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At least 199 records · Page 11Linked to original sources
PubMed1998

Parkinsonian syndrome as a neurological manifestation of Behçet's disease.

BACKGROUND: The central nervous system is often involved in Behcet's disease. Most common are meningoencephalitic and brain stem syndromes. Although basal ganglia involvement is not an uncommon finding on necropsy, there are only single reports on extrapyramidal syndromes-dyskinesia, chorea and Parkinsonism in patients with Behcet's disease. CASE STUDY: We report a patient fulfilling the criteria of the International Study Group for Behcet's disease. He had recurrent oral ulcerations, bilateral posterior uveitis and retinal vasculitis, skin papules and pustules, and recurrent monoarthritis. Neurologic examination revealed pseudobulbar palsy, slight and asymmetric bilateral pyramidal syndrome, muscle rigidity involving the four limbs, bradykinesia, masked face, and impaired postural reflexes. There was postural tremor in the extremities and myoclonic jerks involving the tongue and face muscles. Magnetic resonance imaging demonstrated small bilateral multifocal hyperintense lesions, with right predilection, involving the periventricular white matter, brain stem and basal ganglia. CONCLUSIONS: The Parkinsonian syndrome found in our patient might be due to involvement of both substantia nigra and basal ganglia. This case further emphasizes the wide spectrum of the neurological manifestations of Behcet's disease.

Adult↗
PubMed1997

Neurological dysfunction and hyperactive behavior associated with antiphospholipid antibodies. A mouse model.

Antiphospholipid antibodies (aPL) have been associated with various neurological manifestations, but the underlying mechanism has not been elucidated. We assessed mice with induced experimental antiphospholipid syndrome (APS) for neurological and behavioral changes. After immunization with monoclonal human anticardiolipin antibody (H-3), female BALB/c mice developed elevated levels of circulating anti-negatively charged phospholipids (aPL), anti-beta2-glycoprotein I (abeta2GPI), and anti-endothelial cell antibodies (AECA), along with clinical manifestations of APS like thrombocytopenia and fetus resorption. APS mice were impaired neurologically and performed several reflexes less accurately compared to the controls, including placing reflex (P < 0.05), postural reflex (P < 0.05), and grip test (P = 0.05). The APS mice also exhibited hyperactive behavior in an open field, which tests spatial behavior (P < 0.03), and displayed impaired motor coordination on a rotating bar. aPL in combination with abeta2GPI and AECA is probably involved in the neurological and behavioral defects shown in mice with experimental APS.

Animals↗
PubMed1994

[Evaluation of posturally-induced vasomotor reflexes of the leg in the healthy subject].

The authors' aim was to assess, using a routinely usable methodology, the distal vasomotor reflexes induced by postural changes of the lower limbs in 36 healthy volunteers (18 women and 18 men, mean age: 22.3 years, range 19-26). These distal vasomotor changes were recorded on the great toe using mercury-strain-gauge plethysmography. In the first step, the authors have measured the veno-arterial reflex obtained by elective lowering of the leg, the subject lying strictly horizontally under standardized conditions. Secondly was assessed the distal vasomotor reflex due to orthostatism (seated position, legs hanging). Correlations between these postural reflexes and height, weight, sex, length of the lower limbs, femoral venous diameters assessed by echography were studied. The veno-arterial reflex obtained by elective verticalization of the leg (0.68 +/- 0.21) corresponds to a 32% mean decrease in the amplitude of the plethysmographic recording as compared to the initial amplitude in horizontal position. It is all the more marked as the subject is male and the leg is long, thus inducing a equivalent change of hydrostatic venous pressure during verticalization of this part of the limb. On the other hand, this adaptative reflex appears all the more intense as the basal vascular tone in horizontal position is low. Passing to orthostatism induces a distal vasoconstriction corresponding to a 51% mean decrease in the amplitude of the plethysmographic signal as compared to the initial basal amplitude. This general reflex, playing a part in the keeping of hemodynamic conditions when passing to orthostatism, appeared significantly correlated to the diameter of the common femoral vein when the subject is lying horizontally.

Adult↗
PubMed1996

Loop gain of reflexes controlling human standing measured with the use of postural and vestibular disturbances.

