preoperative clinical status., Conclusions: The clinical, radiographical and surgical approaches to PICA aneurysms still represent a challenge.

The overall performance of a "pointer" neuronavigation system (the ISG ALLEGRO Viewing Wand) in everyday surgical use was evaluated by investigating the practical utility of the technical set-up for one particular surgical task. The basis of the analysis was the numerical evaluation of four areas of fundamental importance for most brain surgery: site and size of craniotomy, localisation of lesion, the trajectory through the brain, and the delineation of the lesion. In a protocol of 65 patients we based our examination on a subjective 4-point rating scale ranging from 0 (= no help) to 3 (= very helpful) for each of the four above categories. We investigated the potential influence of three factors: the lesions histology (4 groups), its size (3 categories) and the depth from the cortical surface (3 levels). Our experience is that the histology of the lesions has significant influence on the relative usefulness of neuronavigation for craniotomy (P < 0.017) and for delineation of the lesion (P < 0.003). We found neuronavigation most helpful for removing gliomas. Second, this system was found to be very helpful in locating small, hitherto hard-to-find, lesions (P < 0.01). Lesion's depth had no effect on the ratings (P > 0.2). Overall, the use of this system led to more precise skin incisions, better site and size of craniotomies tailored to the pathology, the trajectory through the brain, and to more precise delineation of the lesion.

Objective: The non-aneurysmal perimesencephalic subarachnoid hemorrhage (p-SAH) has a favorable outcome. Our objective was to provide a reason for that assessing the association of putative risk factors with this different type of hemorrhage in comparison to the aneurysmal subarachnoid hemorrhage (a-SAH)., Methods: We selected 185 consecutive cases of subarachnoid hemorrhage between September 1994 and August 1998 in a hospital-based case-control study and investigated the influence of hypertension, body weight, smoking and the three interacting blood factors hematocrit, fibrinogen and leukocrit., Results: 1) Risk factors for SAH: For the entire study group an association of hypertension with the incidence of SAH was found both in the univariate analysis of this variable alone (P=0.001) and in the multivariate logistic regression (P=0.0001), aside from the risk factors smoking (P=0.0047) and hematocrit (P=0.0001). As to the risk of hypertensive subjects to experience SAH for different reasons, the logistic regression yielded an odds ratio (OR) of 3.54 [CI (95 %): 2.21-5.56]. 2) Risk factors for p-SAH: Patients with p-SAH differ in their risk profile from typical aneurysmal SAH cases with respect to their blood pressure status (P=0.019) and the investigated hemorheological parameters., Conclusions: A different association between possible risk factors and the two types of subarachnoid hemorrhages was ascertained. In general there seem to be fewer putative risk factors in the perimesencephalic SAH cases compared to the typical aneurysmal hemorrhages.

Objective: The role of hypertension as a major risk factor for the development and rupture of cerebral aneurysms is a subject of considerable debate., Methods: In order to substantiate or weaken the hypothesis of the atherogenic, degenerative origin of this disease, in addition to hypertension the influence of smoking and the covariates body weight, hematocrit, fibrinogen and leukocrit were examined in a hospital-based case-control and cohort study. 141 consecutive patients with subarachnoid hemorrhage (SAH) and verified cerebral aneurysms, admitted between September 1994 and August 1998, were investigated., Results: An association was found between hypertension and SAH of cerebral aneurysm in the entire patient group (P < 0.0001). In the stepwise logistic regression, the exposure odds ratio (OR) for hypertension was 6.8 (CI (95%): 3.53-13.14). Smokers have a twofold higher risk, with an OR of 2.2 (CI (95%): 1.19-4.06). Age was found to have a prognostic impact on the disease (P = 0.0089). Age obviously was a confounding factor for hypertension, which was associated with the outcome (P = 0.048)., Conclusion: Patients with hypertension had a nearly seven-fold higher risk of aneurysmal subarchnoid hemorrhage. This seems to substantiate the hypothesis that aneurysm is an acquired and hemodynamically induced chronic disease.

