Definition of Apraxia
Apraxia is a decrease or difficulty in performing purposeful, skilled movements that cannot be attributed to hemiplegia, lack of effort, elementary motor or sensory deficits, or general cognitive impairment. 1
Core Defining Features
Apraxia represents a cognitive-motor disorder affecting learned, skilled movements, specifically of the upper limbs. The diagnosis requires that movement difficulties occur in the absence of:
- Elementary motor deficits (weakness, paresis)
- Sensory loss
- Abnormalities of posture, tone, or movement
- Lack of understanding or cooperation
- Inattention to commands
- Object-recognition deficits
- Poor oral comprehension 2, 3
Clinical Manifestations
Patients with limb apraxia demonstrate:
- Deficits in spatial-temporal organization and sequencing of goal-directed movements
- Difficulty manipulating and using tools (e.g., cutting with scissors, making coffee)
- Impaired pantomimed or actual tool use
- Difficulty imitating meaningless gestures 4, 2
Epidemiology and Lateralization
Limb apraxia is more common after left hemispheric stroke than right hemispheric stroke 1. The disorder is bilateral, explaining why cognitive motor deficits occur even though the lesion is unilateral 4.
Two Praxis Systems
The disorder involves dysfunction of two distinct systems 2:
Production system (action plan and production)
- Dysfunction produces ideomotor apraxia (difficulty using scissors)
Conceptual system (action knowledge)
- Dysfunction produces ideational apraxia (difficulty making a cup of coffee)
Functional Impact
Although not traditionally believed to affect daily life function, there is now evidence that apraxia is associated with reduced independence in daily life activities 1. This impacts healthcare costs and increases caregiver burden 2.
Common Contexts
Apraxia occurs frequently in:
- Stroke (particularly left hemisphere)
- Neurodegenerative diseases (corticobasal syndrome, Alzheimer's disease) 4
- Traumatic brain injury
- Developmental disorders 2
Critical Diagnostic Caveat
The diagnosis relies primarily on exclusion criteria, and due to diversity in definitions and assessment methods, patients may or may not show apraxia depending on the chosen assessment approach, making the definition somewhat arbitrary 5. This creates significant diagnostic variability in clinical practice.