Apraxia

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). Apraxia should not be confused with aphasia, an inability to produce and/or comprehend language, or abulia, the lack of desire to carry out an action.

The root word of apraxia is praxis, Greek for an act, work, or deed. It is preceded by a privative a, meaning 'without'.

Types

There are several types of apraxia including:

• ideomotor (inability to carry out a motor command, for example, "act as if you are brushing your teeth" or "salute") - the form most frequently encountered by physicians,
  • limb apraxia when movements of the arms and legs are involved,
  • nonverbal-oral or buccofacial (inability to carry out facial movements on command, e.g., lick lips, whistle, cough, or wink),
• ideational (inability to create a plan for or idea of a specific movement, for example, "pick up this pen and write down your name"),
• limb-kinetic (inability to make fine, precise movements with a limb),
• verbal (difficulty planning the movements necessary for speech), also known as Apraxia of Speech (see below)
• constructional (inability to draw or construct simple configurations),
• oculomotor (difficulty moving the eye)

Each type may be tested at decreasing levels of complexity; if the person tested fails to execute the commands, you can make the movement yourself and ask that the person mimic it, or you can even give them a real object (like a tooth brush) and ask them to use it.

Apraxia may be accompanied by a language disorder called aphasia.

Apraxia of speech

Childhood Apraxia of Speech (CAS) 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 with normal coordination of the articulators during speech.

Symptoms of Acquired Apraxia of Speech (AOS) and Childhood Apraxia of Speech (CAS) 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.

Causes

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.

Treatment

Generally, treatment for individuals with apraxia includes physical therapy, occupational therapy or speech therapy, and IVIG.

Prognosis

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

• Epstein, O.; D. Perkin, J. Cookson, D.P. de Bono (2003). Clinical Examination. London: Mosby. pp. 294. ISBN 0-7234-3229-5. http://www.fleshandbones.com/bookshop/title.cfm?ISBN=0723432295. 
• Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL. Harrison's Principles of Internal Medicine. New York: McGraw-Hill, 2005. ISBN 0-07-139140-1.