Biomedical subjects

Gerhard Schuierer

Publications and source records attributed to Gerhard Schuierer.

17 recordsLinked to original sources

PubMed2006

Fischer-344 rats are unsuitable for the MCAO filament model due to their cerebrovascular anatomy.

Middle cerebral artery occlusion (MCAO) in Fischer-344 rats results in a small variance of infarct size. However, complications are frequent especially in aged Fisher-344 rats undergoing endovascular suture occlusion of the middle cerebral artery. Analyzing our experiences with 165 Wistar, 13 Sprague-Dawley and 10 F-344 rats, we compared the incidence of impossible thread advancement and subarachnoid hemorrhage, respectively. Magnetic resonance angiography (MRA) was applied to study the course of the internal carotid artery (ICA) in Fischer and Wistar rats. Finally, we performed a structured review of the literature from 1991 to 2005 evaluating reports on Fischer rats subjected to intraluminal filament MCAO. Complications like fruitless filament advancement or subarachnoid hemorrhage were found to be significantly more frequent in Fischer rats than in other strains. MRA revealed significantly more pronounced kinking of the ICA in F-344 than in Wistar rats. In seven publications available on filament MCAO in F-344 rats, complication rates of 50-100% were reported, corroborating our data. Surgical difficulties accompanied by high complication rates due to their cerebrovascular anatomy make Fischer rats unsuitable for filament MCAO. If the use of Fischer rats for studies on focal cerebral ischemia is indicated, other ischemia models than intraluminal suture occlusion should be chosen.

Aging↗

PubMed2006

Optic neuritis with visual field defect--possible Ibuprofen-related toxicity.

OBJECTIVE: To report a case of optic neuritis with visual field defect associated with ibuprofen. CASE SUMMARY: A 41-year-old white man developed blurred vision in his right eye and pain with eye and head movements that lasted 2 days after use of ibuprofen 400 mg 3 times daily during the preceding 3 weeks. Medical and family histories were negative for significant related disease. Ophthalmologic examination revealed a marked decrease in visual acuity to 20/200 in the right eye with quadrant visual field loss and absent responses in visual evoked potential (VEP). After discontinuation of the drug and treatment with high-dose intravenous methylprednisolone and subcutaneous low-molecular-weight heparin, the patient's vision improved to 20/70, the visual field defect vanished, and the VEP returned to almost normal values during a 1 year follow-up period. An objective causality assessment revealed that the adverse reaction was possibly related to ibuprofen. DISCUSSION: Ocular toxicity with blurred vision and centrocecal visual field defects have been rarely associated with long-term ibuprofen intake. We report a case of retrobulbar optic neuritis with quadrant visual field defect following short-term but regular ibuprofen intake. Although idiopathic optic neuritis cannot be completely ruled out, the absence of other risk factors and additional findings plus the improvement after discontinuation of the drug speak for isolated toxic optic neuritis of the right eye. CONCLUSIONS: Drug toxicity is an important differential diagnosis in retrobulbar optic neuritis. Clinicians should be aware of the potential optic toxicity, even with short-term use of a drug, and perform a thorough medication history in every patient with visual disturbances without a clear cause.

Adult↗

PubMed2005

Serial proton spectroscopy in a case of adult-onset subacute sclerosing panencephalitis.

A case of subacute sclerosing panencephalitis in a 27-year-old man was serially evaluated with proton magnetic resonance spectroscopy. Metabolic abnormalities included decreased N-acetylaspartate and elevated choline and myo-inositol in a lesion visible on magnetic resonance imaging and in normal-appearing white matter. Lactate appeared increased within the lesion. Metabolic impairment was persistent after intrathecal interferon-alpha treatment. Spectroscopy pointing to ongoing inflammation, gliosis, and possible membrane turnover was more sensitive than imaging in detecting widespread pathology within the white matter.

Adult↗

PubMed2005

The role of ECA transection in the development of masticatory lesions in the MCAO filament model.

