PubMed Health⌕ Search

Biomedical subjects

G F Hamann

Publications and source records attributed to G F Hamann.

At least 19 recordsLinked to original sources
PubMed2006

[Diagnosis and therapy of basilar artery occlusion].

In view of the poor prognosis for untreated patients with basilar artery occlusion, rapid delivery of effective treatment has the highest priority. Early recanalization by intra-arterial thrombolysis can improve the outcome in some patients. Apart from this method, specialized centers are increasingly using mechanical devices and glycoprotein IIb/IIIa inhibitors to achieve recanalization. This review focuses on current developments in the diagnosis and treatment of acute basilar artery occlusion.

Cerebral Angiography↗
PubMed2006

[Extradural lipomatosis after long-term treatment with steroids].

Epidural lipomatosis is a rare but severe complication of long-term corticoid treatment. A female who was treated with oral corticoids for more than 4 years developed progressive paraparesis over the course of 2 years. As causal for the clinical symptoms we found a massive epidural lipoma of the thoracic spine. Neurosurgical intervention was necessary.

Anti-Inflammatory Agents↗
PubMed2006

[Endovascular treatment for intracranial stenoses. A common statement by neurologists and neuroradiologists].

Intracranial stenoses cause 5-10% of all strokes and are increasingly detected by means of modern imaging methods. The stroke danger of high-grade symptomatic stenoses is relatively high, with an annual risk of approximately 10% under medical treatment. Coumadin increases the risk of hemorrhage, and after risk/benefit considerations, antiplatelets should be preferred for antithrombotic therapy. Despite optimized medical treatment, a small group of patients with recurrent symptoms or symptomatic stenoses without adequate collateral supply probably carry higher spontaneous stroke risk and may be considered for intracranial stenting, which itself is associated with procedural risks of up to 10%. Currently published case series show relatively high complication rates as a major drawback of endovascular treatment, mainly strokes after occlusion of perforating branches extending from the stenotic vessel segment or hemorrhagic complications. According to data from smaller feasibility studies, stroke rates in follow-up after successful stenting seem to be low. The average rate of high-grade restenosis with possible indication for reintervention is 10%. Improvements in endovascular treatment aim at reducing vessel wall trauma during balloon angioplasty by underdilatation or the use of self-expanding stents. Until complication rates are dependably reduced to values of 5-6%, indication for endovascular treatment should be restricted to patients without therapeutic alternatives. According to limited data with large variation between different studies, a prospective multicentric registry is proposed for systematic evaluation and further development of the method.

Algorithms↗
PubMed2006

[Acute intermittent porphyria. A clinical chameleon: case study of a 40-year-old female patient].

Acute porphyrias are rare, but often misdiagnosed and may take a dramatic clinical course. The combination of various internal, psychiatric and neurological symptoms can mimic different other diseases. We report a 40-year-old female patient who was admitted with a subacute tetraparesis. During the last 2 months the patient was treated several times because of abdominal pain and just before admission to our clinic in a psychiatric hospital because of acute mental changes and hallucinations. The typical combination of abdominal pain, motor neuropathy and psychiatric symptoms confirmed by increased amounts of porphyrins and their precursors, led us to promptly diagnose acute intermittent porphyria. Better knowledge about the pathogenesis has clearly improved the prognosis of acute porphyria. In remission, measurement of enzyme activities or mutation screening can be the only diagnostic verification. A mutation screening for family members should be conducted to identify symptom-free carriers, especially in cases of a positive family history.

Abdominal Pain↗
PubMed2005

Efficacy of stent angioplasty for symptomatic stenoses of the proximal vertebral artery.

BACKGROUND: To evaluate the safety and efficacy of stent angioplasty in the treatment of symptomatic arteriosclerotic stenoses of the proximal vertebral artery (VA). METHODS: Thirty-eight symptomatic stenoses of the vertebral origin were treated with flexible balloon-expandable coronary stents. Angiographic and clinical follow-up examinations were obtained in 26 patients at a mean of 11 months. RESULTS: The immediate post-procedural angiographic results showed no residual stenosis in 33 vessels and mild residual stenoses in five vessels. Periprocedurally, there were two asymptomatic technical complications and one TIA. During follow-up re-stenosis could be detected in 10 cases (36%), and vessel occlusions in two patients. Two stents were broken. One of the restenosis caused a TIA within the follow-up period. CONCLUSIONS: Flexible balloon-expandable coronary stents proved to be save and effective in preventing vertebrobasilar stroke but were incapable to preserve the proximal vertebral artery lumen. For the VA origine an adequate stent, self-expanding, bioresorbable, or drug-eluting has to be found.

Adult↗
PubMed2005

[White matter lesions as a risk factor for stroke and dementia. A population-based study in 85-year-olds].

