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Apraxia and its clinical significance

Apraxia is the failure to carry out well organized voluntary movement, despite normal motor, sensory and co-ordination function. So there is a defect in the ability to carry out known acts in the absence of motor weakness, sensory loss or ataxia.
Consequently, the apraxic patient is unable to make use of objects, but their use can be recognized and described. It is tested by asking the patient to use objects I (lighting a cigar, copying a cube, star, duck) or to carry out or imitate certain movements.
Types of apraxia
  • Ideomotor apraxia
  • Ideational apraxia
  • Limb apraxia
  • Limb kinetic apraxia
  • Buccofacial paraxia
  • Dressing apraxia
  • Constructional apraxia
Ideomotor apraxia 
In this type of apraxia  automatic movement is normal patient is unable to do it on command, like blowing nose, pushing back hair etc. This refers to the condition where the patient is unable to carry out the motor command, inspite of adequate comprehension of the command and adequate motor and sensory functions to perform the act .It is the most frequent type of apraxia. Here the concept is normal, but execution is defective. In this type of apraxia patient  cannot perform imaginary acts but can do when the real object is given associated with aphasic syndrome—seen in lesion of the dominant parietal lobe
Ideational apraxia 
Carrying out the whole of complex movement is defective,but execution of different parts of movement is normal. This refer to the condition in which patients  is apraxic because they have lost the ideas idea  behind the skilled movements is lost. Here the patient with name and define an object. But do not know how manipulate the object when it is placed in the hand. There is  difficulty in the execution of goal directed sequence of movements. It is  associated with diffuse cortical dysfunction delirium and dementia—due to lesion of bilateral parietal lobes
For example -Lighting a cigarette is not possible.
But its different parts of movement is normal, like taking a match box, holding it correctly and opening it, taking the match, cigarette from cigarette box, etc.
Constructional apraxia
Failure to make design.Patient is unable to draw pictures like star
Koh's block - This is a series of blocks with colors occupying the whole half of one side, persons with constructional apraxia is unable to make the simplest design.
It is due to  lesion of nondoininant parietal lobe
Dressing apraxia 
Patient will put the cloth in the wrong way, unable to start the motion for dressing. lesion of nondominant parietal lobe
Limb kinetic apraxia.
This involves a specific motor disability of one limb. usuallv an arm, in the absence of gross weakness or ataxia. Limb Kinetic Apraxia difficulty in the use of tools seen in focal premotor cortex lesions and corticobasal ganglionic degeneration
Buccofacial apraxia.
The term  refers to the condition in which the patic  cannot perform learned skilled movements of
 mouth, bps, cheeks, tongue and throat in the absence of  motor paralysis ot concerned muscles.
Where is the lesion in Apraxia?
It results from damage to the left parietal cortex or to parietal white matter of the left or of both hemispheres, or from disease of the connections between the two hemispheres through the corpus callosum.
It is a disconnection syndrome
Lesion of dominant supramarginal gyrus –produce bilateral apraxia
Connection problems
Lesion of connection of dominant supramarginal gyrus to the left motor cortex - Right sided apraxia
Lesion of connection of dominant supramarginal gyrus to the right motor cortex through corpus callosum produce -Left sided apraxia
Lesion of non-dominant parietal lobe  result in constructional apraxia.