8.1.3 Carbon monoxide (CO)-induced headache

Identification: A 35-year-old male patient presented to the emergency department with a progressive headache lasting 6 hours.

History of Present Illness:

The patient reports a bilateral, pulsatile headache of moderate to severe intensity, associated with nausea and dizziness.

Symptoms began after spending approximately 3 hours in an enclosed space with a malfunctioning gas heater.

The patient denies any previous history of primary headaches, such as migraines or tension-type headaches.

Physical/Neurological Examination:

The patient is conscious but exhibits slight mental confusion.

There is no neurological focality.

Arterial blood gas analysis shows normal PaO₂, but carboxyhemoglobin (COHb) levels are elevated at 25% (normal value < 3% in non-smokers).