1. In this study we measured the loop gain of postural reflexes in standing human subjects. Reflex activity is conventionally described in terms of the muscle activation arising from a perturbation, but in this study the ability of the evoked muscle activity to correct the perturbation was also measured, and the behavior of the entire feedback loop is described. 2. A weak continuous random perturbation was applied at waist level to standing subjects. The effects of the perturbation on body sway and soleus electromyogram (EMG) were identified by cross-correlation, and spectral analysis was used to estimate the open-loop reflex transmission characteristics (i.e., sway to EMG). Under the same conditions, activity in the leg muscles was evoked by galvanic vestibular stimulation with the use of a continuous randomly varying current. The effects on soleus EMG and the subsequent body sway were identified by cross-correlation. This allowed calculation of the open-loop muscle and load behavior (i.e., EMG to sway). From these open-loop reflex and muscle and load transfer functions, the loop gain and phase were calculated. 3. In addition to the gain of the feedback loop, the study describes the transmission characteristics of reflex responses in the leg muscles associated with body sway and the effects of excluding visual and proprioceptive contributions to the response; the transfer function of human soleus with a stimulus that preserves the normal recruitment of motoneurons, including the effects of different load conditions on the muscle; and the transmission characteristics of vestibular pathways that evoke responses in the leg muscles during standing in situations that might modify the reflexes. 4. When standing, the loop gain of reflex feedback is approximately unity and is unchanged by eye closure and stability of support. Reflex transmission introduced a marked phase advance, and this served to offset most of the phase lag introduced by muscle and load. The residual phase lag could explain the frequency of tremor observed during standing (6-8 Hz). 5. The gain of the feedback loop (approximately 1) is higher than suggested by both previous estimates and theoretical considerations, but is still insufficient to explain the stability of normal human standing. This implies that, although sensory information is used to control posture, it does not do so exclusively through a negative feedback control process. The experimental findings are consistent with a reflex response based on a feed-forward process, and this would result in prediction of the response necessary to counteract a postural disturbance.

Adult↗
PubMed1984

Etiology of idiopathic scoliosis.

The following investigations concerning scoliosis are in progress at Tokushima University: (1) a study of the incidence of equilibrial dysfunction; (2) a study of the nature of dysequilibrium, with special reference to the origin (functional or organic); (3) a field survey of scoliosis associated with equilibrial dysfunction in school children; (4) a study of experimental and clinical metabolic disturbances in scoliosis; (5) a study of postural reflex in experimental animals; (6) a study of scoliosis in animals with experimentally produced brain stem lesions; and (7) a study of scoliosis in animals with experimentally produced lesions in the posterior part of the hypothalamus. The hypothetic assumption is that dysfunction of the postural reflex regulation induced by functional or organic disorders at the brain stem center may play an important part in the development of idiopathic scoliosis during the period of rapid growth in children.

Adolescent↗
PubMed2001

[Gait disorders in Parkinson disease. Neuroanatomic and physiologic organization of gait].

GAIT IS A VOLUNTARY, AUTOMATIC AND REFLEX RHYTHMIC ACTIVITY: It is generated by a central pattern generator identified from animal models. This spinal gait generator (SGG) is controlled by various parts of the central nervous system: the descending tracts and locomotor regions of the brainstem, the cerebellum, the basal ganglia, the motor and parietal cortex and the hippocampus. Kinesthetic inputs which project to the SGG and the cerebellum, play an important role in the production of postural reflex responses; vestibular and visual inputs mainly control balance. GAIT MAINLY DEPENDS ON THE RELATIONSHIP BETWEEN POSTURE BALANCE AND MOVEMENT: As concerns posture each segment is under the control of both peripheral and central nervous systems and is used as a system of reference to organize movements of adjacent segments. Balance is maintained by sensory inputs which provide corrective mechanisms: anticipatory postural responses, reflex postural responses and voluntary responses. DIFFERENT DESCRIPTIVE PARAMETERS MAY BE PROPOSED: Analysis of kinematic (displacement, speed and acceleration of segments) and kinetic parameters during the four successive stages of gait (posture, initiation, rhythmic gait and return to the initial posture) provides an understanding of neurological gait disorders. In particular the relationship between the center of pressure and the center of gravity is used to analyze infraclinical gait abnormalities. NEW AND SOPHISTICATED INVESTIGATIONS METHODS ARE AVAILABLE: The optoelectronic system provides a tridimensional analysis of movement and can be combined with forceplate and electromyographic recordings. These methods constitute an interesting contribution to the clinical analysis of gait. CLASSIFICATION: This is established according to clinical data and the positionment of the lesion among the structures of the nervous system. The physiopathological approach is then specified taking into account the lesions of the muscular, skeletal and nervous structures.

