Which statement about cytotoxic edema is true?

• A. It involves extracellular fluid accumulation due to BBB disruption
• B. It involves cellular swelling due to hypoxia/ischemia
• C. It is primarily seen with tumors
• D. It resolves with diuretics alone

Answer: (B)

Cytotoxic edema happens when brain cells swell because their energy supply fails during hypoxia or ischemia. When ATP is depleted, the Na+/K+ ATPase pumps can’t maintain ion gradients, so sodium builds up inside cells and water follows. This intracellular swelling affects neurons, astrocytes, and other glial cells, and it occurs with the BBB largely intact at first. This intracellular process distinguishes it from vasogenic edema, where the barrier is disrupted and fluid leaks into the extracellular space.

So the statement that best fits cytotoxic edema is that it involves cellular swelling driven by hypoxia/ischemia. By contrast, edema caused by extracellular fluid accumulation due to BBB disruption describes vasogenic edema and is more typical around tumors or inflammatory processes. Diuretics alone don’t specifically reverse cytotoxic edema because the issue is cellular swelling from energy failure, not just excess extracellular fluid; treating the underlying ischemia and restoring perfusion is essential, with supportive measures to manage intracranial pressure as needed.