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H Loiseau

Publications and source records attributed to H Loiseau.

At least 19 recordsLinked to original sources
PubMed2005

[Angelman syndrome and intracranial aneurysm: fortuitous association or commune genetic predisposition?].

Although the pathogenesis of cerebral aneurysms has been studied intensively, it is yet poorly understood. However, a genetic predisposition to this pathology has been often suspected. We describe a patient with both intracranial aneurysm and Angelman syndrome. Angelman syndrome is characterized by severe mental retardation, inappropriate laughter, absent speech, dysmorphic facial features and seizures. It is due to genetic abnormalities of chromosome 15. Cerebral aneurysms are sometimes associated with inherited diseases like autosomal dominant polycystic kidney disease. Moreover several candidate genes have been analysed, to search for genetic variants which might be associated with the occurrence of intracranial aneurysms. Our question is: is the association described in our observation fortuitous or do these diseases share a same genetic predisposition? Our observation also supports the hypothesis of a genetic participation in the genesis of cerebral aneurysms.

Angelman Syndrome↗
PubMed2005

[Analysis of target volumes for gliomas].

Gliomas are the most frequent tumors of the central nervous system of the adult. These intraparenchymal tumors are infiltrative and the most important criterion for definition of GTV and CTV is the extent of infiltration. Delineation of GTV and CTV for untreated and resected glioma remains a controversial and difficult issue because of the discrepancy between real tumor invasion and that estimated by CT or MRI. Is particularly helpful a joint analysis of the four different methods as histopathological correlations with CT and MRI, use of new modality imaging, pattern of relapses after treatment and interobserver studies. The presence of isolated tumor cells in intact brain, oedema or adjacent structures requires the definition of two different options for CTV: i) a geometrical option with GTV defined as the tumor mass revealed by the contrast-enhanced zone on CT or MRI and a CTV with an expanded margin of 2 or 3 cm; ii) an anatomic option including the entire zone of oedema or isolated tumor cell infiltration extending at least as far as the limits of the hyperintense zone on T2-weighted MRI. Inclusion of adjacent structures (such as white matter, corpus callosum, subarachnoid spaces) in the CTV mainly depends on the site of the tumor and size of the volume is generally enlarged.

Brain Neoplasms↗
PubMed2004

Mutations within the MGC4607 gene cause cerebral cavernous malformations.

Cerebral cavernous malformations (CCM) are hamartomatous vascular malformations characterized by abnormally enlarged capillary cavities without intervening brain parenchyma. They cause seizures and focal neurological deficits due to cerebral hemorrhages. CCM loci have already been assigned to chromosomes 7q (CCM1), 7p (CCM2), and 3q (CCM3) and have been identified in 40%, 20%, and 40%, respectively, of families with CCM. Loss-of-function mutations have been identified in CCM1/KRIT1, the sole CCM gene identified to date. We report here the identification of MGC4607 as the CCM2 gene. We first reduced the size of the CCM2 interval from 22 cM to 7.5 cM by genetic linkage analysis. We then hypothesized that large deletions might be involved in the disorder, as already reported in other hamartomatous conditions, such as tuberous sclerosis or neurofibromatosis. We performed a high-density microsatellite genotyping of this 7.5-cM interval to search for putative null alleles in 30 unrelated families, and we identified, in 2 unrelated families, null alleles that were the result of deletions within a 350-kb interval flanked by markers D7S478 and D7S621. Additional microsatellite and single-nucleotide polymorphism genotyping showed that these two distinct deletions overlapped and that both of the two deleted the first exon of MGC4607, a known gene of unknown function. In both families, one of the two MGC4607 transcripts was not detected. We then identified eight additional point mutations within MGC4607 in eight of the remaining families. One of them led to the alteration of the initiation codon and five of them to a premature termination codon, including one nonsense, one frameshift, and three splice-site mutations. All these mutations cosegregated with the disease in the families and were not observed in 192 control chromosomes. MGC4607 is so far unrelated to any known gene family. Its implication in CCMs strongly suggests that it is a new player in vascular morphogenesis.

