This document discusses apraxia, which is defined as a disorder of skilled movement not caused by other factors such as weakness or intellectual deterioration. There are three main domains of apraxia: defects in pantomiming actions, imitation of gestures, and object manipulation. The document outlines different types of apraxia including ideational apraxia, which is an inability to properly sequence movements, and conceptual apraxia, which involves errors in tool selection or knowledge of tool functions. Neural substrates for praxis are also discussed.

1. APRAXIAS

2. INTRODUCTION
• Apraxia is classically defined as a disorder of skilled
movement not caused by weakness, akinesia, deafferentiation,
abnormal tone or posture, movement disorders (such as
tremor or chorea), intellectual deterioration, poor
comprehension or uncooperativeness.
Heilman KM, Rothi LJG. Apraxia. In: Heilman KM, Valenstein E (Eds). Clinical Neuropsychology.
New York: Oxford University Press; 1985. pp. 131-50.

3. • It is the “failure to produce the correct movement in response to a
verbal command, failure to imitate correctly a movement
performed by the examiner, failure to perform a movement
correctly in response to a seen object or a failure to handle an
object correctly.”
• Based upon the above definition, the three main domains that
form the principal defects of apraxia can be formulated. These
essentially constitute the steps in evaluation of apraxia and include
defects in
(1) pantomiming an action in response to verbal command,
(2) imitation of gestures,
(3) manipulation of tools and objects.
Geschwind N, Damasio AR. Apraxia. In: Vinken PJ, Bruyn GW, K Lawans HL (Eds). Handbook
of Clinical Neurology. Amsterdam: Elsevier; 1985. pp. 423-32.

4. • According to Liepmann, a pioneer in the concept of
apraxia, patients cannot transform the image of intended
action into appropriate motor command and hence, apraxia
is the disturbance at the interface between the cognition and
the motor control.

5. Historical background
• The first description of apraxia is credited to Jackson
Hughling (1866), who observed a motor intentional deficit in
aphasic patients.
• Those patients were unable to move the tongue or lips on
command, but could carry out these movements in an
automatic movement sequence such as swallowing or eating.
• Jackson observed that this automatic-voluntary dissociation
was not restricted to muscles of the facial region, since some
of those aphasic patients were also unable to move their
right, non-plegic hand on command while the same actions
could be performed correctly in a spontaneous way.

6. • It was Steinthal (1871) who coined the term apraxia.
• He described the case of an aphasic patient who attempted
to write by holding a pencil upside down, or manipulated a
fork and a knife as if he had never used them before.
• Steinthal stressed that it was not the ability to perform
movements of extremities which was defective, but rather the
relationship between the movements and the manipulated
object, thereby suggesting that the absence of action (i.e., “a-
praxia”) might result from a perceptual deficit affecting object
use recognition.

7. • In the early 1900s, Liepmann published a series of papers
that led to the contemporary concept of limb apraxias. He
proposed that the execution of purposeful movements could be
divided into three steps.
• First is the retrieval of the spatial and temporal representation
or “movement formulas” of the intended action from the left
hemisphere.
• Second is the transfer and association of these movement
formulas via cortical connections with the “innervatory patterns”
or motor programs located in the left “sensomotorium” (which
includes premotor and supplementary motor areas).

8. • Third is the transmission of the information to the left
primary motor cortex for performance of the intended
actions in the right limb.
• Finally, in order for the left limb to perform the
movements, the information traverses the corpus
callosum to the right sensomotorium to activate the right
primary motor cortex.

10. Cognitive model of apraxia of Rothi et al

11. • 20 LBD patients who were classified into four groups according to
the locus of lesion (anterior vs. posterior) and whether or not they
were apraxic.
• Apraxia was assessed by asking patients to perform 15 gestures on
verbal command Because patients with fluent aphasia have
generally posterior lesions and those with non-fluent aphasia have
commonly anterior lesions, they used this indicator to determine the
locus of lesions.
• Four groups were thus formed:
1. apraxic patients with anterior lesions/non-fluent aphasia
2. apraxic patients with posterior lesions/fluent aphasia
3. non-apraxic patients with anterior lesions/non-fluent aphasia
4. non-apraxic patients with posterior lesions/fluent aphasia.

12. •All the patients were asked to perform a gesture discrimination
test consisted of 32 trials, each containing three separate
videotaped pantomimed acts
•The results indicated that apraxic patients with posterior/fluent
aphasia (Group 2) performed worse than the three other groups
(Groups 1, 3 and 4), thereby suggesting that gesture production
can be dissociated from gesture recognition and that there
would be two different forms of IMA: The posterior form
(impairment in both gesture recognition and gesture production:
Group 2) and the anterior form (impairment in gesture
production only: Group 1).

