Biomedical subjects

J C Baron

Publications and source records attributed to J C Baron.

264 records · Page 15Linked to original sources

PubMedDate not supplied

Pathophysiologic study of chronic infarcts with I-123 isopropyl iodo-amphetamine (IMP): the importance of periinfarct area.

Seventeen chronic cerebral infarcts were investigated by a highly sensitive, dedicated brain single photon emission computerized tomography system using 123I-isopropyl iodoamphetamine (IMP) and 133Xe. IMP uptake was measured 10 minutes, 2 hours, and 5 hours after injection, and regional cerebral blood flow was measured with 133Xe. In 4 cases a positron emission tomography system was used to measure the rCBF and the regional metabolic rate of oxygen with C15O2 and 15O2. The results obtained allowed us to identify 2 abnormal zones. One, the "central area," was characterized by a severe decrease in IMP uptake and rCBF averaging 34% and 46% respectively and by a hypodense image on the x-ray computerized tomography scan. The second, the periinfarct or "peripheral area" was characterized by a moderate decrease in IMP uptake and regional cerebral blood flow averaging 13 and 19% respectively; this area extended around the central area and had a normal density on computerized tomography scan. The IMP hypofixation of the peripheral area observed at the 10th minute tended to disappear at the 5th hour. The volume of this area was often found to be quite large, covering more than 30% of a hemisphere whereas the central area did not exceed 25%. Volume appeared to be correlated with the neurological status of the patient. The nature of the peripheral area is not established with certainty. It may be caused by deafferentation of areas not directly affected by the ischemic insult and/or selective ischemic neuronal loss. The results stress the important role played by the peripheral area, which may be useful in establishing the prognosis and evaluating the efficacy of therapy in individual stroke cases.

Adult↗

PubMedDate not supplied

Results of diagnostic investigations and long-term outcome of 33 dogs with brain infarction (2000-2004).

Medical records of 33 dogs presented for acute onset, nonprogressive, intracranial dysfunction that had a magnetic resonance imaging diagnosis of brain infarction were reviewed. Postmortem confirmation of brain infarction was available in 10 dogs. All dogs were evaluated by CBC, serum biochemistry, thyroid and adrenal testing, urinalysis, thoracic and abdominal imaging, and cerebrospinal fluid analysis. Results of coagulation profile and arterial blood pressure were available in 32/33 and 28/33 dogs, respectively. On the basis of the imaging findings, infarcts were classified depending on their type (territorial or lacunar) and location within the brain (telencephalic, 10/33; thalamic/midbrain, 8/33; cerebellar, 15/33). No marked associations among location or type of infarct and patient age and sex, occurrence of systemic hypertension, and the presence or absence of a concurrent medical condition were identified. Small breed dogs (< or =15 kg) were significantly more likely to have territorial cerebellar infarcts, whereas large breed dogs (>15 kg) were significantly more likely to have lacunar thalamic or midbrain infarcts. A concurrent medical condition was detected in 18/33 dogs with brain infarcts, with chronic kidney disease (8/33) and hyperadrenocorticism (6/ 33) being most commonly encountered. Of 33 dogs, 10 were euthanized because of the severity and lack of improvement of their neurologic status or the severity of their concurrent medical condition. No association was identified between type or location of infarct and patient outcome. Dogs with concurrent medical conditions had significantly shorter survival times than those with no identifiable medical condition and were significantly more likely to suffer from recurrent neurologic signs because of subsequent infarcts.

Animals↗

PubMedDate not supplied

Clinical and topographic magnetic resonance characteristics of suspected brain infarction in 40 dogs.

Medical records of 40 dogs presented for evaluation of acute-onset, nonprogressive, intracranial dysfunction by means of magnetic resonance imaging (MRI) diagnosis of brain infarction were reviewed. Location of the brain infarcts was: 11 of 38, telencephalic; 8 of 38, thalamic/midbrain; 18 of 38, cerebellar; and 3 of 38, multifocal. Telencephalic infarcts developed within the territory of the middle cerebral (4/11), rostral cerebral (2/11), and striate (5/11) arteries. Thalamic/midbrain infarcts developed within the territory of perforating arteries of the caudal portion of the thalamus and rostral portion of the brainstem (8/8). All cerebellar infarcts (18/38) were within the territory of the rostral cerebellar artery or one of its branches. All infarcts appeared nonhemorrhagic, with marked contrast enhancement observed in only 3 of 38 dogs, all of which were imaged more than 7 days after the onset of signs of neurologic dysfunction. Diffusion-weighted imaging (DWI) sequences were available from 6 dogs, all imaged within 5 days of the onset of signs of neurologic dysfunction. Suspected infarcts were hyperintense on DWI sequences and were hypointense on the apparent diffusion coefficient map. Telencephalic infarcts caused abnormal mental status, contralateral postural reaction deficit, contralateral nasal hypalgesia, contralateral menace deficit, and ipsilateral circling. Thalamic/midbrain infarcts caused contralateral or ipsilateral postural reaction deficit, contralateral menace deficit, ipsilateral head tilt or turn, nystagmus, ventrolateral strabismus, and anisocoria. Cerebellar infarcts caused ipsilateral asymmetric cerebellar quality ataxia, head tilt, intermittent opisthotonus, nystagmus, and ipsilateral menace deficit with apparent normal vision.