Female↗
PubMed2004

[French neurosurgical practice in Neuro-Oncology (national survey--part I)].

OBJECTIVE: The aim of this work is to summarize the elements of the "Cancer Plan" applicable to neurosurgical practice, and to give the results of a national inquiry concerning the daily practice of Neuro-Oncology from the neurosurgical point of view. METHOD: The Neuro-Oncology Group of the French Society of Neurosurgery has submitted a questionnaire to every department of Neurosurgery in France. RESULTS: The response rate of the public centers was 96.5%. Moreover, responses were available from 7 private centers. The results are detailed in the text. CONCLUSION: This national survey highlights the interest and implication of French neurosurgeons in the field of Neuro-Oncology. But also, to be in accordance with the guidelines for good clinical practice, the importance of developing official neuro-oncological networks in order to offer the best access to clinical and fundamental data and hence optimise patient's care. The publication of the "Cancer Plan", the creation of a National Neuro-Oncology Group, and the results of this survey (actual multidisciplinary approach, better information and transparency, individualized care of the patients), are in the line with updating our daily practice, even though discrepancies remain among centers. French neurosurgeons must continue along the same path, but at the same time there is a need for additional help to definitely reach a truly, and homogeneous, optimized care of neuro-oncological patients.

France↗
PubMed2002

Nodular intracerebral lesions can reveal an asymptomatic systemic lymphoma.

OBJECT: To investigate whether a systemic workup is useful to assess the primary or secondary nature of brain lymphoma in immunocompetent patients suffering from nodular intracerebral lesions. METHODS: We retrospectively studied a consecutive series of 62 immunocompetent patients suffering from non-Hodgkin's brain lymphoma and analyzed two parameters: (1) the results of a partial systemic workup and (2) the pattern of relapse for all patients who are currently followed up or were so until death. RESULTS: The workup was conducted with chest X-ray and blood analysis in all cases, total body CT scan in 31 cases, bone marrow biopsy in 30 and serum lactate dehydrogenase in 29. Asymptomatic systemic lymphomatous lesions were found in 9.6% of the cases (n=6/62). Two were nodal lymphomas and four were extranodal (maxillary sinus, testis, cutaneous and osseous). No systemic localization was observed during the follow-up of patients in whom the primary nature of the lymphoma was assessed after their initial negative workup (56/62). In this group, all relapses occurred within the central nervous system, even in those exclusively treated with cerebral radiotherapy (29/56). CONCLUSIONS: Our results indicate that nodular intracerebral lesions can reveal asymptomatic systemic lymphoma. When brain lymphoma is suspected or diagnosed, systemic workup including clinical, biological and radiological examinations is mandatory before assessing the primary or secondary nature of the disease. Node areas, skin, testis, Waldeyer's ring and adjacent structures are of special interest and should be carefully explored.

Adult↗
PubMed2001

[Gross tumor volume (GTV) and clinical target volume (CTV) in adult gliomas].

Glioblastoma multiform and astrocytoma are the most frequent primary cancer of the central nervous system of adult. Definitions of gross tumor volume (GTV) and clinical target volume (CTV) are based on the confrontation of clinical presentation (age, performance status, neurologic symptoms...), histological type and imaging aspects. For glioblastoma multiform, the GTV can be defined by the area of contrast enhancement observed on the CT scan or MRI. Definition of the CTV can be more difficult and have to take into account the risk of presence of isolated malignant cells in the oedema surrounding the tumor or in the adjacent brain structures. The classical concept of GTV plus a safety margin of 2 cm around is discussed with a CTV containing at least all the oedematous area and eventually adjacent brain structures (nuclei, corpus callosum or other long associative fibers...). For low grade astrocytoma, the definition of GTV can be difficult if the tumoral infiltration is diffuse without nodular visible tumor. CTV corresponds to at least T2 MRI hypersignal area when visible. For postoperative tumor, technical considerations are important for the detection of residual tumor. A safety margin around the resected area is designed according to the risk of presence of isolated cells or involvement of adjacent brain structures.

