Ideomotor Dyspraxia
Ideomotor dyspraxia is the most widely recognised type of dyspraxia. In ideomotor dyspraxia the connections which lead from the idea processing and planning areas of the brain to the motor cortex are damaged. When the person is verbally instructed to carry out an action or to mime an action, it is this damage to the connections between areas of the brain which impairs their ability to carry out the requested action. The person may subsequently make errors in the sequence and timing of movements, the amplitude of movements and in the positioning of limbs.
When asked to carry out an action, the person with ideomotor dyspraxia knows what they want to do; they have the concept of what sequence of movements are required (the ‘motor programme’) but are unable to execute the plan of action by putting together the necessary movements. Ideomotor dyspraxia is characterised by deficits in the ability to carry out skilled movements when given a verbal command e.g. when asked to mime an action or when trying to imitate an action. They are unable to translate an idea into the movements that are required.
However, the person with ideomotor dyspraxia is more able to carry out actions spontaneously e.g. the person with ideomotor dyspraxia knows what a toothbrush is for, has the ‘concept’ of which movements are required to perform desired action but may be unable to demonstrate/mime the use of a toothbrush when asked. However, at night, when getting ready for bed, they may use the toothbrush appropriately as part of their automatic night time routine.
Ideational Dyspraxia
The person with ideational dyspraxia has damage to the areas of the brain which are responsible for processing and planning an action. They have lost the ‘concept’ of how to perform actions in order to use an object. They are unable to select the correct ‘motor programme’ (sequence of movements) needed to carry out an action. Thus the ability of these parts of the brain to relay the appropriate plan for the desired action to the motor cortex of the brain is impaired.
The person with ideational dyspraxia may use an object in an incorrect way and have difficulty carrying out the appropriate sequence of actions in order to perform a task. For example, the person may know what a toothbrush is, but has ‘lost’ the concept of the planned, sequence of movements required for its use. The person may use the item incorrectly: hold it incorrectly, try to brush hair with it, fail to put all the necessary movements together in the right order to perform the task.
Ideational dyspraxia can cause the person with brain injury to be significantly disabled in terms of their ability to carry out everyday, functional tasks.