Biomedical subjects

J Guérin

Publications and source records attributed to J Guérin.

At least 37 records · Page 2Linked to original sources

PubMed1995

Fractionated radiation therapy in the treatment of stage III and IV cerebello-pontine angle neurinomas: long-term results in 24 cases.

PURPOSE: To reevaluate long-term results of fractionated radiation therapy (RT) in a previously published series of cerebello-pontine angle neurinomas (CPA). METHODS AND MATERIALS: From January 1986 to May 1992, 24 patients with Stage III and IV CPA neurinomas were treated with external fractionated RT; 7 patients had phacomatosis. One patient was irradiated on both sides and indications for radiotherapy were as follows: (a) poor general condition or old age contraindicating surgery, 14 cases; (b) hearing preservation in bilateral neurinomas after contralateral tumor removal, 5 cases; (c) partial resection or high risk of recurrence after subsequent surgery for relapse, 4 cases; (d) nonsurgical relapse, 2 cases. Most patients were irradiated with 9 MV photons. A three- to four-field technique with coned-down portals was used. Doses were calculated on a 95% isodose and were given 5 days a week for a mean total dose of 51 Gy (1.80 Gy/fraction). RESULTS: Median follow-up from RT was 60 months (7 to 84); five patients died, two with progressive disease. Two patients underwent total tumor removal after RT (one stable and one growing tumor). On the whole, tumor shrinkage was observed in 9 patients (36%), stable disease in 13 (52%), and tumor progression in 3. Hearing was maintained in 3 out of 5 hearing patients with phacomatosis. CONCLUSION: Fractionated RT appears to be an effective and well-tolerated treatment for Stage III and IV CPA neurinomas. Hearing can be preserved for a long time.

Adult↗

PubMed1994

Dimensions of cervical vertebral bodies according to age and sex.

A biometric comparative roentgenological study of the cervical vertebral bodies was performed, according to age and sex, from lateral roentgenograms of 120 adult cervical regions. The sexual dimorphism already described by many authors was confirmed. The vertebral bodies of C2, C3, and C7 have the more variable structure according to age. The results of our measurements are in accordance with clinical findings and provide data on the structural changes of the cervical spine during ageing. In anthropological terms, the vertebral body of C2, in particular its antero-posterior diameter, is the best age indicator, irrespective of individual and exterior variables.

Adult↗

PubMed1993

Thyrotropin-releasing hormone and gonadotropin-releasing hormone-associated peptide modulation of [Ca2+]i in human lactotrophs.

The effect of thyrotropin-releasing hormone (TRH) and gonadotropin-releasing hormone-associated peptide (GAP) was studied on both secretion and intracellular free Ca2+ concentrations ([Ca2+]i) in human pituitary cells cultured from prolactin (PRL)-secreting tumors. Secretion was measured during a 30-min incubation period and we used a microspectrofluorimetric method in individual cells and indo-1 as the fluorescent probe. TRH (10(-8) M) significantly increased PRL release in five out of the six cell populations. In these five cases, more than 68% of individual cells responded to TRH by an increase in [Ca2+]i. No significant increase in PRL secretion was found in another culture in which TRH increased [Ca2+]i in only 37% of the cells. The effect of GAP (10(-7) M) was studied in five cell populations. In three of them, a decrease of 20% to 51% of the PRL basal secretory rate was observed under GAP. GAP inhibited [Ca2+]i in respectively 59%, 46% and 94% of the cells from these cultures. The inhibitory effect of GAP was blocked by a pertussis toxin (PT) pretreatment which demonstrates the involvement of a PT-sensitive G-protein in GAP action. In two other cultures, GAP did not significantly alter PRL secretion or individual cell [Ca2+]i. These observations suggest that GAP might play a role in the control of PRL secretion in the human.

Adenoma↗

PubMed1993

[Widened retrolabyrinthine approach: application to the surgery of acoustic neuroma].

For a long time, the role of the widened retrolabyrinthine approach (WRLA) in surgery of the posterior fossa was restricted to functional surgery of the erebellopontine angle (CPA). The widening technique described makes it possible to adapt it to surgery for the exeresis of APC tumors, irrespective of their histological nature. We have used this approach to treat 19 neurinomas of the VIII and 11 other lesions. The results obtained in the preservation of facial function and hearing match those recorded with more traditional approaches, such as the translabyrinthine and suboccipital retrosigmoid approaches. By its modularity in the access space, it is the multi-purpose approach for the CPA. In our therapeutic armamentorium, given its possibilities to preserve hearing, it has taken the place of the less flexible and more dangerous suboccipital approach.

Ear, Inner↗

PubMed1992

Anatomical basis of the anterior cervical spine approach: topographic study of the nerve structure.

