You are the team doctor with a mountaineering expedition

You are the team doctor with a mountaineering expedition. The group have ascended to a height of 5000m and have set up a forward camp. One mountaineer complains of a headache and nausea that she had initially dismissed as she was keen to make the summit but have been getting worse. The headache is now very severe and other climbers become concerned when she is seen to stagger about the camp. When you see her she confirms that she has a severe headache and is feeling unsteady on her feet. You note that her gait is ataxic.

What is the recommended management of this patient?

Descent
Descent + acetazolamide
Descent + dexamethasone
Descent + phosphodiesterase type V inhibitor
Oxygen