Biomedical subjects

D Boisson

Publications and source records attributed to D Boisson.

At least 37 records · Page 2Linked to original sources

PubMed2003

[Medical treatment of spasticity].

Spasticity is one of the clinical signs observed after a lesion of the pyramidal tract. Clinical manifestations are polymorphous and depend on the location of the lesion on the pre-motoneuron. Functional consequences are also variable. Only negative effects such as painful spasms, stiffness, distortions, are to be treated. Three different categories of drugs are available: GABA-like (baclofen, benzodiazepine), central alpha 2 agonists (tizanidine, clonidine) and peripheral anti-spastics (dantrolene). Baclofen remains the most commonly used anti-spastic. The preferential indication is spasticity from spinal cord disease, especially when the aetiology is multiple sclerosis. Efficacy of benzodiazepines (diazepam, tetrazepam, clonazepam) is comparable with baclofen; however, side effects (drowsiness) are more frequent. Benzodiazepines are indicated when spasticity is associated with anxiety. Tizanidine is an efficient and well tolerated antispastic. In France, prescription requires a temporary authorization of use. Dantrolen has a peripheral mechanism of action and can be prescribed in the different forms of spasticity. There are other compounds with anti-spastic properties (gabapentine, cyproheptadine, piracetam). Their advantage is rather limited when used alone. Generally, they are administrated in combinaison with usual anti-spastic drugs.

Adrenergic alpha-Agonists↗

PubMed2002

Bilateral vestibular stimulation does not improve visual hemineglect.

This work compared the effect of unilateral (right and left) and bilateral vestibular stimulation in a right-brain-damaged patient with neglect. Neglect was improved following left caloric vestibular stimulation, and worsened following right vestibular stimulation. On the other hand, no modification of neglect was observed after bilateral vestibular stimulation. These results support the idea that caloric vestibular stimulation may improve neglect through a specific effect; bilateral stimulation making the putative activation bilateral and symmetrical does not affect the lateral bias of neglect.

Aged↗

PubMed2001

Prism adaptation to rightward optical deviation improves postural imbalance in left-hemiparetic patients.

Left-hemiparetic patients show predominant postural imbalance as compared to right-hemiparetic patients. The right hemisphere is crucial for generating internal maps used for perceptual and premotor processing of spatial information. Predominant postural imbalance with right-brain damage could thus result from a distortion of an internal postural map. Well-known manifestations of distorted internal maps due to right-hemisphere lesions, such as hemineglect, may show improvement following prism adaptation shifting the visual field to the right. We therefore investigated the effect of prism adaptation on postural imbalance in left-hemiparetic patients. Three groups of five patients were either adapted to prisms deviating the visual field to the right or left or exposed to neutral prisms while performing reaching movements of the right arm. Postural imbalance was reduced only following prism adaptation to the right. Thus, brief adaptation (i.e., 3 min) to rightward-shifting prisms can dramatically improve postural imbalance. This result shows that the effect of exposure to prisms that horizontally shift the visual field to the right in a reaching task generalizes to the postural system, and it suggests an interaction between horizontal and vertical reference frames. This also supports the theory that predominant postural imbalance in patients with right-brain damage may be partly related to a distortion of an internal postural map.

Adult↗

PubMed2001

Prism adaptation improves representational neglect.

Previous work has shown that various symptoms of unilateral neglect, including the pathological shift of the subjective midline to the right, may be improved by a short adaptation period to a prismatic shift of the visual field to the right. We report here, in two neglect patients the improvement of imagery neglect after prism exposure. Despite a strong neglect observed for mental images, as well as for conventional tests, the mental evocation of left-sided information from an internal image of the map of France was fully recovered following prism adaptation to the right. This improvement could not be explained by the alteration of visuomotor responses induced by the prism adaptation. Therefore, prism adaptation may act not only on sensory-motor levels but also on a higher cognitive level of mental space representation and/or exploration.

Adaptation, Physiological↗

PubMed2001

[Dissociation of retrograde memory impairment in a case of herpetic encephalitis].

OBJECTIVE: To report an uncommon case of memory impairment after meningoencephalitis. METHOD: Detailed description of the history, the lesions, the evolution and review of the bibliography. RESULTS: A 33 year-old man showed a loss of verbal anterograde memory and a dissociation of retrograde memory impairment after an herpetic meningo-encephalitis with lesions predominant in the left temporal lobe. The patient had impairment of verbal anterograde memory. Visual memory, procedural one were intact. He had normal performances in frontal tests. Neuropsychological assessment revealed major loss of episodic biographical memory and public events memory, but sparing of semantic biographical memory and professional knowledge. This patient who was amnesic but who had not difficulties with visual memory, procedural memory, frontal abilities and didactic memory conserved ability to work. CONCLUSION: This case report emphasize the multiplicity of the memory systems and the likely links between episodic biographical memory, semantic biographical memory, autobiographic episodic memory, public event memory and didactic memory.