In the intraluminal suture model of middle cerebral artery occlusion (MCAO) in the rat, lesions of the masticator muscles associated with impaired functional outcome occur. We evaluated the role of external carotid artery (ECA) transection. We assessed whether isolated interruption of an arterial or a venous connection to the ECA territory was sufficient to induce masticatory hypoperfusion and lesions. We also evaluated a direct access to the common carotid artery (CCA) with subsequent vascular closure with regard to its feasibility, frequency of masticatory lesions, complications, and cerebral ischemia. Cerebral and masticatory lesions and perfusion deficits were assessed by in vivo magnetic resonance imaging (MRI). Vessel patency was evaluated using computerized tomography angiography and histology. An interruption of arterial blood flow led to masticatory hypoperfusion. Masticatory lesions occurred in 6% of the rats. Access to and closure of the CCA were feasible in all animals, leading to moderate or severe vessel stenosis in 20%, and intraarterial thrombosis in 25% of the rats. Reproducible cerebral infarctions were obtained in all animals. In 24% of the rats, hyperintense MRI signal changes were observed in the ipsilateral temporal muscle. Thus, the induction of masticatory hypoperfusion and lesions by arterial transection supports the role of the ECA in this context. Direct access to the CCA with subsequent vessel closure led to stenosis in most animals. Preservation of ECA continuity was not suitable to fully prevent masticatory lesions.

Analysis of Variance↗

PubMed2005

The prognostic value of [F]FDG-PET in nonrefractory partial epilepsy.

PURPOSE: Regional abnormalities of cerebral glucose metabolism, as identified by 18-fluorodeoxyglucose positron emission tomography (FDG-PET) have prognostic value regarding the outcome of epilepsy surgery in patients with refractory partial epilepsy. The value of FDG-PET abnormalities in nonrefractory patients has not been investigated systematically. This study examines whether FDG-PET could be used for early identification of nonrefractory epilepsy in patients who will become pharmacoresistant later during the course of their disease. METHODS: We investigated interictal abnormalities of cerebral glucose metabolism by using FDG-PET in 125 consecutive patients with nonrefractory cryptogenic partial epilepsy and normal cranial magnetic resonance imaging (MRI), and we compared relative changes in seizure frequency in 90 patients after > or =2 years of follow-up. RESULTS: Regional asymmetry of tracer distribution was seen in 43 of the 90 patients. Forty-one patients had regional glucose hypometabolism in the temporal and two patients in an extratemporal region. No difference between patients with and without a hypometabolic focus was found regarding seizure freedom after follow-up. This held true also for the subgroup of patients with epilepsy onset within 1 year before admission. Only patients with regional glucose metabolism showed an increase in seizure frequency. Multivariate analysis showed that only anticonvulsive treatment before index admission and the possibility of localizing the epileptogenic focus by using all available clinical and EEG data were independently associated with continuing seizures after a median follow-up period of 43 months. CONCLUSIONS: Regional hypometabolism in FDG-PET is not significantly associated with a lower likelihood of successful anticonvulsant drug therapy in patients with nonrefractory partial epilepsy. Careful analysis of all routinely available clinical and neurophysiologic data has a much better predictive power to identify patients with medically refractory epilepsy early in the course of the disease. However, if PET data are available, they could help in identifying patients with a less benign course.

Adolescent↗

PubMed2005

Application of clinical scanners in rats: experimental carotid imaging using magnetic resonance imaging, spiral computed tomography, and color duplex ultrasound.

BACKGROUND AND PURPOSE: Noninvasive small animal imaging allows for reduction of the required numbers of animals in research by providing the possibility of long-term follow-up at various time points. Additionally, correlation to the investigated respective human disease is possible as equivalent equipment is employed. The authors therefore evaluate feasibility and potential of color duplex sonography, computed tomography angiography (CTA), and magnetic resonance angiography (MRA) by the use of clinical scanners for carotid artery imaging in rats. METHODS: Male Wistar rats (n = 17) were subjected to color duplex sonography, CTA, and MRA of the common carotid artery (CCA) and the carotid bifurcation. Clinical scanners were used for the experiments and optimal parameter settings evaluated accounting for the different size of the animals. The applied imaging methods were analyzed in regard to image quality and practicability in laboratory settings. RESULTS: The CCA could be clearly displayed by all imaging modalities in all rats. Duplex sonography provided distinct images and reproducible basic functional information. CTA and MRA provided distinct images of the CCA and the carotid bifurcation in both axial and reconstructed 3-dimensional images. The authors further describe different indications for these imaging methods regarding spatial resolution, acquisition times, possible scanning range, and application of contrast agent. CONCLUSIONS: Color duplex sonography, CTA, and MRA are all feasible methods for imaging of the carotid arteries in rats. Images of sufficient clarity and resolution could be obtained by the use of clinical scanners, yielding information about vessel size, direction of blood flow, and adjacent structures. Further studies need to be performed that address investigations of pathological conditions such as flow disturbances or vessel stenosis.

