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Biomedical subjects

S Blond

Publications and source records attributed to S Blond.

At least 19 recordsLinked to original sources

[Brain stem metastasis revealing bronchopulmonary cancer: 2 cases].

INTRODUCTION: Brainstem metastasis is a very rare revealing feature of lung carcinoma. EXEGESIS: We report two cases of brainstem metastasis revealing lung carcinoma. In the first case, diagnosis was made on stereotaxic biopsy. In the second, the biopsy was not necessary as lung lesion was observed on thoracic CT-scan. Diagnosis of metastasis is difficult when a brainstem tumor occurs. CONCLUSION: Stereotaxic biopsy is an interesting tool to distinguish between primary lesion and metastasis, but only when diagnosis work-up of primary cancer is negative.

Adenocarcinoma

[Combination treatment for pilocytic astrocytoma: stereotaxic radiosurgery and endocavitary radiotherapy].

The treatment of a pilocytic astrocytoma located in a functional area can be performed using radiosurgery. We report a 7 year old male, right-handed, who presented with a pilocytic astrocytoma in the left parieto-occipital lobe. After a 7 year follow-up, the tumor became symptomatic (partial and generalized seizures). The CT scan and nuclear magnetic resonance imaging revealed an increased size of the mural tumor and the development of a cystic component. Multi-beam irradiation of the tumor (dose of 30 Gy at the center with 21 Gy on the isodose 70%) was performed with a LINAC for radiosurgery coupling a modified Saturne 18 MeV linear accelerator and a Talairach stereotactic frame. Following multi-beam irradiation, the increase in size of the cyst imposed further intracavitary radiation using Rhenium 186 (186Re) to deliver 400 Gy to the cyst wall. After a period of intense cerebral edema, resolutive with steroid treatment, we obtained progressive cyst disappearance and mural nodule retraction. A PET scan, performed 3 years after this treatment, revealed no metabolic activity in the persistent mural nodule. The patient remains totally asymptomatic.

Astrocytoma

[Acquired lesions of the corpus callosum].

Acquired lesions of the corpus callosum may be related to tumoral, vascular, traumatic or degenerative disorders and, one must not forget, can result from surgical access. Currently, the quality of neuroimaging enables a validation or precision of anatomoclinical, neuropsychological and neurophysiological correlations established from experimental and/or autopsy data. However the "specific" signs of acquired lesions of the corpus callosum are often quite complex and may be readily overlooked or masked within a heterogeneous clinical presentation due to more or less important associated lesions of neighboring structures. Therapeutic management (tumors, arteriovenous malformations, cavernomas) depend on the nature and the extent of the lesion more than the functional nature of this inter-hemispheric commissure with an exceptional functional plasticity, particularly when the lesion is limited.

Brain Diseases

[Pituitary radiotherapy. Current data and future prospects].

Some technical improvements have allowed to minimize the frequency of severe complications following fractionated pituitary conventional radiotherapy, without altering its efficiency. "Conformational" radiotherapy is currently under development, aiming at the best fitting of the tumor borders to the irradiation zone, by the means of stereotactic imaging. More recently, radiosurgery has been proposed for pituitary adenomas. It consists in a single high radiation dose to the tumor, by the means of either cobalt minibeams (Gamma Unit) or photon beams from a linear particle accelerator. These techniques require the use of a stereotactic frame and precise 3D imaging in order to tightly superimpose the target volume to the reference isodose. They must not be viewed as an alternative to conventional radiotherapy. They can be applied only to small lesions (less than 20 mm in their maximal axis) which are distant (> 5 mm) from the optic chiasma and nerves. Their efficiency is similar to the one of fractionated conventional radiotherapy, with a shorter response time. In conclusion, radiotherapy can be used safely for pituitary adenomas. It remains however a second line treatment, when surgery has been incomplete and when a simple, effective and inexpensive medical treatment is not possible.

Adenoma

[Bilateral 3rd cranial nerve palsy disclosing oligodendroglioma].

The patient was a 30 year-old man. He had no previous history. For several months he experienced a slowly progressive horizontal diplopia which was the expression of a bilateral third cranial nerve palsy with an intact intrinsic component. Muscular or neuro-muscular pathology as myasthenia was initially suspected but not confirmed. CT scan and MRI revealed an atypical left temporo-insular lesion which led us to discuss a chronic inflammatory pathology as sarcoidosis or a tumoral process. Finally cerebral biopsy showed a high grade oligodendroglioma. Symptomatology was attributed to infiltration of the peduncles from this tumor. Such a case has never been seen before. Early neuroradiological explorations would be useful in case of clinical suspicion of cranial nerve palsy.

Adult

Effect of thalamic stimulation on gait in Parkinson disease.