Background and Purpose: Circadian blood pressure changes are not infrequently cited as a trigger for the onset of subarachnoid hemorrhage (SAH). Our purpose was to determine the reliability of this chronorisk and study the variability and consequences of it as it occurs in hypertensive and normotensive individuals., Methods: Of 273 consecutive patients with proven SAH of aneurysmal origin seen between January 1990 and December 1993, we studied 120 (44%) for whom the exact time of hemorrhage could be reliably determined. Beyond the recognition of a circadian rhythm for this collective, the patients were then sorted by blood pressure, yielding one group each of 80 normotensive (group N, 66.7%) and hypertensive (group H, 33.3%) individuals. The differential chronorisk of these two groups was studied., Results: A circadian rhythm with a definitive characteristic acrophase was observed for the entire group, occurring between 9 AM and 10 AM (chi 2 test, P < .0005) with a possible secondary peak in the afternoon hours. The separation into two blood pressure groups somewhat surprisingly revealed a different curve for each group (chi 2 test, P = .01). Statistical analysis of each group's separate chronorisk revealed that this acrophase only holds true for hypertensive individuals, whereas normotensive patients not only lack a morning peak, but an apparent elevation in the afternoon is statistically irrelevant, leading to the impression that SAH in normotensive persons seems to be subject to no circadian rhythm at all., Conclusions: The incidence of SAH conforms to circadian blood pressure variation in hypertensive patients, similar to the diurnal rhythms observed with strokes and myocardial infarctions. This leads to the hypothesis that blood pressure elevation is a trigger for the onset of bleeding in this group. In clear contrast, normotensive individuals with cerebrovascular aneurysms seem to have a random 24-hour distribution of SAH onset times, thus leaving the nature of a possible trigger mechanism unresolved.

BACKGROUND A few recent studies dampen the euphoric reports of the value of percutaneous endoscopic lumbar discectomy (PELD) in the treatment of discogenic disease. We felt that a large-scale comparison between PELD and the still minimally invasive open lumbar disk surgery (OLDS) was called for. METHODS This report is based on the surgical experience of one year (1991) and is confined to the intervertebral disk level L4-5. Three hundred thirteen patients treated by open disk surgery were compared with 13 who were selected for percutaneous discectomy. RESULTS Using careful selection criteria, only 13 (4%) of a possible 326 were considered potentially suitable for PELD. Of these, only eight were wholly suitable and were operated on percutaneously. Within the first postoperative month, 62.5% (5 patients) of the PELD group required open surgery for definitive treatment, whereas only 14 (4%) of the 313 OLDS patients had to undergo additional surgery. CONCLUSIONS Although it may of benefit to a very few, we feel that the PELD method cannot be considered a substitute for, or even an alternative to, traditional surgery in most cases.

This is the second case of adjacent occurrence of an acoustic schwannoma and epidermoid cyst in the cerebellopontine angle. This case of a 70-year-old woman is presented with a history of her illness, neuroradiologic data, and photographs during the operation. We compare this case with the first of its kind.

We evaluated the monoclonal antibody MAb, BW 250/183, which is easy to label with Tc-99m, with respect to its clinical application for the detection of inflammatory processes in bone and joint diseases. This monoclonal antibody is a murine immunoglobulin (IgG1 isotype), directed against NCA 95 (nonspecific cross-reacting antigen), which is also present on the surface of neutrophil granulocytes. We investigated patients with acute (n = 9) and chronic (n = 3) osteomyelitis, with coxitis (n = 3) and coxarthrosis (n = 2), with septic hip prosthesis (n = 8) and loosening hip prosthesis (n = 14), with low back pain (n = 4), with spondylitis (n = 5) and with postoperative spondylodiscitis (n = 9). With reference to the total number of patients examined in this study we found 29 true positive results, 22 true negative results, 4 false negative results and 2 false positive results. This gives a sensitivity of 88% and a specificity of 92%. The lesions were already visualized within 4 to 6 hours, but 24 hour pictures are desirable. SPECT pictures are mandatory in patients with diseases of the hip or of the spine because sensitivity is considerably improved thereby.

We have reviewed the cases of 57 patients with medial sphenoid meningioma who were operated on in our department during the period 1976 to 1988. The patients were grouped according to location, and their pertinent clinical features are presented. Given the frequency of invasion of the cavernous sinus by such tumours, the following question must be considered in each individual case: the potential benefit of the most radical surgery possible, to minimize the recurrence rate, must be weighed against the cost to the patient in diminished quality of life of iatrogenic neurological impairment. We currently advocate the following strategy: radical removal of tumour tissue lying within the cavernous sinus is unwarranted for the first operation if it would entail iatrogenic neurological damage. Only if subsequent follow-up reveals either fast growth of this tissue, or neurological signs and symptoms attributable to it, do we then attempt uncompromising radicality at a second operation.