Animals↗

PubMed2004

Neuroplasticity: changes in grey matter induced by training.

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Adult↗

PubMed2004

Clinical progression and genetic analysis in hereditary spastic paraplegia with thin corpus callosum in spastic gait gene 11 (SPG11).

BACKGROUND: Hereditary spastic paraplegia (HSP) with thin corpus callosum (CC) is a rare neurodegenerative disorder classified as a complicated form of spastic paraplegia. Some patients with HSP with thin CC have previously been described in Japanese families, and the genetic locus was linked to chromosome 15q13-15. OBJECTIVE: Our objective was to further clinically and genetically characterize HSP with thin CC. PATIENTS: We describe the clinical, structural, and functional follow-up and the genetic characterization of 2 sisters aged 26 and 31 years who had severe spastic paraplegia and cognitive impairment. RESULTS: Magnetic resonance imaging revealed a thin CC with progressing frontoparietal cortical atrophy paralleled by cognitive decline. Using transcranial magnetic stimulation, we delineated a lack of transcallosal inhibition. Images obtained with(18)fluorodeoxyglucose positron emission tomography showed reduced cortical and thalamic hypometabolism that decreased further within 4 years. Additionally, combined axonal loss and demyelinating sensorimotor polyneuropathy were present. Because other family members were not affected, autosomal recessive inheritance was considered likely. Genetic analysis of this autosomal recessive HSP was consistent with the linkage to 15q13-15 (markers D15S971, D15S118, D15S994, and D15S659). No mutation was found within the SLC12A6 gene. CONCLUSION: Progressive axonal degeneration occurs in the corticocortical projections, corticospinal tract, and peripheral nerves in HSP with thin CC linking to chromosome 15q13-15 in a German pedigree.

Adult↗

PubMed2003

Salvage therapy in patients with glioblastoma: is there any benefit?

BACKGROUND: Survival after first-line therapy is poor for patients with glioblastoma. The role of second-line treatment for recurrent disease is controversial. The authors studied the outcome in a subset of patients with glioblastoma who were selected for an aggressive reintervention strategy at the time of progression. Their objectives were to improve patients' overall survival with sustained quality of life and to make comparisons with overall survival in unselected patients. METHODS: Overall, 168 patients were eligible for retrospective analysis. Ninety patients received specific therapy for disease recurrence (reintervention group) by specific criteria. RESULTS: In the reintervention group, promising median overall survival (mOS) results after diagnosis (61.5 weeks) and progression (33 weeks) were obtained. The progression-free survival (PFS) rate at 12 months and the overall survival rate were superior in the reintervention group (71% at 12 months and 32% at 24 months) compared with the total cohort (45% and 20%, respectively) and the standard group (15% and 5%, respectively). A matched-pair analysis (n = 46 in each group), with an mOS period of 65.5 versus 28.5 weeks, confirmed these data. Quality of life was stable or slightly improved during reinterventions in a subset of patients treated within clinical studies. CONCLUSIONS: The majority of patients in the current series were treated with a reintervention strategy, which had an impact on PFS and mOS. A second resection, focal radiotherapy (in selected cases), and additional chemotherapeutic regimens should be considered for patients with recurrent glioblastoma.

Adult↗

PubMed2003

External carotid artery territory ischemia impairs outcome in the endovascular filament model of middle cerebral artery occlusion in rats.

BACKGROUND AND PURPOSE: Middle cerebral artery occlusion (MCAO) by an intraluminal filament is a widely accepted animal model of focal cerebral ischemia. In this procedure, cutting of the external carotid artery (ECA) is a prerequisite for thread insertion. However, the implications of ECA transsection have not yet been described. METHODS: After 90 minutes of filament MCAO or sham surgery, rats were evaluated for up to 14 days in terms of body weight development, core temperature, and motor performance. Repeated in vivo MRI of the head and neck was performed for quantification of brain edema and infarct volume. The temporal muscles were histologically analyzed postmortem. RESULTS: In 47% of all rats, ischemic tissue damage to the ipsilateral ECA area, including temporal, lingual, and pharyngeal musculature, was detectable by MRI. Histology of temporal muscles confirmed acute ischemic myopathy. Animals with ECA territory ischemia (ECA-I) showed delayed body weight development and poorer recovery of motor function. There was no difference in the extent of brain edema or final cerebral lesion size between ECA-I-affected and unaffected rats. CONCLUSIONS: Filament MCAO was complicated by the consequences of ECA ischemia in approximately half of all rats. Impaired mastication and swallowing functions restricted ingestion and resulted in postsurgical body weight loss and worse motor performance. Impaired cerebral microperfusion resulting from dehydration and reduced spontaneous motor activity resulting from reduced food and water uptake might have contributed to poorer neurological recovery in ECA ischemic rats. Thus, adverse effects caused by extracerebral ischemia with potential impact on outcome have to be considered in this stroke model.

