Question

The earliest sensation to be lost in Hansen's disease is

• A. Touch
• B. Temperature
• C. Pain
• D. Vibration

Hint:

Think about which nerve fibers sit closest to the skin surface, where the bacillus prefers to live.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks which sensory modality is affected first when peripheral nerves are damaged in leprosy.

Step 2: Key Concept or Approach:
Mycobacterium leprae preferentially grows in cooler, superficial tissues and damages the small, thinly myelinated nerve fibers carrying temperature sensation before it affects the larger fibers responsible for touch and pain.

Step 3: Working Through the Options:
Because temperature-sensing fibers lie more superficially and sit in the cooler tissue the bacillus prefers, temperature discrimination is lost first, followed by light touch, then pain, with deep pressure and vibration sense preserved longest. Touch is affected, but only after temperature goes. Pain sensation is typically the last protective sensation lost, which is exactly why patients keep injuring anesthetic hands and feet without noticing. Vibration, carried by large myelinated fibers and the posterior columns, is the most resistant of the four.

Step 4: Conclusion:
Temperature sensation is lost earliest in Hansen's disease, so temperature is correct.