Biomedical subjects

H Loiseau

Publications and source records attributed to H Loiseau.

51 records · Page 3Linked to original sources

PubMed1991

[Pleomorphic xanthoastrocytoma. Apropos of 3 new cases. Review of the literature].

Three cases of pleomorphic xanthoastrocytomas (P.X.A.), a low grade leptomeningeal glioma are reported. Prominent histological features used for diagnosis were a cellular pleomorphism of G.F.A.P. positive cells, with intracytoplasmic lipidic vacuols. A reticulinic network and mononuclear cells infiltrates have been observed. A weak mitotic activity and lack of necrosis and of endothelial cells proliferation were significant additional features necessary for diagnosis. Our cases were observed during the surgical management of young patients with resistant epilepsy. Neuroradiological examinations showed a tumor superficially located within the temporal or the parietal lobe. This tumor could be calcified and/or cystic. Operative aspects showed a firm and non-encapsulated leptomeningeal tumor with possible various colors. Our patients were seizures-free after surgery even during the follow-up. From the currently reported cases clinical follow-up ranging for 1.5 to 3 years is not sufficient to predict a favorable carcinologic prognosis. P.X.A. is an uncommon tumor and less than 50 cases are reported throughout the literature. This tumor affecting young subjects mainly during the second decade is revealed in the majority of cases (3/4) by epileptic seizures, less frequently by a deficit or by an intracranial hypertension. The great majority of clinical events are observed before 20 years. The functional prognosis is rather good after surgery with a disappearance of epileptic fits in about 50% of the cases. Throughout the literature the prognosis of this tumor seems to be comparable to low-grade astrocytomas. Optimal management of P.X.A. seems to be primary surgical resection with later surgery for residual or recurrent tumor. The role of radiotherapy in the management of P.X.A. is at this time uncertain.

Adult↗

PubMed1991

[Continuous CSF aspiration. An alternative in the management of acute hydrocephalus].

As proposed by Marmarou in 1976, in case of acute hydrocephalus high intracranial pressure (I.C.P.) can be controlled by withdrawing the ventricular cerebrospinal fluid (C.S.F.) at a constant rate equal to the rate of C.S.F. formation. We experienced this procedure since 1989 in 17 patients presenting with acute hydrocephalus consecutive to aneurysmal subarachnoid hemorrhage (11 cases) or infratentorial mass (6 cases). A ventricular catheter was connected to an electrical syringe of which the motor driving direction has been inverted. Using an outflow rate ranging from 0.15 to 0.20 ml/mn, i.e. lower than the physiological C.S.F. rate formation, this controlled continuous mechanical ventricular C.S.F. drainage has serious advantages compared to a traditional external ventricular C.S.F. drainage. These advantages are mainly the better control of intracranial pressure (fiability of I.C.P. monitoring, lowered risk of hyperdrainage), more comfort for the patient and the nursing staff and lower cost.

Acute Disease↗

PubMed1990

Relation between epileptic activities and edema formation after cryogenic injury in the rabbit.

Although cryogenic lesions have been widely used as experimental models of either focal epilepsy or focal BE, the relation between these two disorders has never been discussed. In these experiments EA and gray matter edema were correlatively investigated during the early phase (1 to 23 hr) after a cryogenic lesion in the rabbit. Indexes were developed to allow a quantitative assessment of EA. The indexes demonstrated that the early phase of cryogenic epilepsy is a rapid phenomenon during the first 4-hr postlesion. Epileptic activity precedes BE, and in individual animals, there is a significant positive correlation between the total amount of EA and edema. EA and BE are most likely interrelated at the level of pathophysiological mechanisms. Excitotoxins and ions would be possible candidates mediating both phenomena.

Animals↗

PubMed1989

[Clinical, neuroradiologic and developmental aspects of idiopathic benign subarachnoid hemorrhage (subarachnoid hemorrhage of unknown cause). Retrospective study of 65 cases].

Sixty-five patients with a mean age of 50.2 +/- 10.9 were admitted with a subarachnoid hemorrhage and a subsequent normal cerebral panangiography. On admission, 69% of the patients were graded I or II on the Hunt and Hess scale, versus 14% of them admitted on grade IV or V. Fifty-one patients (78%) were submitted to a second angiography between day 10 and day 132 after their hemorrhage (average day 29). A third angiography was performed on twenty-six patients (40%). Angiographic vasospasm was present on 52% of the first angiograms and affected predominantly the vertebro-basilar arterial system. On the second angiography, the vasospasm was still present on 26 out of 32 angiograms performed before day 30, and was only noted on 2 out of 19 angiograms performed later. No rebleeding was recorded in this group of patients who were followed-up for an average of 49 +/- 23 months. Complication as acute hydrocephalus affected 17% of the patients. In two patients (3%), symptomatic vasospasm was judged responsible of a delayed neurological deficit with concomitant hypodensity on the CT scan. Angiographic explorations were complicated by a transient ischemic deficit in 3 cases and by a fatal stroke in one case (4 cases out of 65 procedures, or 6%). As another patient died with bronchopneumonia during the hospitalization, the initial mortality rate was 3%. During the period of follow-up, two patients died from medical causes unrelated to their initial hemorrhage. Finally, 92% of the patients were alive and in an excellent or good clinical condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

[An adult case of Leigh's subacute necrotizing encephalomyelopathy].