Animals↗

PubMedDate not supplied

[Factors determining the therapeutic window in acute ischemic stroke: characteristics of PET studies].

OBJECTIVE: To make a brief review of the use of PET in the study of patients with acute ischemic stroke. DEVELOPMENT: In the cerebral cortex PET may be used to detect a series of changes which permit the definition of three types of patients with different prognoses. The patients of type 1 (severe fall in cerebral blood flow and CMRO2) have an unfavorable prognosis and do not benefit from fibrinolytic treatment and/or neuroprotection to assist recovery of areas of penumbra. Patients of type 2 (marked drop in cerebral blood flow with moderate reduction of CMRO2) have a doubtful prognosis and are those which, in theory, might benefit from fibronolytic and/or neuroprotector treatment to help recovery of zones of penumbra. The patients of type 3 (focal hyperperfusion with CMRO2 maintained) have a favorable spontaneous prognosis. CONCLUSIONS: This technique also shows that the therapeutic window should be individually analyzed in each case. This data is of great interest when planning therapeutic clinical studies.

Acute Disease↗

PubMedDate not supplied

[Cerebral ischemia--challenges and perspectives].

The only treatment for acute ischaemic stroke patients that presently has proven efficacy is intravenous thrombolysis with rt-PA within 3 hrs of onset. However, only at most 5% of the patients are eligible for this therapy. It remains therefore of foremost importance to develop efficacious neuroprotective agents for ischaemic stroke. Unfortunately, despite proven efficacy in the laboratory animal, all clinically-tested neuroprotectants have failed to show significant benefit in well-powered randomized clinical trials. In this article, the possible causes for this situation--either at the level of the design of clinical trials or that of the pre-clinical evaluation--are reviewed, and a number of measures that could be taken to try and solve this awkward situation are proposed.

Brain Ischemia↗

PubMedDate not supplied

[Scrotal trauma. Report of 33 cases].

We report a serial case study of 33 patients from May 1980 to November 1990 presenting a scrotal contusion. In 2/3 of cases, the physical examination showed a scrotal oedema or an hematocele. Ultrasonography showed a testicular injury while clinical examination was subnormal in 2 patients. In the other cases, ultrasonography showed an hematocele without asserting in all cases the traumatic rupture of the tunica albuginea. 27 patients have been surgically explored: 14 ruptures of the testicle, 3 intratesticular haematoma, 3 scrotal open traumatic injuries, and 7 extratesticular haematoma. Only 3 orchidectomies were required for the 6 patients who have not been explored surgically, the testis was normal at one month. The follow-up of these young patients is difficult, 11 had been seen again at 1 month. At long term follow-up, three patients had been seen at 1, 3 or 6 years without testicular after-effects.

Adolescent↗

PubMedDate not supplied

[Ambulatory urologic surgery].

Outpatient urinary tract surgery has been possible in our department since November 1988. In this programme, surgical procedures are performed in patients who do not remain in hospital overnight. Stringent surgical, medical and social criteria are prerequisites to this kind of surgery. Between November 1988 and October 1990, 260 outpatients have been admitted in our department to undergo endoscopic surgery (110 cases), conventional surgery (110 cases), extracorporeal lithotripsy (44 cases) or various types of exploration, local drug perfusions and change or removal of stents (37 cases). Thirty six patients stayed in the inpatient department for the first night. One patient was readmitted the day after his discharge because of clotting after bladder biopsies. At the end of this first experience, ambulatory surgery of the urinary tract has proved to be safe for the patients and to offer many advantages on economical, psychological and medical grounds. It can be predicted that in the future the number of outpatient procedures will increase dramatically.

Adolescent↗

PubMedDate not supplied

[Obsessive-compulsive behavior caused by bilateral lesions of the lenticular nuclei. A new case].

