Apraxia meaning
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Apraxia
Apraxia is the inability to correctly perform learned, skilled movements despite having intact motor strength, sensation, and comprehension. It is fundamentally a cognitive deficit in motor programming — the brain has lost the ability to plan, sequence, or execute purposeful movements, even though the muscles themselves work fine.
Key Distinguishing Features
Apraxia is not caused by:
- Muscle weakness, hemiparesis, or spasticity
- Ataxia or extrapyramidal disturbances (tremor, dystonia, chorea)
- Primary sensory deficits or hemispatial neglect
- Impaired attention, memory, or language comprehension
The errors seen in apraxia are in the spatiotemporal processing of movements or in the content of the action itself.
Types of Apraxia
| Type | Description |
|---|---|
| Ideomotor apraxia | Cannot perform a skilled gesture to command (e.g., "show me how to use a hammer") but may do it automatically in context. Most common type; linked to left hemisphere/parietal lesions. |
| Ideational apraxia | Cannot sequence a multi-step task (e.g., making tea — fills kettle, puts it away wrong). Failure of the overall plan. |
| Conceptual apraxia | Loss of knowledge about tool use and mechanical actions. |
| Limb-kinetic apraxia | Loss of fine, precise finger/hand movements; clumsy execution. |
| Callosal apraxia | Apraxia limited to the non-dominant hand due to corpus callosum disconnection. |
| Oral/buccolingual apraxia | Cannot perform purposeful mouth/tongue movements to command (e.g., lick lips, blow out a match), despite normal automatic use. Localizes to left inferior frontal cortex, insula, or basal ganglia. |
| Apraxia of speech | Impaired motor planning of speech sounds; distinct from oral-buccal-lingual apraxia. |
| Gait apraxia | Difficulty initiating walking ("magnetic gait"); technically not a true apraxia since walking is not a learned skill. |
| Dressing apraxia | Inability to dress correctly; reflects visuospatial dysfunction (non-dominant parietal lobe). |
| Constructional apraxia | Inability to copy or construct figures/patterns; also a non-dominant parietal phenomenon. |
Causes & Prevalence
Apraxia occurs in 50–80% of patients with left hemisphere lesions and persists chronically in 40–50%. It is seen in:
- Stroke
- Alzheimer disease
- Corticobasal syndrome
- Parkinson disease / Dementia with Lewy bodies
- Multiple sclerosis
- Frontotemporal dementia
- Huntington disease, Creutzfeldt-Jakob disease
Clinical Significance
Limb apraxia causes major functional impairment — patients become more dependent on caregivers and struggle with activities of daily living, even when the apraxia appears subtle. Testing for apraxia can help differentiate diseases (e.g., Alzheimer's from frontotemporal dementia).
Sources: Bradley and Daroff's Neurology in Clinical Practice; Adams and Victor's Principles of Neurology, 12th Ed.
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