Diagnosis of lumbar radiculopathy | medical domain (2023)

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Compression of lumbar nerve roots by herniated discs or oversized spinal components are common phenomena. In most cases, these are relatively painless ailments.

Sometimes a pinched nerve root becomes irritated or inflamed, triggering a whole syndrome of pain and nerve dysfunction. This disorder is called radiculopathy.

Figure 1. Illustration and magnetic resonance imaging (MRI) of a herniated disc causing lumbar radiculopathy.

Figure 2. Lumbar nerve roots typically involved in lumbar radiculopathy include the L4, L5, and S1 nerve roots.

When evaluating a patient for lumbar radiculopathy, always look for red flags - signs that the condition may be related to more serious or urgent medical conditions. Ask the patient if he has any of the following stories:

• Krebs
• recent trauma
• osteoporosis
• Infection
• rapidly progressive weakness
• bilateral weakness
• Bowel or bladder dysfunction

symptoms

Always ask about bowel or bladder disorders such as incontinence or retention. Acute spinal disorders (such as compressive metastatic tumors or cauda equina syndrome) are often associated with early bladder dysfunction.

Keep the possibility of myelopathy or cauda equina syndrome in mind during the examination. These are serious conditions that may require urgent surgical intervention.

Figure 3. Myelopathy and cauda equina syndrome are important differential diagnoses for lumbar radiculopathy that may require urgent treatment.

When taking the anamnesis, ask about the treatments that your patient has already started.

If, after a subjective interview, you still suspect lumbar radiculopathy, evaluate your patient for two main symptom characteristics:

1. Type, onset and duration of pain.
2. Associated symptoms

Figure 4. If lumbar radiculopathy is suspected, ask the patient about the type of pain, onset of pain, duration of pain, and associated symptoms.

Type, onset and duration of pain.

In lumbar radiculopathy, the pain must be unilateral. Classically, it is quite strong and more prevalent in the leg than the back. The pain tends to radiate from the back, through the buttocks and into the posterolateral aspect of the thigh and leg, which may (to some extent) follow the dermatome of the affected nerve root. The pain usually radiates to the groin.

Figure 5. Pain associated with lumbar radiculopathy is unilateral and tends to radiate from the back down, through the buttocks and to the posterolateral region of the thigh and leg.

Patients tend to generalize about pain and sensory symptoms, so be careful not to obsess over how pain follows a dermatomal pattern. Pain doesn't have to follow a classic pattern. Most of the pain can be located in the buttocks, groin, lower leg or ankle. This makes diagnosis quite difficult, as many generalized low back pain syndromes and myofascial syndromes can radiate to part of the buttocks and thighs.

However, lumbar radiculopathy is often characterized as having a radiating quality to the entire leg. Radicular pain can take on various characteristics such as: B. shocking, stabbing, sharp, stabbing or burning, and it can be relentless.

Figure 6. Radicular pain associated with lumbar radiculopathy can be jarring, stabbing, stabbing, stabbing, or burning.

Associated symptoms

If lumbar radiculopathy is suspected, ask the patient about paresthesia (pins and needles) and more uncomfortable dysesthesia (burning, tenderness, tingling, or itching). These are commonly associated with radiculopathy pain and should follow a similar pattern down the leg.

Figure 7. Paresthesias and dysesthesias are commonly associated with lumbar radiculopathy.

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The diagnosis of lumbar radiculopathy is usually made on the basis of history alone, as findings on physical examination may be unremarkable. On the other hand, positive findings help to close the diagnosis.

When performing a physical examination for lumbar radiculopathy, seven aspects should be considered:

1. monitoring
2. Physical and neurological exams
3. Cross and Straight Leg Raise Test
4. straight leg raise test
5. related motor dysfunction
6. Patellar and Achilles tendon reflexes
7. sensory test

monitoring

During the physical examination of a patient with suspected lumbar radiculopathy, you simply observe the patient for some time. Patients with severe radiculopathy feel very uncomfortable and adopt awkward positions to somehow relieve pressure on the affected nerve root. A typical position that the patient finds most comfortable is lying on the examination table with several pillows under the affected leg. A seated patient can lean their body to one side or the other.

Figure 8. Observing inappropriate postures in a patient with suspected lumbar radiculopathy.

Perform physical and neurological examinations.