Another case of obsessive behaviour as the consequence of lentiform nuclei lesions is reported. All the aspects of an obsessive neurosis were present: irresistible compulsiveness, acute anxiety in case of non accomplishment, magic-like clues. The symptoms appeared after a carbon monoxide poisoning, in a 31-years-old woman who had previously a pathological personality, of the psychopathic type, but without obsessive features. The onset of compulsions was paralleled by frontal-like psychological changes, but there was no reduction of intellectual or mnesic functions. A previous depressive state continued after the poisoning, so that the patient did not show an empty mind as did the other patients; the loss of "self-psychic activation" was only partial. All these case-reports emphasize the fact that the neuropsychological testing must not be limited to the behaviour and must investigate the "mental content" as well. They also lead us to emphasize similitudes between psychic disorders related to lenticular lesions and those related to frontal lobe lesions, including obsessive-like activities. Such case-reports provide a model in which some components of the obsessive neurosis, hebephrenia and depression are the consequence of an identified brain damage. It can be suggested that the neural circuits involving frontal lobes and parts of the neostriatum and of the pallidum are implicated in the mechanisms of these three types of psychoses.

Adult↗

PubMedDate not supplied

Comparison study of CT and positron emission tomographic data in recent cerebral infarction.

To better understand the pathophysiologic correlates of the computed tomographic (CT) scan changes seen in recent cerebral infarction, 17 patients (20 studies) underwent both x-ray transmission and positron emission CT investigations within 18 days after clinical onset of complicated ischemic stroke in the internal carotid artery territory. The density changes before and after contrast study measured within the CT lesion were correlated to the local cerebral blood flow (CBF), oxygen utilization (CMRO2), and oxygen extraction fraction (OEF) measured with the oxygen-15 steady-state positron technique. Statistically significant linear correlations were found between hypodensity and CBF, hypodensity and CMRO2, and contrast enhancement and CBF, such that the more CBF and CMRO2 were depressed, the more marked was the hypodensity; and the more CBF was elevated, the more marked was the contrast enhancement. Although marked contrast enhancement was associated with decreased OEF (luxury perfusion), it was only rarely associated with increased CBF. Various hypotheses are discussed to explain these findings.

Brain↗

PubMedDate not supplied

[Consequences of lesions of the basal ganglia on cerebral metabolic activity: clinical implications].

This brief overview summarises the literature regarding the effects of lesions of the basal ganglia (BG) on brain metabolism-an index of integrated synaptic activity. Interest in this field is because to show such effects may reveal the implication of neuron networks, damaged at the level of the BG, in the neuropsychological and behavioural expression of BG lesions. As an illustration of this, a parallel is drawn between the loss of psychic self-activation (also named "psychic akinesia" or "athymhormia") that follows bilateral lesions at variable sites of the prefrontal-striatal-pallidal-thalamic loop on one hand, and the mild prefrontal hypometabolism consistently observed in such cases. This paper also reviews the changes in brain metabolism found in progressive supranuclear palsy, Huntington's disease, Parkinson's disease, Wilson's disease and striato-nigral degeneration.

Akinetic Mutism↗

PubMedDate not supplied

[Study of functional neuro-anatomy of perception using positron emission tomography].

The investigation by means of functional neuroimaging techniques, notably positron emission tomography, of the neural networks involved in perceptual processes is presently carried out according to two different though complementary approaches. In one of them, the relationships between impairments in perceptual processes and alterations in resting brain metabolism are studied in brain-damaged subjects, according to the classic paradigm of neuropsychology, but here the metabolic alterations reflect the functional disruption of neural networks directly or indirectly affected by the focal brain lesion. In the other approach, one records the changes in local synaptic activity in response to a given stimulation or task, as compared to a reference condition; thus far this second approach has been mainly applied to the normal human subject. Though different, both approaches highlight the neural networks involved in a given perceptual or cognitive task, which appear as a set of brain areas more extensive than that revealed by classic neuropsychology as necessary to perform the task. PET activation studies in the healthy subject have allowed to investigate, within each domain of perception, the successive "bottom-up" steps of information processing, from the most elementary ones carried out passively, to the most complex ones involving e.g., the semantic representations. The attentional aspects of perception have also been extensively investigated, notably selective "top-down" attention (which modulates the response of those brain areas that process the given perceptual attribute), sustained vigilance (which activates a parieto-prefrontal network in the non-dominant hemisphere), and mental imagery (which activates in a "top-down" fashion the entire perceptual network, including the primary cortices). The wide-scale application of this approach to brain-damaged subjects will seemingly soon provide important clues regarding the neural mechanisms of impaired perception and recovery therefrom.

Brain↗

PubMedDate not supplied

[Shy-Drager syndrome with disturbances of the respiratory rhythm and consciousness. A propos of an anatomo-clinical case].

The case, including pathological description, of a 65 year old man is presented. Severe disturbances in respiratory rhythm and consciousness occurring during wakefulness and sleep, progressing by acute exacerbations, developed after the disease had been present for 4 years and resulted in death after three months. Small degenerative lesions of the pontine nucleus, the locus coerulus, the intermedio-lateral column and the substantia nigra were seen.

Aged↗