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Biomedical subjects

B Dan

Publications and source records attributed to B Dan.

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

Effect of intrathecal baclofen on gait control in human hereditary spastic paraparesis.

The covariation between thigh, shank and foot elevation angles during locomotion was analysed by means of orthogonal planar regression in a patient with pure hereditary spastic paraparesis before and after an intrathecal bolus of baclofen and in seven healthy subjects. The size, shape and spatial orientation of the loop defining patient's planar covariation (thigh angle vs. shank angle vs. foot angle) significantly differed from the controls' before baclofen, whereas these features resumed normal characteristics after baclofen injection. This shows that alteration of the control of phase coupling for the co-ordination of lower limb segments in human gait by increased spinal reflexes can be reversed by intrathecal baclofen injection.

Adult↗
PubMed2000

Connatal Pelizaeus-Merzbacher disease in two girls.

We report the clinical, radiological and electrophysiological signs in two unrelated girls with the connatal form of Pelizaeus-Merzbacher disease (PMD). MRI plays an important role in the diagnosis, demonstrating the virtual absence of myelination. PMD is classically described as an X-linked leukodystrophy. Our two cases reinforce the hypothesis of a possible autosomal recessive transmission of the connatal form of PMD in some families, as recently presented.

Diagnosis, Differential↗
PubMed2000

Peri-optic nerve infiltration during leukaemic relapse: MRI diagnosis.

BACKGROUND: A 10-year-old boy with a history of acute lymphoblastic leukaemia (ALL), but without previous evidence of central nervous system involvement, presented with seizures 3 years after complete remission. MATERIALS AND METHODS: MRI showed bilateral enlargement of the optic nerves despite normal ophthalmological examination. RESULTS: Only the third cerebrospinal fluid examination showed 2 % blasts without concomitant bone-marrow infiltration. Enlargement of the optic nerves was consistent with bilateral leukaemic peri-optic nerve infiltration. The appearances returned to normal after chemotherapy. CONCLUSION: The optic nerves are a potential site of relapse in patients with systemic and meningeal ALL, even in the absence of ophthalmological signs.

Child↗
PubMed2000

MRI spectrum of cortical malformations in tuberous sclerosis complex.

The diagnostic and prognostic value of magnetic resonance imaging in the tuberous sclerosis complex has increasingly been recognized. In this paper, we review the presumed pathogenesis of the cerebral dysgenesis seen in this condition in the light of magnetic resonance imaging features of selected patients. In addition to typical findings related to tubers, we show and discuss varied cortical malformations (from simple localized cortical dysplasia to transmantle dysplasia and schizencephaly) similar to those seen in sporadic cerebral dysgenesis. These cases support the hypothesis that the tuberous sclerosis complex focally affects the radial glial-neuronal complex as a basic unit for brain development. Abnormal stem cells would create dysplastic glia and neurons that fail to differentiate, proliferate, migrate and form a normally organized cortex.

Cell Differentiation↗
PubMed2000

Head stability during whole body movements in spastic diplegia.

Head angular stability is essential for postural control in whole body movement. Using the opto-electronic ELITE system, we have studied head orientation during the movements of squatting from the standing position and straightening-up from the squatting position in 12 children with spastic diplegia and 12 age-matched controls. Although no instruction was given regarding the head, diplegic children consistently performed excessive neck flexion in the squatting movement and excessive hyperextension in the straightening-up movement, whereas normal children maintained the initial orientation throughout both movements. We discuss pathophysiological implications.

Cerebral Palsy↗
PubMed2000

Transcranial magnetic stimulation and other evoked potentials in pediatric multiple sclerosis.

In children, multiple sclerosis is rare and has some clinical and paraclinical differences compared with adults. The assessment of corticospinal motor tracts is expected to be relevant because of their frequent early involvement in this disease. Reported are the results of transcranial magnetic stimulation in two children who presented at 12 and 9 years of age with clinically probable and definite multiple sclerosis, respectively. In Patient 1 the excitatory cortical threshold for the upper limbs was abnormally raised. In Patient 2 the latency of the motor-evoked potentials was considerably increased for the right tibialis anterior muscle, with a slowing of the central conduction time. Although these abnormalities may be consistent with central conduction impairment, they may alternatively suggest early axonal damage because irreversible axonal lesions occurring at the onset of the disease have recently been reported. Testing of central motor tracts, in addition to visual, auditory, and somatosensory pathways, therefore appears appropriate in the multimodal assessment of pediatric patients with suspected multiple sclerosis.

Axons↗
PubMed2000

Intrathecal baclofen normalizes motor strategy for squatting in familial spastic paraplegia: a case study.

