Abnormal Movement Patterns in Hemiplegia

Abstract

All the balance reactions and smooth, harmonious movement sequences described in Chap. 2 are dependent upon normal postural tone and sensation. The prerequisite for normal tone, sensation and movement is unimpaired nerve impulse conduction in a great variety of postures and activities, which necessitates considerable mobility within the nervous system itself. Any loss of the neurodynamic properties of the system will inevitably alter muscle tone and movement patterns, as explained in Chap. 15. “When a person loses the normal mechanics of the nervous system, certain dynamic and static postural patterns emerge to allow the patient to best cope with the neural movement loss” (Butler 1991). Interestingly, Butler illustrates an abnormal or “antalgic” nervous system posture as an example, which, although that adopted by an orthopaedic patient, reveals many postural abnormalities usually associated with hemiplegia. All active movements occur as the result of muscle contractions, but it should not be forgotten that, “a muscle can only be as efficient as the nerve which supplies it!” (Rolf 1997b). A healthy, mobile nervous system is therefore indispensable for the performance of normal movements. The coordinated movements and variation of posture required for skilled function are also dependent upon the ability to move selectively those parts of the body required for the task, while inhibiting the activity of the other parts. According to Bach-y-Rita and Balliet (1987), “Inhibition is much more important than is generally appreciated; much of what is taught emphasizes excitation while virtually ignoring inhibition”. In fact, inhibition of overactivity is one of the most important roles of the central nervous system, and there are more inhibitory than excitatory pathways in the brain stem and spinal cord. Every skilled activity can be said to be surrounded by a “wall of inhibition” (Kottke 1978). When a new skill is being learned, through such inhibition, overactivity decreases proportionally as the performer becomes more skilled.