What is hemianalgesia?

Hemianalgesia refers specifically to the condition of lacking pain sensation on one side of the body. The term is derived from "semi," meaning half, and "analgesia," which refers to the absence of pain. This condition can occur due to various medical reasons, including nerve issues or injuries that affect sensory pathways in the nervous system on one side of the body.

The other options represent different medical concepts. The loss of ability to move one side of the body pertains to paralysis, while increased sensitivity to pain indicates a heightened pain response, also known as hyperalgesia. Complete numbness across the entire body describes a state of anesthesia, which is distinct from hemianalgesia because it affects the whole body rather than just one side. Therefore, the definition of hemianalgesia aligns precisely with the description of a lack of pain sensation on one side, confirming why that answer is correct.