Biomedical subjects

Ruth Thiex

Publications and source records attributed to Ruth Thiex.

10 recordsLinked to original sources

PubMed2006

Basilar megadolicho trunk causing obstructive hydrocephalus at the foramina of Monro.

We report on a 54-year-old man with megadolicho basilar artery presenting with acute signs of raised intracranial pressure due to a compromise of cerebrospinal fluid (CSF) flow at the level of the foramina of Monro by the basilar apex extending more than 3 cm cranially to the dorsum sellae. The diagnosis was confirmed on computed tomographic angiography and emergent CSF drainage relieved symptoms immediately.

Basilar Artery↗

PubMed2005

Minor inflammation after surgical evacuation compared with fibrinolytic therapy of experimental intracerebral hemorrhages.

OBJECTIVES: Toxic components released from the intracerebral blood clot, such as thrombin and hemoglobin, potentially trigger brain edema formation and therefore favor an early evacuation of the clot. Despite a significant reduction in hematoma size in our porcine model of hematoma induction by injecting autologous blood ICP-controlled into the right frontal white matter with subsequent fibrinolysis using recombinant tissue-plasminogen activator (rt-PA) and aspiration of the liquefied clot (n = 9), local rt-PA promoted delayed perihematomatous edema formation and invoked a substantial inflammatory reaction compared with controls (n = 11). METHODS: We therefore modified our formerly developed porcine model of intracerebral hemorrhage in removing the hematoma by open craniotomy and suction of the clot in seven animals. The residual hematoma size and extent of perifocal edema were evaluated over 10 days on planimetry of the MRI data, and correlated to the histopathological changes of edema and inflammation found at autopsy. RESULTS: The edema volume on day 4 was significantly less in the surgical group compared with the lysis group (p < 0.03). On day 10, however, the difference in edema size was not statistically significant compared with the lysis group (p < 0.07) and the control group (p < 0.09). The inflammatory response was minor compared with the lysis and control group. DISCUSSION: In conclusion, despite a significant reduction in hematoma size by surgical removal of the clot, only the inflammatory response, but not the extent of delayed edema can be positively influenced.

Analysis of Variance↗

PubMed2005

Treatment of experimentally induced aneurysms with stents.

OBJECTIVE: Although Guglielmi detachable coil systems have been widely accepted for treatment of intracranial aneurysms, primary stenting of aneurysms using porous stents, stent grafts, or implantation of coils after stent placement constitute emerging techniques in endovascular treatment. The aim of the present study was to use an animal model to investigate these different approaches to treat cerebral aneurysms with regard to the rate of closure and the histopathological changes within the aneurysm cavity and the parent vessel after stent placement. METHODS: We created aneurysms in 30 rabbits by distal ligation and intraluminal incubation of the right common carotid artery with elastase. Ten animals were treated with porous stents alone, 10 animals with stent grafts (covered stents), and 10 animals with stents and additional coiling via the interstices of the stent, which enabled dense packing of the coils. Five animals in each group were observed for 1 month and the other animals for 3 months. Histological analyses were performed, including immunohistochemical investigations for estimating the proliferation of the intima and possible inflammatory infiltration. RESULTS: Covered stents led to a complete and stable aneurysm occlusion with only minimal proliferative carrier vessel wall changes. One covered stent was completely occluded with old thrombus, and the other 9 remained patent. Porous stents occluded two of five aneurysms in the 1-month follow-up group and four of five after 3 months. However, progressive sprouting of neointima inside the carrier vessel that resulted in a stenosis of up to 40% was present. In the Stent + Coil group, one aneurysm showed recanalization after 1 month, and three of five aneurysms were recanalized after 3 months after coil compaction. Moreover, in-stent stenosis of up to 30% was present. CONCLUSION: This study demonstrates the possible shortcomings and problems of emerging stent techniques to treat intracerebral aneurysms, shows where technical advances have to be made, and describes in which cases of aneurysm morphology caution has to be exercised when considering an endovascular approach using stents.

