Updated: Jan 14, 2009
Apraxia is one of the most important and least understood major behavioral neurology syndromes. It is one of the best localizing signs of the mental status examination and also predicts disability in patients with stroke or dementia (unlike aphasia). Patients with apraxia cannot use tools; therefore, they are unlikely to perform activities of daily living well. Patients with aphasia, without coexisting apraxia, can live independently, take the bus or subway, and lead a relatively normal life; a patient with significant limb apraxia is likely to remain dependent.
Heilman defined apraxia in negative terms, "Apraxia is defined as a disorder of skilled movement not caused by weakness, akinesia, deafferentation, abnormal tone or posture, movement disorders such as tremors or chorea, intellectual deterioration, poor comprehension, or uncooperativeness."[1 ]To simplify matters, apraxia can be considered a form of a motor agnosia. Patients are not paretic but have lost information about how to perform skilled movements.
Apraxia is a syndrome reflecting motor system dysfunction at the cortical level, exclusive of primary motor cortex. In planning movements, previously learned, stored complex representations of skilled movements are used. These 3-dimensional, supramodal codes, also called representations or movement formulae, are stored in the inferior parietal lobule of the left hemisphere. Diseases that involve this part of the brain, including strokes, dementias, and tumors, can cause loss of knowledge about how to perform skilled movements.
Apraxia can occur with lesions in other locations as well. Information contained in praxis representations is transcoded into innervatory patterns by the premotor cortices, including the supplementary motor area (SMA) and possibly the convexity of the premotor cortex; the information is then transmitted to the primary motor cortex and a movement is performed. Lesions of the SMA or other premotor cortices also can cause apraxia; in this case, knowledge about movement is still present, but the ability to perform movement is absent.
Apraxia also occurs with lesions of the corpus callosum, such as tumors or anterior cerebral artery strokes. Although the corpus callosum is not known to be involved directly in the performance of skilled movements, it contains crossing fibers from the right hemisphere to the premotor cortex. This type of apraxia represents a classic disconnection syndrome; patients with callosal apraxia typically are apractic only with the left hand.
Few data are available regarding the frequency of apraxia; however, it commonly occurs after stroke and in dementia—2 of the most frequent neurological illnesses.
Few data are available regarding the frequency of apraxia.
Apraxia is not a disease but a syndrome; consequently, it has no attributable morbidity or mortality.
No data are available.
No good data are available.
No good data exist concerning the occurrence of apraxia in different age groups. However, it is more common in older age groups, as they typically have higher frequencies of stroke and dementia.
Frequently, patients with apraxia are unaware of their deficits. Accordingly, history of a patient's ability to perform skilled movements should be obtained from both the patient and caregivers. Caregivers should be asked about the ability of patients to perform activities of daily living, especially those that involve household tools (eg, using a knife, fork, and toothbrush correctly; using kitchen utensils safely and correctly to prepare a meal; using tools such as a hammer or scissors correctly). Caregivers should also be queried about the overall activity level of the patient and whether reductions in their total activities have occurred. The patient may simply sit on the couch and watch television, uninterested in previously important activities. This apathy can be associated with many different kinds of brain dysfunction, but occasionally occurs because the patient is not able to perform his or her usual activities.
As discussed in the introduction, apraxia has a neurological cause that localizes fairly well to the left inferior parietal lobule, frontal lobes (especially the premotor cortex, supplementary motor area, and convexity), or corpus callosum. Any disease of these areas can cause apraxia, although stroke and dementia are the most common causes. Interestingly, callosal apraxia is rare after callosotomy and is much more common with anterior cerebral artery strokes or tumors.
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The differential diagnosis for ideomotor apraxia includes hemiparesis, movement disorders such as Parkinson disease and dystonia, deafferentation, hysteria, and malingering.
The differential diagnosis for corticobasal ganglionic degeneration includes Alzheimer disease, progressive supranuclear palsy, Pick disease, other frontotemporal dementias, and nonspecific progressive gliosis.
The differential diagnosis for the cause of ideomotor apraxia includes stroke, dementia, tumor, other mass lesions, CNS infection and inflammation, and multiple sclerosis.
