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Biomedical subjects

M Sindou

Publications and source records attributed to M Sindou.

At least 55 records · Page 3Linked to original sources
PubMed2000

[The relationships of mononuclear leukocyte beta-adrenergic receptors to aerobic capacity and exercise-induced asthma in asthmatic children].

beta-adrenaline receptors exist on peripheral mononuclear leukocytes as well as in lung tissue. We assessed the relationships of plasma catecholamine release by exercise to aerobic capacity and to exercise-induced asthma (EIA) in asthmatic children (Study 1). We then measured mononuclear leukocyte beta-adrenergic receptor densities at rest and assessed the relationships of the number of receptors to aerobic capacity, EIA, and bronchial responsiveness to acetylcholine (Study 2). Study 1: Eleven children (9 males, 2 females; 11-16 years old) with bronchial asthma participated in this study. The subjects underwent an incremental aerobic exercise test on a cycle ergometer to determine their aerobic capacity at the lactic threshold (LT) and VO2max. Each subject underwent an EIA test of which the intensity was 175% of LT, and plasma catecholamine concentrations were measured before and after exercise. A significant negative relationship was found between the degree of EIA and % change of plasma adrenaline concentrations to rest level (p < 0.05), and a significant positive relationship was found between VO2 max/wt and % change of plasma adrenaline concentrations (p < 0.05). Study 2: Twelve asthmatic children (10 males, 2 females; 11-16 years old) participated in this study. Aerobic capacity, and degree of EIA were also measured in each subject by the same method as that used in Study. 1. The number of mononuclear leukocyte beta-adrenergic receptors at rest was determined by (-) [125I]-iodocyanopindolol binding in each subject. A significant negative relationship was found between the number of adrenergic receptors and Max. % fall in FEV1.0 (p < 0.01), and a significant positive relationship was found between the number of adrenergic receptors and VO2max/kg (p < 0.001). These results suggested that a reduced adrenaline production and a reduced number of beta-receptors contributed to the pathogenesis of EIA.

Adolescent↗
PubMed2000

The role of the insular cortex in temporal lobe epilepsy.

The role of the insular cortex in the genesis of temporal lobe epileptic (TLE) seizures has been investigated in 21 patients with drug-refractory TLE using chronic depth stereotactic recordings of the insular cortex activity and video recordings of ictal symptoms during 81 spontaneous electroclinical seizures. All of the recorded seizures were found to invade the insula, most often after a relay in the ipsilateral hippocampus (19/21 patients). However, 2 patients had seizures that originated in the insular cortex itself. Ictal symptoms associated with the insular discharges were similar to those usually attributed to mesial temporal lobe seizures, so that scalp video-electroencephalographic monitoring does not permit making any difference between ictal symptoms of temporo-mesial and insular discharges. A favorable outcome was obtained after a temporal cortectomy sparing the insular cortex in 15 of 17 operated patients. Seizures propagating to the insular cortex were found to be fully controlled by surgery, whereas those originating in the insular cortex persisted after temporal cortectomy. The fact that seizures originating in the insular cortex are not influenced by temporal lobectomy is likely to explain some of the failures of this surgical procedure in TLE.

Adolescent↗
PubMed2000

[Surgery in the dorsal root entry zone for treatment of chronic pain].

Microsurgical drezotomy (MDT) consists of an incision and bipolar coagulations performed ventro-laterally in the Dorsal Root Entry Zone (DREZ) at the entrance of the rootlets into the dorso-lateral sulcus. The lesion is directed at 35 ventro-medially, and to 2-3 mm deep according to the pre-operative neurological status and the desired effects. MDT i) interrupts the small (nociceptive) fibres regrouped laterally and the large (myotatic) afferents which runs centrally, whilst sparing part of the large medial (lemniscal) fibres, ii) destroys the (excitatory) medial part of the Lissauer's tract, iii) and the cells of the dorsalmost layers of the dorsal horn, which can be the site of hyperactivity, as we were able to record in patients with deafferentation pain. Best indications are: i) well-localized cancer pain, such as Pancoast syndrome; ii) neuropathic pain due to: brachial plexus injuries; cauda equina and/or spinal cord lesions (especially for pain corresponding to segmental lesions); peripheral nerve injuries, amputation, herpes zoster - especially when the predominant component of pain is of the paroxysmal type and/or corresponds to provoked hyperalgesia/allodynia); iii) excess of spasticity, especially when associated with severe pain.