OBJECTIVE: To assess the influence of ventral intermediate thalamic nucleus stimulation on gait in idiopathic Parkinson disease. DESIGN: Clinical and physiological assessments were compared in patients with and without ventral intermediate thalamic nucleus stimulation. SETTING: The research clinic of a university department of gait analysis. PATIENTS: Seven patients with idiopathic Parkinson disease who had long-term monopolar stimulation of the ventral intermediate thalamic nucleus to control a large-amplitude tremor. MAIN OUTCOME MEASURES: Gait kinematic parameters were autonomically recorded using the Vicon optoelectric system for movement analysis. Measures of locomotor displacement (cadence, walking speed, stride and step times, single and double support times, and stride and step lengths) were computed successfully during 2 conditions: stimulation on and off. Traces of ankle joint position were also analyzed for the left and right lower limbs and for the affected and unaffected lower limbs. RESULTS: No difference in mean values was observed between the 2 conditions. CONCLUSION: This study seems to confirm that ventral intermediate thalamic nucleus stimulation, effective in reducing tremor, does not modify gait parameters in idiopathic Parkinson disease.

Ankle Joint

[MRI aspect and course of supra-tentorial sarcoidosic lesions].

Central nervous system lesions resulting from sarcoidosis occur in 5% of cases, but supratentorial mass lesions are uncommon. We report 3 cases of intracranial pseudo-tumoral lesions, due to sarcoidosis: 1 woman and 2 men. Clinical features included left facial myoclonus, headache and vertigo, right hemiparesis and unique general seizure. Sarcoidosis was diagnosed upon conjonctival biopsy in the first case, infiltrative lesions of the lungs and mediastinal lymph nodes in the second case, and intracerebral lesion plus lymph nodes biopsies in the last case. In the first case, CT scan and MRI images showed diffuse subcortical high signal, suggesting pachymeningitis with vasogenic oedema. In the second case, GT scan and MRI revealed numerous small granuloma in the left rolandic area, and one in the striatum. In the third case, CT scan showed an enlargement of the left temporal horn, due to an enhanced left periventricular lesion. MRI with gadolinium showed that the lesion encircled the ventricle horn. In all cases, clinical and radiological improvement was obtained after corticoid therapy.

Adult

Treatment planning optimization by conjugate gradients and simulated annealing methods in stereotactic radiosurgery.

PURPOSE: This paper presents a new optimization method of treatment planning in linac stereotactic radiosurgery. METHODS AND MATERIALS: On a workstation integrating x-rays, computed tomography (CT), magnetic resonance imaging (MRI), and digital subtracted angiography (DSA) images, we first determine the outlines of the target volume and surrounding healthy tissues to spare. To achieve complete optimization of the treatment plans, this method decomposes the optimization process in two steps. The position of the isocenters and the diameter of the collimators are first deduced by a conjugate gradients method, from the position and size of ellipsoids or spheres modeling the target volume. The other irradiation parameters, such as the isocenter dose, the aperture, and the weight of each irradiation plane and of their irradiation sectors are finally deduced by a simulated annealing optimization algorithm. RESULTS: The system can perform multitarget/multisector treatment plans that are automatically obtained in a satisfactory time (as a rule, 20 min for a two-target irradiation), much faster than the time needed for a manual treatment planning. We present the results in two cases: the simulation of a single-target treatment and a two-target real treatment with constraints. In these two cases, we can control the dose received by target and sensitive volumes. CONCLUSION: This method achieves an excellent conformation of the estimated isodose curves with the outlines of the target volume, which allows us to avoid the surrounding healthy tissues, thanks to the different weighting factors given on each volume concerned according to the importance we grant to each of them.

Angiography, Digital Subtraction

A frameless stereotaxic localisation system using MRI, CT and DSA.

The authors present a method of stereotaxic localisation using magnetic resonance imaging (MRI) computerized tomography (CT) and digital subtracted angiography (DSA) which does not require localisation frams fixed to the patient's skull, but uses only four cranial landmarks corresponding to the holders of the neurosurgical stereotaxic frame. The method presents no major constraints in routine examinations. The geometrical distortions of the imaging devices are corrected. Three-dimensional localisation is performed using sagittal and axial slices in MRI, axial slices in CT and only two associated frontaly and lateral views in DSA. The images data are transferred to a PC-based system. By locating the landmarks on the images, the transformation matrixes can be computed to obtain the 3D coordinates of a target in the stereotaxic space and in any imaging modality. The results obtained show the precision of the corrections and the millimetre accuracy of pin-point target localisation.

Angiography, Digital Subtraction

Cerebral arteriovenous malformations in children: report on 62 cases.

A series of 62 children with cerebral arteriovenous malformations admitted to our department in the course of 17 years (1975-1992) was reviewed in a retrospective study. In 54 cases hemorrhagic stroke was the first presenting symptom, followed by epilepsy in five cases. On admission 26 children presented with a neurological deficit, and 21 were admitted with a grade 3 status according to Botterell. Fifty-one malformations were supratentorial (41 hemispheric, 10 deep-seated) while 11 were infratentorial. According to Mori's criteria, 28 lesions were small, 19 medium, and 15 large. Fifty-two children were operated on, with total excision of the malformation achieved in 47 cases. In two children the malformation recurred. The evolution of neurological disorders has been studied with a mean follow-up of 8.5 years. Fifty patients had a satisfactory outcome on the Glasgow Outcome Scale. Four children died. These results were compared with those reported elsewhere in the pediatric literature.