13. • The action-lexicon- Rothi et al. (1991) proposed the term
“lexicon” to refer to the movement formulae of Liepmann
(1908) and the visuokinesthetic motor engrams of Heilman et
al.
• The model says that input and output processing of praxis
require division of the action-lexicon into an input action-
lexicon (devoted to gesture recognition) and an output action-
lexicon (devoted to gesture production).

14. • Input modality selectivity - Rothi et al. (1991) proposed that there would
be selective input into the action-lexicons according to modality.
• This proposal is based, for example, on the observation of some patients
who are able to perform gestures to command correctly, but who cannot
produce visually-presented gestures.
• On the basis of these findings as well as other somewhat similar findings,
the model suggests the existence of separate input systems for visually
presented gestural information (imitation), visually presented objects
(pantomime or actual tool use), and auditory presented verbal information
(gestures to command)

15. NEURAL SUBSTRATES FOR PRAXIS
• Praxis functions are distributed across several distinct
anatomofunctional neural systems that work together and
mainly involve the parietofrontal systems controlling
reaching/grasping processes and the frontostriatal system
controlling sequential motor acts.
• The posterior parietal cortex plays a key role and consists of
several functionally distinct areas.

16. NEURAL SUBSTRATES FOR PRAXIS
•The superior parietal lobule has been found to be
involved in somatosensory transformation of reaching
movements.
• The inferior parietal lobule, which is separated from
the superior parietal lobule by the intraparietal sulcus is
mainly involved with visuomotor transformation of
grasping movements.

19. TYPES OF APRAXIA

20. Ideational Apraxia
• Ideational apraxia is the inability to correctly order or
sequence a series of movements to achieve a goal.
• It is a disturbance in an overall ideational action plan.
• When these patients are given components necessary to
complete a multistep task, they have trouble carrying out the
steps in the proper order, such as preparing, addressing and
then mailing a letter.
• The individual steps, however, are performed accurately.

21. • Patients with “Ideational Apraxia” fail to generate
movement formulae and therefore, show impairment in
the real and pantomimed use of tools.
• The lesion responsible for ideational apraxias is not
clear; the deficits usually occur in patients with diffuse
cerebral processes such as dementia, delirium, or
extensive lesions in the left hemisphere that involve the
frontal lobe and SMA.

22. Conceptual Apraxia
• Conceptual apraxia results in errors in the content of the
action, such as in tool-selection errors or in tool–object
knowledge.
• Conceptual apraxia is the loss of mechanical knowledge.
• Patients with conceptual apraxia are unable to name or point
to a tool when its function is discussed, or recall the type of
actions associated with specific tools, utensils, or objects.
• They make content errors in which they substitute the action
associated with the wrong tool for the requested tool.

23. • For example, when asked to demonstrate the use of a
hammer or a saw either by pantomiming or using the tool, the
patient with the loss of tool–object action knowledge may
pantomime a screwing twisting movement as if using a
screwdriver.
• Other terms used to describe these errors include
disturbances in mechanical knowledge or in action semantics .
• Conceptual apraxia is most common in Alzheimer disease, in
other dementias (Ochipa et al., 1992), and in patients with
diffuse posterior cerebral lesions, particularly involving the left
hemisphere

24. • There are several subtypes of conceptual apraxia:
1. problem unawareness,
2. tool-selection deficit,
3. tool action– association deficit
4. impaired mechanical advantage knowledge
Subtypes of conceptual apraxias

25. Problem unawareness
•The first step is the recognition that something needs to be
altered.
• Some patients cannot identify that an alteration action is
required. This subtype of conceptual apraxia is called
problem unawareness.

26. Tool selection
• Some patients cannot recognize the tool that is needed to
perform or complete the required action or the tool that works
on specific objects (eg, hammers are used with nails). This
impairment is called a tool-selection deficit
• Patients are shown the picture of an incomplete task, such
as a nail that is only partially driven into the wood.
• They are shown an array of five different tools, such as a
handsaw, wrench, hammer, screwdriver, and knife, and are
asked to select the tool to be used to complete this task.

