Understanding Apraxia: Types and Assessment Techniques

Apraxia

The inability to perform a voluntary act even though the motor system, sensory system, and mental status are relatively intact.

Face-tongue Apraxia

The inability to efficiently produce or imitate movements involving the face, tongue, mouth, jaw, or palate on command.

Ideomotor Apraxia

Apraxic patients are often unaware of their deficits and may do an act automatically that they cannot do on command.

Constructional Apraxia

A form of apraxia where the patient has difficulty in constructing or drawing objects.

Technique to test Face-tongue Apraxia

Ask the Pt to protrude the tongue and move it up, down, right, and left and lick the lips.

Technique to test Ideomotor Apraxia

Ask the patient to demonstrate a sequence: how to use silverware, thread a needle, strike a match and light a candle, and use a key to lock and unlock a lock, or use scissors or other tools.

Common Causes of Apraxia

Left hemisphere lesions, particularly in Broca's area (inferior frontal gyrus).

Distinction between Apraxia and Other Motor Deficits

Impairment in performing learned, skilled movements on command while still being able to perform them automatically in a natural context.

Pyramidal Lesions

Frequently associated with stroke, Alzheimer's disease, or Parkinson's disease.

Cerebellar Lesion

The Pt with a cerebellar lesion retains the ability to perform an act but cannot perform it smoothly.

Basal Motor Nuclei Lesions

Involuntary movements or rigidity impede down the act, but the sequence of the act remains possible.

Formal Criteria to Distinguish Apraxia

The Pt's motor system is sufficiently intact to execute the act, the Pt's sensorium is sufficiently intact to understand the act, the Pt comprehends and attempts to cooperate, the Pt's previous skills were sufficient to perform the act, and the Pt has an organic cerebral lesion as the cause of the deficit.

Patients struggle with tasks such as

Blowing a kiss, sticking out the tongue, puffing cheeks, whistling, and licking lips.

Aphasia

Usually the patients with ideomotor apraxia also have aphasia.

Both hands affected

Both hands are usually affected, although the lesion is unilateral.

Praxia

Ability to execute a voluntary act.

Praxis

Action, as in practice.

Apraxia definition

Inability to act.

Constructional Apraxia

the inability of patients to copy accurately drawings or three-dimensional constructions (Russell, et al., 2010).

Technique to test Constructional Apraxia

Ask the Pt to copy geometric figures (a cross, interlocking pentagons, or clock face) or construct them out of matchsticks.

Right Parietal Lobe Damage

more severe impairment in spatial perception (e.g., neglecting one side of space, distorted drawings).

Left Parietal Lobe Damage

more impairment in motor planning (e.g., difficulty sequencing steps of a drawing).

Face tongue Apraxia

Left Frontal Lobe.

Broca's area

Premotor Cortex.

Ideomotor Apraxia

Left Parietal Lobe, Premotor Cortex, Supplementary Motor Areas (sometimes).

Somatosensory System

A network of neurons and specialized receptors that allows for the perception of touch, pressure, temperature, pain, and proprioception.

Pathway of Sensory Input

Sensory neurons enter the spinal cord → cross to the opposite side → ascend to the thalamus → projects to the somatosensory cortex.

Lower Limb Examination

A test to elicit neurological signs in the legs and feet.

Altered sensations in patients

Patients may present with altered sensations, numbness, or loss of power of a limb.

Neuropathies

Other neuropathies can occur as foot drop or 'glove and stocking'.

Full neurological examination

includes an assessment of both the motor and sensory systems of the legs.

Dorsal Column Tract

also known as the Dorsal Column-Medial Lemniscus Pathway, carries fine touch, vibration, and proprioception.

Dermatomes

specific regions of the skin where sensory information are organized.

Spatial tasks in Constructional Apraxia

Both 2D and 3D spatial tasks, such as copying geometric figures, arranging blocks in a pattern, drawing a clock face correctly, and assembling a puzzle.

Misplacement of movements

using the wrong body part for an action, like pretending to use a toothbrush with their finger instead of mimicking holding a brush.

Patients' spontaneous actions

the patient cannot do it, but they may spontaneously wave when saying goodbye to someone.

Patients' task performance

they may struggle, but they can brush their hair when actually holding a brush.

Severe spatial deficits

Right = severe spatial deficits.

Motor planning deficits

Left = motor planning deficits.

External changes detection

detects external changes.

Numbness in limbs

Patients may present with numbness.

Loss of power in limbs

Patients may present with loss of power of a limb.

Sensory input pathway

Sensory neurons enter the spinal cord, cross to the opposite side, ascend to the thalamus, and project to the somatosensory cortex.

Dermatome

Each dermatome corresponds to a spinal nerve root that supplies sensation to a particular area of the body.

Mapping

Mapping is important in diagnosing nerve injuries, spinal cord lesions, etc.

Pathway of Sensory Input

Peripheral receptors → Dorsal Columns of the Spinal Cord → synapses in the Medulla → crosses to the opposite side → Thalamus and Somatosensory Cortex.

Spinothalamic Tract

Transmits pain, temperature, and crude touch.

Sensory Endings

Sensory endings are widely distributed and found throughout the body in both somatic and visceral areas.

General Procedure for Sensory Function Testing

Key points to remember when testing the sensory function of the lower extremity.

