A patient has an acute onset of low back pain with left leg pain reproduced by a straight-leg raise at 40 degrees, and the left Achilles reflex is 1+. The patient MOST likely has which condition?

A patient has an acute onset of low back pain with left leg pain reproduced by a straight-leg raise at 40 degrees, and the left Achilles reflex is 1+. The patient MOST likely has which condition?

• A. Large central disc herniation
• B. Left lateral spinal stenosis
• C. Lateral disc herniation
• D. Right lumbar structural scoliosis

Answer: (C)

The main idea is unilateral nerve-root compression from a disc herniation causing radicular pain with focal reflex changes. When a disc herniates to the left side, it tends to compress the left exiting nerve root (in this scenario, the S1 root), producing radicular leg pain that can be reproduced with a straight-leg raise as the nerve is stretched. The left Achilles reflex being reduced to 1+ points to S1 involvement, which fits a left-sided L5–S1 disc herniation. This pattern is less consistent with a large central disc herniation, which would more likely cause bilateral symptoms or cauda equina signs; spinal stenosis, typically seen in older individuals, presents with neurogenic claudication and pain worsened by walking rather than an acute, focal radiculopathy. Structural scoliosis doesn’t explain an acute unilateral radicular pain with a diminished deep tendon reflex. So, the presentation aligns best with a left lateral disc herniation compressing the left S1 nerve root.

The main idea is unilateral nerve-root compression from a disc herniation causing radicular pain with focal reflex changes. When a disc herniates to the left side, it tends to compress the left exiting nerve root (in this scenario, the S1 root), producing radicular leg pain that can be reproduced with a straight-leg raise as the nerve is stretched. The left Achilles reflex being reduced to 1+ points to S1 involvement, which fits a left-sided L5–S1 disc herniation.

This pattern is less consistent with a large central disc herniation, which would more likely cause bilateral symptoms or cauda equina signs; spinal stenosis, typically seen in older individuals, presents with neurogenic claudication and pain worsened by walking rather than an acute, focal radiculopathy. Structural scoliosis doesn’t explain an acute unilateral radicular pain with a diminished deep tendon reflex.

So, the presentation aligns best with a left lateral disc herniation compressing the left S1 nerve root.