Animals↗

PubMed2003

Do highly concentrated gadolinium chelates improve MR brain perfusion imaging? Intraindividually controlled randomized crossover concentration comparison study of 0.5 versus 1.0 mol/L gadobutrol.

PURPOSE: To assess the potential advantages of using a 1.0 mol/L versus 0.5 mol/L gadobutrol formulation for magnetic resonance (MR) brain perfusion imaging. MATERIALS AND METHODS: Forty-three healthy volunteers were enrolled in an intraindividually controlled, randomized crossover comparison study. Two gadobutrol formulations-0.5 and 1.0 mol/L- were randomly injected during two separate treatment periods. For intraindividual comparison of effectiveness parameters, single-section gradient-echo brain perfusion MR imaging was performed under identical conditions for both investigations. Quantitative and qualitative evaluations were performed. Differences between the two gadobutrol formulations were evaluated at analysis of covariance and tested for statistical significance (P <.05) with a t test. RESULTS: Use of 1.0 mol/L gadobutrol resulted in a significantly smaller bolus width at half maximum signal intensity decrease, a smaller mean peak time, a higher contrast and contrast-to-noise ratio between gray and white matter, and significant increases in both maximum change in transverse relaxation rate (DeltaR2max) and differences in peak enhancement in gray matter among all volunteers (P <.001). In white matter, increases in DeltaR2max (P =.262) and in differences in peak enhancement (P =.262) were smaller and not significant (P =.292). Parameter map analysis revealed improved quality and superior contrast in relative regional cerebral blood flow (P =.034) and mean transit time (P <.001). The lack of difference regarding relative regional cerebral blood volume maps was consistent with the use of the same dose of each gadobutrol formulation. CONCLUSION: Brain perfusion images obtained with 1.0 mol/L gadobutrol were superior to those obtained with 0.5 mol/L gadobutrol in healthy volunteers examined with the described MR imaging protocol.

Adult↗

PubMed2003

["Acquired Psychopathy" and the Neurobiology of Emotion and Violence]

"Psychopathy" describes a type of personality disorder characterized by a dysregulation of emotion processing. Social behaviour, emotion regulation and competency are of particular relevance in forensic psychiatry. Structural-morphological and functional imaging studies prove that emotion regulation, aggressive-impulsive behaviour and learning from negative experiences are greatly influenced by frontal brain regions. These abilities are impaired in severe cases of dissocial personality disorders and in traumatic "pseudopsychopathy". We illustrate the importance functional neurobiological changes in patients personality disorders and "acquired psychopathy" by two case reports on patients who were admitted to a forensic-psychiatric facility for sexual crimes.

Journal Article↗

PubMed2003

[Frontotemporal Dementia Presenting as Acute Late Onset Schizophrenia]

The concept of frontotemporal lobar degeneration comprises a heterogenous group of cortical dementias, including frontotemporal dementia, as the major clinical variant. Because of their highly variable clinical presentation, to establish the diagnosis of frontotemporal dementia could be a diagnostic challenge for the clinician. Here we report a 53 years old caucasian male patient who was admitted for hospitalization due to acute severe schizophrenia-like symptoms. The leading symptomatology comprised acoustic and bizarre optical hallucinations with euphoria and self-overestimation. Remission of the psychotic symptoms demasked the clinical picture of a rapidly progressive frontotemporal dementia with marked apathy, indifference, emotional blunting, loss of insight, change of personality and typical cognitive impairment. The diagnosis was supported by the results of cerebral MRI and FDG-18 PET. This first clinical manifestation of a schizophrenia-like syndrome in the 6 (th) life decade implicates frontotemporal dementia as an important differential diagnosis of schizophrenic disorders in late life. In addition of basically thinking about frontotemporal dementia, a detailed medical history, cognitive testing, neuroimaging and eventually the evaluation of the further disease course are necessary to establish a diagnosis of frontotemporal dementia.