Astrocytoma↗
PubMed2000

Squamous cell carcinoma developing in an intracranial prepontine epidermoid cyst.

Intracranial epidermoid cysts represent around 0,2 to 1 % of all intracranial tumours. Rare malignant transformation of these benign lesions may occur. A 66-year-old man presented with a state of confusion. MRI demonstrated a heterogeneous signal in front of the pons and ventricular dilatation. Cerebrospinal fluid examinations disclosed inflammatory cells. The patient died six months after his first admission to hospital. At autopsy, a firm greyish tumour (3 cm-long and 1 cm-thick) was present in front of the brain stem encasing the basilar artery. Microscopic examination revealed a well-differentiated epidermoid carcinoma arising from a cystic lesion whose wall was lined by a squamous epithelium with a benign appearance. The walls of all the ventricles were lined by carcinomatous cells. There was no leptomeningeal metastasis. Twenty three other cases of such squamous cell carcinoma have been reported and most of them had died within a few months.

Basilar Artery↗
PubMed2000

Histopathological variants of central neurocytoma: Report of 10 cases.

Central neurocytoma is a rare neuronal tumor affecting young adults and usually located in the lateral ventricles. Post-operative prognosis is generally good. Histologically, central neurocytoma is composed of isomorphous small round or ovoid cells alternating with irregularly shaped patches of fibrillary matrix similar to the neuropile. In a series of 10 cases, two central neurocytomas were histologically "atypical" at first examination. One was intra-ventricular, and the second had an intra-parenchymatous juxta-ventricular location. Both were highly cellular with mitotic activity, and tumor necrosis was seen in one. Neuronal differentiation was assessed by synaptophysin immunoreactivity in all 10 cases and by ultrastructural examination in four, including the two "atypical" forms. Neuronal differentiation was less marked in these "atypical" forms, one also presenting focal GFAP immunoreactivity. The proliferative potential was determined by MIB-1 labeling index and compared with clinical outcome. The eight classical central neurocytomas had a MIB-1 labeling index < 2.3%, whereas the two "atypical" forms had a MIB-1 labeling index > 5.2% and both recurred. We think that there is a spectrum of small-cell neuronal tumors. The two extremes could be the central neurocytoma and the primary cerebral neuroblastoma, while the intermediate forms might be qualified as "atypical neurocytoma". In our series, the histological and immunohistochemical criteria of biological aggressiveness appeared to be high mitotic activity, tumor necrosis, loss of neuronal differentiation and high MIB-1 labelling index.

Adult↗
PubMed2000

[The role of surgery in the treatment of glial tumors].

Indications for surgery in the management of glial tumors is twofold. Surgery provides a pathology-based diagnosis that is mandatory in every patient with a clinical diagnosis of glial tumor. However, its role in duration of survival is controversial. Total surgical removal is the best prognostic factor in grade 1 glioma. For grade 2 to 4 gliomas, the results of surgery are variable. Surgical resection is undoubtedly associated with clinical improvement. Its impact on duration of survival is not firmly established, due to, on the one hand, the infiltrative pattern of these types of tumors and, on the other hand, to the inherent difficulty in evaluating their size either pre- or postoperatively. However, the sole clinical improvement related to surgical resection appears sufficient to justify patients' exposure to resective surgery. The surgical risk has dramatically decreased over the last few years mainly due to technical improvements.

Brain Neoplasms↗
PubMed1999

p73 gene transcripts in human brain tumors: overexpression and altered splicing in ependymomas.