AIM: This study was performed to determine whether white matter lesions on cranial computed tomography (cCT) are associated with increased prevalence and incidence of stroke, dementia, and mortality. METHODS: A representative sample of 239 85-year-olds living in Gothenburg, Sweden, was examined in a population-based study. Stroke was defined by information from patient reports, key informants, and an inpatient register system. Dementia was diagnosed according to DSM-III-R. White matter lesions (WML) and infarcts were determined by cCT. Follow-up examinations were performed 3 years later. RESULTS: White matter lesions doubled the odds of previous stroke (OR 1.8, 95% CI 1.03-3.3). Individuals with WML and stroke showed higher prevalence of dementia (OR 16.5, 95% CI 6.5-41.8) and mortality (OR 12.4, 95% CI 5.1-30.0) than those without WML and stroke. CONCLUSION: White matter lesions are common in the elderly, and these changes have clinical consequences increasing the risk of stroke. Whether preventive mechanisms could lead to risk reduction should be clarified in further studies.

Aged↗
PubMed2004

Contralateral cerebral blood flow velocity changes after intracarotid amobarbital injection.

BACKGROUND AND PURPOSE: The intracarotid amobarbital procedure (IAP) leads to a prompt decrease in ipsilateral middle cerebral artery (MCA) mean blood flow velocity (MFV). Little is known about contralateral MFV changes. METHODS: The authors investigated bilateral MCA MFV using transcranial Doppler sonography (TCD) in 8 patients with epilepsy undergoing IAP. Measurements were excluded from analysis if angiography revealed any signs of interhemispheric cross-flow. RESULTS: With in 64 seconds after amobarbital injection, ipsilateral MFV decreased to a mean of 44.4% +/- 7.5% of baseline value (P < .01). In the absence of interhemispheric cross-flow and within 68 seconds, contralateral MFV decreased to 83.1% +/- 7.9% (P < .01). CONCLUSIONS: The observed decrease of contralateral MFV was not caused by amobarbital cross-perfusion. A possible underlying mechanism may be interhemispheric deafferentation.

Adult↗
PubMed2003

Microvascular damage following experimental sinus-vein thrombosis in rats.

We evaluated effects of thrombosis of the superior sagittal sinus, its bridging and cortical veins (SVT) on the cerebral microvasculature in rats. Cryosections of brains ( n=7) were examined for venous infarction and microvascular basal lamina damage 3 h after SVT by immunohistochemical staining of microtubule-associated protein 2 and collagen type IV. Microvessels in the infarctions showed a decrease in the number (23.5+/-6.1%, P<0.002) and the total area (24.9+/-6.5%, P<0.011) of collagen type IV-positive vessels in contrast to control areas (21.7+/-12.4%, P<0.007; and 26.3+/-15.1%, P<0.026 in contrast to control areas of unoperated animals). This study showed a significant alteration of the cerebral microvasculature in SVT, which might contribute to edema and hemorrhagic transformation.

Animals↗
PubMed2003

[Experimental microvascular and clotting changes--significance for acute stroke therapy].

Ischemia and reperfusion cause significant alterations in the structure and functional integrity of the cerebral microvasculature. Clinical sequelae include cerebral oedema, haemorrhagic transformation with the extravasation of cellular blood elements, and possible parenchymal haemorrhage. Vascular changes originate from structural changes of the vascular wall and from interactions with blood components such as leukocytes. This leads to the activation of various pathophysiological cascades including the clotting system, its inhibitors,matrix metalloproteases, and serine proteases. This article focuses on the degradation of the microvascular basal lamina, which is formed by extracellular matrix proteins such as type IV collagen, fibronectin, and laminin. Extracellular matrix proteins are degraded by matrix metalloproteases and serine proteases. Tissue plasminogen activator (t-PA), a serine protease commonly administered for thrombolysis, activates matrix metalloproteinases in turn, amplifying local proteolytic activity. Clinical implications and possible therapeutic strategies are discussed.

Animals↗
PubMed2003

R1--systemic thrombolysis in German stroke units--the experience from the German Stroke data bank.