Journal Article↗

PubMed2003

[A case of schizophreniform disorder in frontotemporal dementia (FTD)].

The concept of frontotemporal lobar degeneration comprises a heterogenous group of cortical dementias, including frontotemporal dementia, as the major clinical variant. Because of their highly variable clinical presentation, to establish the diagnosis of frontotemporal dementia could be a diagnostic challenge for the clinician. Here we report a 53 years old caucasian male patient who was admitted for hospitalization due to acute severe schizophrenia-like symptoms. The leading symptomatology comprised acoustic and bizarre optical hallucinations with euphoria and self-overestimation. Remission of the psychotic symptoms demasked the clinical picture of a rapidly progressive frontotemporal dementia with marked apathy, indifference, emotional blunting, loss of insight, change of personality and typical cognitive impairment. The diagnosis was supported by the results of cerebral MRI and FDG-18 PET. This first clinical manifestation of a schizophrenia-like syndrome in the 6th life decade implicates frontotemporal dementia as an important differential diagnosis of schizophrenic disorders in late life. In addition of basically thinking about frontotemporal dementia, a detailed medical history, cognitive testing, neuroimaging and eventually the evaluation of the further disease course are necessary to establish a diagnosis of frontotemporal dementia.

Acute Disease↗

PubMed2003

["Acquired psychopathy" and the neurobiology of emotion and violence].

Adult↗

PubMed2002

Application of NMR spectroscopy to monitoring MELAS treatment: a case report.

1H magnetic resonance spectroscopy (MRS) of the brain and (31)P MRS and saturation transfer of resting skeletal muscle were used to investigate intracellular metabolites and fluxes through the creatine kinase (CK) reaction in a patient with the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). Acute cortical lesions were characterized by severely elevated lactate levels and reduced concentrations of N-acetylaspartyl compounds, glutamate, and myo-inositol. Similar but less extreme alterations were also observed in gray matter regions that appeared normal on magnetic resonance images. Investigation of the gastrocnemius muscle at rest demonstrated a reduced phosphocreatine level, elevated concentrations of inorganic phosphate and free adenosine 5'-diphosphate, and an abnormally low phosphorylation potential. Besides a moderately increased muscular phosphocreatine concentration, none of the metabolic disturbances detected on MRS improved with oral creatine supplementation. Forward and reverse fluxes through the CK reaction did not significantly change upon creatine treatment. Follow-up MRS investigations may thus provide objective markers of treatment response in vivo without the hazards or inconvenience of biopsy.

Adolescent↗

PubMed2002

Observation on the integrity of the blood-brain barrier after microbubble destruction by diagnostic transcranial color-coded sonography.

OBJECTIVE: To investigate alteration of the blood-brain barrier from ultrasonic contrast agent destruction by diagnostic transcranial color-coded sonography using gadolinium-enhanced magnetic resonance imaging. METHODS: Healthy male volunteers received 10 mL (400 mg/dL) of Levovist (SH U 508A; Schering AG, Berlin, Germany; n = 6) or 3 mL of Optison (FS069; Mallinckrodt Inc, St Louis, MO; n = 4) followed by 0.3 mmol/kg magnetic resonance imaging contrast agent (Magnevist; Schering) intravenously. Then transcranial color-coded sonography was performed with a conventional color duplex sonographic system, which insonated the brain in a slightly angulated axial plane with temporal average intensity of less than 700 mW/cm2 or acoustic pressure amplitude of less than 2.69 MPa, attenuated by the temporal bone. Before, immediately after, and 2 hours after insonation, T1-weighted axial magnetic resonance imaging was performed. All magnetic resonance images were individually assessed, and T1 signal intensities were measured in 2 regions of interest in both hemispheres at the 3 time points. RESULTS: No focal contrast enhancement or damage to the brain and no significant difference between T1 signal intensities in the right and left brain regions could be detected during early or late phases when either ultrasonic contrast agent was used. CONCLUSIONS: This bioeffects study gives further evidence of the safety of ultrasonic destruction of Levovist and Optison microbubbles by diagnostic transcranial color-coded sonography. However, more subtle local effects may have been missed by gadolinium-enhanced magnetic resonance imaging. Studies on diagnostic contrast-enhanced transcranial color-coded sonography as well as microbubble-based drug delivery strategies should consider ultrasonic contrast agent microbubble characteristics and concentration as well as ultrasound transmission power levels.

Adult↗