Adult↗

PubMed2001

[Otolith manifestations in Wallenberg syndrome].

Central vestibular pathways issuing from the otolith may be involved in Wallenberg syndrome, resulting in specific symptoms. These "otolith" symptoms are less well known than vestibular symptoms issuing from the canal. We report 15 patients with Wallenberg syndrome who had one or more clinical signs suggestive of otolith pathway involvement. Clinical examination looked for: Eleven patients presented ipsilesional skew deviation; ipsilesional tilt of subjective visual vertical was found in 8 patients; a room tilt illusion was described in 4 patients in either the frontal or the sagittal plane: 9 patients presented axial lateropulsion toward the lesioned side; 8 patients presented ipsilesional ocular lateropulsion, 6 of them in association with axial lateropulsion. Finally, 3 patients presented positional nystagmus evoked by head tilt in the roll or the pitch plane. Pathophysiology of these symptoms and evidence for an otolith pathway involvement are discussed.

Adult↗

PubMed2001

[Role of rehabilitation in hemineglect syndromes].

Unilateral neglect syndrome compromises functional outcome of left hemiparetic patients. Treatment of this syndrome is a challenge in motor rehabilitation in order to reduce the incapacity and improve the prognosis. In this study, we present a review of the literature focusing on the different rehabilitation techniques proposed and their theoretical basis: improvement of the ability to maintain attention, improvement of spatial selective attention by implicit or explicit cueing, reduction of rightward orienting bias by sensory manipulations. Recently, we reported the improvement of symptoms of unilateral neglect syndrome after a prism adaptation to a rightward optical deviation. Unlike previous physiological manipulations used to improve neglect, this improvement lasted for at least two hours after prism removal. These results are most promising for rehabilitation programs. They may be linked to a stimulation of a short-term plasticity of brain functions and underline the interest of action in rehabilitation of neglect.

Adaptation, Physiological↗

PubMed2000

An 'automatic pilot' for the hand in human posterior parietal cortex: toward reinterpreting optic ataxia.

We designed a protocol distinguishing between automatic and intentional motor reactions to changes in target location triggered at movement onset. In response to target jumps, but not to a similar change cued by a color switch, normal subjects often could not avoid automatically correcting fast aiming movements. This suggests that an 'automatic pilot' relying on spatial vision drives fast corrective arm movements that can escape intentional control. In a patient with a bilateral posterior parietal cortex (PPC) lesion, motor corrections could only be slow and deliberate. We propose that 'on-line' control is the most specific function of the PPC and that optic ataxia could result from a disruption of automatic hand guidance.

Adult↗

PubMed1999

Regression of vasomotor disorders under intrathecal baclofen in a case of spastic paraplegia.

Continuous intrathecal baclofen infusion via a subcutaneously implanted programmable pump has been used in the treatment of severe spasticity. Improvement classically concerns the neurological (hypertonia, spasms, hyperreflexia), urological (bladder function) and other clinically relevant outcomes, such as functional status of daily living. This short note reports on another effect of intrathecal baclofen on vasomotor disorders and cyanosis in the lower limbs, described in a patient with spastic paraplegia.

Adult↗

PubMed1998

Prism adaptation to a rightward optical deviation rehabilitates left hemispatial neglect.

A large proportion of right-hemisphere stroke patients show hemispatial neglect-a neurological deficit of perception, attention, representation, and/or performing actions within their left-sided space, inducing many functional debilitating effects on everyday life, and responsible for poor functional recovery and ability to benefit from treatment. The frequent parietal locus of the lesion producing neglect reflects the impairment of coordinate transformation used by the nervous system to represent extrapersonal space. Given that adaptation to a visual distortion can provide an efficient way to stimulate neural structures responsible for the transformation of sensorimotor coordinates, the aim of our study was to investigate the effect of prism adaptation on various neglect symptoms, including the pathological shift of the subjective midline to the right. All patients exposed to the optical shift of the visual field to the right were improved on their manual body-midline demonstration and on classical neuropsychological tests. Unlike other physiological manipulations used to improve neglect, this improvement lasted for at least two hours after prism removal and thus could be useful in rehabilitation programmes. The positive effect found for both sensorimotor and more cognitive spatial functions suggests that they share or depend on a common level of space representation linked to multisensory integration.