BACKGROUND: Systemic thrombolysis with tissue plasminogen activator (t-PA) for treatment of acute ischemic stroke was approved in Germany in 2000. Up to now, only data from single centers have been available for the study of the use of thrombolysis in a hospital-based approach outside controlled trials. We therefore sought to determine the frequency of application and complications as well as the patient outcome after t-PA treatment in clinical routine of specialized stroke centers in Germany. METHODS: Within the German Stroke Data Bank Collaboration, 6234 consecutive patients with ischemic stroke were prospectively documented in 20 stroke centers between 1998 and 1999. The patients were centrally followed via telephone interview after 3 months and 1 year to assess global functional outcome using the Modified Rankin Scale. RESULTS: 250 patients (4 %) received systemic t-PA treatment during the study period. The baseline characteristics of these patients were comparable to large clinical trials and phase IV studies. Symptomatic and asymptomatic parenchymal hemorrhage occurred in 22 patients (8.8 %) and was fatal in 3 patients. Follow-up data after 3 months were obtained in 82.4 % of all patients, of which 35 % had a favorable functional outcome (mRS </= 1), while 23.8 % were severely disabled (mRS >/= 4) and 17 % had died. CONCLUSION: The results of our study agree with the assumption that thrombolytic therapy can be performed safely and effectively in daily clinical practice. Nevertheless, the small proportion of patients receiving thrombolysis even in specialized stroke centers calls for further improvement of acute stroke management in Germany.

Cerebral Hemorrhage↗
PubMed2003

Combined cerebellar and bilateral cervical posterior spinal artery stroke demonstrated on MRI.

Combined cerebellar and spinal ischemic stroke is a rare, critical condition. We report a patient with combined cerebellar and bilateral posterolateral cervical spinal cord infarction due to bilateral stenosis of the vertebral arteries. MRI is the method of choice for imaging this condition; diffusion-weighted imaging of the spinal cord gives reliable results.

Cerebellar Diseases↗
PubMed2002

A gelatin in situ-overlay technique localizes brain matrix metalloproteinase activity in experimental focal cerebral ischemia.

To determine the activity of matrix metalloproteinases (MMP), especially MMP-2 and MMP-9, which play an important role in ischemic stroke and intracerebral hemorrhage, we adapted a simple and rapid method for localizing gelatinase activity to a gelatin film in situ-overlay technique previously used in cancer research. Ten micrometer cryosections of rat brain from controls and animals subjected to 3 h of ischemia and 48 h of reperfusion (suture model for transient cerebral ischemia) were used. After thawing, a gelatin film with a polyester base was put on the slide, incubated for 24 h at 37 degrees C, stained with Ponceau S, and then discolored in bi-distilled water. Non-staining areas on the film corresponded to lysis zones, caused by activated MMPs. This was proven by MMP incubation at various concentrations on the plain gelatin film and pretreatment with EDTA (an MMP inhibitor), which prevents lysis zones in normal and ischemic brains. As confirmatory tests, SDS-PAGE zymography was used to define MMP activity, and also MMP-2 immunohistochemistry to detect the possibly cellular origin of MMPs. Normal rat brain exhibited a low background activity, which was visible as a light halo-like lysis zone over and around the brain. Areas in normal brain with medium MMP activity were within the white matter (corpus callosum, anterior commissure, and cerebellum). Ischemic brain exhibited high activity lysis zones within the infarcted area (detected by microtubuli associated protein-2 staining). These zones consisted of microscopically small lysis holes with a diameter of about 10-20 microm. Immunohistochemistry showed that especially microvessels expressed MMP antigen. SDS-PAGE zymography differentiated between a high level of activated MMPs in the ischemic area and a low level in the non-ischemic basal ganglia. The gelatin film in situ-overlay technique is able to localize MMP activity in ischemic rat brain tissue on a microscopic level.

Animals↗
PubMed2002

[Cerebrovascular reserve capacity].

Cerebrovascular reserve capacity (CVR) describes how far cerebral perfusion can increase from a baseline value after stimulation. Measurement of cerebral blood flow (CBF) can be done by PET or SPECT. Noninvasive and easily performed transcranial Doppler sonography (TCD) is mostly used as indirect perfusion measurement. Stimulation of cerebral perfusion is often done by CO2 inhalation or acetazolamide injection. Alternative stimuli are breath holding or cerebral activation by hand-gripping. Normal values for these tests are presented. The hemodynamic effect of stenoses of the internal carotid artery (ICA) can be estimated using CVR. The relevance of CVR is discussed controversially, since cerebral infarction due to stenosis of arteries supplying the brain is probably mostly of embolic, not hemodynamic origin. The indication for carotid artery surgery according the NASCET and ECST investigations takes into account only the degree of the stenoses and not the CVR. According to recent studies, the risk of cerebral infarction in these patients is considerably higher with reduced CVR. Therefore, CVR can be used as an additional parameter if the indication for surgery is not defined, especially in asymptomatic carotid artery stenosis. It seems also possible to identify patients who might profit from an extra-intracranial bypass operation and high-risk patients for cerebral ischemia with cerebral microangiopathy. Furthermore, the risk of cerebral infarction during carotid artery surgery and also during heart surgery can be estimated using CVR. More studies with a higher number of patients are needed to confirm the potential predictive diagnostic value of CVR in order to establish CVR measurement as part of a routine diagnostic neuroangiologic program.

Blood Flow Velocity↗