History
The onset of symptoms in patients with lumbosacral radiculopathy is often sudden and includes LBP. Some patients state the preexisting back pain disappears when the leg pain begins.
Sitting, coughing, or sneezing may exacerbate the pain, which travels from the buttock down to the posterior or posterolateral leg to the ankle or foot.
Radiculopathy in spinal nerve roots L1-L3 refers pain to the anterior aspect of the thigh and typically does not radiate below the knee. These levels are affected in only 2-5% of all disc herniations. In contrast, 95-98% of clinically important lumbar disk herniations occur at either the L4-5 or L5-S1 intervertebral level, with neurologic impairments in the motor and sensory dermatomes and myotomes of the L5 and S1 spinal nerve roots corresponding to the dorsum of the foot and lateral aspect of the posterolateral (L5) and posterior lower leg and lateral foot (S1). [7]
When obtaining a patient's history, be alert for any red flags (ie, indicators of medical conditions that usually do not resolve on their own without management). Important relevant medical history such as active or previous cancer diagnosis, use of high doses of steroids, or recent intravenous access for any reason should be known. Such red flags may imply a more complicated condition that requires further workup (eg, tumor, infection). [8] The presence of fever, weight loss, or chills requires a thorough evaluation. Patient age is also a factor when looking for other possible causes of the patient's symptoms. Individuals younger than 20 years and those older than 50 years are at increased risk for more malignant causes of pain (eg, tumor, infection). [9]
Physical Examination
A comprehensive physical examination of a patient with acute LBP should include an in-depth evaluation of the neurologic and musculoskeletal systems.
The neurologic examination should always include an evaluation of sensation, strength, and reflexes in the lower extremities. This portion of the examination allows the examiner to detect sensory or motor deficits that may be consistent with an associated radiculopathy or cauda equina syndrome. Often, an assessment of the L5 reflex (medial hamstrings) is helpful. Also, in L5 radiculopathy, the presence of weakness in foot invertors should raise the additional suspicion of a peroneal nerve palsy.
When differentiating between an L3 radiculopathy versus a femoral neuropathy, weakness in the hip adductors in addition to the quadriceps group would indicate an L3 radiculopathy. In an isolated femoral neuropathy, only the quadriceps group would show weakness.
Provocative maneuvers, such as the straight-leg raising test or the slump test, may provide evidence of increased dural tension, indicating underlying nerve root pathology. Attempts at pain centralization through postural changes (ie, lumbar extension) may suggest a discogenic, facetogenic, or vertebrogenic etiology for pain and may also assist in determining the success of future treatment strategies when correlated with imaging findings.
The musculoskeletal evaluation should include an assessment of the lower extremity joints, as pain referral patterns may be confused with focal peripheral involvement. For example, a patient with anterior thigh and knee pain may actually have a degenerative hip condition rather than an upper lumbar radiculopathy. By assessing lower extremity flexibility, hip rotation, muscular balance, and ligamentous stability, the evaluating physician might be alerted to the patient's predisposition toward an acute LBP episode.
Combining the findings of the patient's history and physical examination increases the overall predictive value of the clinical evaluation process. Further diagnostic studies are indicated only upon the completion of a thorough history and physical examination and the establishment of a differential diagnosis.
A study by Zheng et al found that tarsal tunnel syndrome coexisted in 27 (4.8%) of the study's 561 patients with lumbosacral radiculopathy. [10]
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Sagittal magnetic resonance image showing loss of intervertebral disc height at L5/S1. Herniations of the nucleus pulposus are noted at L4/5 and L5/S1. Courtesy of Barton Branstetter, MD.
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Discogram showing examples of an intact disc and a disrupted disc at the lumbar level.
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Magnetic resonance image demonstrating extension of the nucleus pulposus to the right paracentral region of the spinal cord. The disc is adjacent to the inflamed right L5 nerve root. Courtesy of Barton Branstetter, MD.
