Reflex Testing: A Step-by-Step Guide

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Content

Preparing Tools and Positioning the Subject

Triggering a Reflex Response

Evaluating Reflex Reactions

Muscle reflex testing helps evaluate how well the central and peripheral nervous systems are working. When a tendon is tapped with a reflex hammer, the muscle should react if the neural pathways are functioning correctly. Abnormal or absent reflexes can indicate neurological concerns, prompting further medical evaluation.

Instructions

Preparing Tools and Positioning the Subject

Select a reflex hammer. Reflex hammers come in various designs—some lightweight and suited for light taps, others slightly heavier to rely on gravity for force. These tools can be purchased through online shops or medical supply stores.

With a rubber head, the reflex hammer is designed to strike tendons gently without causing pain.

Choose a muscle group to examine. Reflex responses can be tested in many muscles, with the knee being the most frequently assessed. Other commonly checked areas during a neurological exam include:

Ankle
Knee
Abdomen
Forearm
Biceps
Triceps

Identify the tendon to strike. To properly evaluate reflexes, target the tendon connecting the muscle and bone. Gently palpate the area to locate the tendon—it should feel like a firm band beneath the skin.

For example, when checking the knee reflex, tap the patellar tendon just below the kneecap. You can have the person move their knee slightly if needed to better spot the tendon.

Ensure the muscle is relaxed and can move freely. Reflex testing requires the muscle to be at rest so it can react naturally. Avoid any restriction to its movement. For instance, if you're checking knee reflexes, the subject should sit with legs dangling off an exam table.

For biceps testing, have the person sit with their arm resting on their lap, elbow bent slightly past 90 degrees.

Try testing your own reflexes. Although not typical, self-testing is possible. As reflexes are automatic, proper positioning and accurate tapping should still produce a response.

Some areas, like the Achilles tendon, may be harder to reach and test by yourself.
Practicing on yourself can help refine your reflex testing technique.
If self-testing raises any health concerns, consult a doctor for a more dependable assessment.

Triggering a Reflex Response

Grip the hammer gently. When using a light reflex hammer, hold it between your thumb and forefinger. For heavier, weighted hammers, use your whole hand, but keep your grip relaxed.

A light hold helps control the force applied during the tendon tap.

Strike once with a swift motion. Only one quick, deliberate swing is needed. Move your wrist in a 45 to 60-degree arc and strike the center of the tendon with confidence and precision.

Apply just enough pressure. A firm but painless tap is enough to trigger a reflex. Aim to use the minimum force necessary to activate the response—practice helps.

Weighted hammers are calibrated to deliver the right amount of force when dropped from a height of 10 to 12 cm (3.9 to 4.7 in). Let gravity do the work; don’t add extra force.

Evaluating Reflex Reactions

Watch for a rapid contraction. A healthy reflex produces a noticeable muscle twitch within a second after the tendon is tapped. The response should be quick, even if not instantaneous.

Watch for overactive or repeating reflexes. Hyperreflexia occurs when a muscle contracts repeatedly after being triggered. This pattern of repeated movement is usually visible immediately after stimulation.

Such a response often points to disrupted signaling within the spinal cord.

Determine if a lack of response is testing error or a real issue. If there's no reaction after tapping the tendon, repeat the test several times to confirm. This helps rule out mistakes in technique.

No reflex reaction is referred to as hyporeflexia.

Compare reflexes bilaterally. Evaluating the same muscle on both sides of the body helps identify irregularities. For instance, test one ankle, then the other, and observe differences in reflex strength or timing.

Assign a reflex grade. Reflex responses are commonly scored on a 0 to 4 scale, sometimes modified with plus or minus signs to show subtle variations:

0: no reaction
1: minimal response
2: expected, normal reaction
3: unusually strong response
4: excessively repetitive reflex

Use reflex scores for diagnostic insight. Doctors interpret reflex ratings to understand nerve function. A normal reflex implies healthy communication between muscles and the brain. Poor or absent reflexes suggest nerve pathway issues, prompting further investigation.

Conditions linked to impaired reflexes include multiple sclerosis, diabetes, alcoholism, amyloidosis, uremia, vitamin deficiencies, toxin exposure, and certain cancers.

Sources

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