Aneurysm↗

PubMed2005

Functional outcome after surgical treatment of spontaneous and nonspontaneous spinal subdural hematomas.

OBJECT: Because of the rarity of spinal subdural hematomas (SDHs), the literature offers scarce estimates of the outcome and predictive factors in patients suffering from these lesions. In addition, single-institution surgical series are still lacking. Therefore, the authors retrospectively evaluated the early and long-term functional outcomes measured in eight patients with spontaneous and nonspontaneous spinal SDHs in whom the clot had been evacuated. METHODS: The patients' charts were evaluated for origin of the lesion, risk factors, and neurological deficits at symptom onset and at 28 days after extirpation of the spinal SDH. Long-term clinical outcome (Barthel Index [BI]) was evaluated by administering a telephone questionnaire to the patient or a relative. Only one patient with a spontaneous spinal SDH was identified. Four patients were undergoing anticoagulant therapy, and three patients had undergone a previous anesthetic/diagnostic spinal procedure. Twenty-eight days postoperatively, neurological deficits improved in six of eight patients; however, in two of the six patients, the improvement did not allow the patients to become independent again. In two patients, surgery did not affect the complete sensorimotor deficits. In the long-term survivors (median 45 months) a median BI of 55 was achieved. The latency between symptom onset and surgery did not correlate with functional outcome in this series. The preoperative neurological condition and location of the hematoma correlated positively with early and long-term functional outcome. CONCLUSIONS: To the best of their knowledge, the present study is the largest single-institutional study of patients with surgically treated spinal SDHs. Despite some postoperative improvement of sensorimotor deficits in most patients, the prognosis is poor because 50% of the patients remain dependent. Their outcome was determined by the preoperative sensorimotor function and spinal level of the spinal SDH.

Adult↗

PubMed2004

Frame-based and frameless stereotactic hematoma puncture and subsequent fibrinolytic therapy for the treatment of spontaneous intracerebral hemorrhage.

OBJECTIVES: Comparison of two minimally invasive procedures for the treatment of intracerebral hemorrhage and subsequent lysis with regard to technical implications and clinical outcome of the patients. METHODS: Retrospective analysis of 126 patients with spontaneous supratentorial intracerebral hemorrhage treated by frame-based (n=53) or frameless (n=75) hematoma aspiration and subsequent fibrinolysis with recombinant tissue plasminogen activator (rt-PA). Data were analysed for the whole group as well as for the two subsets of patients with regard to hematoma reduction, procedure-related complications, and the early and long term clinical outcome of the patients. Functional outcome was rated using the Glasgow Outcome Scale (GOS) and Barthel-Index (median follow-up 178 weeks). The prognostic impact of patient related covariates on the GOS was analysed using logistic regression analysis. RESULTS: 49 out of 126 patients (38.9 %) died, 25 of them in the early postoperative period. Only 22/126 (17.5 %) had a favorable long term outcome (GOS >3). Age > 65 years was significantly (p<0.03, OR 3.6) associated with a higher risk for an unfavorable long term outcome (GOS < or = 3). Treatment had no impact on outcome. Both techniques were highly effective in reducing the intracerebral blood volume by 75.8+/-21.4% of the initial hematoma volume in frame-based and 64.8+/-25.4 % in frameless stereotaxy within 2 days of rt-PA-therapy. Malpositioning of the catheter occurred more often in the frameless group (21.3% vs. 9.4 % in the frame-based procedure) without gaining statistical significance. CONCLUSIONS: Frame-based and frameless stereotactic hematoma aspirations with subsequent fibrinolysis are effective in volume reduction of intracerebral hemorrhage with comparable clinical outcome. The frameless procedure is associated with a higher risk for malpositioning of the catheter. Despite effective hematoma reduction with both techniques, the percentage of patients with a good clinical outcome remained limited especially in the elder subpopulation.

Aged↗

PubMed2004

The role of endogenous versus exogenous tPA on edema formation in murine ICH.

