NeuroRehabilitation - Volume 10, issue 2

Authors: Dietz, V.

Article Type: Introduction

DOI: 10.3233/NRE-1998-10201

Citation: NeuroRehabilitation, vol. 10, no. 2, pp. 89-89, 1998

Authors: Illert, M. | Boczek-Funcke, A.

Article Type: Research Article

Abstract: The recovery of motor functions after CNS lesions is a complex action with several restitutional processes occurring in parallel. To describe the function-oriented phenomena and to understand the organisational changes within the neuronal systems in question there is the urgent need for investigations relating the impairment of defined neuronal systems with quantitative and qualitative changes of a behavioural motor paradigm. The system of the C3-C4 propriospinal neurones in the cat is one of the models which could serve such a purpose. It relays disynaptic excitation from several supraspinal motor centres to forelimb motoneurones, parallel to the input to the motoneurones …from the same centres via the segmental reflex apparatus. Behavioural studies indicate that the motor command for reaching towards a target with the forelimb is to a large extent mediated in the C3–C4 propriospinal system, whereas the command for taking of the object seems to be organised in the interneuronal systems of the forelimb segments, not depending on an integration in the C3–C4 propriospinal relay. The paper reviews different studies which have analysed the effects of lesions of various motor centres and tracts on this behavioural paradigm. It becomes evident that different components of the motor behaviour have different restitutional capacities. The quantitative analysis of the various dimensions of the cat forelimb together with the possibility to perform localised lesions within defined neuronal systems make this experimental approach suited for the investigation of integrative aspects related to the restitution of function within systems organising motor behaviour. Show more

Keywords: C3-C4 propriospinal system, Forelimb movements, Motor behaviour, X-ray cinematography, Spinal cord lesions, Movement kinematics

DOI: 10.3233/NRE-1998-10202

Citation: NeuroRehabilitation, vol. 10, no. 2, pp. 91-106, 1998

Authors: Duysens, J. | Pearson, K.G.

Article Type: Research Article

Abstract: On the assumption that locomotion is partly produced by a central pattern generator (CPG) in the spinal cord of both cat and man, it is essential to learn more about how such a CPG is controlled by sensory input produced during gait. For the cat there is evidence that load receptor input both from extensor muscles and from cutaneous receptors from the foot, is able to reinforce the ongoing extensor activity in the stance phase and delay the ensuing swing phase. Original data on electrical stimulation of nerves in walking premammillary cats with one hindlimb fixed, support the notion that …this type of load afferent input acts directly on the CPG. A second potential source of sensory input on the CPG is derived from sensory signals related to hip position. One would therefore expect that hip position is a more tightly controlled variable than the position of other joints. This was investigated by measuring these angles under conditions of constrained gait (crouch). It was found that cats indeed maintained the maximum excursions of hip flexion and extension within stricter limits than the corresponding angles at other joints. Finally, experiments on hip joint denervation show that there is very little effect on step cycle parameters, thereby supporting the idea that the important hip signal is unlikely to be derived from hip joint afferents. It is suggested that procedures aimed at activating the locomotor CPG in SCI patients could benefit from the use of periodic stimulation of ankle muscle load afferents and hip flexor stretch receptors. Show more

Keywords: Cat, Muscle afferents, Skin afferents, Reflex control of locomotion, Central pattern generator (CPG)

DOI: 10.3233/NRE-1998-10203

Citation: NeuroRehabilitation, vol. 10, no. 2, pp. 107-118, 1998

Authors: van de Meent, Henk | Schwab, Martin E.

Article Type: Research Article

Abstract: The ability of the adult central nervous system to recover from injury is highly limited. Limiting factors in the repair process appear to be a combination of an inhibiting environment and the restricted intrinsic capacity of the neuron to reactivate its regenerative machinery. Studies using experimental treatments designed to neutralize the inhibiting environmental conditions and/or to enhance the intrinsic regenerative capacity have brought anatomical evidence of axonal regrowth over long distances in the injured spinal cord. In addition, function recovery in association with axonal regrowth has been reported. This article reviews recent developments in experimental approaches to the repair of …the injured spinal cord in mammals. Show more