Patient Preparation

Make them feel comfortable and relaxed before beginning any test.

Eyes Closed Assessment

Ensure the patient has their eyes closed for the assessment.

Demonstrate Normal Sensation

Demonstrate normal sensation on the patient's dermatomal boundaries to minimize the risk of misinterpretation.

L1 Dermatome

Inguinal region and the very top of the medial thigh.

L2 Dermatome

Middle and lateral aspect of the anterior thigh.

L3 Dermatome

Medial aspect of the knee.

L4 Dermatome

Medial aspect of the lower leg and ankle.

L5 Dermatome

Dorsum and medial aspect of the big toe.

S1 Dermatome

Dorsum and lateral aspect of the little toe.

Light (Crude) Touch

Touch impulses ascend to the somesthetic cortex by two spinal pathways.

Abnormal Response to Light Touch

Loss of sensation, hypersensitivity or heightened sensation to light touch.

Delayed Response

Decussates at the level of entry of the dorsal root.

Temperature/Pain Perception

Temperature and pain impulses ascend to the somatosensory cortex via the lateral spinothalamic tract.

Test for Light Touch

Ask the Pt to say 'touch' in response to each touch by a wisp of cotton.

Types of Pain

Fast - sharp and bright; Slow - dull, diffuse, stinging, or burning pain.

Analgesia

Loss of pain sensation.

Thermoanesthesia

Loss of temperature sensation.

Test for Temperature

Show Pt that you will place two stimuli up and down the trunk to discover a dermatomal loss or spinal cord sensory level around the lower limbs.

Temperature Discrimination Test

Test using different objects (warm and cold tubes or a tuning fork) applied to the legs to assess the patient's ability to discriminate temperature.

Test Procedure for Temperature

Hold the cold object to the dorsum of the hands, feet, and face, then replace it with a warm object, starting from the foot to the upper thigh.

Quantitative Testing of Touch and Pressure

Involves the use of graded monofilaments and von Frey hairs of different strengths to assess touch and pressure sensitivity.

Pain Perception Test

Involves pricking the patient with a pin while they have their eyes closed to assess their ability to feel pain.

Localization of Touch

After detecting light touch with eyes closed, the patient must place a finger on the exact site touched.

Normal Response to Sensation

Patient verbally confirms sensation when lightly touched with a wisp of cotton, with no delay or loss of sensation.

Abnormal Response to Sensation

Includes inability to detect coldness/warmth or pain, delayed pain perception, feeling stimulus only on one side, or referred pain.

Sensitivity Variation

Different areas of the skin exhibit varying thresholds for touch, with the back and buttocks being less sensitive than the face or fingertips.

Screening Purposes for Sensory Examination

Determine how far to extend the sensory examination based on patient history.

Common Pathway for Pain and Temperature Receptors

Pain and temperature receptors overlap and share a common pathway in the spinal tract, making temperature testing relevant for both.

Vibration Perception

Dorsal column pathways mediate vibration, with evidence suggesting pathways may also travel in the dorsal part of the lateral columns.

Effects of Thalamic Injury on Sensation

Sensory deficits depend on the area of thalamic injury, with interruption of pathways reducing vibratory perception.

Suprathalamic Lesions

These lesions more or less spare vibration perception.

Testing Temperature Discrimination

If the patient discriminates temperature normally and history does not suggest neurologic disease, there is no need for further pain testing.

Patient Preparation for Pain Test

Show the patient the pin to be used for pricking before asking them to close their eyes.

Testing Order for Pain

Prick the patient in each leg from distal to proximal.

Threshold for Touch

Different skin areas have different thresholds for touch, with the face and fingertips being more sensitive.

Patient Response to Coldness/Warmth

Patient feels coldness/warmth or pain upon applying the stimulus.

Equal Sensation in Legs

Patient feels the same level of stimulus in both legs.

Delayed Pain Perception

A condition where the patient experiences a delay in feeling pain after a stimulus is applied.

Referred Pain

The site at which the patient feels pain may not correspond to the site of the stimuli applied.

Vibration Sense

Involves the Dorsal Column Pathway which is related to vibration sensation.

Pallanesthesia

Loss of vibration sense due to lesion or injury in the pathway.

Reidel-Seiffer tuning fork

The most practical tool for routine clinical use in quantitative tests of vibration.

Normal Response

Usually coupled with other neurologic tests to verify diagnosis.

Vibration Sense Test

Applied to a bony prominence to assess vibration sensation.

Preparation of the Patient

Start with the Patient's eyes open and show what you will do, but perform the test with the Patient's eyes closed.

Abnormal Response

Absent or decreased vibration sensation at distal sites, delayed perception, or asymmetric response.

Test Procedure

Hold a tuning fork (128 or 256 cps) and apply it to the Patient's toenails or proximal to the nail bed.

Digital Position Sense Test

Instruct the Patient to remain relaxed while testing the position of a digit.

Reliability Monitoring

Use of varying intensities and standard anatomic sites to improve accuracy in testing for pallanesthesia.

Interpretation of Vibration Testing

Involves assessing the Patient's ability to detect vibration and reporting the position of a digit.

Aging Effect on Vibration Sense

Increases the threshold to vibration and reduces sensitivity.