The p73 gene encodes a protein that shares structural and functional homologies with the p53 tumor suppressor protein. The p73 gene is monoallelically expressed in normal tissue, maps to chromosome 1p36 and is deleted in human neuroblastoma cell lines. Alternative splicing of exon 13 in p73 transcripts generates two isoforms, p73alpha and p73beta, that differ in their carboxy-terminus and in their ability to form homotypic interactions. In this study, we investigated, in 129 human central nervous system tumors of various histological types, the levels of p73 transcripts and the splicing characteristics of p73 mRNA. Whereas p73 mRNA content was consistently low in most tumoral types, especially in meningiomas, some glioblastomas, medulloblastomas and metastases exhibited elevated p73 mRNA content. However, ependymomas expressed consistently high amounts of p73 mRNA, significantly different from the other tumoral types. Whereas the short (p73beta) isoform accounted for 20-25% of the total p73 mRNA in most of the tumors, these splicing characteristics were altered in ependymomas (only 9% of p73beta) and in neurinomas (up to 53% of p73beta). These observations suggest tissular or tumoral differences in the control of p73 gene transcription and alternative splicing, and raise the problem of the role of p73 isoforms in the control of tumor growth, particularly in ependymomas.

Alternative Splicing↗
PubMed1999

[An unusual form of neurosarcoidosis isolated in association with a tumoral lesion, chronic meningitis, hydrocephalus and hypothalamo-hypophyseal involvement].

A 30-year-old woman developed progressive left sided hemiparesis with intracranial hypertension signs. CT scan and MRI showed a large temporo parietal cystic mass with marked surrounding edema. Surgical excision was performed, and histological analysis revealed an inflammatory granuloma. No disease elsewhere was found and all classical causes of granulomas such as tuberculosis, toxoplasma, fungus infections, inflammatory diseases, lymphomas and cancers were excluded. No treatment was administered and she remained neurologically stable for two years. Afterwards, she developed chronic meningo-encephalitis, hypothalamic-pituitary dysfunction and hydrocephalus requiring decompression. Sarcoidosis was suspected, a steroid therapy was initiated, she gradually improved and a ventricular biopsy confirmed this diagnosis. Nervous system lesions complicate the course of sarcoidosis in 5 to 15% of patients and most commonly involve the cranial and peripheral nerves. CNS involvement is typically meningeal with a predilection for the hypothalamic region. Intracranial mass lesions are rare and their occurrence in the absence of disease elsewhere is still more unusual. Three presentations have been described: an isolated intra parenchymatous mass, multiples nodules, and subdural plaques, that can be mistaken for meningiomas, gliomas or metastases. When systemic manifestations of sarcoidosis are absent, the diagnosis is difficult, and Gd-enhanced MRI is now considered the diagnostic method of choice. However brain biopsy is sometimes necessary. Corticosteroids are the mainstay of therapy. Immunosuppressive agents are also used and brain irradiation has been tried in some refractory cases. Surgical approach may be indicated to establish tissue diagnosis, to perform decompression and to remove brain tumors.

Adult↗
PubMed1998

p53 protein expression in grade II astrocytomas: immunohistochemical study of 100 cases with long-term follow-up.

p53 protein expression was evaluated by immunohistochemistry in a homogeneous series of 100 supratentorial grade II astrocytomas with long-term follow-up. The staining was positive in 72 cases. The proportion of p53 positive tumors was slightly higher in younger patients. The tumor regrowths which derived from p53 positive tumors were themselves p53 positive, and this p53 immunopositivity was often stronger than in the initial tumors. All of the 10 gemistocytic astrocytomas included in our series were p53 positive, and age more than histological type appeared decisive in prognosis. p53 protein expression did not quite reach statistical significance as an independent predictive variable in multivariate analysis, whereas survival was related with age, mass effect, surgery and tumor location. Only a tendency to a longer survival was observed on the curves in younger patients with mildly positive tumors.

Adolescent↗
PubMed1998

[Temporal lobe epilepsy and ganglioglioma in children. Clinical aspects, imagery and neuropathology; nosological discussion of six cases].

BACKGROUND: Gangliogliomas belong to debated nosological entity. They are classified as neuronal or neuroglial tumors. PATIENTS AND METHODS: Six children aged from 4 months to 15 years (mean age: 4 years and 6 months) were initially seen for partial seizures resistant to treatment. Tumoral resection was performed in all six. Diagnosis was made from immunohistological study of the tumor. DISCUSSION: Gangliogliomas are non-malignant, with a good prognosis, even if inaugural clinical manifestations are severe. Neuroradiological diagnosis with astrocytomas and cortical dysplasia is not easy, and pathological distinction from cortical dysplasia is difficult. CONCLUSION: The immunohistochemical confirmation of diagnosis permits a logical therapeutic attitude: complete resection of tumor is followed by an excellent outcome.