Brain↗
PubMed1989

[Effects of early multimodal stimulation on preterm newborn infants].

During the last trimester of pregnancy, newborns are deprived of both maternal biorhythms, tactile, kinesthetic and auditory stimulation which characterize the intrauterine environment. The purpose of this study is to determine if supplemental multimodal stimulation improves neurobehavioral performance, increases weight gain and shortens hospital stay. Nine neonates with the following characteristics were included in an early multimodal stimulation program: 1) gestational age less than or equal to 34 weeks, 2) feeding through orogastric tubing, 3) hemodynamically stable, with no signs of hemorrhaging, infections, or any suggestion of neurological damage, convulsions or congenital malformations. A control group with the same characteristics was also included in the study. Risk factors for each patient were evaluated and their evolution was closely watched while still in the hospital. Both the postural reflexes and neurobehavioral performance were assessed at the time the child left the hospital and a month afterwards. Statistically significant differences were found in the neurobehavioral performance and postural reflexes of those included in the study group.

Acoustic Stimulation↗
PubMedDate not supplied

[The effect of weak electromagnetic fields and ionizing radiation on the regeneration of the murine sciatic nerve].

The influence of X-ray impulses (dose 0.003 cGy, longitudity 10 ns) and EM impulses (induction 0.003 mT) on sciatic nerve regeneration in mice after crush lesion was studied. Limb jerk amplitude at electric stimulation of nerve and postural reflex in thin rod in X + EM and EM groups were restored within 13th days after lesion, in control group within 15 days (p < 0.05). The beginning of repairing of postural reflex was early in X + EM group than on EM group, rehabilitation of limb jerk amplitude--in EM group. Histological examination demonstrated that myelin degenerated in EM group more rapidly as compared with X + EM and control groups. This data suppose different effects of EM and X + EM impulses on nerve-regenerating processes.

Animals↗
PubMed1994

THE POSITION-DEPENDENT NATURE OF POSTURAL RESISTANCE REFLEXES IN THE LOCUST

The resistance reflexes of tibial extensor and flexor muscles, of all six legs in the locust, show changes in gain at different femur&shy;tibia angles (FTA). In all muscles the gain is high for small angles (near full flexion) and low for large angles (near full extension, approximately 160 &deg;). An exception occurs in the mesothoracic flexor muscle, which shows two modes: one as above and another in which maximum gain occurs at 100&shy;120 &deg; FTA. The position-dependent character is evident at each stage of the reflex pathway: motor neurone, non-spiking interneurone and femoral chordotonal organ (the afferent source of the reflex). We conclude that position-dependency originates from a decrease in the number of phasic femoral chordotonal organ neurones sensitive to joint movement as larger FTAs are approached. Position-dependency is only roughly correlated with the postural FTAs most commonly observed in the meso- and metathoracic legs of unrestrained resting locusts; no such correlation was evident for prothoracic legs. We propose that the major role of position-dependency is to allow resistance reflexes efficiently to counter torque introduced onto the femur&shy;tibia joint by perturbations in the horizontal plane when the insect rests on a horizontal substratum and in the vertical plane when it rests on a vertical substratum.

Journal Article↗
PubMed1994

Control of posture in patients with neurologically asymptomatic HIV infection and patients with beginning HIV-1-related encephalopathy.

OBJECTIVE: Stance control measurements (sway velocity, sway area, and postural reflexes) were performed in 36 patients with neurologically asymptomatic human immunodeficiency virus infection (HIV) and in 10 patients with beginning HIV type 1 (HIV-1)-related encephalopathy. All recordings were performed using a movable platform system. OBSERVATIONS: Static posturography and postural reflexes revealed pathologic results in patients with beginning HIV-1-related encephalopathy and in about 25% of patients with nonsymptomatic HIV infection in comparison with age- and sex-matched control subjects. CONCLUSIONS: Postural control is well preserved in early HIV infection; thus, it is not an appropriate measure for detecting subclinical deficits, but disturbances of postural control seem to be one of the first neurological abnormalities in patients with beginning HIV-1-related encephalopathy.

AIDS Dementia Complex↗
PubMed1997

Transient middle cerebral artery occlusion by intraluminal suture: II. Neurological deficits, and pixel-based correlation of histopathology with local blood flow and glucose utilization.