Chronic Disease↗
PubMed1999

Hyperalgesia with reduced laser evoked potentials in neuropathic pain.

Nociceptive evoked potentials to laser stimuli (LEPs) are able to detect lesions of pain and temperature pathways at peripheral, spinal and supraspinal levels. It is commonly accepted that LEP attenuation correlates with the loss of pain and temperature sensations, while pathological heat-pain hypersensitivity has been associated with increased LEP amplitude. Here we present two patients in whom increased pain sensation (hyperalgesia) to laser stimuli was, on the contrary, associated to delayed, desynchronized and attenuated LEPs. Both patients experienced increased unpleasantness and affective reactions to laser, associated to poor ability to localize the stimulus. In both cases the results may be explained by an overactivation of the 'medial pain system', in one patient due to deafferentation of cortical sensory areas by a capsular lesion, and in the other to imbalance between A-delta and C fiber excitation due to peripheral nerve injury. Our results suggest that LEPs, as currently recorded, reflect the activity of a 'lateral' pain system subserved by rapidly conducting fibers. They may therefore, assess the sensory and cognitive dimensions of pain, but may not index adequately the affective-emotional aspects of pain sensation conveyed by the 'medial' pain system. The dissociation between pain sensation and cortical EPs deserve to be added to the current semiology of LEPs, as the presence of abnormal pain to laser on the background of reduced LEPs substantiates the neuropathic nature of the pain.

Adult↗
PubMed1999

Electrical stimulation of motor cortex for pain control: a combined PET-scan and electrophysiological study.

Although electrical stimulation of the precentral gyrus (MCS) is emerging as a promising technique for pain control, its mechanisms of action remain obscure, and its application largely empirical. Using positron emission tomography (PET) we studied regional changes in cerebral flood flow (rCBF) in 10 patients undergoing motor cortex stimulation for pain control, seven of whom also underwent somatosensory evoked potentials and nociceptive spinal reflex recordings. The most significant MCS-related increase in rCBF concerned the ventral-lateral thalamus, probably reflecting cortico-thalamic connections from motor areas. CBF increases were also observed in medial thalamus, anterior cingulate/orbitofrontal cortex, anterior insula and upper brainstem; conversely, no significant CBF changes appeared in motor areas beneath the stimulating electrode. Somatosensory evoked potentials from SI remained stable during MCS, and no rCBF changes were observed in somatosensory cortex during the procedure. Our results suggest that descending axons, rather than apical dendrites, are primarily activated by MCS, and highlight the thalamus as the key structure mediating functional MCS effects. A model of MCS action is proposed, whereby activation of thalamic nuclei directly connected with motor and premotor cortices would entail a cascade of synaptic events in pain-related structures receiving afferents from these nuclei, including the medial thalamus, anterior cingulate and upper brainstem. MCS could influence the affective-emotional component of chronic pain by way of cingulate/orbitofrontal activation, and lead to descending inhibition of pain impulses by activation of the brainstem, also suggested by attenuation of spinal flexion reflexes. In contrast, the hypothesis of somatosensory cortex activation by MCS could not be confirmed by our results.

Adult↗
PubMed1999

MRI assessment of the anatomy of optic radiations after temporal lobe epilepsy surgery.

OBJECTIVE: The aim of this study was to determine the course of the temporal optic radiations. MATERIAL AND METHODS: Eighteen patients were included in this prospective study. All of them underwent a temporal lobectomy for epilepsy, including the mesial temporal structures and a variable extent of lateral neocortex (from 2 to 7 cm behind the temporal tip). An MRI was performed 2 months postoperatively, allowing assessment of the extent of lateral resection. Postoperative visual fields were determined by automatic static perimetry (ASP). RESULTS: (1) No patient complained of a disabling visual field deficit. (2) ASP, a highly sensitive technique, however, detected postoperative visual field deficits in 83% of patients, confined to the superior homonymous field contralateral to the resection. (3) A strong correlation was found between the presence of a visual field deficit and the extent of laterotemporal resection. (4) The smallest anteroposterior resection resulting in a field defect was limited to 20 mm from the temporal tip. CONCLUSION: (1) This study confirms a strong correlation between postoperative visual field deficits and the extent of lateral neocortical temporal resection. (2) The anterior limit of Meyer's loop is likely to be located more rostrally than previously believed. (3) Despite this, lateral resection remains useful in some cases for seizure control.