To minimize the neurotoxic injury by clot-derived substances after intracerebral hemorrhage (ICH) on the surrounding brain tissue, minimally invasive neurosurgical protocols have evolved evacuating the hematoma by stereotaxic injection of a fibrinolytic agent such as recombinant tissue plasminogen activator (rtPA), followed by aspiration of the lysed clot. However, the possible contribution of the presence of exogenous tPA itself to the toxic effects of hematoma-derived factors complicates the rationale and efficacy of this therapeutic approach. To clarify the role of exogenous rtPA on edema development, we examined the extent of edema formation in a murine model of collagenase-induced ICH, which included tPA-deficient (tPA-/-) and wild-type (wt) mice. In 16 (7 tPA-/- and 9 wt mice) out of 32 mice, 1 mg/kg rtPA was injected into the hematoma 5 h after ICH induction followed by aspiration of the liquefied clot 20 min later. In the control group (8 tPA-/- and 8 wt mice), only collagenase was injected. The edema volume was quantified using SPOT software on Luxol Fast Blue and Cresyl violet-stained cross-sections 24 h, 3, and 7 days post surgery. Twenty-four hours after ICH induction, tPA-/- mice had a significantly smaller edema volume (P< 0.01), even when rtPA was administered. Between days 3 and 7 after ICH, exogenous rtPA exerts its edema-promoting effect irrespective of the underlying genotype and exhibits an extensive microglial activation adjacent to the clot. In conclusion, the role of the endogenous tPA appears to be limited to the early phase of edema formation, whereas exogenous rtPA is edema-promoting between days 3 and 7 after ICH.

Animals↗

PubMed2003

A refined method for creating saccular aneurysms in the rabbit.

We describe a refined animal model of human intracerebral aneurysms for testing endovascular devices for interventional neuroradiological procedures. Saccular aneurysms resulting from a stump of the right common carotid artery (CCA) were created in 15 New Zealand White rabbits by intraluminal incubation of elastase that was applied to the CCA after distal ligation of the CCA and proximal occlusion of the vessel using a pliable balloon. Subsequently a microcatheter was advanced to a position cranial to the balloon and the elastase was infused under fluoroscopic guidance to avoid retrograde flow to the trachea via aberrant vessels. Contrast-enhanced (CE) MRA at 1.5 T and conventional digital subtraction angiography was performed to test for aneurysm size, morphology and neck anatomy. In all 15 animals aneurysms resulted from the stump of the right CCA, ranging in size from 2.0 to 9.9 mm (mean 6.3 mm) in craniocaudal direction, 1.0 to 5.5 mm (mean 3.8 mm) in mediolateral direction and 1.0 to 3.8 mm (mean 2.4 mm) in neck diameter. Aneurysm morphology could be adequately demonstrated using CE MRA. On histological evaluation a loss of the internal elastic lamina was noted. The described method represents an easy, reliable, and reproducible method of aneurysm creation in the rabbit in an area of high shear stress. These aneurysms can be used for testing new endovascular devices for embolization of intracranial aneurysms.

Angiography, Digital Subtraction↗

PubMed2003

The long-term effect of recombinant tissue-plasminogen-activator (rt-PA) on edema formation in a large-animal model of intracerebral hemorrhage.

Hematoma puncture, fibrinolysis, and aspiration of the liquefied clot is a promising new treatment strategy for large intracerebral hemorrhages (ICH). Characteristics of the cellular injury and neuronal and glial cell death associated with ICH and the administration of fibrinolytic agents still need to be defined. We developed a porcine model to study the histopathological effects of recombinant tissue-Plasminogen-Activator (rt-PA) on perihematomatous cell integrity. In 20 pigs, lobar hematomas were induced by intracranial pressure (ICP)-controlled injections of 7.6 +/- 1.6 ml of autologous blood into the white matter of the right frontal hemisphere. In nine animals, the clots were lysed with rt-PA, thereby facilitating aspiration 2 h after hematoma induction. In 11 control pigs, the hematoma resorption followed its natural course. The rate of hematoma reduction and edema formation over 10 days was evaluated on planimetry of the MRI data and correlated to the histopathological changes found at autopsy. Although rt-PA significantly accelerated clot resolution compared to controls (p < 0.02), the increase of perihematomatous edema volume within 10 days was not significantly ameliorated in rt-PA-treated animals compared to controls on MRI. The extent of inflammatory infiltrates on histology was more pronounced in animals treated with rt-PA. In conclusion, despite significant reduction in the size of the hematoma clot liquefication with rt-PA and aspiration invokes a substantial inflammatory response when studied after 10 days and does not result in a reduction of the perihematomatous edema.