Leigh's encephalomyelopathy has been mainly observed in infancy and childhood. A later onset, during adolescence or adulthood has been rarely reported. Our patient was a 35 year-old man who died after 10 months of evolution of a subacute neurological syndrome, beginning with behavioural changes then a confusional state, epileptic fits, ataxia, autonomic disorders, abnormal alimentary behaviour and dementia. Diagnosis was only obtained by neuropathology, as in most of the published reports. However this diagnosis is suggested when exists an acute or subacute neurological pattern, beginning with visual defects and alimentary and social impairment, followed by a brain-stem syndrome. CT and M.R.I. will make it more easy. An earlier diagnosis could perhaps allow to discover the suspected enzymopathy responsible for Leigh's encephalomyelopathy and make clearer the relationship between Leigh's disease and encephalopathies with abnormal mitochondria.

Adult↗

PubMed1987

Na+-K+-ATPase activity of glial, neuronal, and synaptosomal enriched fractions from normal and freezing-injured rabbit cerebral cortex.

This paper investigates the kinetic parameters of Na+-K+-ATPase in glial, neuronal, and synaptosomal enriched fractions isolated from rabbit cerebral cortex. Under normal conditions, kinetic parameters-Vmax and KK+0.5- of Na+-K+-ATPase are the same in the three fractions, suggesting that this enzyme behaves as the same molecular entity. Following a cryogenic lesion, the alterations of these parameters appear to be different in the different fractions. These data suggest that the same enzyme exhibits various responses when exposed to the same pathological event. The dissimilar lipid composition of the Na+-K+-ATPase environment, and/or different adaptative responses to abnormal ion concentrations in glial, neuronal, and synaptosomal fractions could account for these different responses.

Animals↗

PubMed1987

Relationship between epileptic activity and edema formation in the acute phase of cryogenic lesion.

Following cryogenic lesions of the brain in the rabbit, ictal activity appears within min with a maximum at 2 h. Brain edema increases rapidly between 2-4 h with a maximum at 8 h. The glutamate concentration reaches 209% of control in the perilesional area at 2 h and the time course of glutamate/GABA ratio parallels the time course of epileptic activity. The impairment of Na+-K+-ATPase activity (rise of KMapp for K+) in the glial fraction coincides with the increase of edema. A positive correlation is found between the total amount of ictal activity and the total amount of edema in individual animals, suggesting that epilepsy may enhance edema formation.

Animals↗

PubMed1986

[Amino acids in human epileptogenic foci].

The functional status of GABA synapses together with tissue levels of other putative neurotransmitter amino acids was studied in epileptogenic foci (identified by stereo-EEG) removed neurosurgically from 14 epileptic patients unresponsive to anti-epileptic medication. L. glutamic acid decarboxylase was lower than normal in epileptogenic cortical tissue from 10 to 12 patients. 3H-GABA-"A" receptor binding was low in all epileptogenic tissue examined. GABA levels were unchanged, whereas glutamate was increased in 7 patients. These studies confirm previous observations that there is a decreased functional activity of GABA synapses in a high proportion of epileptogenic foci. Therefore these data indicate that there is indeed an imbalance between excitatory and inhibitory neurotransmitter systems.

Amino Acids↗

PubMed1986

Alterations of GABA-mediated synaptic transmission in human epilepsy.

Although animal models consistently indicate that gamma-amino-butyric acid (GABA) synaptic function (GABA levels, synthesis, uptake and/or receptors) is decreased in seizure states, there is little evidence to date in support of such a hypothesis for human epilepsy. This chapter presents the results of an in-depth study of the activity of the GABA-synthesizing enzyme L-glutamic acid decarboxylase (GAD) in brain tissue removed during neurosurgical resection for intractable epilepsy. The tissue studied is unique in that identified (by stereo EEG) foci were excised (rather than large blocks of tissue containing mixtures of foci and nonepileptic material) and compared with nonepileptic (stereo EEG and morphological definitions) tissue from the same patients. In patients in which there was no indication of a tumor, GAD activity in the foci was low in more than 50% of the patients examined. Furthermore, when the population distribution of GAD was compared in epileptic versus nonepileptic tissue fragments from all patients, the peak distribution of epileptic tissue fragments occurred at much lower GAD activities than for the nonepileptic fragments (0-20 versus 41-80 nmol CO2/mg protein X hr, respectively). A small subgroup of epileptic fragments occurred with a normal GAD distribution, indicating that the presence of an epileptic focus was not invariably associated with low GAD activity. When the low levels of GABA "A" binding sites in these epileptic tissue fragments are taken into consideration in combination with the low GAD levels, then it can be estimated that 60 to 70% of the present patient population had deficient GABAergic transmission in epileptic foci as compared to nonepileptic brain tissue from the same patients. It follows that the GABA hypothesis of human epilepsy is not an exclusive or unitary hypothesis, and some patients appear to have normally functioning GABA synapses (as assessed biochemically) in epileptogenic areas. Thus, other neurotransmitter and neurohumoral systems certainly play a role in the epileptic process.