Adult↗
PubMed1999

Precentral cortex stimulation for the treatment of central neuropathic pain: results of a prospective study in a 20-patient series.

The authors report a series of 23 patients with central neuropathic pain who were treated with the recently developed technique of precentral cortex stimulation (PCS). Of the 20 patients with a follow-up of more than 1 year (mean of 23 months) 25% had an excellent, 35% a good and 15% a fair relief of pain. In 25% the method failed. On the basis of these findings and the literature data (127 reported cases), the authors advocate PCS in patients with severe and medically refractory poststroke pain.

Adult↗
PubMed1999

A new type of microelectrode for obtaining unitary recordings in the human spinal cord.

OBJECT: In this paper the authors report on the conception and adjustment of a microelectrode used to obtain unitary recordings in the human spinal cord. METHOD: To overcome the difficulties related to intraoperative pulsations of the spinal cord, the authors opted to use a floating microelectrode. Because the recordings are obtained most often from spontaneous activities, it is difficult, with a single microelectrode, to separate spikes from electrical artifacts that are related to the switching of devices. Consequently, the authors designed a dual microelectrode made of two tungsten-in-glass-attached microelectrodes separated by 300 microm. Because the two electrodes cannot obtain recordings in the same neuron, it is possible to distinguish unambiguously spikes (recorded on one tip) from electrical artifacts (recorded simultaneously on the two tips). The dual microelectrode is 2 cm long, with a 20-microm tip length, and 800 to 1200-Ohms impedance. This microelectrode can be implanted "free hand," in the dorsal horn, by using a microsurgical forceps under a surgical microscope. The data analysis is performed off-line with spike sorter hardware. In the dorsal horns in 17 patients who were selected to undergo a dorsal root entry zone (DREZ) rhizotomy to treat various pathological conditions, unitary recordings were obtained using this double microelectrode. The authors recorded 57 neurons in good conditions of stability and isolation. CONCLUSIONS: The microelectrode described in this paper was successfully used to obtain recordings in neurons in more than 85% of the patients. This simplified, floating double microelectrode can therefore be considered for use in microsurgical DREZ rhizotomy to obtain unitary recordings in the human spinal dorsal horn.

Artifacts↗
PubMed1999

[Chronic hydrocephalus in an adult due to congenital membranous occlusion of the apertura mediana ventriculi quartii (foramen of Magendie). Report of two cases and review of the literature].

Congenital membranous obstruction of the apertura mediana ventriculi quartii (foramen of Magendie) is a rare entity, as only 8 adult cases are mentioned in all medical literature. We report here the cases of 2 patients (35 and 68 year-old) with chronic hydrocephalus due to congenital membranous obstruction of the foramen of Magendie. Both these two patients presented with headaches, nausea, and impairment of gait and memory. CT and MRI examination showed a communicating hydrocephalus, with particular enlargement of the fourth ventricle. Both patients were operated on for microsurgical exploration of the outlet of the fourth ventricle, which demonstrated membranous obstruction of the foramen of Magendie. Microsurgical perforation of the foramen of Magendie was performed, and a ventriculo-cisternal shunt was left in place. The two patients were cured, with a follow-up of 7 years in one case, and 5 years in the other case. Despite its rare occurrence, congenital imperforation or membranous obstruction of the foramen of Magendie must be considered as a possible etiology of chronic hydrocephalus in adult, especially in case of non proportioned enlargement of the fourth ventricle, associated to signs of increased intra-cranial pressure. According to us, the best surgical procedure consists in a microsurgical exploration of the foramen of Magendie associated to a ventriculo-cisternal shunting (from the fourth ventricle to the cisterna magna). Such a procedure can be considered as curative, and has more advantages than a simple ventriculo-peritoneal shunting.

Adult↗
PubMed1998

Glutamate-modulated production of GABA in immortalized astrocytes transduced by a glutamic acid decarboxylase-expressing retrovirus.