The results of the surgical anterior approach to the cervical spine are marked in a number of cases by dysphagia and dysphonia, especially when the approach is extensive or performed at the upper cervical spine. 35 cadaver dissections were performed to define the topography of the nerve structures during operative exposure at various vertebral levels: superior and recurrent laryngeal nerves, hypoglossal nerve and its superior root of the ansa cervicalis. The authors suggest some technical improvements, for each stage of surgical dissection.

Aged↗

PubMed1992

Fractionated radiation therapy in the treatment of stage III and IV cerebello-pontine angle neurinomas: preliminary results in 20 cases.

From January 1986 to March 1989, 20 patients with stage III and IV cerebello-pontine angle neurinomas were treated with external fractionated radiation therapy; seven patients had phacomatosis. Indications for radiation therapy were as follows: (a) poor general condition or old age contraindicating surgery, 10 patients; (b) hearing preservation in bilateral neurinomas after contralateral tumor removal, 5 patients; (c) partial resection or high risk of recurrence after subsequent surgery for relapse, 4 patients; (d) non-surgical relapse, 1 patient. Most patients were irradiated with a 9 MV linear accelerator. A 3 to 4-field technique with 5 x 5 cm portals was used. Doses were calculated on a 95% isodose and were given 5 days a week for a mean total dose of 5140 cGy (180 cGy/fraction). Median follow-up from radiation therapy was 30 months (7 to 46); 4 patients died, 2 with progressive disease. Two patients underwent total tumor removal after radiation therapy (1 stable and 1 growing tumor). On the whole, 14 tumors remained stable, 3 decreased in size, and 3 progressed. CT scan or NMR tumor changes consistent with partial tumor necrosis appeared in four cases. Hearing preservation was obtained in 3/5 hearing patients with phacomatosis. When surgery is not indicated or incomplete, fractionated radiation therapy appears to be an effective and well-tolerated treatment for stage III and IV neurinomas. Hearing can be preserved.

Adult↗

PubMed1992

Cerebral arterial fenestrations associated with intracranial saccular aneurysms.

Fenestrations of cerebral arteries other than the anterior communicating artery are rare congenital anomalies, which may be associated with saccular aneurysms. In such cases, the aneurysms may be located at the fenestration itself or may involve other intracranial vessels. This kind of association is not infrequently the cause of angiographic diagnostic problems, as well as surgical difficulties, and consequently needs to be well known to physicians. Four recent cases of rare fenestrations of cerebral arteries associated with intracranial aneurysms are reported in this study and discussed together with a review of the literature.

Adult↗

PubMed1992

Experimental evaluation of a collagen-coated vicryl mesh as a dural substitute.

Dural substitutes must provide immediate restitution of a membranous covering for the brain without inducing any adverse reaction in the host or provoking adhesions to underlying nervous tissues. Ideally, the material should disappear completely and be replaced by tissues similar to the dura mater. In this study, parietal dural defects were created in 12 beagle dogs and closed with a vicryl mesh prosthesis made watertight by a film of bovine collagen. Clinical and biological tolerances were satisfactory. There was one case of early local infection. Gross and microscopic examinations performed between 7 days and 9 months after implantation showed degradation of the prosthetic mesh and connective tissue growth into the implant mimicking dura mater as early as 15 days after implantation. There was no attendant inflammatory reaction or cortical adhesions or other adverse reactions. The authors conclude that collagen-embedded vicryl mesh provides satisfactory biological function and compatibility when used as a substitute for dura mater in the dog.

Animals↗

PubMed1992

A new way to monitor external ventricular drainage.

External ventricular drainage is prone to mechanical complications and monitoring the system is not easy. It requires repeated checking of the drip or the level of the drained cerebrospinal fluid (CSF) in the bag. It was thus proposed that an efficient method by which to monitor the complete external ventricular drainage system would be by continuously weighing the drained CSF. Using weighing scales, a converter, and a recorder, the CSF weight was displayed as a function of time (i.e., flow, if the specific gravity of the CSF is 1, which is usually the case as an approximation). This system was used in 16 comatose patients (11 with subarachnoid hemorrhages and 5 with hydrocephaly during 204 recorded periods of 22.7 +/- 2.8 hours (mean +/- standard deviation). The mean flow was 0.17 +/- 0.05 ml/min. A cessation of CSF flow was seen graphically as a plateau. This occurred 18 times because of obstruction, which was relieved before clinical worsening by making minor adjustments in 15 patients and by reinsertion of a drain in 3 patients. Nociceptive stimuli like tracheal suctioning were also clearly visible on the graph (increased slope, i.e., increased CSF flow). This type of external ventricular drainage monitoring appears to be safe and reliable, giving indications before changes in medical condition. The observed flow, however, is not equal to its rate of secretion but rather to the difference between CSF secretion and reabsorption.

Adolescent↗

PubMed1992

[Infantile spasms associated with a brain tumor].

