68-year-old man with 4 weeks of low back and leg pain
A 68-year-old man comes to the clinic for a 4-week history of worsening low back pain that radiates down his right leg to the top of his foot. The pain is sharp, rated 7/10, and often wakes him from sleep. He has a history of prostate cancer treated with radiation 5 years ago and has been in remission since. On examination, his temperature is 37.1°C (98.8°F), and other vital signs are normal. There is tenderness to palpation over the L5 spinous process. Straight leg raise on the right is positive at 40 degrees, reproducing his radicular pain. Strength is 4/5 with right great toe extension. Sensation is decreased over the dorsum of the right foot. Which of the following is the most appropriate next step in management?
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D
Explanation
Clinical Pearl:
In a patient with new-onset back pain and radiculopathy, the presence of red-flag features such as a history of cancer, age over 50, or nocturnal pain that disturbs sleep mandates prompt imaging with MRI to evaluate for serious spinal pathology like malignancy or infection.
Explanation:
This patient presents with signs of lumbar radiculopathy (pain radiating in a dermatomal pattern, positive straight leg raise, focal weakness, and sensory loss) along with several red-flag features: age over 50, a history of cancer, and nocturnal pain. These features raise concern for a serious underlying etiology, such as spinal metastatic disease, which must be excluded. According to major orthopedic and rheumatology society guidelines, urgent imaging is indicated in patients with back pain and red flags. MRI is the most sensitive and specific imaging modality for evaluating the spinal cord, nerve roots, and vertebral bodies for evidence of tumor, infection, or compression. The addition of gadolinium contrast is crucial in this setting to better characterize potential epidural or marrow-infiltrating lesions. Therefore, an MRI of the lumbar spine with and without contrast is the most appropriate next step. Conservative management with physical therapy and NSAIDs is inappropriate given the red flags. Plain radiography is less sensitive than MRI for detecting early metastatic disease and cannot visualize soft tissues like nerve roots or the spinal cord. Electromyography is useful for confirming radiculopathy but is not the first-line investigation when a structural lesion like a tumor is suspected, as it will not identify the cause. A course of oral corticosteroids would be premature and could mask symptoms or delay the diagnosis of a serious condition.
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