Assessment of deep tendon reflexes

Reflexes are involuntary muscle contractions in response to a stimulus and are classified as deep, superficial, or pathological (Hinkle, 2021). The mostly tested reflexes are the deep tendon reflexes, which include the biceps, triceps, brachioradialis, quadriceps (patella), and Achilles (ankle). When testing deep tendon reflexes, ensure the patient is totally relaxed, as eliciting these reflexes could be difficult when the muscles are tense. Holding the handle of the reflex hammer loosely between your thumb and forefinger, chill out your wrist and strike the tendon vigorously with the pinnacle of the hammer using a fast flick of the wrist. Let the hammer do the work and hit the tendons in the next areas (Gelb, 2022):

• Biceps reflex – just before the elbow
• Triceps reflex – just behind the elbow
• Brachioradialis reflex – roughly 2 to 4 inches above the wrist, on the radial side of the forearm
• Quadriceps (patellatellar) reflex – slightly below the kneecap
• Achilles reflex (ankle) – just behind the ankle

Deep Tendon Reflex Assessment Scale (Bickley et al., 2021)

Note the speed, strength and amplitude of the reflex response and rate the response using the 0 to 4 scale below. Always compare the response of 1 side to the opposite.

4 = Very energetic, with clonus (rhythmic oscillations between flexion and extension)
3 = More energetic than average; probably, but not necessarily, indicates disease (hyperactivity)
2 = average; normal
1 = Slightly reduced or needs strengthening (hypoactive)
0 = no reflex

The results could be written as a fraction indicating the range of the size, for instance 2/4 (2 on a scale of 4). Scale rankings could be subjective, so some clinicians may select to make use of the terms , and . The response depends partly on the force of the blow to the tendon, but simply enough force ought to be used to supply a powerful response. Increased, decreased and even absent reflexes observed symmetrically could also be normal. Excessive reflexes may indicate damage to the central nervous system (CNS), affecting the descending corticospinal tract. Check for added motor symptoms corresponding to weakness, spasticity, and/or a positive Babinski sign. Underactive or absent reflexes may indicate changes within the peripheral nervous system (PNS), affecting spinal nerve roots, the brachial or lumbosacral plexus, or peripheral nerves. Check for added lower motor neuron symptoms corresponding to weakness, atrophy, and/or fasciculations. (Bickley et al., 2021)

Reinforcement

If the reflex is weakened or absent, try using reinforcement to extend the activity of the reflex. Strengthening involves isometric contraction of other muscles for as much as 10 seconds, which might increase reflex activity. For example, to strengthen arm reflexes, ask the patient to grit his teeth or squeeze each knees together. If leg reflexes are decreased or absent, ask the patient to interlace his fingers and produce one hand to the opposite. Ask the patient to drag just before hitting the patella or Achilles tendon (Bickley et al., 2021).

Interpretation of deep tendon reflexes (Gelb, 2022)

While it’s important to evaluate reflexes, comparing reflexes on one side of the body to the opposite is much more essential. The most vital thing is to check the suitable and left sides, where the asymmetry could be significant. When making an assessment, test the reflexes on one side immediately after testing the corresponding reflex on the opposite side, fairly than testing all reflexes in a single limb after which testing the opposite. If your reflexes are fast, it could be difficult to detect asymmetry. Try to melt the stimulus until it barely produces a response. Check and document the next (Gelb, 2022):

• Is the brink stimulus the identical on each side, or should one side be hit harder than the opposite?
• If the brink stimulus is similar on either side, does it produce the identical level of response on either side?

Remember:

• Make sure the joint is totally relaxed at 90 degrees.
• Hit the joint only hard enough to trigger a response.
• If the reflex is weakened or absent, try using reinforcement to extend the activity of the reflex.
• Check for asymmetry in reflex reactions between the suitable and left sides of the body.

Bickley, L. S., Szilagyi, P. G., Hoffman, R. M., & Soriano, R. P. (2021). Bate’s guide to physical examination and interviewing (thirteenth ed.). Wolters Kluwer Health: Philadelphia.

Gelb, D. (2022, July 1). Detailed neurological examination in adults. Current. https://www.uptodate.com/contents/the-detailed-neurologic-examination-in-adults

Hinkle, J. (2021). Brunner and Suddarth’s textbook of medical-surgical nursing (fifteenth edition)^vol ed.). Wolters Kluwer Health. https://wolterskluwer.vitalsource.com/books/9781975161057