High Altitude Cerebral Edema Hace

Overview

High altitude cerebral edema (HACE) is a rare but very serious condition where the brain swells because of low oxygen at high altitude. "Cerebral edema" means swelling of the brain. It usually happens above about 2,500 to 3,000 metres (roughly 8,000 to 10,000 feet), and almost always in someone who went up too fast without giving their body time to adjust. HACE is the most severe form of altitude sickness, and it is a medical emergency. When it is recognised early and the person goes down to a lower altitude straight away, most people recover fully.

HACE is uncommon. Mild altitude sickness is much more common, affecting many people who go quickly to high places. Only a small number of those people go on to develop HACE, and it becomes rarer when people climb slowly and acclimatise (give their bodies time to adjust).

Anyone who travels to high altitude can be affected, including fit young people, athletes and experienced mountaineers. Risk is higher in people who go up quickly, who have had altitude sickness before, who sleep at high altitude soon after arriving, and in people whose bodies seem to handle low oxygen less well. Children and older adults can also be affected. Having a heart or lung condition can add to the risk, so it is worth asking a travel health professional before going to high altitude.

Symptoms

Common symptoms

• A headache that is often severe and does not ease with usual pain relief
• Feeling confused, muddled, or not making sense when talking
• Trouble walking steadily, stumbling, or feeling like you are drunk
• Feeling very sleepy, unusually tired, or hard to wake
• Nausea and vomiting
• Dizziness and light-headedness
• Blurred vision or changes in eyesight
• Unusual behaviour, irritability, or seeing or hearing things that are not there
• Weakness or clumsiness in the arms or legs

Symptoms in children

• Being unusually sleepy, floppy, or hard to wake
• Crying in a way that is hard to settle, or being very irritable
• Poor feeding or drinking, and vomiting
• Not responding normally, or seeming confused
• Stumbling or losing the ability to walk steadily
• Children may not be able to explain a headache, so watch for changes in behaviour

Symptoms in older adults

• Confusion or drowsiness that may be mistaken for tiredness or ageing
• Unsteadiness that may be blamed on other health problems
• Symptoms can be harder to spot if the person also has heart or lung disease
• Any new confusion at altitude should be treated as an emergency until proven otherwise

Causes

Main causes

• Going to high altitude faster than the body can adjust, so the air is thinner and you take in less oxygen
• Low oxygen levels causing tiny blood vessels in the brain to leak fluid, which makes the brain swell
• Usually starting as milder altitude sickness that then gets worse
• Sometimes happening together with high altitude pulmonary edema (HAPE), which is fluid in the lungs

Risk factors

• Climbing or travelling up too quickly, especially sleeping at a much higher place after a short time
• Not taking rest days to acclimatise
• Having had altitude sickness before
• A personal pattern of getting altitude sickness easily
• Strenuous activity soon after arriving at height
• Drinking alcohol or taking sedative-type medicines at altitude
• Dehydration and getting cold
• Being at very high altitude, generally above 2,500 to 3,000 metres
• Existing heart or lung conditions

When to see a doctor

See a doctor urgently if:

• Any confusion, clumsiness or trouble walking at altitude — treat it as an emergency and get medical help while starting to descend
• Altitude sickness symptoms that get worse rather than better after resting
• Vomiting that stops you keeping fluids down
• Breathlessness at rest, or a cough that will not settle

Book a routine appointment if:

• Before a trip to high altitude, especially if you have a heart or lung condition or have had altitude sickness before — ask a travel health professional for advice
• After recovering from altitude sickness, to check that you are fully well and to plan safer travel next time
• If you notice ongoing tiredness, headaches, poor concentration or low mood for weeks after your trip

Diagnosis

HACE is usually diagnosed from the story and the symptoms. A doctor or trained mountain guide will check whether the person has been at high altitude, whether they have a bad headache, and most importantly whether they are confused or unsteady on their feet. In the mountains, treatment and descent often start straight away based on these checks, without waiting for tests.

