## **Core Concept**
The question tests knowledge of the clinical presentation of tuberculous cord compression, a serious complication of spinal tuberculosis. Tuberculous cord compression occurs when the tuberculosis infection spreads to the spine (Pott's disease) and compresses the spinal cord. Early recognition of symptoms is crucial for timely intervention.

## **Why the Correct Answer is Right**
The correct answer, **D. Weakness of lower limbs**, is right because the earliest symptom of tuberculous cord compression often relates to the motor pathways. The compression of the spinal cord typically affects the corticospinal tracts, which are responsible for motor function. This leads to weakness or loss of power in the muscles supplied by the segments below the level of compression. Given that the lower limbs are commonly affected in spinal tuberculosis due to the predilection of the disease for the thoracic and lumbar spine, weakness in these areas is a presenting complaint.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Radicular pain might occur due to the involvement of the nerve roots, but it is not typically the first symptom of cord compression itself. It can be a presenting feature of spinal tuberculosis but is more related to the local disease process rather than cord compression.
- **Option B:** Loss of sensation can occur as a result of cord compression, affecting the spinothalamic and dorsal columns. However, this usually follows the onset of motor symptoms.
- **Option C:** Bladder and bowel dysfunction can occur due to cord compression, affecting the autonomic pathways. While significant, these symptoms often appear after the initial motor symptoms.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that in spinal tuberculosis, the disease process starts in the vertebral bodies and can lead to cord compression through abscess formation or bony destruction. Early symptoms of cord compression, such as **weakness of the lower limbs**, necessitate urgent imaging and intervention to prevent irreversible neurological damage. A classic clinical correlation is that any patient with spinal tuberculosis and neurological symptoms requires immediate MRI and possible surgical intervention.

## **Correct Answer: D. Weakness of lower limbs**