Which is an acute CNS change related to dehydration?

Which is an acute CNS change related to dehydration?

• A. Nystagmus
• B. Hypertension
• C. Hypothermia
• D. Restlessness

Answer: (D)

Restlessness appears as an acute CNS change because dehydration raises plasma osmolality, causing brain cells to shrink and become irritable. This osmotic brain irritation often presents as agitation or restlessness early on, even before more severe confusion or lethargy develops. In contrast, nystagmus points to other neurologic or vestibular issues, hypertension isn’t a typical result of volume loss (dehydration more commonly causes lower blood pressure), and hypothermia is not a hallmark feature of dehydration alone. So restlessness best reflects the immediate CNS response to fluid deficit.

Restlessness appears as an acute CNS change because dehydration raises plasma osmolality, causing brain cells to shrink and become irritable. This osmotic brain irritation often presents as agitation or restlessness early on, even before more severe confusion or lethargy develops. In contrast, nystagmus points to other neurologic or vestibular issues, hypertension isn’t a typical result of volume loss (dehydration more commonly causes lower blood pressure), and hypothermia is not a hallmark feature of dehydration alone. So restlessness best reflects the immediate CNS response to fluid deficit.