|Dysarthria |Apraxia | |
|Etiology |Dysarthric errors result from a disruption |Apraxia results from an impaired ability to| | |of muscular control due to lesions of |generate the motor programs for speech | | |either the central or peripheral nervous |movements rather than from the disordered | | |systems. In this way, the transmission of |transmission of controlling messages to the| | |messages controlling the motor movements |speech musculature. Apraxia is a | | |for speech is interrupted. Because it |planning/programming problem, not a | | |involves problems with the transfer of |movement problem like dysarthria. | | |information from the nervous system to the |Apraxia occurs following damage to Broca's | | |muscles, dysarthria is classified as a |Area, or Brodmann's area 44, which is | | |neuromotor disorder. |located on the third gyrus of the left | | |Central Nervous System Lesions |frontal lobe. Thus, apraxia is always the | | |Damage to the pyramidal tract causes |result of a central nervous system lesion. | | |spastic dysarthria. Lesions of the |It is a cortical problem, not a motor | | |substantia nigra cause hypokinetic |impulse transmission problem like | | |dysarthria. Disruption of feedback loops |dysarthria. | | |involving the cerebellum cause ataxic | | | |dysarthria. | | | |Peripheral Nervous System Lesions | | | |Finally, damage to any part of the | | | |peripheral nervous system serving the | | | |muscles of speech causes flaccid | | | |dysarthria. | | |Type Of Errors |In dysarthria, errors are consistent and |In apraxia, errors are inconsistent and | | |predictable. |unpredictable. Different error patterns | | |There are no islands of clear speech; no |occur in spontaneous speech versus | | |matter what the speaking task or materials |repetition. Patients' spontaneous speech | | |used, the patient will exhibit the same |contains fewer errors than does his/her | | |amount and types of errors. |speech in repetition tasks. | | |Errors are mainly distortions and |There are islands of clear speech; when | | |omissions. Distortions are the most...
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