What is reflex testing?

Reflex testing, commonly referred to as a tendon jerk, involves evaluating the response of the phasic component of the stretch reflex pathway (S2.13). The test is referred to as a tendon reflex because a sharp stretch applied to the tendon by the therapist produces a corresponding stretch in most or all of the stretch receptors (muscle spindles) within the muscle itself. The result is temporal summation of the excitatory action potentials (S2.6) at the alpha motor neuron, which leads to a muscle contraction.

Why do I need to assess reflexes?

Assessing reflexes can give the therapist important information related to:

How do I assess reflexes?

Tendon jerk

Patient

The patient should be comfortable and relaxed so that the testing can be completed with the muscle in a resting state. The position will therefore alter depending upon the muscle being tested.

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Therapist

1 Reflexes are assessed using a reflex hammer (Fig. 22.1).

2 Palpate the tendon to be tested to establish the point of contact for the reflex hammer.

3 The hammer is held loosely with the handle uppermost allowing momentum to swing the hammer freely.

4 The head of the hammer is then used gently to apply a stretch to the tendon of the relevant muscle.

Biceps (C5, C6) (Fig. 22.2)

a The patient’s arm should be flexed at the elbow with the palm down

b Place a thumb or finger firmly on the biceps tendon

c Strike your finger with the reflex hammer

d Note any elbow flexion.

Triceps (C6, C7) (Fig. 22.3)

a Support the upper arm in a position of 90° abduction. Then let the patient’s forearm hang free

b Strike the triceps tendon above the elbow with the hammer

c Note any elbow extension.

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Quadriceps (L2, L3, L5) (Fig. 22.4)

a Have the patient sit or lie down with the knee relaxed and flexed

b Strike the patellar tendon just below the patella

c Note any knee extension.

Plantar flexors (S1, S2) (Fig. 22.5)

a Position the patient in long sitting or prone. Dorsiflex the foot at the ankle

b Strike the Achilles tendon

c Note any plantar flexion at the ankle.

Figure 22.1 The reflex hammer.

Figure 22.2 Tendon jerk testing for biceps.

Figure 22.3 Tendon jerk testing for triceps.

Figure 22.4 Tendon jerk testing for quadriceps femoris.

Figure 22.5 Tendon jerk testing for plantar flexors.

  Caution

Reflex response depends on the force of your stimulus. Use no more force than you need to provoke a definite response.

5 The response may be graded as follows:

− or 0 absent

− or 1 diminished

+ or 2 normal/average

++ or 3 brisk

+++ or 4 exaggerated.

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Does the muscle being tested respond at all? Yes, the neural pathway and muscle are intact for the spinal root levels indicated. For example, an appropriate response from biceps indicates that levels C_5,6 are intact. If there is no response, then a lesion involving the neural pathway at the same levels should be suspected.

How does the muscle respond? A response greater than 2 indicates hyper-reflexia and therefore it may be wise to look for other signs of spasticity (e.g. hypertonia). A diminished response indicates hypo-reflexia.

Plantar response (Babinski sign) (Fig. 22.6)

Patient

The patient should be in supine or long sitting and be well supported so that the testing can be completed with the muscles of the lower limb in a resting state.

Figure 22.6 Testing for the Babinski sign.

Therapist

1 Using the end of a reflex hammer

2 Draw the end upwards along the lateral border of the foot

3 At the base of the 5th toe move medially across the ball of the foot (Fig. 22.6)

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4 This is performed in a continuous movement and at a fairly quick speed

5 Note the movement of the toes

6 A normal response is flexion (withdrawal). Extension of the big toe with fanning of the other toes is abnormal. This is referred to as a positive Babinski sign and is indicative of a lesion of the central nervous system.

Recording

Recording by the therapist usually consists of a simple list comprising the muscle tested and the response gained. For example:

Analysis

It is important to remember that the findings from reflex testing need to be considered alongside other assessment findings. For example, in pathologies affecting the peripheral nervous system analysis should be in conjunction with results from the assessments of myotomes (S3.31) and dermatomes (S3.24). In pathologies affecting the central nervous system analysis may be in conjunction with findings related to the assessment of muscle tone (S3.21).

Outcome measure