Replication-defective Moloney murine leukemia virus expressing the GAD67 gene under the control of the GFAP promoter was produced using selected clones of a fibroblast-packaging cell line. A spontaneously immortalized astrocyte cell line was infected with this virus and cellular clones expressing GAD67 selected. Astrocyte and fibroblast clones expressed functional GAD (detected by glutamic acid decarboxylation), but only fibroblasts were able to also produce GABA in the extracellular medium. When exposed to 200 microM glutamate, despite an observed difference in the rates of glutamate accumulation in control and GAD67-expressing astrocytes, similar proportions of glutamate taken up were detected. In GAD67-expressing astrocytes, the glutamate was mainly converted into GABA, suggesting GAD transgene activity to be dominant over other glutamate metabolic pathways, such as glutamine synthetase and glutamate dehydrogenase. Moreover, rapid GABA release into the cell medium was also observed, suggesting the involvement of reverse GABA transporters. The use of the GFAP promoter might be able to take advantage of its activation in response to factors inducing reactive gliosis observed in pathological insults. GAD67-expressing astrocytes might therefore be used for future grafting in pathological situations in which an excess of glutamate results in neuronal dysfunction or cell death.

4-Aminobutyrate Transaminase↗
PubMed1998

Aneurysmal remnants after microsurgical clipping: classification and results from a prospective angiographic study (in a consecutive series of 305 operated intracranial aneurysms).

The aim of this prospective study, carried out in a consecutive series of 305 microsurgically clipped aneurysms, was to check the absence of an aneurysmal remnant on post-operative angiography, and if a remnant was found to quantify its size in order to consider additional clipping to avoid the risk of rebleeding. Out of the 305 aneurysms, 292 (96%) were located in the anterior and 13 (4%) in the posterior circulation. Post-operative angiography was performed on average two weeks after surgery. Determination of the presence or not of an aneurysmal remnant and its quantification was done by an independent observer (JCA). Aneurysmal remnants were classified into 5 grades: grade I: less than 50% of neck size, grade II: more than 50% of neck size, grade III: residual lobe of a multilobulated sac, grade IV: residual sac of less than 75% of aneurysmal size and grade V: residual sac of more than 75% of aneurysmal size. Correlations between presence (and size) of the remnant and anatomical-surgical data obtained from the operative report were studied. Clipping was considered incomplete in 18 of the 305 aneurysms (5.9%). The group with residual neck only (grade I = 8 cases, Grade II = 4 cases) amounted to 4% of the whole series, whereas the group with residual neck + sac (grade III = 4, grade IV = 1, Grade V = 1) to 1.9%. Only this latter group was amenable to re-operation for complementary clipping without creating a stenosis of the parent artery. Our results are in the range of those of other published series. Anatomical-surgical factors for predisposition to incomplete clipping are discussed. The rates of sac obliteration using microsurgical clipping are to be compared with those recently achieved by electrically detachable coiling. The classification which we have developed is proposed for future comparison with endovascular results.

Adolescent↗
PubMed1998

Topographical reliability of mesio-temporal sources of interictal spikes in temporal lobe epilepsy.

PURPOSE: Localization of hippocampal paroxysmal activities in temporal lobe epilepsy (TLE) by means of dipole modeling has often been criticized because of the supposed inaccuracy of this technique in localizing deep sources of EEG signals. This study aimed at assessing the relevance of mesio-temporal dipoles, as identified by modeling of scalp recorded spikes in TLE. METHODS: Surface and depth EEG activities were simultaneously recorded using scalp and intracranial electrodes implanted through the foramen ovale (FO) in 3 patients with refractory TLE seizures. Intracranial FO spikes were used as triggers for scalp EEG averaging. The averaged signals were modeled by current dipoles, the localization of which were fused with patients' 3D-MRI. RESULTS: Individual FO spikes were undetectable on visual analysis of raw scalp EEG but were reflected by low-amplitude scalp EEG transients on averaged signal. Dipole modeling of this EEG deflection consistently identified a mesio-limbic source in a position close to that of the FO pole recording the intracranial spike with its maximal amplitude. CONCLUSION: This result suggests that mesio-temporal sources can be accurately localized by modeling the signals recorded on the scalp, thus validating the anatomical and clinical relevance of hippocampal sources identified by modeling scalp interictal averaged spikes in TLE.

