We're often taught that a headache at altitude is Acute Mountain Sickenss (AMS) until proven otherwise. This is true but let’s whisper it, AMS is not the only cause of headache in the mountains! If we're going to practise our craft to a high standard it's worth being aware of other causes too! Before we look at these let’s take a quick look at some AMS facts...
AMS is a very common condition that occurs in poorly acclimatised individuals who ascend to 2500m or higher.
Symptoms of headache, nausea, dizziness and fatigue start within 6 to 12 hours of arriving at a new altitude.
An AMS headache is bilateral and feels dull or pressing in nature. It is aggravated by movement and improves on lying flat.
By simulating a descent, a portable hyperbaric chamber (PAC) can be useful in the diagnosis of AMS. Symptoms of AMS should disappear within minutes of entering the PAC.
AMS is associated with life threatening conditions such as High Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema (HACE).
The mildest forms of AMS can resolve with rest and simple analgesia, however those with more severe forms of the condition need to descend.
Now, here are five other causes of headache to consider!
1 - Tension Headache – These are responsible for more than 90% of headaches at sea level and don't go away in the mountains! Typically, they are bilateral and feel like a tight band of pressure around the head. Unlike AMS they are unaffected by movement and they are rarely associated with other symptoms. Stress often plays an important part in tension headaches. Whilst handing over a couple of paracetamol and telling them to rest may be a good first step, if it’s proving a big hindrance why not try to work out what’s causing it? Homesickness? Poor sleep? Fear of what’s to come? Whilst you might not be able to solve the problem you can at least offer a sympathetic ear and you might even ease their headache!
2 - Migraine - A unilateral pulsing headache. Migraines are sometimes preceded by an "aura" - a set of visual or sensory changes that typically last for up to an hour. Nausea is common. Symptoms are worsened by movement. Sufferers will know how to manage their migraines. Most will need a dark, quiet room and a supply of analgesia and anti-emetics. Some will be aware of what triggers their migraines. Before heading into the mountains, work with sufferers to minimise their exposure to them.
3 Hangover – In recent years alcoholic drinks have become more widely available in the mountains. Hangovers are becoming increasingly common! Unfortunately, the effects of excess alcohol can sometimes be difficult to distinguish from AMS. I've not always been successful in distinguishing the two - to my shame I have confused a hangover with the early signs of HACE! Nevertheless, here's a few ideas. Start off by taking a thorough history. Is this consistent with the patient's previous hangovers? Hangovers usually improve with a “lie in”, two paracetamol and something to drink. If symptoms persist or worsen, it's unlikely to be a hangover. In these circumstances it might be worth using the portable hyperbaric chamber to help you confirm your diagnosis. I missed HACE because I let the "lie in" run on too long. It wasn't until his friends found him struggling to walk later that evening that I realised it was much more serious than what I thought. To avoid any confusion try to encourage your group to keep their alcohol consumption to a minimum during the acclimatization period and save it for the descent instead!
4 Caffeine Withdrawal – Many of us need a cup of “good” coffee to get us moving in the morning. Especially if it's 5am and your two year old is wide awake! But what if that's the first of half a dozen cups? What happens when you go on a trek and are suddenly denied all that caffeine? My experience is that within 24 hours, many will complain of a headache and flu-like symptoms. Tiredness, low mood and aches are common. The solution? Give them their caffeine back! Sachets of “good” coffee are now available and should quickly restore the patient to full health. In the past I’ve carried “Pro Plus” tablets in my medical kit. These tablets contain 50mg of caffeine and 3 or 4 taken with water have been a really useful tool to distinguish AMS from caffeine withdrawal.
5 Who Knows?!? - In 2012, Jon Dallimore published a study in Wilderness and Environmental Medicine that charted the incidence of AMS amongst teenagers on a 3 day trek. The clever part of Jon’s study was the fact that the trek took place less than 500m above sea level. In theory, the incidence of AMS should have been 0%! However this was not the case – between 7 and 11% of trekkers satisfied the diagnosis of AMS during the trek! The bottom line is that headaches often occur in mountainous areas and won’t be the result of poor acclimatisation. On many occasions you simply won’t find a cause. The key to good practice is to be aware that there are many causes of headache in the mountains. Identify those that can be treated and manage them appropriately. But just as important, be honest with those who defy diagnosis and do the best you can!
Jon's study can be found here.