Reflex Exam

What is a deep tendon reflex exam?

A deep tendon reflex exam is a crucial component of the neurological examination that provides valuable insights into the functioning of the nervous system. This non-invasive test assesses the integrity of the central and peripheral nervous systems by evaluating the body's automatic response to muscle stretch.

During a deep tendon reflex exam, specific tendons are tapped with a reflex hammer, causing a sudden stretch in the associated muscle. This stretch activates muscle spindles, sending sensory neurons signals to the spinal cord. The spinal cord then rapidly processes this information and sends a response back through motor neurons, causing the muscle to contract. This process occurs without conscious thought and is known as the reflex arc.

The reflex arc, which forms the basis of these reflexes, involves:

1. Afferent nerves that carry sensory information from muscle spindles
2. The spinal cord, which processes the information
3. Motor nerves that carry signals back to the muscle

Abnormalities in reflex responses can indicate issues in the central nervous system, peripheral nervous system, or both.

How does this reflex examination work?

Performing a deep tendon reflex exam is an essential aspect of a physical and neurological exam, allowing healthcare providers to assess the integrity of the nervous system. This quick and straightforward exam can provide valuable diagnostic information for various conditions. Here is the step-by-step process of performing reflex testing:

Step 1: Prepare the patient and environment

Ensure the patient is relaxed and positioned appropriately. For upper limb reflexes, the patient should be seated with their arms relaxed. For lower limb reflexes, the patient can be seated with legs dangling or lying down with knees slightly flexed. Explain the procedure to reduce anxiety and promote cooperation.

Step 2: Use the reflex hammer

Hold the hammer loosely and strike the tendon with a quick, firm tap. The movement should come from the wrist, not the entire arm, to ensure precision.

Step 3: Test and observe

Test the main deep tendon reflexes:

• Biceps: Tap the biceps tendon in the antecubital fossa
• Triceps: Tap the triceps tendon above the olecranon
• Brachioradialis: Supination of forearm
• Patellar: Tap the patellar tendon below the kneecap
• Achilles: Tap the Achilles tendon while dorsiflexing the foot

Observe the muscle's response immediately after tapping. Look for the speed, amplitude, and symmetry of the response.  

Step 4: Grade and interpret

Grade the reflexes tested on a scale from 0 to 4. Lower motor neuron lesions can depress reflexes, leading to reduced or absent responses. Compare reflexes bilaterally and interpret findings in the context of the patient’s overall clinical picture. Abnormal responses may indicate various neurological conditions and should prompt further investigation.

Scoring and interpretation

This Reflex Exam can be scored using a grading system ranging from 0 to 4, with 0 indicating no response and 4 indicating a very brisk response.

To score the assessment, the clinician should first observe the expected response for each reflex and then compare it to the actual response observed in the patient. The grading is typically done on a scale of 0 to 4, with 0 indicating no response, 1 indicating a very weak response, 2 indicating a normal or average response, 3 indicating a brisk response, and 4 indicating a very brisk or hyperactive response.

It's important to note that reflexes can vary depending on age, gender, and underlying medical conditions, so the clinician should consider these factors when interpreting the exam results. Additionally, the clinician should assess reflexes bilaterally and compare responses on both sides of the body, as asymmetrical reflex response may point to other medical conditions.

Overall, the deep tendon reflex exam is a simple and valuable tool for assessing the integrity of the central and peripheral nervous system and can provide helpful information for diagnosing neurological conditions.

When to use this Reflex Exam?

Reflex testing can be used in various clinical settings and situations. Here are some instances when it may be appropriate to use this resource:

• Regular check-ups: The deep tendon reflex exam is a routine part of a physical exam and can be used during regular check-ups to assess the function of the nervous system.
• Neurological disorders: This reflext test can diagnose and monitor neurological disorders, such as multiple sclerosis and spinal cord injuries.
• Trauma: This can also assess the severity of nerve damage in patients who have suffered trauma, such as a spinal cord injury or head trauma.
• Medication management: The deep tendon reflex exam can also monitor the effects of certain medications, such as muscle relaxants and anticonvulsants, on the nervous system.
• Geriatric care: The test can assess changes in the nervous system that may occur with aging, such as decreased reflexes.

The deep tendon reflex exam is a valuable tool that can be used in various clinical settings to assess the function of the nervous system. Healthcare providers should consider using this resource during regular check-ups, in the diagnosis and monitoring of neurological disorders, in trauma cases, during medication management, and in geriatric care.