Keywords: Spinal cord injury, Regeneration

DOI: 10.3233/NRE-1998-10204

Citation: NeuroRehabilitation, vol. 10, no. 2, pp. 119-129, 1998

Authors: Hallett, Mark | Wassermann, Eric M. | Cohen, Leonardo G. | Chmielowska, Jolanta | Gerloff, Christian

Article Type: Research Article

Abstract: Patients who have suffered hemiplegia from stroke may have some spontaneous recovery that is likely due to reorganization within the cerebral cortex. Understanding this physiology should be useful in devising ways to help patients have better improvement. Techniques, such as transcranial magnetic stimulation and neuroimaging with positron emission tomography, can be used to demonstrate the organization of the human motor system and do reveal plastic reorganization in a number of situations. In relation to stroke, the best recoveries are seen when there is preservation of the corticospinal tract from the hemisphere contralateral to the weakness, but it may well be …that areas nearby to the normal motor output areas can partially substitute. There is some evidence for increased corticospinal tract activity originating ipsilateral to the hemiplegia in patients, but this may actually be associated with worse recovery. Patterns of use can influence cortical organization and should play a valuable role in rehabilitation. Certain drugs may affect this process either positively or negatively. Show more

Keywords: Stroke, Hemiplegia, Plasticity, Rehabilitation, Corticospinal tract, Transcranial magnetic stimulation, Positron emission tomography

DOI: 10.3233/NRE-1998-10205

Citation: NeuroRehabilitation, vol. 10, no. 2, pp. 131-142, 1998

Authors: Roelcke, Ulrich | Leenders, Klaus L. | Curt, Armin | Dietz, Volker

Article Type: Research Article

Abstract: Positron emission tomography (PET) provides non-invasive measures of brain physiology and biochemistry in quantitative terms and is frequently applied to the investigation of cerebral blood flow (CBF) and glucose metabolism (CMRGlu) in health and disease. Both CBF and CMRGlu may serve as indicators of regional neuronal activity and may provide tools for functional brain imaging of cerebral plasticity following central nervous system injury. This review will briefly describe the technique currently used to investigate brain function with PET and will summarize results on motor activation in healthy subjects. It will further illustrate how resting brain energy metabolism changes following transverse …spinal cord injury. In addition, data from activation studies in stroke patients will be presented which indicate that recovery of motor function is associated with the recruitment of cortical regions of the non-damaged hemisphere and with the extension of activated brain areas adjacent to brain lesions themselves. Show more

Keywords: Central nervous system injury, Cerebral sensorimotor systems, Positron emission tomography, Perfusion, Metabolism

DOI: 10.3233/NRE-1998-10206

Citation: NeuroRehabilitation, vol. 10, no. 2, pp. 143-149, 1998

Authors: Nielsen, Jørgen F. | Andersen, Jacob B. | Barbeau, Hughes | Sinkjær, Thomas

Article Type: Research Article

Abstract: The input-output properties of the soleus stretch reflex during walking and sitting were examined in 11 spastic stroke patients and 10 healthy subjects. In the early swing phase, the threshold of the input-output relation was significantly lower in the patient group – on average 108°/s compared to 309°/s in the control group (P=0.02). The slope of the input-output properties was unchanged in patients and in control subjects (P=0.39). In stroke patients we found a minor, but significant, difference in threshold with 108°/s in the early swing phase compared to 74°/s in sitting position at matched TA EMG activity (P=0.01). Furthermore, …we found an unchanged slope of 0.25μVs/° during walking and 0.28μVs/° in the sitting position (P=0.21). In contrast, control subjects showed a large difference in the threshold in the early swing phase during walking (309°/s) compared with findings in the sitting position at a matched TA EMG activity (71°/s, P=0.004). The slope was unchanged during walking and when the subject was sitting (P=0.22). There was a significant correlation between clinical spasticity score and stretch reflex threshold in the early swing phase (P=−0.61, P=0.04) and between clinical spasticity score and the slope in the early swing phase (P=0.72, P=0.009). It is concluded that in the early swing phase, the markedly reduced soleus stretch reflex threshold was preventing the stroke patients from making fast dorsiflexion of the foot at the ankle joint and thereby impairing the walking speed. Show more

Keywords: Soleus stretch reflex, Gain, Threshold, Walking, Stroke, Spasticity

DOI: 10.3233/NRE-1998-10207

Citation: NeuroRehabilitation, vol. 10, no. 2, pp. 151-166, 1998