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Biomedical subjects

A Bouthillier

Publications and source records attributed to A Bouthillier.

12 recordsLinked to original sources

A motor resonance mechanism in children? Evidence from subdural electrodes in a 36-month-old child.

The presence of a neural mechanism matching execution and observation of actions in the adult human brain is well established. In children, however, description of a resonance motor mechanism is still preliminary. In the present study, we recorded electroencephalographic signals from a subdural 64-contact grid electrode in a 36-month-old child with epilepsy. Spectral analysis was performed on sequences where the child drew with her right hand, watched an experimenter drawing with his right hand or was at rest. Contact sites corresponding to sensorimotor areas were discovered where absolute power was decreased during both observation and execution of hand/arm actions. These data suggest the presence of a mirror neuron system early in the developing brain.

Analysis of Variance↗

The pathological basis of temporal lobe epilepsy in childhood.

OBJECTIVE: To characterize the pathologic findings of temporal lobe epilepsy (TLE) in children undergoing temporal lobectomy for refractory seizures and to correlate these findings with clinical presentation. METHODS: The authors reviewed the charts of all children who underwent anterior temporal lobectomy for refractory TLE from 1979 through 1999. A new neuropathologic analysis was performed blinded to clinical features and outcome. RESULTS: Twenty-two children met inclusion criteria. Mean age at onset of epilepsy was 3 years, 7 months (range 1 month to 10 years). Mean age at surgery was 10 years, 11 months (range 1 to 18 years). All patients had complex partial seizures, 48% with secondary generalization. Most had daily seizures. Auras were reported in 45% of patients. Post-resection follow-up averaged 5 years, 2 months (range 2 to 19 years). Seizure-free status was achieved in 41% of patients, and 14% had residual auras only. The most frequent neuropathologic abnormalities were cortical dysplasia (CD) of the temporal neocortex (14 of 22) and mesial temporal sclerosis (MTS) (12 of the 15 children with available hippocampal tissue). These two findings coexisted in seven children. MTS was associated with extra-hippocampal pathology in 8 of 12 (67%) of the cases. CONCLUSIONS: MTS occurs frequently in association with CD in this population of children. The high incidence of dual pathology could explain the early age of seizure onset and high seizure frequency rate observed. TLE in childhood may constitute a different entity than in adults, from both the clinical and neuropathologic perspectives.

Adolescent↗

Control of vascular tone by endogenous endothelin-1 in human pial arteries.

BACKGROUND AND PURPOSE: Endothelin-1 (ET) has been shown to be involved in human pathological conditions, but its physiological function remains to be elucidated. The aim of this work was to assess whether endothelium-derived ET was involved in the overall responsiveness of freshly isolated human pial arteries. METHODS: Samples of cerebral cortex, otherwise discarded, were obtained during tumor or epileptic lesion resections (n = 10 donors). Arterial segments were isolated and mounted on a microvessel myograph. RESULTS: Inhibition of nitric oxide (NO) formation with N omega-nitro-L-arginine (L-NA, 100 micromol/L) increased basal tone by 7+/-1% Emax (n=5). This increase in tone was fully abolished in the presence of BQ123 (1 micromol/L; ET(A) receptor antagonist, P<.05) but potentiated by a subthreshold concentration of exogenous ET (1 nmol/L; 33+/-8% Emax; P<.05). In the presence of L-NA, serotonin (10 micromol/L)-induced tone was doubled compared with the control response (P<.05) but reduced by 90% in the presence of BQ123 (P<.05). In the absence of L-NA, BQ123 prevented serotonin-induced tone (n=3). Oxymetazoline, a selective alpha2-adrenergic receptor agonist, induced an endothelium-dependent relaxation of preconstricted human pial arteries. The relaxation was partially sensitive to NO synthase inhibition and fully prevented by the addition of ET, whereas substance P-induced relaxation was preserved. Glibenclamide (1 micromol/L), an inhibitor of ATP-sensitive K+ channels and tetraethylammonium (1 mmol/L), an inhibitor of Ca2+-activated K+ channels had no effect on oxymetazoline-induced relaxation. CONCLUSIONS: The results of this study suggest first that ET is involved in the tonic response induced by NO synthase inhibition; second, part of the contractile response induced by serotonin is endothelium-dependent and sensitive to BQ123; and third, the data suggest that activation of alpha2-adrenergic receptors generated an endothelium-dependent relaxation that was selectively inhibited by exogenous ET.

Adolescent↗

Endovascular treatment of ophthalmic segment aneurysms with Guglielmi detachable coils.

