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Biomedical subjects

J Hugon

Publications and source records attributed to J Hugon.

At least 91 records · Page 5Linked to original sources
PubMed1988

[Tropical African neuromyelopathies: 61 studied cases in the Ivory Coast].

Sixty one cases of tropical myeloneuropathies (TNM) from Abidjan, Ivory Coast, are reported. The mean age of patients was 35 years. The socioeconomic level was often very low and puerperality was a common initiating factor. Several clinical forms are noted: pure pyramidal (16 cases), pure ataxic (11 cases), sensory motor polyneuritis (8 cases), combined sclerosis of the spinal cord (1 case), ataxic polyneuritis (25 cases). In fact the extent of the pathobiological process was more severe as shown by slowings of peripheral motor nerve conduction velocities, prolonged central conduction time determined after cortical and spinal stimulations, and a severe sensory axonal impairment on nerve biopsies. These changes were observed with varying degrees in all clinical forms. As long as the etiological factors of TMN are not known (preventing from the possibility to split this disease in several entities) it is preferable to speak about one global disorder and not isolated various clinical forms (e.g. particulary: tropical spastic paraplegia). HTLV-I retrovirus seems to play a limited role in the etiology of TMN in Ivory Coast (1 positive case).

Adolescent↗
PubMed1988

[The concept of tropical neuromyelopathy].

Since the beginning of this century, the concept of tropical neuromyelopathy (T. N. M.) was progressively elaborated in tropical areas. This disorder is constituted by three main clinical syndromes (e.g.: polyneuropathy, spastic paraplegia, ataxia). Abnormal clinical, electrophysiological and pathological features, observed in all clinical forms argue in favor of a diffuse pathobiological process of the nervous system. The association with positive HTLV-1 serology, has recently induced a great interest for the spastic forms of T. N. M. Tropical spastic paraplegia tend to be individualized. This attitude differs from the global concept of T. N. M. which allows gathering similar clinical syndromes. This T. N. M. group should be kept intact until the discovery of new etiologies. Toxic (manioc, lathyrism) or deficiency (hypovitaminosis, malabsorption) causes are incriminated. Otherwise etiologies are unknown.

Ataxia↗
PubMed1988

[Motor evoked potentials. Technic and results in the normal subject].

The transcranial stimulation of the motor cortex and spinal cord was introduced in clinical neurology by Merton and Morton (1980). This reproducible and non invasive technique gives the possibility to elicit unilaterally or bilaterally evoked motor potentials. It is possible to define a Total Conduction Time (TCT) from cortex to muscle and a Peripheral Conduction Time (PCT) from spinal cord to muscle. The central conduction time is given by the latency difference between TCT and PCT. This delay represents the duration of the descending corticospinal volley plus the delay necessary to depolarize spinal motor neurons. For central pathways supplying the upper limbs TCT is 4.3 milliseconds and for central pathways supplying the lower limbs TCT is 9.3 milliseconds. This technique of central motorpathway assessment can be used to define the magnitude of a central motor deficit in neurological diseases affecting the corticospinal tract, during surgical procedures involving the spinal cord and in comatose patients. The new magnetic stimulation is painless and will probably widen the utilization of this method.

Electric Conductivity↗
PubMed1987

Cytotoxic properties of glutamate and aspartate in rat peripheral nerves: histological findings.

Two excitatory neurotransmitters, L-glutamate and L-aspartate, known for their neurotoxic properties in the central nervous system were injected in rat sciatic nerve. The morphological results are compared with sodium chloride injections in sciatic nerve on the other side. Rats were sacrificed 24 h to 1 month after the administration of compounds. Marked endoneural edema with global axonal loss of myelinated fibers were observed in animals injected either with glutamate or aspartate. A demyelinating process was also associated with axonal damages. Sodium chloride did not induce similar morphological abnormalities. This model of toxic neuropathy may be mediated by the excitotoxic properties of L-aspartate and L-glutamate.

Animals↗
PubMed1987

Guam amyotrophic lateral sclerosis-parkinsonism-dementia linked to a plant excitant neurotoxin.