27. Mechanical advantage - alternative tools
• Patients are shown a series of pictures that are the same as
above, but in this test the tool that usually performs this action
is not present and the patient must find an alternative tool to
complete the task.
• For example, after being shown a partially driven-in nail, the
patient is shown five tools (eg, handsaw, wrench, screwdriver,
knife, and wire cutter and is asked to point to the tool he or
she would use to complete the task

28. Mechanical advantage - tool fabrication
• Ochipa and colleagues developed a test in which subjects
would have to make a tool to solve a mechanical problem.
• For example, they had to retrieve a block with an eye hook
on top that was in the bottom of a Plexiglas cylinder and were
provided with a straight wire.
• To correctly solve this problem, they had to bend the wire to
make a hook that they could place in the eye and use this wire
with hook to retrieve the wooden block.

29. Ideomotor apraxia
• Ideomotor apraxia is a disturbance in programming the
timing, sequencing and spatial organization of gestural
movements.
• Here the identification of the gesture and the
discrimination of the gesture are intact (unlike the
apraxia of the conceptual system) and thus is an error of
the production system.

30. • Patients with ideomotor apraxia (IMA) make three types of
spatial errors:
(1) postural errors or internal configuration errors;
(2) egocentric movement errors (use of incorrect joints or
incorrect coordination between joints);
(3) allocentric movement errors in which their actions are
not correctly targeted to the real or imaginary object upon
which the tool works.

31. • When pantomiming a transitive act, patients with IMA will
often fail to place their hand, forearm, and arm in the position
that would enable them to correctly hold a tool or implement.
• Transitive pantomimes are more affected than intransitive
ones, and acting with real objects is better performed than
pantomiming their use.
• Actions improve with imitation rather than with acting to
verbal commands, i.e., pantomime.

32. • This is because acting with objects provides tactile and
kinesthetic cues and helps the patient in performing the
movement in a more natural context.
• This is responsible for the so-called voluntary automatic
dissociation, where they can perform their daily activities
while being disproportionately disable during examination.
• Ideomotor apraxia usually results from lesions of the
parietal association area, and less likely from lesions of the
premotor and supplementary motor areas and the white
matter bundles that connect the latter to subcortical
structures

33. • Heilman et al. and Rothi et al. suggested two forms of
ideomotor apraxia:
1. the posterior variant (parietal variant)
2. the anterior variant (disconnection variant)

34. Ideomotor Apraxia, Parietal Variant
•The parietal variant of ideomotor apraxia may be the most
common and prototypical limb apraxia.
•Disruption of the movement formulas in the inferior parietal
lobule impairs skilled movements on command and to imitation,
as well as the recognition of gestures.
•Patients make spatial and temporal errors while producing
movements.
•There is a failure to adopt the correct posture or orientation of
the arm and hand or to move the limb correctly in space and at

35. the correct speeds.
• Spatial errors involve the configuration of the hand and fingers,
the proper orientation of the limb to the tool or object, and the
spatial trajectory of the motion.
• A major distinguishing feature of the parietal variant of ideomotor
apraxia is difficulty recognizing or identifying gestures, implicating
damage to the praxicons, visuokinesthetic motor engrams, or
movement formulas themselves

36. Ideomotor Apraxia, Disconnection Variant
• This form of ideomotor apraxia is a disconnection of an intact
parietal region from the pathways to primary motor cortices.
• The disconnection variant of ideomotor apraxia results from
disruptions of motor programs in the SMA or in their intra and
interhemispheric connections (Heilman and Watson,2008).
• These lesions result in impaired pantomime to verbal
commands, impaired imitation of gestures, and the presence
of spatiotemporal production errors.

37. • The movement formulas themselves are preserved, but in
contrast to the parietal variant of ideomotor apraxia, these
patients can recognize and identify gestures.
• The lesions lie along the route from the left inferior parietal
cortex to primary motor cortices .
• Although SMA lesions tend to affect both upper
extremities, if the SMA lesion is limited to the right, apraxia
may be limited to the left upper extremity.

38. Limb Kinetic Apraxia (Innervatory Apraxia)
• Limb-kinetic apraxia is the inability to make finely graded,
precise, coordinated individual finger movements.
• Patients with limb-kinetic apraxia complain of a loss of
dexterity or deftness that makes fine motor movements
such as buttoning or tying shoes difficult.
• Weakness or changes in muscle tone do not account for
this “clumsiness” and limb kinetic apraxia may be
intermediate between paresis and other limb apraxias.
• Usually confined to the limb contralateral to a
hemispheric lesion.

39. • Limb-kinetic apraxia results from lesions in the primary
motor cortex or corticospinal system.
• Liepmann (1920) also thought that limb-kinetic apraxia could
result from lesions in the sensory motor cortex.
• Kleist (1931) attributed it to damage in the premotor areas.