Tests that may be done

• Checking how alert and clear-thinking the person is
• Asking the person to walk heel-to-toe in a straight line to test balance
• Looking at the eyes for signs of pressure inside the head
• Checking oxygen levels in the blood with a small finger clip (a pulse oximeter)
• In hospital, a scan of the brain may be done to rule out other causes
• Blood tests and other checks to look for related problems such as fluid in the lungs

What to expect at your appointment

If HACE is suspected, the priority is not tests but action — going down to a lower altitude and getting oxygen and medical care. In hospital, staff will monitor the person closely, check their breathing, alertness and balance, and may do a brain scan to confirm what is happening and exclude other conditions.

Treatment

HACE is treated as an emergency. The most important step is to descend to a lower altitude as quickly and safely as possible, and to get medical help on the way. Extra oxygen and, where available, a portable pressurised bag can help until the person is lower down. Hospital care may be needed for close monitoring and support.

Self-care at home

• If you have any confusion or unsteadiness at altitude, do not stay put and hope it passes — descend straight away with someone who can help you
• Stop going higher and rest until you are well below the height where symptoms started
• Keep warm, drink fluids if you can keep them down, and avoid alcohol
• Do not go back up to high altitude until you have fully recovered and been checked by a doctor
• Tell someone responsible where you are and what is happening, so help can be arranged

Medical treatments

Treatment is led by trained medical staff or mountain rescue teams. It includes taking the person down to a lower altitude, giving extra oxygen, and using a portable pressurised bag when descent is not immediately possible. A doctor may prescribe medicines that reduce swelling in the brain or help with breathing and acclimatisation. In severe cases, hospital care with close monitoring and breathing support may be needed. Anyone who has had HACE should be checked by a doctor afterwards before travelling to altitude again.

When is surgery considered?

Surgery is not usually part of treating HACE. It may only be considered if a scan shows another cause for the swelling, such as a bleed or a growth, which is uncommon.

Living with this condition

After HACE, recovery usually happens over days to a few weeks. Many people feel tired, have headaches, or find it harder to concentrate for a while. Give yourself time, keep well rested and hydrated, and avoid rushing back to high altitude.

Lifestyle tips

• Take it easy for the first few days after recovery and build your activity back up slowly
• Avoid alcohol and sedative-type medicines while you are recovering
• Sleep well and keep warm
• If you travel to altitude again, plan a slower route with rest days
• See a doctor if tiredness, headaches or poor concentration last more than a few weeks

Diet and exercise

There is no special diet for HACE. Eating regular meals and drinking enough fluids helps your body cope, especially at altitude where you lose more water. After recovery, gentle activity such as walking is fine, and you can go back to your normal exercise routine as you feel ready. If you plan another high-altitude trip, build fitness beforehand, but remember that fitness alone does not prevent altitude illness.

Mental health and emotional wellbeing

Being seriously ill in a remote place, or seeing someone else become ill, can be frightening. Some people feel anxious about going back to the mountains, or have upsetting thoughts about what happened. These feelings are common and usually settle. Talk to someone you trust, and speak to a doctor or a mental health professional if worry, low mood or bad dreams are affecting your daily life. If you ever feel you cannot cope, contact your local crisis support service or emergency number right away.

Prevention

You cannot remove all risk, but you can greatly lower it. The main way is to go up slowly and let your body adjust. Above about 3,000 metres, a common approach is to sleep no more than around 500 metres higher each day, and to take a rest day every three to four days. Avoid alcohol and sedative-type medicines at altitude, keep warm, drink enough fluids, and start gently rather than doing hard exercise on the first day. Learn the warning signs of altitude sickness and never ignore a headache with confusion or unsteadiness.

Vaccines

There is no vaccine for HACE. Vaccines are not part of prevention for this condition, but it is still worth checking that your routine vaccinations and any travel vaccines are up to date before a trip.

Screening programmes

There is no routine screening test for HACE. Instead, a travel health professional can review your health and your planned route before you go, especially if you have a heart or lung condition or have had altitude illness before. They can also advise whether any preventive medicine is suitable for you.

Complications

If left untreated

• Reduced awareness and coma
• Permanent brain injury
• Fluid in the lungs (high altitude pulmonary edema), which makes breathing very difficult
• Death, particularly if the person stays at high altitude

Long-term outlook

With early recognition and prompt descent, the outlook is good, and most people recover fully within days to a few weeks. Some people notice tiredness or trouble concentrating for a while afterwards, but this usually improves. If you have had HACE once, you are more likely to get altitude sickness again, so plan future trips more slowly and speak to a travel health doctor beforehand.

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