The decline in the high incidence of amyotrophic lateral sclerosis, parkinsonism, and Alzheimer-type dementia among the Chamorro population of the western Pacific islands of Guam and Rota, coupled with the absence of demonstrable viral and hereditable factors in this disease, suggests the gradual disappearance of an environmental factor selectively associated with this culture. One candidate is seed of the neurotoxic plant Cycas circinalis L., a traditional source of food and medicine which has been used less with the Americanization of the Chamorro people after World War II. Macaques were fed the Cycas amino acid beta-N-methylamino-L-alanine, a low-potency convulsant that has excitotoxic activity in mouse brain, which is attenuated by N-methyl-D-aspartate receptor antagonists. These animals developed corticomoto-neuronal dysfunction, parkinsonian features, and behavioral anomalies, with chromatolytic and degenerative changes of motor neurons in cerebral cortex and spinal cord. In concert with existing epidemiological and animal data, these findings support the hypothesis that cycad exposure plays an important role in the etiology of the Guam disease.

Amino Acids, Diamino↗
PubMed1987

Human T-lymphotropic virus type I antibodies in the serum of patients with tropical spastic paraparesis in the Seychelles.

Tropical spastic paraparesis (TSP), a chronic myelopathy of unknown etiology, was studied in the Seychelles. Human T-lymphotropic virus type I (HTLV-I) and human immunodeficiency virus antibodies were determined using an enzyme-linked immunosorbent assay and confirmed with an indirect fluorescent antibody test in serum samples of 20 patients with TSP and 16 controls. Test results indicated that 17 patients (85%) and two controls (transverse myelopathy and clinically probable multiple sclerosis) were positive for HTLV-I. Serum samples of nine healthy controls and five with other neurologic diseases were negative for HTLV-I. No serum samples were positive for human immunodeficiency virus. Estimated relative risk for TSP in those subjects whose serum is positive for HTLV-I antibodies is 40. This result is highly statistically significant. Although primarily associated with adult T-cell leukemia and non-Hodgkin's lymphoma, HTLV-I could also be an etiologic agent of TSP.

Adult↗
PubMed1987

Discovery and partial characterization of primate motor-system toxins.

beta-N-Oxalylamino-L-alanine (BOAA) and beta-N-methylamino-L-alanine (BMAA) are chemically related excitant amino acids isolated from the seed of Lathyrus sativus (BOAA) and Cycas circinalis (BMAA), consumption of which has been linked to lathyrism (an upper motor neuron disorder) and Guam amyotrophic lateral sclerosis (ALS), respectively. Both diseases are associated with degeneration of motor neurons. Experimentally, single doses of BOAA or BMAA induce seizures in neonatal mice and postsynaptic neuronal oedema and degeneration in explants of mouse spinal cord and frontal cortex. Preliminary studies show that these behavioural and pathological effects are differentially blocked by glutamate-receptor antagonists. In macaques, several weeks of daily oral doses of BOAA produce clinical and electrophysiological signs of corticospinal dysfunction identical to those seen in comparably well-nourished animals receiving a fortified diet based on seed of Lathyrus sativus. By contrast, comparable oral dosing with BMAA precipitates tremor and weakness, bradykinesia and behavioural changes, with conduction deficits in the principal motor pathway. BOAA and BMAA (or a metabolite thereof) are the first members of the excitotoxin family to have been shown to possess chronic motor-system toxic potential. These observations provide a rational basis for searching for comparable endogenous neurotoxins in sporadic and inherited forms of human motor neuron disease.

Alanine↗
PubMed1987

Central motor conduction in motor neuron disease.

Central motor conduction was assessed in 13 patients with motor neuron disease and in 15 control subjects. All patients with motor neuron disease, even those without clinical pyramidal signs, had slowed central motor conduction, and in some the delays were asymmetrical. Evoked motor potentials represent a new and reliable method to detect physiological abnormalities of central motor pathways early in the course of motor neuron disease.

Action Potentials↗
PubMed1987

Congenital hypo- and hypermyelination neuropathy. Two cases.

Two young patients were referred recently to the authors for investigation of a peroneal atrophy syndrome. Since the first symptoms were observed in infancy, a congenital hypomyelination neuropathy was suspected, and superficial peroneal nerve biopsies were taken. Signs of severe and widespread demyelination/remyelination were observed. These features appeared morphologically similar to those observed in the globular or tomaculous neuropathies. The mechanism of the hypermyelination is discussed.

Child↗
PubMed1987

Non-invasive assessment of the pyramidal tract and motor pathway of primates.