PURPOSE: To evaluate the safety and efficacy of endovascular treatment of ophthalmic segment aneurysms with Guglielmi detachable coils (GDCs), as well as the primary indications for such treatment. METHODS: We conducted a prospective study of 26 patients with 28 aneurysms of the ophthalmic segment in whom treatment with GDCs was attempted. Anatomic results were measured by statistical analysis of variance for such factors as age, sex, presence of subarachnoid hemorrhage, anatomic type (ophthalmic or superior hypophyseal), size of aneurysmal sac, and width of aneurysmal neck. Clinical evaluation and control angiography were performed at 6 and 18 months. RESULTS: Overall, complete occlusion was obtained in 14 aneurysms (50%) and small residual necks were left in 11 aneurysms (39%). Three treatment attempts failed (11%). Complete occlusion was obtained in 76% of small-necked aneurysms as opposed to 9% of aneurysms with a large neck. The best predictor of anatomic result was the size of the aneurysmal neck. Complete occlusion was obtained in 85% of superior hypophyseal aneurysms of the paraclinoid variant. One permanent complication was related to treatment. CONCLUSION: Endovascular treatment with GDCs appears to be a safe and efficient alternative approach for ophthalmic segment aneurysms, especially for paraclinoid variants of superior hypophyseal aneurysms, which tend to have a small neck.

Adult↗

Segments of the internal carotid artery: a new classification.

This study proposes an anatomically based nomenclature for the internal carotid artery (ICA) that can be applied by all disciplines. In 1938, Fischer published a seminal paper describing five segments of the ICA that were designated C1 through C5. These segments were based on the angiographic course of the intracranial ICA rather than its arterial branches or anatomic compartments. Subsequent attempts to apply modern nomenclature to these numerical segments failed to recognize Fischer's original intent of describing patterns of arterial displacement by tumors and, therefore, resulted in a nomenclature that was anatomically inaccurate. Fischer's system was further limited, because segments were numbered opposite the direction of blood flow and the extracranial ICA was excluded. The authors propose a new classification, which includes the entire ICA, uses a numerical scale in the direction of blood flow, and describes the segments of the ICA according to a detailed understanding of the anatomy surrounding the ICA and the compartments through which it travels. Twenty cadaveric specimens with intravascular injection of silicone rubber were used for microscopic dissection and 20 dry skulls were inspected. Histological sections in critical areas were examined. The authors' classification has the following seven segments: C1, cervical; C2, petrous; C3, lacerum; C4 cavernous; C5, clinoid; C6, ophthalmic; and C7, communicating. This classification is practical, accounts for new anatomic information and clinical interests, and clarifies all segments of the ICA.

Brain↗

Seizure occurrence during long-term monitoring.

PURPOSE: Intensive long-term monitoring (LTM) for patients with refractory seizures is common and expensive. Methods to decrease the length of stay would improve patient experience and reduce cost. Therefore, we prospectively analyzed seizure occurrence in 36 patients who had LTM. METHODS: Antiepileptic drug (AED) levels and reduction were monitored and seizures were related to these changes. Patients were divided into temporal and extratemporal groups. RESULTS: Twenty patients had partial seizures of temporal lobe origin. The temporal lobe partial seizures occurred between LTM days 1 and 16. All but 4 of the patients required reduction or discontinuation of a least one AED and had subtherapeutic levels of the tapered medications. In 16 patients with extratemporal partial seizures, seizures occurred between LTM days 1 and 8. Six of these patients required reduction of at least one AED, and 5 of the 6 had subtherapeutic levels of that medication. These differences between length of monitoring and AED reduction in temporal and extratemporal patients were statistically significant. The groups did not differ significantly with respect to number or identity of tapered or nontapered medications or levels of nontapered medications. Reported seizure frequency at home was significantly related to number of seizures recorded in the temporal group only. The only significant predictor of secondarily generalized seizure activity during monitoring was a history of such activity occurring at home. CONCLUSIONS: We conclude that patients with extratemporal partial seizures need little reduction of AED for seizures to be captured in a minimal time period. Patients with temporal lobe seizures, however, required drastic reduction of AEDs to allow capture of seizures in a long time period.

Anticonvulsants↗

[Research and surgical treatment of epilepsy].

