Makindo Medical Notes.com

About

• Apraxia is a disorder of learned, voluntary actions resulting from neurological impairment. An often-unsuspecting cause of post stroke functional impairment which can be missed unless looked for.
• Seen in 1/3 of those in rehabilitation centres and nursing homes following left hemisphere stroke

Introduction

• People with motor apraxia after a left hemispheric (dominant) stroke often have difficulty carrying out everyday activities such as making a hot drink.
• Some people cannot select the right object at the right time or have difficulty using objects (such as a spoon) correctly. Other difficulties include using toothbrushes, razors, combs, and brushes or in the kitchen an inability to use forks, knives, spoons, and other household equipment.
• There is insufficient evidence to support or refute the effectiveness of specific therapeutic interventions for motor apraxia after stroke. However, it needs to be identified and actions are undertaken to support improvement and help improve functional outcomes and independence.

Definitions

• Apraxia is defined as an inability to correctly carry out purposeful and often learned skilled movements and actions when this deficit is not caused by elemental motor or sensory deficits, abnormal involuntary movements, or cognitive disorders. A simpler definition is that is a higher order-disorder of movement that is not due to elementary sensory and/or motor deficits.
• An impairment of the storage and transformation of motor representations in the brain, either through degradation of the semantic knowledge of gestures and tool use or through inability to translate the neural representations of higher-level goals accurately into lower-level patterns of muscle activation and inhibition.
• Liepmann proposed that left hemispheric lesions tend to cause bilateral upper limb apraxia and suggested a model of motor control in which the left parietal lobe stores a 'space-time form picture' of a movement. For a movement to be executed, its picture must be retrieved and activated and then be associated via cortical projections with the relevant motor engrams in the prefrontal regions. From here the information passes to the primary motor cortex before being fed down the corticospinal tracts. For the right upper limb to move the information remains contained within the left hemisphere, but for the left upper limb to move the information from the left parietal lobe must first be sent to the right prefrontal and frontal regions through the corpus callosum.

Anatomical basis

• Apraxia is a condition localised to the dominant left hemisphere
• Involves the supramarginal gyrus and deep white matter of the left parietal lobe.
• Apraxia can co-exist with a Wernicke's aphasia, but they can also occur independently.

Types

• Ideational apraxia: A disorder in the performance of skilled activity because there is a disruption of the space-time picture, in which the idea of the movement itself is lost or degraded. In concept of the action related to the object is impaired. A disturbance in the conceptual organisation of actions. The patient cannot pantomime tool use to command.
• Ideomotor apraxia: the idea of the movement is intact but there is an inability to map this accurately on to the motor engrams in the frontal lobes. A disorder in the initiation and execution of planned sequences of movement. The concept of the task is understood but the movements lack the correct force, direction and timing to achieve a motor goal. It is an impairment in the timing, sequencing and spatial organisation of gestural movements. Tasks for example are - using a key, using a hammer, lighting a match. One key finding is the "body-part-as-object error", where the patient substitutes a body part for the tool in question e.g. brushing the fingers through the hair when asked to demonstrate how it should be combed and to rub a finger against the teeth when asked to demonstrate how to use a toothbrush.

There are a whole variety of Apraxia

Clinical: Screening tasks

• Pantomiming: Show me how you would…Brush your teeth, Comb your hair, Hammer a nail, Use a pair of scissors
• Meaningful hand gestures: Salute, Hitch a lift, Wave goodbye
• Buccofacial apraxia: Lick your lips, Blow out a match, Drink through a straw
• Other Tasks which can be used in a functional setting
• Making a cold drink
• Putting paper in an envelope
• Hole punching paper and putting it in an A4 file.

Ideomotor Apraxia Performance errors

• Spatial orientation errors
• Temporal imprecision errors (timing errors)
• Errors of the force of movement
• Poor distal differentiation
• Body part as object ? Gestural enhancement ? Vocalisation

Ideational Apraxia Performance errors

• Using the wrong object
• Disordered Sequencing with omission or incomplete actions
• Blending sequences together
• Action overshoots what's required
• Action remains incomplete
• Perseveration

Management

• Therapy involvement to identify and focus on therapeutic strategy
• Involvement with Initiation, Execution, Control with Intervention, Instruction, assistance and feedback

References

• Cassidy A. The clinical assessment of apraxia. Practical Neurology 2016;16:317-322.
• Apraxia: a review. Progress in Brain Research, Vol. 164 ISSN 0079-6123
• Apraxia following stroke: Identification and interventions. (Jackson)
• Cochrane. Interventions for motor apraxia following stroke. 23 January 2008