CHAPTER 26 Coordination

What is coordination?

Successful movement involves the complex coordination of multiple joints and muscles which is achieved via the appropriate sequencing, timing and grading of muscle recruitment (Shumway-Cook and Woollacott 2007; Berthier et al. 2005). Even a simple reaching task involves all levels of the central and peripheral nervous system with the integration of these sensorimotor systems occurring primarily in the cerebellum (S2.12) (Fuller 2004). Smooth accurate movement involves the interaction of hand–eye coordination, inter-limb and trunk coordination.

Incoordinated movement

Incoordination presents as a lack of smooth sequenced movement which is often awkward and uneven and may involve both limb and trunk muscles. The incoordination is attributed to a loss of synergistic interplay between muscles as a result of disruption in muscle:

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• Activation

• Sequencing

• Timing

• Grading.

As the control facilitating coordinated movement is highly complex and involves many nervous system structures it follows that incoordination can be a consequence of damage to any one of them. This includes:

• Cerebellum (S2.12)

• Motor cortex (S2.7)

• Basal ganglia (S2.11)

• Sensory feedback: Proprioception (S2.23) or vision (S2.10 and S3.27)

• Motor output: Altered muscle tone (S3.21) or muscle weakness (S3.30).

Ataxia

Ataxia is a term used to describe the motor incoordination presented by patients with a deficit affecting the cerebellum (S2.12) during voluntary movement. It includes symptoms such as nystagmus, reduced manual dexterity, poor balance and altered gait (Bakker et al. 2006; Ilg et al. 2008), dysarthria and dysmetria (Thoma et al. 2008). Dysmetria, is a problem with judging the distance of movement and is often referred to as intention tremor. The outcome is inaccurate movement with overshooting (hypermetria) and undershooting (hypometria) during the task. Ataxia can affect the trunk (trunk ataxia) or limbs (limb ataxia) or both, depending on whether the lesion is in midline or the cerebellar hemispheres, respectively. The incoordinated movement that is produced affects mobility, when the patient presents with a drunken swaggering gait and all other functional activities. Ataxic movement is thought to occur due to impairment in the timing and duration of muscle activation, or the magnitude and grading of force production (Ausim 2007).

Caution

Incoordinated movement which mimics cerebellar ataxia can occur as a result of sensory loss (sensory ataxia). The causes are very different.

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Why do I need to assess coordination?

Incoordinated movement is often inaccurate, effortful and ultimately leads to a reduced functional outcome. This presentation is observed in many neurologically impaired patients whether the pathology affects the central or peripheral nervous system.

How do I assess coordination?

Observation of functional tasks

Assessment of coordination usually begins by observing the patient’s ability to perform simple functional tasks (S3.18) taking note of the accuracy, speed and trajectory of movement.

The activities observed should challenge both the limbs and trunk. To identify a trunk deficit in isolation, the patient could be requested to sit unsupported with upper limbs held in a static position away from the body. Excessive movement of the trunk could indicate incoordination. However, the therapist should be mindful that there is a great deal of overlap between the concepts of trunk coordination, trunk stability (S3.25) and balance (S3.32). The therapist should also be aware that any problems with trunk coordination will also affect the accuracy of limb movements.

Simple tests of limb coordination

A comparison of right and left should be made, allowing for handedness during the performance. If there is an unaffected side this should be tested first to ensure understanding of the procedure.

The patient is scored as:

5 – Normal

4 – Minimal impairment

3 – Moderate impairment

2 – Severe impairment

1 – Unable to perform (Schmitz 2001).

Finger-to-nose test

Patient

The patient is sitting.

Therapist

1 The therapist sits in front of the patient, facing them.

2 The therapist holds their finger in front of the patient at eye level (approx. arms length from the patient).

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3 With eyes open the patient is asked to touch their own nose with their index finger and then touch the therapist’s finger (Fig. 26.1).

4 This is repeated several times and should be accomplished smoothly and easily.

5 If the performance is accurate, ask the patient to repeat the movement faster.

6 Modify the position of the therapist’s finger and repeat the test, to test different planes of movement.

7 This test can be repeated with eyes closed with the patient only touching their own nose.

Figure 26.1 Finger–nose test.

Heel–shin test

Patient

Patient should be in supine on a plinth or sitting on a chair.