Then complete a general physical examination and a targeted neurological examination and ensure that seven key assessments are included:

1. brain scan
2. Examination of the upper limbs
3. coordination check
4. Cranial nerve examination
5. motor reflexes
6. sensory reflexes
7. deep tendon reflexes

Should beNOUpper extremity findings or myelopathic findings on examination. There should also be no findings on the leg opposite the painful leg.

Figure 9. Physical and neurological examinations are part of the evaluation of patients with suspected lumbar radiculopathy.

Do a straight leg cross raise test

Gently extend the unaffected leg while the patient is in a supine position. If this causes pain in the affected leg, it is a strong sign of nerve root compression. This finding is called a positive crossed straight leg raise test.

Figure 10. A positive cross-straight leg raise test for lumbar radiculopathy causes pain in the affected leg when the opposite leg is straightened in the supine position.

Take a straight leg raise exam

To perform a straight leg scan, gently lift the affected leg and keep it straight, preferably with the patient in a supine position. Elevating the leg 10-15° should not increase pain. If so, suspect another pathology (or even simulation).

If the patient's radiating pain is intensified by elevating the leg 30 to 45 degrees, there is a high probability of radiculopathy due to a pinched nerve root. This finding is called a positive straight leg lift test.

Bending the ankle when lifting the leg usually makes the pain worse. These maneuvers irritate an affected nerve root, stretching the nerve over the compressing entity (such as a herniated disc).

Figure 11. A positive finding on a straight leg elevation scan is when pain increases when the affected leg is elevated from 30 to 45°. This suggests that the patient is suffering from radiculopathy due to a pinched nerve root.

Look for related motor disorders

Then look for evidence of associated motor dysfunction. Remember that lumbar radiculopathy affects lower motor neurons. Therefore, you should look for typical findings associated with lower motor neuron involvement:

• weakness
• diminished sound
• Atrophy
• diminished reflexes

Look for weakness in specific muscle groups. This means that the whole leg should not be weak. Furthermore, it is unusual for a muscle group to have no function. If the radiculopathy lasts long enough, you may see atrophy in the affected muscles. Depending on the severity, this could take weeks to months.

Figure 12. Typical findings of lower motor neuron involvement in lumbar radiculopathy include weakness, decreased tone, atrophy, and decreased reflexes.

Affected patients tend to be very cautious, so muscle testing can be unreliable. This is usually unconscious, and repeated stimulation often causes them to fully engage each muscle group. If they show obvious weakness in multiple groups, don't give up! Push the exam until you are confident in the results.

Weakness, if present, should follow a pattern consistent with the affected nerve root:

• L4 compression leads to quadriceps weakness.
• Compression of L5 creates weakness in foot and big toe dorsiflexion.
• S1 compression generates weakness in plantar flexion of the foot.

Figure 13. Weakness in lumbar radiculopathy should follow a pattern consistent with the affected nerve root. Compression of L4 causes quadriceps weakness, compression of L5 causes poor dorsiflexion of the foot and big toe, and compression of S1 causes poor plantarflexion of the foot.

Assess patellar and Achilles tendon reflexes

Reflex findings in patients with lumbar radiculopathy are asymmetrical. A diminished unilateral reflex indicates a nerve root disorder. To substantiate your suspicion of lumbar radiculopathy, abnormal reflex findings must be associated with the affected nerve root:

• Compression of L4 results in decreased knee reflex.
• S1 compression produces a decrease in the Achilles tendon reflex.

Figure 14. Reflex findings in lumbar radiculopathy are asymmetrical (eg, decreased only on the affected side). Compression of L4 leads to a decrease in the patellar reflex and compression of S1 leads to a decrease in the Achilles tendon reflex.

Other reflex findings

Hyperreflexia or a positive Babinski sign indicates an upper motor neuron process. If Babinski's sign is present, you should suspect a problematic spinal cord or brain and not a lumbar nerve root.

Figure 15. Hyperreflexia or a positive Babinski sign does not indicate the presence of lumbar radiculopathy and is indicative of an upper motor neuron process.

Take a sensory test

Perform a light and accurate sensory examination on both legs and trunk. Loss of sensation in one or both legs suggests other disorders or possibly a psychosomatic reaction.

Figure 16. Bilateral sensory loss is not a finding typically associated with lumbar radiculopathy.

In lumbar radiculopathy, you should ideally find a specific dermatomal distribution of sensory loss that corresponds to the nerve root you suspect is being compressed. However, sensory studies are notoriously inconsistent, so don't be fooled by the lack of perfect dermatomal distribution. Sensory loss approaching all or part of the dermatome supports the diagnosis.

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