Adolescent

Association of Lhermitte-Duclos and Cowden disease: report of a new case and review of the literature.

Lhermitte-Duclos disease is a rare entity, and its pathological features are unique. Pathological findings are characteristic of the disease, with global hypertrophy of the cerebellum, coarse gyri, and the typical "inverted cortex" pattern. Several associated lesions were noted in many patients with Lhermitte-Duclos disease. It is only recently that an association between Lhermitte-Duclos disease and Cowden disease was reported. Cowden disease, or multiple hamartomas syndrome, is a familial disease associating breast cancer, cutaneomucous tricholemmomas, and various other tumoural and dysplasic conditions. A new case of Lhermitte-Duclos disease associated with Cowden disease is reported. A review of the literature found 72 cases of Lhermitte-Duclos disease; 26 had conditions suggesting Cowden disease and seven were definite cases of Cowden disease. The association of Lhermitte-Duclos disease and Cowden disease is probably underestimated. Cowden disease represents a new form of phakomatosis; Lhermitte-Duclos disease may occur as a sporadic disease, or as part of familial Cowden disease. The possibility of preneoplastic states in Cowden syndrome stresses the importance of a thorough screening when Lhermitte-Duclos disease is diagnosed.

Adult

Long-term thalamic stimulation in Parkinson's disease: postmortem anatomoclinical study.

Parkinsonian tremor may be suppressed by thalamic stimulation. For an equivalent clinical efficacy, its obvious advantage over micro-thalamotomy is its reversibility. This patient experienced postural tremor at the age of 44 years and akineto-rigid syndrome 8 years later. At the age of 60 years, intrathalamic stimulation was applied over a long-term period of 43 months until death and was efficient on tremor with low stimulation. This case is the first with anatomic verification. The extent of the lesion provoked by the electrode is very small. The location of the stimulation site was in the medio-inferior part of the intermedius complex at the entrance of cerebello-thalamic fibers. The stimulation of the cerebellar afferent axons could be the cause of the clinical effect. The stimulation site corresponds to the thalamic source of the precentral and accessory motor cortex, which correlates with changes observed in our PET study showing a regional cerebral blood flow decrease in cerebellar nuclei and also in precentral and accessory motor cortex. The places and mechanisms of the effects of stimulations and lesions could be different.

Adult

[Drug therapy of pain in oncology: keep it simple!].

Pain is the most common symptom in patients suffering from cancer, in particular for advanced diseases. Unfortunately, one third of the patient do not benefit from optimal pain control. One must stress the importance of defining the etiology of pain and subsequently its pathophysiology. This thorough evaluation can help to formulate a proper strategy for a treatment of pain that could be adapted to the disease evolution. A multidisciplinary approach with respect to the WHO prescribing criteria is the most appropriate way to control severe cancer pain syndromes.

Analgesics

[Stereotaxic biopsies of pineal tumors. Comments on their risk and implication apropos of 370 cases].

370 stereotactic biopsies of pineal region tumors, from 15 neurosurgical centers in France have been reviewed with the goal to evaluate the mortality/morbidity rates and diagnostic yield of this procedure. The impact of neuroradiological means of localisation, the probe trajectory, the type of biopsy instrument, the time of shunting are discussed in order to maximize the diagnostic yield and minimize the mortality/morbidity rates. Stereotactic biopsy contribution, as compared to other diagnostic methods, in pineal region tumors was evaluated. The mortality rate was 1.3 % (5 patients of 370), 3 patients suffered severe neurological complication. In relation to the large number of patients in this study, we can assess that the mortality rate of stereotactic biopsy in this region doesn't significantly exceed that of stereotactic brain tumor biopsies in general.

Adolescent

A case of symptomatic hemidystonia improved by ventroposterolateral thalamic electrostimulation.

A 16-year-old boy presented with a left anterothalamic lesion secondary to an extradural hematoma. A few months later, a right hemidystonia developed. The dystonic posture, which predominated in the right hand, was not associated with any motor deficit or sensory loss. Superficial sensory stimulation of the right palm and forearm and proprioceptive stimuli induced by passive movements of the right thumb decreased the dystonic posture. Electrical stimulation of the left ventroposterolateral nucleus of the thalamus induced a dramatic improvement in the dystonic postures and movement of the upper right limb. This finding suggests that the role of tactile and proprioceptive stimulation should be analyzed in patients presenting with a symptomatic hemidystonia. When such sensory stimulation is effective, thalamic stimulation may be tried in patients whose condition is incapacitating.

Adolescent