Animals↗

PubMed1984

[Role of interstitial radiation in the treatment of glioma].

Therapy of glioma is a function of numerous factors: their histology, localization and size, but also the age and functional state of the patient. Interstitial radiation by temporary implantation of Iridium 192 needles is recommended only under certain precise conditions: for tumors surgically inaccessible because of their deep localization or their site in a highly functional region, and for those with diameters of less than 35 mm. This restricts the number of cases that can be treated (45 in the present series). Numerous adverse reactions developed, either in the short (initial deficit and edematous reactions), medium (epilepsy) or long term (radionecrosis). However, many were regressive and the treatment is satisfactorily tolerated in view of the localization of these tumors in highly functional regions.

Adult↗

PubMedDate not supplied

Eating seizures.

An 18-year old man had a cluster of three seizures in a few hours and then remained seizure-free without medication; his mother has experienced seizures induced by movement. A 29-year-old man has had recurrent seizures for six years. In both cases, seizures were partial motor seizures induced by chewing. They are considered to be a particular variety of movement-induced seizures triggered by proprioceptive afferents of muscular origin. This explanation does not account for the great majority of the 63 published cases of seizures precipitated by eating. Eating seizures represent a heterogeneous group of seizures with discrete electroclinical signs and mechanisms. The term "eating seizures" should be preferred to the term "eating epilepsy."

Adolescent↗

PubMedDate not supplied

The early phase of cryogenic lesions: an experimental model of seizures updated.

Following cryogenic lesions in 64 rabbits, epileptic activity and gray matter edema were correlatively investigated during the initial phase (23 h). Indexes were developed to allow a quantitative assessment of epileptic activity. The indexes demonstrated that the early phase of cryogenic epilepsy is a very rapid phenomenon during the first 4 h postlesion. Epileptic activity precedes brain edema, and in individual animals, there is a significant positive correlation between the total amount of epileptic activity and the total amount of edema. The relationship between epileptic activity and brain edema are most likely interrelated at the level of pathophysiological mechanisms and several mechanisms can be postulated.

Animals↗

PubMedDate not supplied

Quinolinic-phosphoribosyl transferase activity is decreased in epileptic human brain tissue.

The presence of the excitotoxic and convulsant agent quinolinic acid (QUIN) in human brain has led to the hypothesis that an increase of this tryptophan metabolite could serve as an endogenous epileptogen. A possible mechanism for a pathological accumulation of QUIN being a deficiency in its degradation, we have measured the activity of quinolinic-phosphoribosyl transferase (QPRTase) (its first degradative enzyme) in stereo-EEG identified biopsies of human brain tissue. A specific reduction of QPRTase activity was observed in tissue primarily involved in the epileptic discharge compared to values from postmortem human brain tissue with no neurological disorders or nonpathological tissue from epileptic brains. A more severe decrease was noticed in the frontal and temporal cortices as compared to the amygdala or Ammon's horn. We suggest that this local deficit may contribute to the establishment or maintenance of an epileptic focus.

Adolescent↗

PubMedDate not supplied

Subcutaneous tumoral seeding from a glioblastoma following stereotactic biopsy: case report and review of the literature.

Extracranial metastases from glioblastoma are uncommon, likely because short patient survival time prevent them to occur. Most of the few previously reported cases occurred after invasive surgical procedures. We describe a case of glioblastoma with concomitant seeding along the stereotactic biopsy trajectory and subcutaneous metastasis. A 60-year-old woman presented with severe headache. Neuroradiological work-up (including cranial computed tomographic scan and magnetic resonance imaging) showed a heterogeneous hyperdensity, suggestive of malignant glioma, in the left parietal region. A computed tomographic-guided stereotactic biopsy was performed and microscopic examination attested a diagnosis of glioblastoma. Radiotherapy and chemotherapy were administered. Eight months later, the patient presented with a subcutaneous tumor in the left occipital region. A cranial computed tomographic scan revealed a large enhancement of the initial tumor, intracranial tumor seeding along the stereotactic biopsy trajectory, and a subcutaneous tumor. Partial resection of the subcutaneous lesion was performed, and histological examination identified an extracranial metastasis from the glioblastoma. Although uncommon, this observation points to the risk of tumor seeding following stereotactic biopsy, and to the close connection between this intracranial seeding and subcutaneous metastasis.

Biopsy↗

PubMedDate not supplied

Lhermitte-Duclos type cerebellum hamartoma and Cowden disease.

A Lhermitte-Duclos type cerebellum hamartoma is reported in a woman with a diffuse hamartomatous condition involving the breast, thyroid, colon, skin, and kidney. The family history demonstrated the autosomal dominant transmission of this hamartomatous syndrome, and indicated the diagnosis of Cowden disease. This observation supports the recent hypothesis of Lhermitte-Duclos disease associated with Cowden disease as being a single phakomatosis.

Axons↗