We aimed to assess whether intrathecal baclofen could alter the motor strategy for squatting of a patient with pure familial spastic paraplegia. Before baclofen injection and two, four and six hours after it, the patient was evaluated as follows: self-report of walking stiffness and movement initiation; muscle tone with the Ashworth scale; and kinematic and electromyographic analysis of the squatting movement using the opto-electronic ELITE system. The patient's subjective improvement and decrease in muscle tone were dramatic after baclofen injection. Kinematic analysis of squatting showed gradual improvement. Before the injection, the movement was performed with loss of trunk verticality, backward shift of the hip, multiphasic ascending phase of the knee angular velocity and dynamic ankle stiffening. After baclofen injection, the movement was made with vertical translation of body segments and monophasic ascending phase of the knee angular velocity. The effect was maximal six hours after the injection. Electromyographic activities showed a non-specific co-contraction pattern before the injection, and a reciprocal pattern two hours after it. Moreover, a physiological anticipatory deactivation of the hamstring muscles appeared two hours after the injection. In this study of a single patient with familial spastic paraplegia, intrathecal baclofen has facilitated the emergence of normal, supraspinally determined movement patterns.

Adult↗
PubMed2000

Sensory and motor interfering influences on somatosensory evoked potentials.

The interfering influences by which the different components of the early somatosensory evoked potentials are modified are reviewed from both neurophysiologic and clinical perspectives. Special consideration is given to the specific differences between sensory and motor interferences. In this context, the specific effect of the mental movement simulation task on the frontal N30 component is discussed in relation to the involvement of this evoked wave as a physiologic index of the dopaminergic motor pathways. Relevant interfering approaches, including concurrent events ranging from tactile stimulation to locomotion, are reviewed and discussed insofar as these data provide insights into the neurophysiologic processes of interaction between competing internal models controlling motor acts and sensory information.

Afferent Pathways↗
PubMed2000

[Value of brain MR imaging in infants with a severe idiopathic apparent life threatening event].

OBJECTIVE: Prognostic value of a magnetic resonance imaging (MRI) scoring system in infants with a severe apparent life threatening event (ALTE). METHODS: Ten infants with an ALTE (aged between 6 and 31 weeks) were clinically graded according to the PRISM score and evaluated with EEG, evoked potentials and MRI. The 18 MRIs obtained were distributed in 3 classes according to the delay after which they were obtained; class A (n=5): within the first 48 hours after the event, class B (n=7): between day 3 and 8 and class C (n=6): between day 9 and 50. The 18 MRIs were evaluated retrospectively using a scoring system based on 3 categories of lesions: edema, basal ganglia injury and watershed injuries. Five infants died between day 2 and day 15 after the event. The five surviving infants had follow up neurodevelopmental testing after 38 to 77 months. RESULTS: There was no correlation between the 5 MRIs of class A and the neurological outcome. For the MRIs of class B and C, the scoring system can be of great value when combined with the scores of EEG, EP and PRISM. CONCLUSIONS: The scoring system for MRI performed within 48 hours after the event is falsely reassuring. MRI can be helpful as early as 3 days after the event when combined with the score of the electrophysiological investigations and the PRISM.

Basal Ganglia Diseases↗
PubMed1999

Adaptive motor strategy for squatting in spastic diplegia.

Motor strategies, defined by kinetic, kinematic and/or muscle activation patterns, reflect neural planning of movement, which takes into account central as well as peripheral constraints. Major alteration is expected in cerebral palsy, a condition characterized by abnormal posture and movement secondary to early lesion of the brain. The objective of this study was to characterize the motor strategies involved in disruption of posture in cerebral palsy of the spastic diplegia type and compare them with normal controls. The optoelectronic ELITE system was used to record and analyse the movement of squatting from the standing position with the arms extended forward in 11 children with spastic diplegia aged between 3 and 12 years and 11 age-matched normal controls. Normal children maintained gaze and arm horizontality and trunk verticality throughout the movement. The knee followed an oblique trajectory. Its angular velocity profile showed a short, single-peaked, ascending phase. The onset of movement was preceded by deactivation of the semimembranous muscle. In diplegic children, gaze and arm horizontality and trunk verticality were lost. The ankle was rigidified, resulting in spatial fixation of the knee. The ascending phase of the knee velocity profile was prolonged and multi-peaked. There was widespread muscle co-contraction from the outset of movement. No anticipatory deactivation was evidenced, but anticipatory bursts appeared in the soleus. Patients with cerebral palsy have to organize a limited motor repertoire from a restricted neural potential. Consequent motor strategies presently demonstrated in spastic diplegia are distinct and appear as an original alternative to those of normal subjects.

Biomechanical Phenomena↗