Adult↗
PubMed1998

Venous reconstruction in surgery of meningiomas invading the sagittal and transverse sinuses.

SURGERY OF MENINGIOMAS INVOLVING MAJOR DURAL SINUSES LEAVES THE SURGEON CONFRONTED WITH A DIFFICULT DILEMMA: leave the fragment invading the sinus in place and have a higher risk of recurrence, or attempt a total removal with or without venous reconstruction and expose the patient to a potentially greater operative danger. The authors report a series of 47 meningiomas (41 of the sagittal sinus, 4 of the transverse sinus and 2 of the torcular) in whom gross total removal was achieved in all cases, and venous reconstruction (of various types) attempted in a majority. Thirty-nine patients had a good outcome and resumed their previous activities. There was a permanent neurological deficit in five due to infarction secondary to injury of central veins (all in the sagittal sinus midthird). Three patients died from brain swelling; all with meningioma totally occluding the sinus and in whom resection was achieved without sinus reconstruction. There were two recurrences in this series which has a mean follow-up of 7.5 years.The authors' surgical experience led them to favor whenever possible, total removal with sinus reconstruction, using a patch for meningiomas with partial sinus invasion and a venous bypass for those with total sinus occlusion.

Journal Article↗
PubMed1998

Chemotherapy for aggressive or anaplastic high grade oligodendrogliomas and oligoastrocytomas: better than a salvage treatment.

This series reports a pilot study of chemotherapy conducted for newly diagnosed and relapsing patients with oligodendrogliomas and oligoastrocytomas. Twenty-three patients with clinically or histologically aggressive tumours were eligible to receive procarbazine CCNU and vincristine (PCV) chemotherapy followed by radiotherapy in previously non irradiated patients. Sixteen (69%) responded to chemotherapy with complete responses in two patients and partial responses in 14. Previously irradiated patients were as likely to respond to PCV as those previously non irradiated. An over 1-year history of seizures was the main clinical prognostic factor of response. All toxicities were manageable and no treatment related deaths occurred. Chemotherapy is an effective treatment in aggressive oligodendrogliomas. Further studies must assess the role of chemotherapy in the multidisciplinary management of oligodendroglioma.

Adolescent↗
PubMed1998

Selective neurotomy of the tibial nerve in the spastic hemiplegic child: an explanation of the recurrence.

A series including 13 unilateral selective tibial neurotomies for spastic foot in hemiplegic children is reported. The results were considered excellent in three cases. Two cases needed additional corrective casts postoperatively. Eight cases had poor result with recurrence of the same deformity. The authors conclude that the effect of tibial neurotomy for spastic foot in hemiplegic children is transient in 61% of cases with a recurrence of the same deformity. Four of the patients with failed treatment underwent orthopedic surgery with muscle biopsies. Histologic data clearly demonstrate that previously denervated muscle fibers were reinnervated carrying into extensive motor units. This finding can explain the recurrence of the foot spasticity and deformity in neurotomized children.

Adolescent↗
PubMed1998

A stereoelectroencephalographic (SEEG) study of light-induced mesiotemporal epileptic seizures.

PURPOSE: This study explored the mechanism of light-induced complex partial seizures by using ictal intracerebral recordings in a patient with refractory epilepsy of the right temporal lobe. METHODS: Presurgical evaluation of this patient was realized by means of video-EEG recordings, WADA test, magnetic resonance imaging (MRI), F18-deoxyglucose and C11-flumazenil positron emission tomography (PET) interictal neuroimaging data, and stereoelectroencephalographic (SEEG) ictal recordings. RESULTS: SEEG investigations demonstrated the right mesiotemporal origin of all the patient's seizures. This result was confirmed by a successful right temporal lobectomy. Moreover, SEEG recordings revealed a frequent interictal spiking activity in the right occipital visual cortex that was undetectable on scalp recordings. However, the occipital cortex was not involved at the onset of mesiotemporal ictal discharges and was not hyperresponsive to focal electrical stimulation. CONCLUSIONS: This study shows that, in spite of interictal occipital spiking, the photosensitivity of mesiotemporal seizures can be observed in both the absence of occipital cortex involvement during ictal discharges and demonstrable hyperexcitability of the occipital cortex to light or direct electrical stimulation.

Adult↗