A patient with suspected apraxia should undergo neuroimaging (either CT scan or MRI) to exclude a mass lesion and to evaluate for possible atrophy suggestive of a degenerative condition.
The histologic findings in apraxia depend on the underlying cause, ie, stroke, degenerative disease, or tumor. Specific histologic findings most often can be found in degenerative diseases. In Alzheimer disease, amyloid plaques and neuritic tangles are found. In Pick disease, Pick bodies are seen. In corticobasal ganglionic degeneration, balloon neurons with neuronal achromasia are characteristic.
Patients with apraxia may have difficulty knowing how or what to eat. If a patient is losing weight or nutritional deficiencies are suspected, nutritional supplements or dietary assistance might be provided.
Patients with certain types of dementia may have a high risk of falling. Patients with corticobasal ganglionic degeneration or progressive supranuclear palsy may have a high fall rate relatively early in the disease, whereas patients with Alzheimer are more likely to fall in the middle to late stages. Patients with a useless upper limb may develop a clenched painful fist that severely limits activity.
Patients with certain progressive diseases such as progressive supranuclear palsy, corticobasal ganglionic degeneration, and stroke may be at high risk of falling. Patients with useless limbs syndrome can progress to a painful clenched fist. Patients with dementias can develop secondary nutritional deficiencies.
Patients with apraxia, in general, become dependent for their activities of daily living and require at least some degree of supervision. Patients with stroke may have a stable course and even improve somewhat. Patients with degenerative diseases or tumors usually progress to increased levels of dependence.
For excellent patient education resources, visit eMedicine's Stroke Center and Dementia Center. Also, see eMedicine's patient education articles Stroke and Stroke-Related Dementia.
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apraxia and related syndromes, behavioral neurology syndrome, apraxia of speech, buccofacial apraxia, callosal apraxia, conceptual apraxia, dyspraxia, ideomotor apraxia, ideational apraxia, limb apraxia, limb kinetic apraxia, magnetic apraxia, motor agnosia, oral apraxia, parectropia, disorder of voluntary movement, voluntary movement disorder, alien hand syndrome
Jasvinder Chawla, MBBS, MD, MBA, Associate Professor of Neurology, Director of Neurology Residency Training Program, Director of Clinical Neurophysiology Laboratory, Assistant Director of Neurology Clerkship Program, Department of Neurology, Loyola University Medical Center
Jasvinder Chawla, MBBS, MD, MBA is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Clinical Neurophysiology Society, and American Medical Association
Disclosure: Nothing to disclose.
Daniel H Jacobs, MD, Associate Professor of Neurology, University of Central Florida College of Medicine
Daniel H Jacobs, MD is a member of the following medical societies: American Academy of Neurology, American Society of Neurorehabilitation, and Society for Neuroscience
Disclosure: Teva Pharmaceutical Grant/research funds Consulting; Biogen Idex Grant/research funds Independent contractor; Serono EMD Royalty Speaking and teaching; Pfizer Royalty Speaking and teaching; Berlex Royalty Speaking and teaching
Stephen T Gancher, MD, Adjunct Associate Professor, Department of Neurology, Oregon Health Sciences University
Stephen T Gancher, MD is a member of the following medical societies: American Academy of Neurology, American Neurological Association, and Movement Disorders Society
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.
Richard J Caselli, MD, Professor, Department of Neurology, Mayo Medical School, Rochester, MN; Chair, Department of Neurology, Mayo Clinic of Scottsdale
Richard J Caselli, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Medical Association, American Neurological Association, and Sigma Xi
Disclosure: Nothing to disclose.
Matthew J Baker, MD, Consulting Staff, Collier Neurologic Specialists, Naples Community Hospital
Matthew J Baker, MD is a member of the following medical societies: American Academy of Neurology
Disclosure: Nothing to disclose.
Howard A Crystal, MD, Professor, Departments of Neurology and Pathology, State University of New York Downstate; Consulting Staff, Department of Neurology, University Hospital and Kings County Hospital Center
Howard A Crystal, MD is a member of the following medical societies: American Academy of Neurology and American Neurological Association
Disclosure: Pfizer Honoraria Speaking and teaching; Myriad Honoraria Consulting
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