BACKGROUND: Infantile spasms are exceptionally associated with a focal cerebral lesion such as a brain tumor. CASE REPORT: A 15 month-old girl was treated with hydrocortisone and valproic acid for infantile spasms that had appeared a few days earlier. Her psychomotor development was considered normal and the CT scan was normal. Clinical symptoms disappeared within 10 days and the EEG became normal except for a few epileptiform discharges in the frontal areas. The girl developed partial seizures at the age of 5 years. Imaging techniques showed a brain tumor in the right frontal lobe. Surgical excision was followed by radiation therapy. Analysis of the tumor showed an astrocytoma. The girl is normal 18 months after intervention. CONCLUSION: It is difficult to determine a relationship between the infantile spasms and the brain tumor in this case. The moderately asymmetrical pattern of the EEG after infantile spasms, the fact that these spasms appeared relatively late and the persistence of discharges, lead to repeated specialized investigations.

Astrocytoma↗

PubMed1992

[Biological and developmental aspects of macronodular adrenal hyperplasia in Cushing's disease].

The pathophysiology of macronodular adrenocortical hyperplasia (MNH) associated with Cushing's diseases remains debatable. Some authors have claimed that MNH represents an autonomous condition that has to be treated by surgical adrenalectomy while others advocate the use of pituitary surgery. We have compared the biochemical features, before and after pituitary surgery, between 7 cases of MHN and 22 cases of diffuse hyperplasia (DH) associated with Cushing's disease. In addition, the diameter of the adrenal nodules after surgery was evaluated in 6 cases. The mean ACTH level in MNH and DH subjects was similar. Dexamethasone suppressibility and the stimulatory effect of metyrapone on ACTH secretion were less in MNH than in DH subjects, suggesting a greater degree of adrenal autonomy in the former. The cortisol responses to metyrapone and CRF tests suggested an increased responsiveness of the adrenals to endogenous ACTH in the MNH group. Only one MNH patient had biochemical features suggesting a primary adrenal disease. The use of a sensitive ACTH assay and the results of inferior petrosal sinus sampling identified the ACTH-dependency of the disease. A short to medium term remission of the disease was obtained in all cases of MNH and in 87% of cases of DH after surgery. The diameter of the adrenal nodules significantly decreased in only 43% of cases. Our results suggest that the adrenal autonomy in MNH is incomplete and that, despite the persistence of the adrenocortical nodules, the disease can be cured with pituitary microsurgery in most cases.

Adrenal Glands↗

PubMed1992

[Arachnoid cysts of the cerebellopontine angle].

The authors report two cases of arachnoid cysts of the cerebello-pontine angle. The otologic symptoms were unsteadiness, hearing fall and tinnitus. In the first case, the patient who presented a cerebellar syndrome was operated. Afterwards the hearing felt and he developed a transient hydrocephalus. The symptoms disappeared in 9 months. In the second cas, the patient was not operated. She was treated medically and supervised. Then the symptoms disappeared too. The authors review the paraclinic exams especially MR, relevant to the diagnosis and discuss the opportunity of a surgical operation.

Adult↗

PubMed1992

[Medulloblastoma in children. Prognostic incidence of vascular hyperplasia, coagulation necrosis and postoperative clinical state on survival].

Fifty consecutive children with cerebellar medulloblastoma were operated on May, 1971 to December, 1988. At 5 and 10-years, actuarial survival rates were respectively 46% & 42%. To determine prognostic factors, various clinical and histological features were analysed: multivariate analysis showed that increased vascularity, coagulative necrosis, and postoperative clinical status have a significant influence survival. When necrosis and/or increased vascularity were present (H+), the 5-year survival rate was 17%, whereas it was 70% when absent (H-) (p less than 0.0001). Postoperative clinical status was described as poor when neurological symptoms such as vigilance or vegetative disorders, akinesia, hypotonia, apragmatism, mutism and emaciation were associated; the 5-year survival rate was 10% in the presence of such deficits (C+) and 55% in their absence (C-) (p = 0.0002). From these results, 2 distinct groups were identified: Group 1: 23 patients without pejorative factors (H- and C-); 5 and 10-year survival rates were 80%. Group 2: 27 patients with one or two pejorative factors (H+ and/or C+); 5 and 10-year survival rates were respectively 18% and 12% (p. less than 0.0001). From our experience, it appears that histology and postoperative clinical status can be early predictors of patient outcome, since neurosurgical and radiation therapy techniques have been largely optimized. These factors could be the basis for developing adapted treatment protocols.

Actuarial Analysis↗

PubMed1991

Use of ketoconazole in the treatment of Cushing's disease and ectopic ACTH syndrome.