We conducted a pixel-based analysis of the acute hemodynamic and metabolic determinants of infarctive histopathology in a reproducible model of temporary (2-hour) middle cerebral artery occlusion (MCAO) produced in rats by an intraluminal suture. Three-dimensional averaged image data sets of local cerebral blood flow (LCBF) and glucose utilization (LCMRglc) acquired in the companion study (Belayev et al., 1997) either at the end of a 2-hour period of MCAO or after 1 hour of recirculation were comapped (using digitized atlas-templates) with data sets depicting the frequency of histological infarction in a matched animal group (n = 8) in which 2 hours of MCAO was followed by 3-day survival, sequential neuro behavioral examinations, and perfusion-fixation and paraffin-embedding of brains for light-microscopic analysis. All rats developed marked postural-reflex and forelimb-placing deficits at 60 minutes of MCAO, signifying high-grade ischemia. Tactile placing deficits persisted during the 72-hour observation period while visual placing and postural-reflex abnormalities variably improved. Comapping of LCBF and histopathology showed that in those pixels destined to undergo infarction, LCBF measured at 2 hours of MCAO showed a sharp distributional peak centered at 0.14 mL/g/min. In 70% of pixels destined to infarct, LCBF at 2 hours of MCAO was 0.24 mL/g/min or below, and in 89% LCBF was below 0.47 mL/g/min (the upper limits of the ischemic core and penumbra, respectively, as defined in the companion study [Belayev et al., 1997]). Local cerebral glucose utilization measured at approximately 1 hour after 2 hours of MCAO was distributed bimodally in the previously ischemic hemisphere. The major peak, at 22 mumol/100g/min, coincided exactly with the distribution peak of pixels destined to undergo infarction, while in pixels with a zero probability of infarction, LCMRglc was higher by 12 to 13 mumol/100g/min. These results indicate that local blood flow at 2 hours of MCAO is a robust predictor of eventual infarction. Pixels with ischemic-core levels of LCBF (0% to 20% of control) have a 96% probability of infarction, while the fate of the penumbra is more heterogeneous: below LCBF of 0.35 mL/g/min, the probability of infarction is 92%, while approximately 20% pixels in the upper-penumbral LCBF range (30% to 40% of control) escape infarction. Our data strongly support the view that the likelihood of infarction within the ischemic penumbra is highly influenced by very subtle differences in early perfusion.

Animals↗
PubMed1991

Electrophysiological correlates of postural instability in Parkinson's disease.

Postural reflexes in response to sudden toe-up tilts of a supporting forceplate platform were studied in free-standing patients with stage III (N = 5) and stage IV (N = 5) Parkinson's disease and compared to 5 age- and sex-matched normals. Latencies of the short (SL), medium (ML) and long latency (LL) responses were normal in the patients. The normalized mean amplitudes of the ML responses were significantly increased only in the stage IV Parkinson patients (P less than 0.0005). The distal-proximal activation sequence of LL responses observed in all 5 controls was reversed in 1 of the stage III and 4 of the stage IV Parkinson patients. Both the enlargement of the ML response (P less than 0.01) and the inverted activation sequence of LL responses (P less than 0.01) were significantly correlated with severity of the disease. The data establish an association between abnormal modulation of postural reflexes in the lower extremity and clinically rated balance impairment in Parkinson's disease.

Aged↗
PubMed1977

Locomotor recovery after unilateral hindlimb deafferentation in cats.

After hindlimb deafferentation, recovery of locomotor patterns may be distinguished from recovery of accurate movements. Cats were timed while crossing wide runways requiring that locomotion be present, and narrow runways which require that it also be accurate. Locomotion recovers soon after deafferentation and becomes almost normal in speed, although accuracy is still absent. This accuracy returns 10 days postoperatively. Ventral root afferents with cell bodies in dorsal root ganglia are unnecessary for recovery. Postural reflexes (and other non-topographic feedback) are used as cues for limb guidance after removal of that limb's topographic feedback. Anatomical experiments show that a thoracic root sprouts during the recovery period. This sprouting may increase the potency of postural reflexes. Although lower thoracic roots contribute to recovery, they are not essential. Ipsilateral descending system are essential, and represent the final common path for all recovery after deaffernting a hindlimb. Contralateral descending and afferent systems alone cannot mediate overground locomotion. Thus there is a difference between the systems which mediate overground locomotion and those used by animals in treadmill locomotion or with L-DOPA or clonidine or brain stem stimulation. The proposed mechanism underlying recovery of accurate locomotion is behavioral substitution which may be faciliated by collateral sprouting of relevant systems.

Animals↗