Adaptation, Ocular↗

PubMed1998

Improvement of the motor deficit of neglect patients through vestibular stimulation: evidence for a motor neglect component.

The effect of vestibular stimulation on motor performance has been studied comparatively in 2 groups of hemiplegic patients, one including 9 right brain-damaged patients (RBD) with neglect, the other 9 left brain-damaged patients (LBD) without neglect. In the RBD group, a transient but significant improvement of motor performance was observed following stimulation, although motor scores remained unchanged in two cases. Moreover, a temporary remission of personal neglect and anosognosia was obtained in 8 out of 9 patients. In contrast to the RBD group, the motor performance of the LBD group was not improved through vestibular stimulation, although a moderate improvement of force was noticed in one ambidextrous patient who had shown transient signs of neglect at the acute stage. These results suggest the participation of a motor neglect component in the motor deficit of neglect patients. The motor neglect component may be considered as one of the many manifestations of the neglect syndrome and, as such, can be improved by the sensory manipulations which presumably restore a conscious representation of the left side of space.

Adult↗

PubMed1998

Postural asymmetry reduction by vestibular caloric stimulation in left hemiparetic patients.

The purpose of this study was to investigate the effects of caloric vestibular stimulation on the postural sway characteristics of hemiparetic patients. Two groups of 15 hemiparetic patients each (right and left) were compared to a group of 15 control subjects. Hemiplegic patients were selected for the study if they showed ability to stand without external support for at least 30 seconds. Posturographic evaluation was performed on a statokinesimetric platform just before and after a cold contralesional ear irrigation (20 degrees C) during 60 seconds. Two quantitative parameters were analysed: the antero-posterior difference and the lateral difference, reflecting the asymmetry of standing in the antero-posterior and frontal planes, respectively. The results of the 3 groups studied were compared with a Student's t-test. Before stimulation, as previously reported, left hemiparetic patients showed a predominant lateral displacement of the centre of pressure toward the side of the lesion, as compared to right hemiparetic patients. After vestibular stimulation, the lateral displacement was reduced in both patient groups, predominantly in the left hemiparetic group. After vestibular stimulation, the lateral displacement thus was not different in both patient groups and in the control group. Antero-posterior differences were not significantly different in the patient groups and in the control group before stimulation and were not affected by vestibular stimulation. The suggestion is made that greatest postural imbalance produced by right brain damage could reflect a persistent distorsion of a "spatial postural representation". Vestibular stimulation may restore symmetrical activity in the cerebral structures involved in the generation of this "spatial postural representation".

Adult↗

PubMed1998

[The development of gait in the hemiplegic patient after selective tibial neurotomy].

BACKGROUND AND PURPOSE: Spastic Foot may constitute a severe functional deficit leading to instability in stance and inappropriate prepositioning of the foot for its initial contact with the ground. The purpose of the study was to analyze the results of selective tibial neurotomy on gait. METHOD: After clinical examination of nine hemiplegic patients, gait was recorded before surgery and six months after. Three-dimensional bilateral kinematic data were obtained with a motion measurement system (VICON), and muscular electrical activity on affected side was detected with surface electrodes. The patient walked barefoot, with his free velocity, on a ten meter track in the lab. An analogic visual scale was used by the patient to evaluate gait discomfort. RESULTS: After neurotomy, triceps surae spasticity decreased and passive motion of ankle increased. Gait comfort was better, claw toes and sore skin disappeared. Kinematics data were modified by neurotomy in all patients. On the affected side, ankle dorsiflexion improved during stance for five patients and residual motricity improved during the swing phase for two patients. Stance knee hyperextension was corrected in the five patients. EMG data: Selective tibial neurotomy caused disappearance of triceps surae peak activity at the beginning of the stance phase and at the end of swing phase. The time activity of the other muscles did not change. CONCLUSION: Selective tibial neurotomy can cure foot deformity and modify ankle motion during gait. It corrects knee hyperextension during stance phase.

Adult↗

PubMed1997

Predominance of postural imbalance in left hemiparetic patients.

