RESUMEN
OBJECTIVE: To investigate the predictive value of paired transcranial magnetic stimulation (TMS) at rest in stroke patients in comparison with the predictive value derived from data obtained by single TMS during facilitation. METHODS: Fifty-six patients with a single ischemic lesion and no electromyographic responses from single TMS in the resting affected hand muscles participated in the study. TMS assessment was performed 32 days post-stroke. It consisted of a single stimulation at maximal output during facilitation (controlateral hand grip and elbow flexion) and a paired-pulse stimulation at rest with two stimuli at maximal output at interstimulus intervals ranging from 15 to 100 ms. Two blind clinical assessments using the 'motricity index' were carried out 26 and 76 days post-stroke. RESULTS: Thirty-seven percent of patients were responsive to single TMS during facilitation, had better clinical scores at both evaluations and better clinical recovery. Fifty-four percent of patients responded to paired TMS, had better clinical scores at the second evaluation and better clinical recovery. All patients who responded to the single stimulation paradigm also responded to the paired one. CONCLUSIONS: A positive correlation was found between the responsiveness to both the TMS paradigms (facilitation procedure and paired stimulation) and clinical recovery. This underlines the importance of facilitation during single TMS in stroke patients and suggests that paired TMS at rest might supplement this procedure in stroke studies.
Asunto(s)
Isquemia Encefálica/diagnóstico , Isquemia Encefálica/fisiopatología , Potenciales Evocados Motores , Accidente Cerebrovascular/diagnóstico , Accidente Cerebrovascular/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Estimulación Eléctrica , Femenino , Humanos , Magnetismo , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Pronóstico , Recuperación de la FunciónRESUMEN
Spastic diplegia is commonly due to periventricular leucomalacia associated with premature birth. It is also a feature of Angelman syndrome (AS), a neurogenetic disorder with developmental delay, absent speech and mirthful behaviour. We studied the kinematics and kinetics of the squatting movement and associated electromyographic (EMG) activities in 20 children with spastic diplegia associated with periventricular leucomalacia (SDPL) or AS and 18 unimpaired children. While movement of normal subjects consisted of vertical translation of most body segments, the movement of SDPL children was operated around the fixed knee with backward shift of the hip, and AS children performed a forward flexion of the trunk over the thigh. Trunk stability was correlated with movement velocity in both pathological groups. In normal subjects, anticipatory EMG pattern consisted of silencing of hamstring muscle tonic activity prior to movement onset. This deactivation was not present in spastic diplegia. In SDPL, anticipatory overactivation of ankle joint actuators was recorded and tonic co-contraction persisted throughout the movement. In AS, rhythmic EMG bursting was seen during the movement. Shoulder, hip and knee trajectories in the sagittal plane showed marked within-group stereotypies in orientation, shape and length. The patterns in both pathological groups were therefore distinctive. We speculate that they reflect corticospinal impairment in SDPL and combined corticospinal and cerebellar dysfunction in AS.
Asunto(s)
Síndrome de Angelman/complicaciones , Parálisis Cerebral/etiología , Parálisis Cerebral/fisiopatología , Recien Nacido Prematuro , Articulaciones/fisiopatología , Leucomalacia Periventricular/complicaciones , Fenómenos Biomecánicos , Niño , Electromiografía , Humanos , Recién Nacido , Pierna/fisiopatología , Movimiento , Valores de ReferenciaRESUMEN
We analysed the co-ordination of the elevation angles of the thigh (alpha(t)), shank (alpha(s)) and foot (alpha(f)) during walking in 19 adults and 21 children (aged 11--144 months), including the very first unsupported steps in four. Cross-correlation functions (CCF) maturation of pairs of elevation angles was quantified by a global error parameter (Et((CCF))) reflecting the difference between particular CCF value of toddlers and mean adult value (Ea((CCF))). During the very first step, Et((CCF)) could be five times higher than Ea((CCF)). With walking experience, Et((CCF)) for both alpha(t)-alpha(s) and alpha(s)-alpha(f) pairs evolved following a biexponential profile, with a fast time constant below 6 months. Adult-like CCF parameters were reached earlier for alpha(s)-alpha(f) than alpha(t)-alpha(s), indicating disto-proximal maturation of the temporal co-ordination of the lower limb segments in human locomotion.
Asunto(s)
Envejecimiento/fisiología , Sistema Nervioso Central/crecimiento & desarrollo , Marcha/fisiología , Pierna/fisiología , Locomoción/fisiología , Músculo Esquelético/fisiología , Adulto , Fenómenos Biomecánicos , Sistema Nervioso Central/fisiología , Niño , Preescolar , Femenino , Humanos , Lactante , Pierna/inervación , Masculino , Modelos Neurológicos , Músculo Esquelético/inervación , Factores de TiempoRESUMEN
The purpose of this study is to analyze the coordination patterns of the elevation angles of lower limb segments following the onset of unsupported walking in children and to look for the existence of a planar covariation rule as previously described in adult human locomotion. The kinematic patterns of locomotion were recorded in 21 children (11-144 months of age) and 19 adults. In 4 children we monitored the very first unsupported steps. The extent to which the covariation of thigh, shank, and foot angles was constrained on a plane in 3D space was assessed by means of orthogonal regression and statistically quantified by means of principal component analysis. The orientation of the covariation plane of the children was compared with the mean value of the adults' plane. Trunk stability with respect to the vertical was assessed in both the frontal (roll) and sagittal (pitch) planes. The evolution with walking experience of the plane orientation and trunk oscillations demonstrated biexponential profiles with a relatively fast time constant (< 6 months after the onset of unsupported locomotion) followed by a much slower progression toward adult values. The initial fast changes of these walking parameters did not parallel the slow, monotonic maturation of anthropometric parameters. The early emergence of the covariation plane orientation and its correlation with trunk vertical stability reflect the dynamic integration of postural equilibrium and forward propulsion in a gravity-centered frame. The results support the view that the planar covariation reflects a coordinated, centrally controlled behavior, in addition to biomechanical constraints. The refinement of the planar covariation while morphological variables drastically change as the child grows implies a continuous update of the neural command.
Asunto(s)
Locomoción/fisiología , Desempeño Psicomotor/fisiología , Envejecimiento/fisiología , Fenómenos Biomecánicos , Niño , Preescolar , Femenino , Humanos , Lactante , Pierna/fisiología , Masculino , Tórax/fisiologíaRESUMEN
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.
Asunto(s)
Parálisis Cerebral/fisiopatología , Movimientos de la Cabeza/fisiología , Postura/fisiología , Niño , Preescolar , Humanos , Recién Nacido , Leucomalacia Periventricular/fisiopatología , Reflejo Vestibuloocular/fisiologíaRESUMEN
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.
Asunto(s)
Baclofeno/farmacología , Marcha/efectos de los fármacos , Relajantes Musculares Centrales/farmacología , Paraparesia Espástica/fisiopatología , Adulto , Baclofeno/administración & dosificación , Baclofeno/uso terapéutico , Fenómenos Biomecánicos , Humanos , Inyecciones Espinales , Locomoción/efectos de los fármacos , Relajantes Musculares Centrales/administración & dosificación , Relajantes Musculares Centrales/uso terapéutico , Paraparesia Espástica/genética , Valores de Referencia , Factores de TiempoRESUMEN
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.