Animals↗

PubMed2002

Time-of-flight-, phase contrast and contrast enhanced magnetic resonance angiography for pre-interventional determination of aneurysm size, configuration, and neck morphology in an aneurysm model in rabbits.

We describe three different magnetic resonance (MR)-angiography techniques to evaluate aneurysm size, configuration, and neck morphology of experimentally created aneurysms in a rabbit model. In five New Zealand White rabbits an aneurysm was created by endovascular occlusion of the right common carotid artery (CCA) using a pliable balloon and subsequent endoluminal incubation of elastase within the proximal CCA above the balloon and distal ligation of the vessel. In all animals, time-of-flight (TOF), phase contrast and contrast enhanced (CE) MR angiographies (MRA) were performed and compared to conventional digital subtraction angiography results. We found, that aneurysms are best visualized employing CE MRA, however, neck morphology was also found to demonstrate interpretable results when evaluating the axial source data of the TOF MRA. The animal model we used can be employed for testing endovascular devices such as new coil material, or covered stents. The described MRA techniques might then be helpful for pre-interventional planning and maybe even for the follow-up of the thus treated aneurysms.

Aneurysm↗

PubMed2002

Fibrinolysis therapy achieved with tissue plasminogen activator and aspiration of the liquefied clot after experimental intracerebral hemorrhage: rapid reduction in hematoma volume but intensification of delayed edema formation.

OBJECT: Fibrinolysis therapy accomplished using tissue plasminogen activator (tPA) and aspiration is considered to be a viable alternative to microsurgery and medical therapy for the treatment of deep-seated spontaneous intracerebral hematomas (SICHs). Tissue plasminogen activator is a mediator of thrombin- and ischemia-related delayed edema. Because both thrombin release and ischemia occur after SICH, the authors planned to investigate the effect of fibrinolytic therapy on hematoma and delayed edema volume. METHODS: A spherical hematoma was created in the frontal white matter of 18 pigs. In the tPA-treated group (nine pigs), a mean of 1.55 ml tPA was injected into the clot and the resulting liquefied blood was aspirated. Magnetic resonance (MR) imaging was performed on Days 0 (after surgery), 4, and 10, and the volumes of hematoma and edema were determined. In the animals not treated with tPA (untreated group; nine pigs), the volume of hematoma dropped from 1.43+/-0.42 ml on Day 0 to 0.85+/-0.28 ml on Day 10. In the tPA-treated group, the volume of hematoma was reduced from 1.51 +/- 0.28 ml on Day 0 to 0.52 +/- 0.39 ml on Day 10. In comparison with the untreated group, the reduction in hematoma volume was significantly accelerated (p = 0.02). In the untreated group, perihematomal edema increased from 0.32 +/- 0.61 ml to 1.73 +/- 0.73 ml on Day 4, before dropping to 1.17 +/- 0.92 ml on Day 10. In the tPA-treated group, the volume of the edema increased from 0.09 +/- 0.21 ml on Day 0 to 1.93 +/- 0.79 ml on Day 4, and further to 3.34 +/- 3.21 ml on Day 10. The increase in edema volume was significantly more pronounced in the tPA-treated group (p = 0.04). CONCLUSIONS: Despite a significantly accelerated reduction in hematoma volume, the development of delayed perifocal edema was intensified by fibrinolytic therapy, which is probably related to the function of tPA as a mediator of edema formation after thrombin release and ischemia. Further experimental and clinical investigations are required to establish the future role of fibrinolysis in the management of SICH.

Animals↗