A headache is the result of which dive injury?

• A. Hypercapnia
• B. Decompression sickness
• C. Hypoxia
• D. Oxygen toxicity

Answer: (A)

Elevated CO2 in the diver’s system is the most direct cause of a headache in this context. When ventilation is inadequate or breathing gas is being rebreathed or not cleared properly, CO2 accumulates (hypercapnia). The excess CO2 causes cerebral vasodilation and increased blood flow to the brain, which tends to produce a headache and can be accompanied by dizziness or a feeling of pressure.

Decompression sickness involves gas bubbles forming in tissues after ascent and has a broader symptom profile, such as joint or muscle pain, dizziness, fatigue, or neurological signs, rather than a solitary headache being the defining feature. Hypoxia would present with signs of insufficient oxygen delivery like confusion, cyanosis, or impaired function, not a classic isolated headache. Oxygen toxicity can cause headaches too, but it is usually tied to high partial pressures of oxygen with additional symptoms as exposure continues, not the typical immediate cause of a standalone headache.