Apraxia is a cognitive-motor disorder that impacts the performance of learned, skilled movements. Limb
apraxia, which is the topic of this chapter, is specific to disordered movements of the upper limb that cannot be explained by weakness, sensory loss, abnormalities of posture/tone/movement, or a lack of understanding/cooperation. Patients with limb
apraxia have deficits in the control or programming of the spatial-temporal organization and sequencing of goal-directed movements. People with limb
apraxia can have difficulty manipulating and using tools including cutting with scissors or making a cup of
coffee. Two praxis systems have been identified including a production system (action plan and production) and a conceptual system (action knowledge). Dysfunction of the former produces
ideomotor apraxia (e.g., difficulty using scissors), and dysfunction of the latter induces
ideational apraxia (e.g., difficulty making a cup of
coffee). Neural mechanisms, including how to evaluate
apraxia, will be presented in the context of these two praxis systems. Information about these praxis systems, including the nature of the disordered limb movement, is important for rehabilitation clinicians to understand for several reasons. First, limb
apraxia is a common disorder. It is common in patients who have had a
stroke, in
neurodegenerative disorders like
Alzheimer disease, in
traumatic brain injury, and in developmental disorders. Second, limb
apraxia has real world consequences. Patients with limb
apraxia have difficulty managing
activities of daily living. This factor impacts healthcare costs and contributes to increased caregiver burden. Unfortunately, very few treatments have been systematically studied in large numbers of patients with limb
apraxia. This overview of limb
apraxia should help rehabilitation clinicians to educate patients and caregivers about this debilitating problem, and should facilitate the development of better treatments that could benefit many people in the future.