Non-invasive direct stimulation of the motor cortex of cynomolgus monkeys has been used to assess in awake and anesthetized animals the central and peripheral conduction times of the motor pathway and to measure the latencies of the descending spinal volley of the pyramidal tracts. Repetitive stimulation failed to induce convulsive activity or detectable pathological changes. Peripheral latencies were comparable with those obtained from F-wave analysis. Central conduction times for corticospinal tracts regulating the upper and lower limbs were 2.7 msec and 5.4 msec, respectively, the estimated conduction velocity (67.5 m/sec) corresponding to results obtained by invasive methods. These studies provide a new and apparently safe technique to assess non-invasively the functional status of the central motor pathway in primates, a method that might also find utility in clinical practice.

Animals↗
PubMed1987

Tick bite meningoradiculitis. Ten cases.

A study was undertaken on 10 cases of meningoradiculitis following a tick bite. All patients developed neurologic manifestations and C.S.F. abnormalities. Electrophysiologic studies demonstrated decreased motor potential amplitude and normal motor conduction velocity suggesting distal axonal involvement. Radicular lesions were suspected due to the presence of delayed F waves. This is the first study to confirm these electrical findings by histologic examination of the superficial peroneal nerve of the leg during the course of thick meningoradiculitis.

Aged↗
PubMed1987

Studies on the aetiology and pathogenesis of motor neuron diseases. 1. Lathyrism: clinical findings in established cases.

Lathyrism is a toxic disease of the motor system constantly associated with primary consumption of the seed of Lathyrus sativus (chickling or grass pea). Neurological examination was performed on 38 affected subjects drawn from four regions of the Indian subcontinent endemic for lathyrism. All showed a consistent and largely symmetric pattern of neurological deficit similar to that displayed by 5 Europeans with longstanding lathyrism now living in Israel. Hallmarks of lathyrism include a pyramidal pattern of motor weakness combined with greatly increased tone in the thigh extensors and adductors and in the gastrocnemius muscles so that the more severely affected walk on the balls of their feet with a lurching scissoring gait. Extensor plantar responses are uniformly present in such cases, and the knee and ankle tendon reflexes are exaggerated and often clonic. Hoffmann signs and exaggerated biceps and/or triceps tendon jerks are also found in the most severely affected. Sensory signs are absent, although perverse sensations in the legs are frequently reported at the onset. Walking difficulties commonly begin suddenly but may also appear subacutely or insidiously. Some individuals experience partly reversible symptoms suggestive of a diffuse CNS excitation of somatic, motor and autonomic function.

Adult↗
PubMed1987

Tick-bite meningoradiculoneuritis: clinical, electrophysiologic, and histologic findings in 10 cases.

We studied 10 adults with meningoradiculitis several weeks after a tick bite (Ixodes). EMG evidence of denervation was associated with normal motor conduction velocities, prolongation of distal latencies, and low sensory amplitudes, suggesting axonal neuropathy. Sural nerve biopsies confirmed the axonal involvement. Infiltrations of lymphocytes and plasma cells, sometimes forming thick pericapillary cuffs with no accompanying necrosis of vessel walls, were numerous. Many capillaries of the endoneurium, perineurium, and epineurium were affected in this way.

Aged↗
PubMed1987

Tropical spastic paraparesis in the Seychelles Islands: a clinical and case-control neuroepidemiologic study.

We confirmed the occurrence of endemic tropical spastic paraparesis (TSP) in the Seychelles. Most patients (14/21) were low-income black women. Mean age at onset was 42.8 years (range, 20 to 65). In 62%, onset and progression were slow. Complete paralysis developed in 8/21 (38%) after an evolution of 2 to 15 years. All patients had bilateral pyramidal signs. Loss of vibratory perception occurred in 6/21 (28%). A case-control study of putative risk factors failed to show significant differences. The clinical and epidemiologic features of TSP in the Seychelles appear to be similar to those described in other tropical countries.

Adolescent↗
PubMed1987

[Neuropathies of unknown etiology. A study of 48 cases].

A prospective study, carried out over 7 years, showed that out of 432 peripheral neuropathies followed up for 12 months, no cause could be discovered in 48 (11%). This is discussed with respect to the previous few reports. In fact none of these studies is strictly comparable. In spite of complementary investigations and observation of the course of the disease, it may be difficult to be sure to which etiology any individual case belongs; e.g. genetically determined neuropathies, chronic inflammatory polyradiculoneuritis or drug-induced neuropathies. However, it is clear that the group of neuropathies of undetermined origin, is clinically, pathologically and developmentally heterogeneous. This suggests that these patients should be classified as having a yet undetermined disease process. In our series, long term follow up enabled us finally to find a cause in a significant number of cases.

Adolescent↗