Co-contraction of antagonist muscles is characteristic of spasticity arising from perinatal brain damage but not in spasticity occurring after brain damage in adulthood. Such co-contraction is a normal feature of early post-natal motor development. Heteronymous, monosynaptic Group Ia projections from biceps brachii to both the antagonist triceps brachii and to other synergist and non-synergist muscles of the upper limb occur in the newborn baby and become restricted during the first 4 years to motor neurons of primarily synergistic muscles. Longitudinal and cross-sectional studies have been performed to test the hypothesis that inappropriate heteronymous excitatory projections persist in children with perinatal brain damage who develop spasticity. Subjects with spasticity, from brain damage acquired in adulthood were also studied to determine if these projections simply become unmasked as part of spasticity, independent of the age of occurrence of the brain damage. Twenty-nine healthy newborn babies and 29 at high risk for cerebral palsy, 12 of whom developed spastic quadriparesis, were studied longitudinally for 4 years. Thirty-eight subjects, aged 8-30 years, with spasticity of perinatal origin (11 hemiplegic, 11 quadriplegic, 16 with Rett syndrome) and 11 subjects with stroke in adulthood and spastic hemiplegia were also studied. The results were compared with those obtained in 372 normal subjects aged from birth to 55 years. Small taps were delivered to the tendon of biceps brachii using an electromechanical tapper. Surface EMG was recorded from biceps and triceps brachii, pectoralis major and deltoid. In the longitudinal study, those developing spastic quadriparesis showed persistent low thresholds for the homonymous phasic stretch reflex, which had abnormally short onset latencies. There was persistence of short onset heteronymous excitatory responses in triceps brachii, while a normal pattern of restriction of heteronymous responses to pectoralis major and deltoid occurred. The same pattern was observed in older subject groups with spasticity of perinatal origin. In adults with hemiplegia following stroke the threshold of the homonymous phasic stretch reflex was low, but it had a normal onset latency. There was no evidence of abnormal heteronymous excitatory responses. In conclusion, exaggerated excitatory responses to primary muscle afferent input were observed in the homonymous (biceps brachii) and antagonist (triceps brachii) motor neurons in subjects with spasticity arising from perinatal brain damage. They are likely to play an important role in the predominant co-contraction of agonist/antagonist muscles during voluntary movement observed in subjects with spastic cerebral palsy.
Objective. To determine the efficacy of an individualized, family-based intervention with preterm infants and their families. Design. Randomized, repeated measures intervention outcome study. Setting. Level III neonatal intensive care nursery. Patients. Random sample of 34 preterm infants ≤1500 g and their families. Interventions. Individualized, family-based intervention during the hospitalization and transition to home addressed problems identified by parents in four domains including: infant behavior and characteristics, family organization and functioning, caregiving environment, and home discharge and community resources. Measurements and Main Results. Standardized questionnaires were administered at baseline and discharge to mothers, and predischarge bottle-feeding interactions were videotaped and coded by two blinded observers. Results were in favor of intervention (Int) versus control (Con) mothers (baseline; discharge) (P < .05) on the Parental Stressor Scale Sights and Sounds subscale (Int 2.4 ± 1.0; 2.0 ± 0.8 vs Con 2.4 ± 0.9; 2.6 ± 0.8); Child's Appearance and Behavior subscale (Int 2.8 ± 1.0; 2.5 ± 1.1 vs Con 2.8 ± 0.8; 3.1 ± 0.6); and Total Stressor Score (Int 93.9 ± 36.6; 72.3 ± 41.8 vs Con 87.5 ± 26.7; 87.8 ± 26.2). On the Beck Depression Inventory, intervention mothers had significant decreases in depressive symptoms (39%; 11%) vs control mothers (31%; 44%). Maternal self-esteem in both groups improved over time. There were no significant group differences in family environment. During feeding interactions, intervention infants grimaced (P < .001) and gagged (P < .05) less than controls. Intervention mothers less frequently interrupted feedings (P < .001); less frequently stimulated infant sucking (P < .01); smiled more (P < .001); vocalized more (P < .01); demonstrated greater sensitivity to infant behavior (P < .001), better quality of physical contact (P < .001), and more positive affect (P < .01). Conclusions. Individualized, family-based intervention appears to reduce maternal stress and depression, and to enhance early mother-infant feeding interactions. Further research is needed to determine whether these short-term beneficial effects persist beyond the newborn period.
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