A 42-year-old man comes to the office due to back pain. Yesterday, the patient was moving furniture when he suddenly had sharp, shooting pain in the lower back and buttocks that radiated down the back of the legs. He took acetaminophen and rested, but the pain was persistent. When the patient woke up today, his legs felt numb and weak, and he also had to strain to urinate. He has no chronic medical conditions and takes no medication. Vital signs are within normal limits. Physical examination shows lower lumbar spine tenderness on palpation. Bilateral lower extremity strength is 4/5, and ankle reflexes are absent bilaterally. Sensation to touch is decreased in the perineal region and buttocks. Straight leg raise testing is positive. Which of the following is the most appropriate next step in management of this patient?

Question

A 42-year-old man comes to the office due to back pain.  Yesterday, the patient was moving furniture when he suddenly had sharp, shooting pain in the lower back and buttocks that radiated down the back of the legs.  He took acetaminophen and rested, but the pain was persistent.  When the patient woke up today, his legs felt numb and weak, and he also had to strain to urinate.  He has no chronic medical conditions and takes no medication.  Vital signs are within normal limits.  Physical examination shows lower lumbar spine tenderness on palpation.  Bilateral lower extremity strength is 4/5, and ankle reflexes are absent bilaterally.  Sensation to touch is decreased in the perineal region and buttocks.  Straight leg raise testing is positive.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d0f7_a4f6_bc81_5d327a9753ff_MD0003_00 This patient's urinary difficulty, saddle anesthesia (decreased sensation in the buttocks/perineum), and bilateral lower extremity motor/sensory/reflex abnormalities raise strong suspicion for cauda equina syndrome (CES). Most cases arise when a large, central lumbar disc herniation at the L4-S1 level bulges into the lumbar cistern and compresses multiple spinal nerve roots in the cauda equina. Injury to the cauda equina, which is composed of nerve roots for L2-L5, S1-S5, and the coccygeal nerve, usually results in severe back pain radiating into one or both legs and loss of lower extremity motor strength, sensation, and reflexes in the affected dermatomes. Saddle anesthesia is highly suggestive of CES and reflects impingement of S2-S4 nerve roots; bladder (eg, urinary straining) and rectal sphincter paralysis can also occur due to damage to S3-S5 nerve roots. Loss of ankle reflex indicates damage to S1-S2 nerve roots. Straight leg raise testing (worsened sciatic pain when straight leg is raised to 30-70 degrees) is positive in >90% of those with acute lumbar herniation and may aid diagnosis. Confirmation requires urgent MRI of the lumbosacral spine. Because patients with CES (particularly in the setting of bladder or rectal dysfunction) are at high risk for permanent neurologic sequelae, surgical decompression is then usually necessary. (Choice B) A plain radiograph of the lumbosacral spine can diagnose degenerative disc disease or bone lesions. However, it does not allow clear enough visualization of the spinal canal and intravertebral discs to definitively rule out CES; lumbosacral spine MRI is considered the test of choice for diagnosis. (Choices C, D, and E) Acute lumbosacral radiculopathy is usually caused by disc herniation and is marked by impingement of ≥1 lumbosacral nerve roots. Although patients often have low back pain that radiates into one or both legs (and may occasionally have dermatomal motor weakness or loss of reflex), other neurologic issues such as saddle anesthesia and bowel/bladder dysfunction are generally absent (in contrast to CES). Acute lumbosacral radiculopathy is typically managed with nonsteroidal anti-inflammatory drugs, acetaminophen, and activity modification to lessen pain. Physical therapy with graduated exercises may be recommended in some cases; prolonged bed rest and inactivity is not recommended and may worsen outcomes. Educational objective: Cauda equina syndrome is most common following a large lumbosacral disc herniation. Suspicion should be raised in those with severe low back pain radiating into one or both legs with accompanying saddle anesthesia (sensory change in the genitals/perineum) and/or bladder, bowel, or sexual dysfunction. An urgent lumbosacral spine MRI is required for diagnosis, followed by surgical decompression.

A 42-Year-Old Man Comes to the Office Due to Back