The currently available surgical procedures for the treatment of epilepsy, from fundamental data to therapeutic results, including various means of investigation are reported. The work is based on a review of the literature and on the cases studied by the two teams from the Universities of Montreal and Bordeaux who share the same concept of epilepsy surgery. The patient groups of the two teams include 316 S.E.E.G., 214 cortectomies, 39 callosotomies and 2 multiple sub-pial transsections. In the first part, the authors attempt to demonstrate that the epileptic focus corresponds to the region where the seizures arise, that this focus is not directly comparable to the region where inter-ictal spikes are recorded and sometimes becomes autonomous from the causal lesion. The epileptic phenomenon has a definite harmful effect on cerebral functions and a probable self-aggravating potential. The second chapter summarizes the clinical data on which the indications and contraindications are based. These obviously depend on whether the intervention is intended to be curative or palliative. Various non-invasive and invasive investigations are then reviewed, according to their relative importance and the experience of each team. The main points developed are: the electroclinical correlations during seizures, the symptomatological data for differentiating between temporal and frontal lobe seizures, the contribution of M.R.I. in demonstrating the epileptogenic and epileptic lesions, the electrophysiological information suggesting that S.E.E.G. remains the most informative mean of investigation. The various methods of investigation of assessing electrical, functional (cerebral blood flow, metabolism) and morphological aspects of epilepsy, supply non-redondant findings about the localisation of the epileptic focus. The chapter on surgical techniques mainly discusses the various modes of implantation of subdural and intracerebral electrodes and reports the same rate of morbidity in both cases. Orthogonal teleradiography is still perfectly suited to the implantation of intracerebral electrodes. S.E.E.G. is still the most anatomically precise technique. However, in certain conditions, extraoperative E.Co.G. is more adequate. New surgical modalities have recently appeared such as the multiple subpial transsections which allow treatment of epileptic foci unapproachable by cortectomy and such as modified techniques of hemispherectomy, which by decreasing morbidity, renew interest in them. In the chapter on surgical results, the authors emphasize the methodological problems of evaluation that partly account for their wide variability. The results obtained with the various surgical modalities are reviewed. The outcome in cortectomies is discussed at length in terms of the data from the literature as well as the results reported by both teams.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

Flerobuterol, a beta-adrenoceptor agonist, enhances serotonergic neurotransmission: an electrophysiological study in the rat brain.

The two beta-adrenoceptor agonists salbutamol and clenbuterol have been shown to be effective antidepressant drugs. Flerobuterol, a new beta-adrenoceptor agonist, exhibits antidepressant activity in animal models. Given the long-standing notion that the serotonergic (5-HT) system might be involved in the etiology and/or the therapeutics of affective disorders and that this class of adrenergic agents can alter factors regulating 5-HT transmission, the effects of acute and repeated administrations of flerobuterol on the 5-HT system were studied. Acute administration of flerobuterol (up to 2 mg/kg, IV) did not modify the firing rate of dorsal raphe 5-HT neurons. However, the sustained administration of flerobuterol for two days (0.5 mg/kg/day, SC. delivered by an osmotic minipump) produced a marked decrease of the firing rate of 5-HT neurons. The reversal of this effect of flerobuterol by the somatodendritic 5-HT autoreceptor antagonist spiperone suggests that this decrease in the firing activity of 5-HT neurons in rats treated for 2 days with flerobuterol resulted from an enhanced synaptic availability of 5-HT. This initial decrease in firing activity of 5-HT neurons was followed by a progressive recovery to normal after 14 days of treatment with flerobuterol. At this point in time, the effect of intravenous lysergic acid diethylamide on the firing of 5-HT neurons was attenuated, indicating that the somatodendritic 5-HT autoreceptors had desensitized. The effectiveness of the electrical stimulation of the ascending 5-HT pathway in suppressing the firing activity of dorsal hippocampus pyramidal neurons was markedly enhanced in rats treated with flerobuterol for 14 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗

Long-term benzodiazepine treatment reduces neuronal responsiveness to cholecystokinin: an electrophysiological study in the rat.

Acute benzodiazepine administration has been reported to antagonize the effect of cholecystokinin both in the periphery and in the central nervous system. A two-week treatment with either diazepam (5 mg/kg per day) or flurazepam (15 mg/kg per day) markedly reduced the excitatory effect of microiontophoretically applied sulphated cholecystokinin octapeptide-(26-33) on rat CA3 hippocampal pyramidal neurons but not that of acetylcholine. In view of the sustained anxiolytic activity of benzodiazepines that contrasts with their transient sedative effect, the present results suggest that the reduction of neuronal responsiveness to cholecystokinin by these drugs might be related to their anxiolytic property.

Acetylcholine↗

Long-term antidepressant treatment reduces neuronal responsiveness to flurazepam: an electrophysiological study in the rat.

Long-term administration of various types of antidepressant drugs has been recently reported to reduce the density of benzodiazepine receptors in the rat CNS. In the present study, using the microiontophoretic technique, the effect of flurazepam application on cholecystokinin-induced activation of hippocampal pyramidal neurons was assessed in rats treated with the antidepressants desipramine, trimipramine and citalopram, and the antipsychotic chlorpromazine, for 3 weeks. All 3 antidepressant drugs, but not chlorpromazine, reduced the efficacy of flurazepam. A two-week treatment with desipramine produced a similar effect, whereas a one-week treatment with this drug failed to alter the effect of flurazepam. These results constitute further evidence that long-term antidepressant treatment down-regulates benzodiazepine receptors.

Acetylcholine↗