Ketoconazole, an imidazole derivative which inhibits adrenal steroidogenesis, has been used with success for the metabolic control of Cushing's disease. Few data are available about the use of ketoconazole in the management of the ectopic ACTH syndrome. We have used ketoconazole in eight patients: four patients with Cushing's disease, two patients with overt and two with occult ectopic ACTH syndrome. Among patients with Cushing's disease, reversible hypoadrenalism occurred once. All had full clinical and biochemical regression of the disease for more than 6 months with 400-1200 mg ketoconazole per day. Patients with ectopic ACTH syndrome received 1200 mg ketoconazole per day for at least 2 months. Partial biochemical regression was observed in two and a secondary escape to adrenal blockade in two others. These findings further indicate that ketoconazole is a valuable tool for the metabolic control of Cushing's disease. On the contrary, in ectopic ACTH syndrome, this aim can be impossible to reach with ketoconazole although the reasons for its ineffectiveness remain to be determined.

ACTH Syndrome, Ectopic↗

PubMed1991

[Medulloblastoma: towards new prognostic factors].

Current therapeutic protocols for medulloblastoma combining, with surgery, radiation therapy and chemotherapy allow 5-year survival rates of over 50%. However these therapies induce mainly in children long-term adverse effects, which produce a therapeutic dilemma emphasizing the need for reliable prognostic factors in order to adapt the treatment modalities to the degree of the tumor's aggressiveness. Contradictory results have been reported concerning the conventional clinical and histological prognostic factors in medulloblastoma. Recent development and simplification of cell biology technologies could now help in the resolution of this issue. The aim of this review is to present some new prognostic factors available from these advances, and to discuss their potential usefulness in the field of medulloblastoma: The measurement of the proliferative potential of tumors using thymidine analogues such as bromodeoxyuridine (BUdR), or the monoclonal antibody Ki-67 is promising. The flow cytometric determination of D.N.A. content in medulloblastomas appears to show a correlation of diploidy with a worse prognosis than aneuploidy. Modern cytogenetic and molecular biology techniques are permitting the current assessment of amplification and overexpression of oncogenes, or the presence of deletions, as prognostic factors in medulloblastoma. The study of the cellular phenotype and particularly the search for differentiation markers has not yet led to clear-cut results from a prognostic viewpoint, but further advances are to be expected in this field, thanks to the development of more specific monoclonal antibodies. The investigation of the tumoral stroma and metabolism is very promising too. These novel approaches to prognostic factors in medulloblastoma should allow a better classification and management of these tumors in the near future.

Antibodies, Monoclonal↗

PubMed1990

[Value of the corticoliberine test in the etiologic diagnosis of Cushing's syndrome].

Several studies have demonstrated that the corticotropin-releasing factor test (CRF) is useful for the aetiological diagnosis of Cushing's syndrome: in Cushing's disease, as opposed to ectopic ACTH secretion syndrome, the hypothalamus-pituitary-adrenal (HPA) axis can still be stimulated by CRF. In the present study, we compared the CRF test with the reinforced dexamethasone suppression test in 18 patients: 11 with Cushing's disease, 6 with ectopic ACTH secretion and 1 with adrenal gland adenoma. We obtained 2 false-negative results with the CRF test and 1 false-positive result with the dexamethasone suppression test. Our study, together with published data, suggests that the CRF test is useful in the exploration of Cushing's syndromes of uncertain origin. However, the results obtained with this test must be compared with those of other methods used to explore the HPA axis and which are still necessary.

Adolescent↗

PubMed1990

[Irradiation of neurinoma. Why? How? First results].

The treatment of acoustic neurinomas is above all surgical. Five situations lead us to opt for radiotherapy: the patient's poor general condition, tumoral bilaterality with a single ear, tumoral remnants, evolutive recurrences or relapses and lastly, tumoral hypervascularization (pre-operative radiotherapy). Therefore, 19 patients were treated between 1986 and 1988 by linear accelerator photons or cobalt, at doses of 50 to 60 Gy (1.8 Gy per session). Indubitable effectiveness was observed on the tumoral volume in the form of stabilization or regression in 14 cases. The evolution of hearing after treatment is not as favorable: out of 8 patients with good hearing on the irradiated side, 3 maintained identical thresholds, but 5 secondarily developed total deafness. The therapeutic protocol change will perhaps allow for improvement in hearing preservation.

Adult↗

PubMed1990

[Radiation-induced sarcoma, apropos of a case with cervical and intrapetrous development].

The authors report on a case of fibrosarcoma of the secondary petrous part of the temporal bone following irradiation, eight years earlier, of a cerebellar astrocytoma. Based on a review of the literature, they recall the characteristic traits of these tumors: development in the field of irradiation, prolonged latency period, exact histology, rarity of cervico-cephalic locations. The treatment usually associates wide surgical exeresis and chemotherapy. The prognosis remains poor due to local recurrences and visceral metastases (20 to 60% at five years).

Adult↗