Which objective finding is MOST likely in a patient diagnosed with amyotrophic lateral sclerosis?

• A. Normal deep tendon reflexes
• B. Preserved respiratory function
• C. Preserved sensory function
• D. Bowel and bladder incontinence

Answer: (C)

ALS primarily damages motor neurons—both upper and lower motor neurons—while sensory pathways are typically spared. This means patients often have weakness, muscle atrophy, fasciculations, and spasticity with signs like brisk reflexes, but their sensation remains intact. That preserved sensory function is the most characteristic objective finding in this condition. In contrast, respiratory function tends to decline as accessory and diaphragmatic muscles weaken, and bowel/bladder control is usually preserved until later stages, so those options aren’t as typical early or general findings. The combination of motor signs with intact sensation is what makes preserved sensory function the best fit for an ALS presentation.