Adolescent↗
PubMed1998

[Primary central nervous system lymphomas. Diagnostic and prognostic effect of steroid-induced remission].

PURPOSE: Non-AIDS primary central nervous system lymphomas may respond totally or partially to corticosteroids. These corticoid-induced remissions seems to be very specific for this disease. They have been proposed as diagnostic test. The effect of these remissions on prognosis remains unknown. METHODS: A retrospective study was conducted. Corticosteroid sensibility, duration of survival, duration of disease free interval and type of treatment were compared between two groups of patients. The first one (group 1) included 44 patients in which exact diagnosis was made by stereotactic biopsy or surgery. The second group (group 2) included 5 patients exhibiting typical neuroradiological aspects of primary lymphoma in whom corticosteroid therapy produced a total regression of the lesions. RESULTS: In group 1, 29.1% of the lymphomas exhibited cortico-sensitivity. Duration of free interval of disease accounted for 75% of the overall duration of survival. Age was the only significant factor predicting remission (p = 0.019). The sole factor influencing total duration of remission was the type of treatment (p = 0.03). Duration of remission was significantly shorter in group 2 versus group 1 patients (p = 0.007). CONCLUSIONS: Duration of the first remission is of paramount importance on survival as well as the quality of first line therapy. In these conditions the absence of precise diagnosis due to corticoid-induced remissions could be dramatically deleterious.

Adrenal Cortex Hormones↗
PubMed1998

[Chronic bilateral subdural hematomas].

BACKGROUND AND PURPOSE: Are chronic bilateral subdural hematomas different from unilateral forms in terms of delay of diagnosis, clinical presentation and post-operative recovery or recurrence? METHODS: Etiological, clinical, and radiological aspects and management outcome of bilateral chronic subdural hematomas consecutively managed from 1990 to 1995 were retrospectively analyzed and compared with unilateral forms managed in the same neurosurgical unit during the same period of time. RESULTS: There were 236 cases. Bilateral subdural hematomas occurred in 41 patients (17.4%). A good outcome was obtained in 97.5% of the cases and morbidity was 14.6%. The differences significantly observed between unilateral and bilateral subdural hematomas were duration of the prediagnostic period, pneumatoceles and recurrence rates (12%). Recurrences were all observed during the first postoperative month and treated with the same initial standardized procedure. The rate of infection or epileptic seizures was low. CONCLUSIONS: There are few limited differences between uni- and bilateral chronic subdural hematomas. In the latter, a possible correlation between the duration of prediagnostic period and an increased rate of recurrence could be explained by poorer cerebral reexpansion. The overall prognosis of bilateral hematomas is comparable with that observed in unilateral forms. A simple and routinely used burr hole procedure either under local or general anesthesia associated with closed drainage is a safe surgical procedure for either bilateral or unilateral forms and can be performed in all the cases including recurrences. Systematic antiepileptic drugs or antibiotherapy are unnecessary in the medical management of chronic subdural hematomas. One late delayed postoperative clinical control seems to be sufficient.

Aged↗
PubMed1997

[Isolated involvement of the trigeminal nerve of sarcoidosis origin].

Sarcoidosic neurological manifestations are uncommon. Isolated cranial nerve's injury is exceptional. The authors report the case of a 29 year-old woman with a trigeminal nerve tumor. Surgery and anatomopathology led to the diagnosis of sarcoidosic infiltration. No other neurological or extra-neurological localization was found. Cranial fifth nerve injury was observed in 14 cases of the literature. In all cases, trigeminal nerve injury was described as associated with another disease's localization (neurological and/or extra-neurological). This observation seems unusual due to isolated nature of the presentation and complete resolution after surgery. This case illustrated the diagnosis and nosologic difficulties raised by granulomatous lesions, symptomatic or not, in the absence of systemic localization.

Adult↗