40. Callosal Apraxia
• Several limb apraxia syndromes can result from callosal lesions
• What distinguishes these patients is that their apraxia is confined
to the nondominant limb, usually the left arm or hand in right-handed
individuals.
•The right limb may be affected in left-handed individuals, or they
may have a similar lateralization as right-handers.
• Liepmann and others described left-sided disconnection-variant
ideomotor apraxia due to callosal lesions and strokes (Heilman and
Watson, 2008). These patients cannot pantomime with their left
hand to verbal command or imitate but can recognize and identify
gestures.

41. • Patients who have had surgical disconnection of the corpus
callosum could not gesture normally to command with their left arm
and hand but performed well with imitation and actual tools.
• Some patients have had a combination of both disconnection-
variant ideomotor and dissociative apraxia of their left arm and hand
manifested by unrecognizable movements on verbal command and
spatiotemporal errors on imitation.
• Other patients have a callosal “alien limb” with independent
movements of the nondominant limb, sometimes with “diagonistic
apraxia” or the intermanual conflict of the hands acting in opposition
to each other.

42. • The classic example of this is the split-brain patient who has
undergone a corpus callosotomy who finds that his or her left
hand is unbuttoning his shirt or blouse while the right one is
trying to button it.
• Finally, there is a rare description of callosal lesions
resulting in conceptual apraxia, indicating that conceptual
knowledge as well as movement formulas have lateralized
representations, and that such representations are
contralateral to the preferred hand.

44. Orobuccal Apraxia
• Patients with orofacial (or buccofacial) apraxia exhibit
difficulties with performing voluntary meaningful and
meaningless movements with facial structures including the
cheeks, lips, tongue and eyebrows.
• Attempting to perform a pantomime to verbal command may
result either in no response or often a characteristic verbal
repetition of the target action. For some patients, imitation of an
examiner’s pantomime may be achieved more accurately.
• Orofacial apraxia may occur independently of limb apraxia.
• Commonly associated with damage in the left frontal
operculum and insula.

45. Dressing apraxia
• Patient loses the ability to don clothes correctly.
• Loss of ability to manipulate clothes in space and to
understand its three dimensional relationships.
• Occurs in conjunction with constructional apraxia.

46. Constructional apraxia
• Occurs due to lesions in parietal lobe.
• The patient is unable to copy geometrical forms of any
complexity due to loss of visuospatial skills.
• May be able to draw individual shapes but cannot synthesise
them into a more complex geometric figure.

47. Apraxia of speech
• Apraxia of speech is a disorder of the programming of
articulation of sequences of phonemes, especially consonants
• The motor speech system makes errors in selection of
consonant phonemes, in the absence of any “weakness,
slowness or incoordination” of the muscles of speech
articulation (Wertz et al., 1991).
• Hillis and colleagues (2004) gave a more informal definition
of apraxia of speech, in terms of a patient who “knows what
he or she wants to say and how it should sound,” yet cannot
articulate it properly.

48. •The four cardinal features of apraxia of speech are:
(1) effortful, groping, or “trial-and error” attempts at speech,
with efforts at self-correction;
(2) dysprosody;
(3) inconsistencies in articulation errors
(4) difficulty with initiating utterances.
• More recent MRI correlations of apraxia of speech in acute
stroke patients by Hillis and colleagues (2004), however, have
pointed to the traditional Broca’s area in the left frontal cortex
as the site of apraxia of speech, and as the site where
programming of articulation takes place.

49. Gait, leg and trunk apraxia
• Gait apraxia refers to an impaired ability to execute the highly
practised, co-ordinated movements of the lower legs required for
walking, but remains rather poorly specified
• However, it remains unclear whether leg apraxia and gait apraxia
should be considered manifestations of damage to a common lower
limb praxic centre, or whether leg apraxia is more closely related to
the ideomotor apraxia more typically described in the upper limbs.
• A clearer dissociation has been described between limb apraxias
and axial or trunk apraxia, in which patients may have difficulty
generating body postures (e.g. stand like a boxer), rising from a lying
position, rolling over or adopting a sitting position.

50. TESTING FOR LIMB APRAXIAS
• Prior to testing of praxis, a neurological examination should
be done to exclude the presence of
- motor deficits
- sensory deficits
- cognitive disorders
 First, the testing of praxis itself begins with asking the
patient to pantomime to command

51. • The movements are transitive (associated with tool or instrument
use) and intransitive (associated with communicative gestures such
as waving goodbye).
• For transitive movements, the examiner asks the patient to
demonstrate how to comb their hair, brush their teeth, or use a pair
of scissors.
• For intransitive movements, the examiner asks the patient to
demonstrate how to wave goodbye, beckon somebody to come.
• The testing involves the right and left limbs independently. The
examiner observes the patient’s responses for the presence of
temporalspatial or content errors.