Postural sway characteristics in a group of 15 left hemiparetic patients were compared with those in a group of 15 right hemiparetic patients using a statokinesimetric platform. The results in the two patient groups were also compared with those derived from a group of 15 age-matched healthy control subjects. Three postural sway parameters were used: the total sway area, the anteroposterior sway and the lateral sway. Hemiparetic patients showed a larger sway area and a lateral displacement of the center of pressure toward the side of the lesion compared to normal subjects. Furthermore, left hemiparetic patients showed greater sway area and lateral displacement compared to right hemiparetic patients. We suggest that the predominance of postural imbalance in left hemiparetic patients could be due to a displacement of postural reference toward the lesion's side.

Adult↗

PubMed1996

Inverse relationship between sensation of effort and muscular force during recovery from pure motor hemiplegia: a single-case study.

A 39-year-old patient with a right pure motor hemiplegia, who complained of a striking sensation of effort when he performed a movement, was regularly examined during 4 months. The effort sensation and the force recovery have been measured during the execution of upper limb movements: shoulder antepulsion up to horizontal, supined elbow flexion up to horizontal and full hand digital grip. The subject was asked to realize a movement with the paretic arm and to concentrate on the felt effort; then he had to perform the same movement against a resistance with the healthy arm, until the perceived heaviness matched the effort sensation felt on the other side. Recovery of force and evolution of effort sensation did not follow linear trends over time. The curves displayed significant steps and plateaus, which were mainly observed for the proximal movements. The steps tended to be clustered within a few days, consistent with crucial periods in the restoration process. Within these, significant reduction of the effort sensation and increase of the force were together observed. These critical moments of the motor recovery could be analyzed as the result of an improvement of the neural traffic in the internal capsule and an activation of specific structures involved in the representation of the force and effort.

Adult↗

PubMed1995

Implicit processing of somaesthetic information: a dissociation between where and how?

We present the case of a patient with a lesion of the thalamus who was completely anaesthetized on his right side. He was unable to detect and describe a tactile stimulus applied to his affected right arm, but could direct his normal left hand toward the specific right hand site where the stimulus had been applied when so instructed ('blind touch'). Strikingly, this pointing ability disappeared when the patient had to indicate on a picture of an arm where the stimulus was applied, and when he had to name the stimulus location during his pointing. Similar results were also obtained for localizing the unfelt fingertip ('blind proprioception'). Neuropsychological case studies have demonstrated that brain lesions can produce reciprocal dissociations between object identification (what is the object) and object-oriented action (how to direct a movement to the object). Along these lines, it is suggested that our patient exhibited a dissociation between a 'where' system and a 'how' system for tactile and proprioceptive stimuli.

Cerebral Hemorrhage↗

PubMed1995

[Disulfiram (Esperal) toxicity. Apropos of 3 original cases].

Prescribed since 1948 to control chronic alcoholism, disulfiram may cause severe toxicity as report in three cases of acute motive axonal polyneuritis. Disulfiram toxicity may present different clinical aspects: 1) Cytolytic hepatitis with fatal evolution in 30% of cases (fulminant hepatitis), and full recovery for the other 70%. The onset of the symptoms usually occurs as early as 15 days to a maximum of 6 months (most within 2 months) after initiation of treatment. 2) Severe optic neuritis with full recovery in 2 months. 3) Peripheral neuropathy usually dose dependent, with different clinical presentations: polyneuritis with sensory, motor, or both deficits, and few cases of tetraplegia. 4) Encephalopathy frequently associated with one of the precedent symptoms, having a favorable outcome (probably resulting in inhibition of dopamine-beta-hydroxylase by disulfiram). The mechanism of toxicity (direct or idiosyncractic) remain unclear. Disulfiram has been used safely in millions of people since 1948, and we have only few cases reports of severe toxicity. From a practical point of view, treated patients should benefit by a neurological examination once a month, ophtalmological examination every 2 months, and hepatic enzymes monitored twice a month during the 2 first months. This is the price to prevent and to detect side effects of disulfiram therapy.

Adult↗

PubMed1995

[Neglect of the representational space: demonstration by mental evocation of the map of France].

Neglect of the representational space has been shown in 8 patients asked to evoke mentally the map of France and to name as many towns as possible successively on each side of a vertical axis splitting the map in two equivalent halves. They had first to imagine the map with an axis in the south-north direction and then with an axis in the reverse direction (north-south). The results were similar to those reported by Bisiach and Luzzatti (1979). They reflect a disturbance of the mechanisms involved in conscious representation of space. In addition we report on the effects of vestibular stimulation on the reversibility of representational neglect in 3 patients. These preliminary results provide support for the idea that vestibular stimulation would play centrally by restoring the symmetry of the internal representation of egocentric space.

Analysis of Variance↗