The law of shunting reaction
- A phenomenon of efferent inflow being short-circuited either temporarily (the athetoid patient) or more permanently (the spastic patient) into patterns of abnormal co ordination released from higher inhibitory control.
- A patient with abnormal motor out put who moves abnormally in response to motivation & normal sensory inputs will still only experiences & memories the sensation of his abnormal movement of excessive efforts & lack of co ordination.
- He will therefore be unable to develop & lay down the memory of normal sensory motor patterns.
Application of shunting rule in treatment
- Magnus stated that at any movement during a movement, the central nervous system mirrors the state of elongation & contraction of the musculature.
- It is therefore, the body musculature which controls the opening & closing of synaptic connections within the central nervous system & determines the subsequent outflow.
- The greatest effect of shunting is obtained from the proximal parts of the body.
- In accepting the role of shunting, it is clear that we have a means of influencing and changing motor out put from periphery, i. e. from proprioceptive system, beginning usually with proximal parts of the body.
- By changing the relative positions of the parts of the body & limbs when handling a hemiplegic patient, we can change his abnormal postural pattern & stop (inhibit) the outflow of excitation in to established shunts of spastic patterns.
- We can at the same time direct patient’s active responses into the channels of higher integrated & complex pattern of more normal coordination.
- In this way, spasticity becomes reduced by inhibition of its patterns, while more normal postural reactions & movement are facilitated.
