Apraxia is a neurological disorder characterized by loss of the ability to execute or carry out learned purposeful movements, despite having the desire and the physical ability to perform the movements. It is a disorder of motor planning which may be acquired or developmental, but may not be caused by incoordination, sensory loss, or failure to comprehend simple commands (which can be tested by asking the person tested to recognize the correct movement from a series).
The root word of Apraxia is praxis, Greek for an act, work, or deed. It is preceded by a privative a, meaning 'without'.
There are several types of apraxia including:
- limb-kinetic apraxia (inability to make fine, precise movements with a limb),
- ideomotor apraxia (inability to carry out a motor command),
- ideational apraxia(inability to create a plan for or idea of a specific movement),
- buccofacial apraxia or facial-oral (inability to carry out facial movements on command, i.e., lick lips, whistle, cough, or wink) - which is perhaps the most common form,
- verbal apraxia (difficulty coordinating mouth and speech movements),
- constructional apraxia (inability to draw or construct simple configurations),
- and oculomotor apraxia (difficulty moving the eyes).
Developmental Apraxia of Speech (DAS) presents in children who have no evidence of difficulty with strength or range of motion of the articulators, but are unable to execute speech movements because of motor planning and coordination problems. This is not to be confused with phonological impairments in children wtih normal coordination of the articulators during speech.
Symptoms of Acquired Apraxia of Speech (AOS) and Developmental Apraxia of Speech (DAS) include inconsistent articulatory errors, groping oral movements to locate the correct articulatory position, and increasing errors with increasing word and phrase length. AOS often co-occurs with Oral Apraxia (during both speech and non-speech movements) and Limb Apraxia.
Ideomotor apraxia is almost always caused by lesions in the language-dominant (usually left) hemisphere of the brain, and as such these patients often have concomitant aphasia, especially of the Broca or conduction type. Left-side ideomotor apraxia may be caused by a lesion of the anterior corpus callosum.
Ideational apraxia is commonly associated with confusion states and dementia.
Generally, treatment for individuals with apraxia includes physical therapy, occupational therapy, speech therapy, music therapy, or Oral Motor Therapy and IVIG. If apraxia is a symptom of another disorder (usually a neurologic disorder), the underlying disorder should be treated.
The prognosis for individuals with apraxia varies. With therapy, some patients improve significantly, while others may show very little improvement. Some individuals with apraxia may benefit from the use of a communication aid.
References & Bibliography
- Riddoch, M. J., Humphreys, G. W. & Price, C. J. (1989) Routes to action: Evidence from apraxia. Cognitive Neuropsychology, 6, 437-454.
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