Therapist

1 The patient is asked to place the heel of one lower limb to touch the knee of the opposite leg.

2 The patient is requested to run the heel down the shin towards the ankle joint (Fig. 26.2). This should be accomplished smoothly and easily.

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3 If the performance is accurate this can be repeated several times with increasing speed.

4 Repeat with eyes closed.

Figure 26.2 Heel–shin test.

Caution

Patients with very poor coordination should be advised to take care during both the finger–nose and heel–shin tests to avoid any damage to eyes or the skin of the lower limb.

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Dysdiadochokinesia

This is the inability to perform rapidly alternating movements.

Patient

Patient should be sitting.

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Therapist

1 The patient should start with one hand rested on their thigh (palm down).

2 They are then asked to turn the hand over (palm up) and continue alternating between palm up and down at a reasonable speed (Fig. 26.3).

3 Repeat with the other hand.

4 This test can be modified so that the patient performs the task at 90° shoulder flexion or by alternating different opposing muscle groups around other peripheral joints (e.g. flexion and extension of the knee).

Figure 26.3 Testing for dysdiadochokinesia.

Note: Dysdiadochokinesia is commonly seen as part of ataxia (cerebellar lesion) but is also difficult to achieve for patients with hypertonia and hypotonia (S3.21).

Hand ‘flip’ test (inter-limb coordination)

Patient

Patient is sitting.

Therapist

1 The patient starts with left hand palm down on their lap (the stationary hand).

2 The patient is asked to touch the back of the left hand with the anterior aspect of the fingers of the right hand (Fig. 26.4).

3 The left hand is then turned over (palm up) and the patient touches the palm with the posterior aspect of the fingers of the right hand (Fig. 26.4).

4 This is repeated several times as quickly as possible.

5 Repeat the test with the right hand stationary.

6 Repeat with eyes closed.

Figure 26.4 Hand ‘flip’ test.

Other simple tests

• Drawing a circle in the air – upper or lower limb

• Hand tapping

• Foot tapping.

Is there any deviation from the expected smooth accurate movement?

Does the heel fall off the anterior part of the shin?

Is there evidence of hand slapping rather than a touch?

Does the performance deteriorate when the speed is increased?

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Does the patient overshoot or undershoot the target? Yes, this is dysmetria.

Does the performance deteriorate significantly with eyes closed? If the original task was accurate this may indicate a deficit of proprioception.

Is there excessive trunk movement during the task? This could indicate trunk involvement. Sit the patient supported and re-test.

Recording

A simple text description of what was tested and the findings is sufficient.

Example

Finger–nose test

• Left: Nothing abnormal detected (NAD)

• Right: Inaccurate and slow.

Analysis

Testing coordination informs the therapist of the existence of a movement dysfunction but not about its cause. Further investigation using other objective assessment tools (S3.19–34), integrated with knowledge related to the patient’s pathological condition will facilitate analysis of the causal factors.

References and Further Reading

Ausim AS. And the olive said to the cerebellum: organization and functional significance of the olivo-cerebellar system. Neuroscientist. 2007;13:616-626.

Bakker M, Allum JH, Visser JE, et al. Postural responses to multidirectional stance perturbations in cerebellar ataxia. Experimental Neurology. 2006;202:21-35.

Berthier NE, Rosenstein MT, Barto AG. Approximate optimal control as a model for motor learning. Psychological Review. 2005;112:329-346.

Crawford JD, Medendorp WP, Marotta JJ. Spatial transformations for eye–hand coordination. Journal of Neurophysiology. 2004:92110-92119.

Fuller G. Neurological examination made easy, ed 3. Edinburgh: Churchill Livingstone; 2004.

Ilg W, Giese MA, Gizewski ER, et al. The influence of focal cerebellar lesions on the control and adaptation of gait. Brain. 2008;131:2913-2927.

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Johansson RS, Westling G, Bäckström A, et al. Eye–hand coordination in object manipulation. Journal of Neuroscience. 2001;2117:6917-6932.

Schmitz TJ. Coordination assessment. In O’Sullivan SB, Schmitz TJ, editors: Physical rehabilitation assessment and treatment, ed 4, Philadelphia: FA Davis, 2001.

Shumway-Cook A, Woollacott MH. Motor control translating research into clinical practice, ed 3. Philadelphia: Lippincott Williams and Wilkins; 2007.

Thoma P, Bellebaum C, Koch B, et al. The cerebellum is involved in reward-based reversal learning. Cerebellum. 2008;7:433-443.