Biomedical subjects

Ingmar Blümcke

Publications and source records attributed to Ingmar Blümcke.

40 records · Page 3Linked to original sources

PubMed2002

Gangliogliomas: an intriguing tumor entity associated with focal epilepsies.

Gangliogliomas represent the most frequent tumor entity in young patients suffering from chronic focal epilepsies. In a series of 326 gangliogliomas collected from the University of Bonn Epilepsy Surgery Program and other departments of neuropathology in Germany, Austria, and Switzerland, epidemiological findings and histopathological hallmarks of gangliogliomas are systematically reviewed. The majority of these tumors occur within the temporal lobe and reveal a biphasic histological architecture characterized by a combination of dysplastic neurons and neoplastic glial cell elements. However, gangliogliomas exhibit a considerable variability in their histopathological appearance. Immunohistochemical studies are an important tool to discriminate these neoplasms from other tumor entities. Almost 80% of gangliogliomas reveal immunoreactivity for CD34, a stem cell epitope not expressed in normal brain. Immunohistochemical reactions for MAP2 or NeuN can be employed to characterize the dysplastic nature of neurons in those areas difficult to discriminate from pre-existing brain parenchyma. Less than 50% of the cases display binucleated neurons. With the frequent finding of "satellite" tumor clusters in adjacent brain regions, gangliogliomas are microscopically less circumscribed than previously assumed. The distinction from diffusely infiltrating gliomas is of considerable importance since tumor recurrence or malignant progression are rare events in gangliogliomas. Only little is known about the molecular pathogenesis of these glioneuronal tumors. Our findings support a dysontogenic origin from a glioneuronal precursor lesion with neoplastic, clonal proliferation of the glial cell population. Candidate genes appear to associate with neurodevelopmental signaling cascades rather than cell cycle control or DNA repair mechanisms. The reelin signaling and tuberin/insulin growth receptor pathways have recently been implicated in ganglioglioma development. Powerful new molecular genetic and biological tools can now be employed to unravel the pathogenesis of these intriguing lesions.

Adolescent↗

PubMed2002

Ammon's horn sclerosis: a maldevelopmental disorder associated with temporal lobe epilepsy.

Ammon's horn sclerosis (AHS) is the major neuropathological substrate in patients with temporal lobe epilepsy (TLE). Histopathological hallmarks include segmental loss of pyramidal neurons, granule cell dispersion and reactive gliosis. Pathogenetic mechanisms underlying this distinct hippocampal pathology have not yet been identified and it remains to be resolved whether AHS represents the cause or the consequence of chronic seizure activity and pharmacoresistant TLE. Whereas the clinical history indicates an early onset in most patients, ie, occurrence of febrile seizures at a young age, surgical treatment is usually carried out at an end stage of the disease. It has, therefore, been difficult to analyse the sequential development of hippocampal pathology in TLE patients. Recent molecular neuropathological studies focusing on developmental aspects of hippocampal organization revealed 2 intriguing findings in AHS specimens: i) The persistence of Cajal-Retzius cells in AHS patients points towards an early insult and an altered Reelin signaling pathway and ii) increased neurogenesis in and abnormal architectural organization of the dentate granule cell layer can be observed in young patients with early hippocampal seizure onset. These findings would be compatible with a model that involves a neurodevelopmental component in the formation of AHS. Its association with a lowered seizure threshold and an increased susceptibility for segmental cell loss in the hippocampus during the long course of the disease may constitute additional elements in a pathogenic cascade.

Amygdala↗

PubMed2002

Surgery to treat focal frontal lobe epilepsy in adults.

OBJECTIVE: To report clinical, neuropathological, and outcome data for a series of adult patients with focal frontal lobe epilepsy (fFLE) who underwent nonlobar resection restricted to the frontal lobe. METHODS: Sixty-eight adult cases (24 female and 44 male patients) were included in the study, on the basis of prospectively collected data that were retrospectively evaluated. There were 68 lesionectomies, 17 of which were combined with multiple subpial transection, with a mean follow-up period of 28.4 +/- 23.3 months. Cases involving additional extrafrontal surgery were excluded. RESULTS: Thirty-seven patients underwent invasive preoperative evaluations, and 31 underwent noninvasive evaluations. Intraoperative electrocorticography was used in 32% of cases. There were 24 tumors, 18 dysgenetic lesions, 14 gliotic lesions, and 10 vascular malformations. Fifteen tumors were of glial origin, one was a dysembryoplastic neuroepithelial tumor, and eight were gangliogliomas. The most common dysgenetic lesions were hamartomas (15 cases). Outcomes (classified into four Engel groups) were as follows: Class I, 54%; Class II, 19%; Class III, 15%; Class IV, 12%. Seizure-free rates were comparable for tumor and dysgenesis cases and were not as good for vascular malformation and gliosis cases. Outcome differences were not significant with respect to aura presence, side of surgery, age at the time of surgery, and age at seizure onset. There were 3 cases of surgical complications, 10 cases of transient neurological disturbances, and 1 case involving a permanent neurological deficit. No deaths occurred. CONCLUSION: Outcomes with fFLE surgery have improved, compared with historical series. fFLE resections restricted to the frontal lobe did not yield seizure-free rates as good as those for comparable nonfocal frontal lobe epilepsy series. All fFLE cases demonstrated histological lesions. fFLE surgery was associated with a higher risk of transient neurological deficits, most likely because of the necessity for multiple subpial transection. The outcomes and higher rates of invasive evaluations and intraoperative electrocorticography indicate the special complexities of frontal lobe epilepsy. The permanent neurological disability rate was low in this series, and there were no deaths.

Adolescent↗

PubMedDate not supplied

MR imaging in the presurgical workup of patients with drug-resistant epilepsy.

BACKGROUND AND PURPOSE: Whether an epileptic lesion is detected with MR imaging depends on the quality of the images and the expertise of the reader. We analyzed the role of 1.5-T MR imaging in the presurgical evaluation of patients with drug-resistant epilepsy at one center. METHODS: In a 2-year prospective study, 385 patients with drug-resistant epilepsy underwent standardized MR imaging at 1.5 T. We analyzed whether lesions were detected, whether they were precisely characterized by MR imaging, and whether lesion characterization allowed us to estimate seizure outcomes. RESULTS: Lesions were found on MR images in 318 patients (83%). Following presurgical evaluation, 209 (66%) underwent surgery, and 109 (34%) did not. Freedom from seizures was achieved in 130 (70%) of 186 patients. Nine (14%) of 66 patients without an MR imaging lesion underwent surgery; histopathologic findings were unrevealing in seven patients, and five (56%) achieved freedom from seizures. Hippocampal sclerosis was the most common lesion (52%) and correctly characterized in 101 (97%) of 104 patients. Glioneuronal tumors (20%) were sometimes imprecisely characterized: Four nonenhancing gangliogliomas were mistaken for focal cortical dysplasias. Outcomes were not different between lesion groups. However, there were trends toward a favorable outcome for focal cortical dysplasias with balloon cells and an unfavorable outcome for gyral scars. CONCLUSION: MR imaging detection of lesions influences further presurgical workup, though lesion characterization does not allow us to predict seizure outcome. If MR imaging fails to depict a lesion and patients undergo surgery because of electrophysiologic findings, histopathologic findings are often unrevealing.

Adolescent↗