A previously healthy 45 yrs old laborer suddenly develops acute lower back pain with right-leg pain and weakness of dorsiflexion of the right great toe. Which of the following is TRUE?
**Core Concept**
The sudden onset of acute lower back pain with radiculopathy (nerve root involvement) suggests a possible diagnosis of lumbar disc herniation. The presence of weakness in dorsiflexion of the right great toe, a specific motor function, indicates involvement of the L5 nerve root.
**Why the Correct Answer is Right**
The correct answer is related to the clinical presentation of lumbar disc herniation and its effect on the L5 nerve root. The L5 nerve root is responsible for controlling the muscles involved in dorsiflexion of the foot, among other functions. When the L5 nerve root is compressed or damaged, it can lead to weakness in this specific motor function. In the context of lumbar disc herniation, the most common nerve roots involved are L4-L5 and L5-S1, with L5 being particularly susceptible to compression due to its anatomical location.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the clinical presentation described.
**Option B:** While radiculopathy can be a symptom of lumbar disc herniation, this option does not specifically address the motor weakness described in the question.
**Option C:** This option may be related to other conditions, but it does not directly address the acute lower back pain and specific motor weakness described in the question.
**Clinical Pearl / High-Yield Fact**
In patients presenting with acute lower back pain and radiculopathy, it is essential to carefully examine the motor functions of the lower extremities to identify specific nerve root involvement, as this can guide further investigation and treatment.
**Correct Answer:** C.