52.  Second, if the patient has difficulty pantomiming movements, the
examiner tests their ability to imitate gestures.
• For gesture imitation, the examiner performs both transitive and
intransitive movements and asks the patient to copy the movements.
• Gesture imitation should also include meaningless, or
nonrepresentational, gestures interlocking circles made with the
thumb and index finger on each hand.
• Disturbed meaningless gestures indicate either an inability to
apprehend spatial relationships involving the hands and arms in
parietal-variant ideomotor apraxia or a basic disturbances in
idiokinetic movements

53.  Third, for gesture knowledge, the examiner performs the same
transitive and intransitive gestures and asks the patient to identify
the gesture.
• The patient must identify the gesture and discriminate between
those that are well and poorly performed.
 Fourth, the patient must perform tasks that require several motor
acts in sequence, such as making a sandwich or preparing a letter
for mailing.
• The pattern of deficits will determine the types of apraxia .

54.  Fifth, the examiner shows the patient pictures of tools or objects
or the actual tools or objects themselves. The examiner then
requests that the patient pantomime the action associated with the
tool or object.
 Finally, the examiner checks for fine finger movements by asking
the patient to do repetitive tapping, picking up a coin with a pincer
grasp, and twirling the coin. Additional impairment in the patient’s
ability to use real objects indicates marked severity of the limb
apraxia.

60. ETIOLOGICAL CONSIDERATIONS

61. APRAXIA IN CORTICOBASAL DEGENERATION
• Corticobasal degeneration is an asymmetric akinetic rigid
syndrome, with majority of affected individuals demonstrating
ideomotor apraxia, while few have orofacial apraxia.
• Forty percent of patients present with apraxia at disease onset,
and 72% develop apraxia later in the course of disease.
• characterized by involvement of the frontoparietal and
frontostriatal networks that underlie praxis.
• Patients with CBD can sometimes function normally with relatively
preserved activities of daily living by the aid of tactile cues by
manipulating the actual object or visual cues by the target of action.

62. APRAXIA IN STROKE
• Apraxia occurs in 50–80% of patients with left hemispheric stroke
and can persist as a chronic deficit in 40–50%.
• In majority of the patients with left hemispheric lesions, the
presence of coexisting aphasia masks the apraxia that can be
mistaken as a comprehension deficit.
• Similarly, the coexisting right hemiparesis masks the right limb
apraxia.
• Patients with stroke who have distal impairment have involvement
of the contralateral limb alone unlike in CBD, and the type of
apraxia is innervatory apraxia or limb kinetic apraxia.

63. REHABILITATION FOR LIMB APRAXIAS
• The presence of limb apraxia, more than any other
neuropsychological disorder, correlates with the level of
caregiver assistance required six months after a stroke,
whereas the absence of apraxia is a significant predictor of
return to work after a stroke.
• The treatment of limb apraxia is therefore important for
improving the quality of life of the patient.
• There are no effective pharmacotherapies for limb apraxia,
and treatments primarily involve rehabilitation strategies.

64. • Buxbaum and associates (2008) surveyed the literature on the
rehabilitation of limb apraxia and identified 10 studies with 10
treatment strategies:
- multiple cues
- error type reduction
- six-stage task hierarchy,
- conductive education,
- strategy training,
- transitive/intransitive gesture training,
- rehabilitative treatment,
- error completion,
- exploration training
- combined error completion and exploration training.

65. • Most of these approaches emphasize cueing with multiple
modalities, with verbal, visual, and tactile inputs, repetitive
learning, and feedback and correction of errors.
• One novel study uses sensors embedded in household tools
and objects to detect apraxic errors and guide rehabilitation
(Hughes et al., 2013).
• patients can learn and produce new gestures, but the newly
learned gestures may not generalize well to contexts outside the
rehabilitation setting.

66. • Nevertheless, some patients with ideomotor apraxia have
improved with gesture-production exercises (Smania et al., 2000),
with positive effects lasting two months after completion of gesture
training (Smania et al., 2006), and patients with apraxia would
benefit from referral to a rehabilitation specialist with experience in
treating apraxias
• Additional practical interventions for the management of limb
apraxias involve making environmental changes.
• This includes removing unsafe tools or implements, providing a
limited number of tools to select from, replacing complex tasks with
simpler ones that require few or no tools and fewer steps, as well as
similar modifications.

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