Apraxias

Learning objectives

Learning
Understand
Integrate
Reflect

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 identified and actions undertaken to support improvement and help improve functional outcome 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 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

Form	Definition
Ideational apraxia	Initially used to refer to impairment in the conceptual organization of actions, assessed with sequential use of multiple objects. Later defined as conceptual apraxia.
Conceptual apraxia	Impairment in the concept of a single action, characterized by content errors and the inability to use tools.
Ideomotor apraxia	Impairment in the performance of skilled movements, characterized by spatial or temporal errors in the execution of movements.
Limb-kinetic apraxia	Slowness and stiffness of movements with a loss of ?ne, precise and independent movement of the fingers.
Constructional apraxia	Difficulty in drawing or copying drawings of 3D structures. Impairment in the combinatory or organizing activity in which details and relationship among the component parts of the entity must be clearly perceived.
Developmental dyspraxia	Disorders affecting the initiation, organization and performance of actions in children.
Modality-specific apraxias	Localized within one sensory system.
Pantomime agnosia	Normal performance in gesture production tests both on imitation and on verbal command, but poor performance in gesture discrimination and comprehension. Patients with pantomime agnosia can imitate pantomimes they cannot recognize.
Conduction apraxia	Superior performance on pantomime to verbal command than on pantomime imitation.
Visuo-imitative apraxia	Normal performance on verbal command with selectively impaired imitation of gestures. Also used to designate the defective imitation of meaningless gestures combined with preserved imitation of meaningful gestures. Optical (or visuomotor) apraxia Disruptions to actions calling upon underlying visual support.
Tactile apraxia	Disturbance of transitive hand movements for use of, recognition and interaction with an object, in the presence of preserved intransitive movements.
Upper/lower face apraxia	Impairment in performing actions with parts of the face.
Oral apraxia	Inability to perform skilled movements with the lips, cheeks and tongue.
Orofacial (or buccofacial) apraxia	Difficulties with performing intentional movements with facial structures including the cheeks, lips, tongue and eyebrows.
Lid apraxia	Difficulty with opening the eyelids.
Ocular apraxia	Impairment in performing saccadic eye movements on command.
Limb apraxia	Used to refer to ideomotor apraxia of the limbs frequently including the hands and fingers.
Trunk (or axial) apraxia	Difficulty with generating body postures.
Leg apraxia	Difficulty with performing intentional movements with the lower limbs. Task-specific apraxias Gait apraxia Impaired ability to execute the highly practised, co-ordinated movements of the lower legs required for walking. Gaze apraxia difficulty in directing gaze.
Apraxia of speech (or verbal apraxia)	Disturbances of word articulation.
Apraxia agraphia	A condition in which motor writing is impaired but limb praxis and non-motor writing (typing, anagram letters) are preserved.
Dressing apraxia	Inability to perform the relatively complex task of dressing.
Dyssynchronous apraxia	Failure to combine simultaneous preprogramed movements.
Orienting apraxia	Difficulty in orienting one's body with reference to other objects.
Mirror apraxia	A deficit in reaching to objects presented in a mirror.
Lesion-specific apraxias
Callosal apraxia	Apraxia caused by damage to the anterior corpus callosum that usually affects the left limb.
Sympathetic apraxia	Apraxia of the left limb due to damage to the anterior left hemisphere (the right hand being partially or fully paralyzed).
Crossed apraxia	The unexpected pattern of apraxia of the right limb following damage to the right hemisphere

Clinical: Screening tasks

Pantomiming: Show me how you wouldâ€¦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