[Focus on current research: improving the mobility of paraplegic patients]

Since the first paraplegic centre was established in 1945, life expectancy and life quality of paraplegics have considerably improved. However, endeavours to enhance the mobility of these patients have been less successful. The most promising approach, functional electric stimulation of paralysed muscles, is poorly accepted by patients at present because of technical problems. This study describes current approaches which may help to improve patients' mobility. A central motor lesion is perceived by the patient as a movement disorder of the legs, e.g. a gait disorder. Neurological investigation indicates, on the basis of exaggerated tendon reflexes and increased resistance of the non-activated leg muscles to stretching, that spastic paresis underlies the movement disorder. This combination of symptoms and clinical (physical) signs suggests that the exaggerated tendon tap reflexes are responsible for muscle hypertonia and the latter causes the movement disorder. However, electromyography during movement shows that the exaggerated short latency reflexes are associated with loss or attenuation of the functionally essential polysynaptic spinal reflexes. In the event of impaired supraspinal control there is loss of monosynaptic stretch reflex inhibition combined with reduced facilitation of polysynaptic spinal reflexes. Development of tension in tonically active calf muscles in patients with spastic paresis during gait occurs independently of spinal reflex activity. From electrophysiological and histological observations it can be assumed that transformation of motor units resulting in simple and less well adapted regulation of muscle tone allows movements such as gait. The reduction of muscle tone obtained with antispastic drugs is usually associated with paresis and may therefore hamper locomotion. Locomotor training represents a new attempt to improve the mobility of patients with incomplete paraplegia. It includes activation of neuronal circuits within the spinal cord below the level of the lesion. In incomplete paraplegics a coordinated leg muscle activation pattern and corresponding leg movements can be triggered and trained in patients standing on a treadmill with partial weight support. Improvement of training of the spinal cord locomotor centre can be expected from triggering of spinal cord reflexes and regeneration of spinal tract fibres, which is expected to be possible in the near future.