What is High Altitude Cerebral Edema?
High Altitude Cerebral Edema (HACE) is a serious and possibly life-threatening condition that can occur when you’re at high altitudes. Its common symptoms are problems with coordination (ataxia), tiredness, and changes in how you think or feel. HACE is typically seen as a very severe or advanced form of Acute Mountain Sickness (AMS). Even though HACE is the rarest type of illness caused by high altitudes, it can turn severe very quickly. If not found and treated promptly within a day, it can lead to a coma and even death due to a condition called brain herniation, where the brain is squeezed due to pressure.
What Causes High Altitude Cerebral Edema?
HACE, or high altitude cerebral edema, typically happens after spending two days at an altitude above 4,000 meters, though it can occur as low as 2,500 meters or come on more quickly. Some people, but not all, might experience symptoms of acute mountain sickness (AMS) – which includes headache, trouble sleeping, loss of appetite, and nausea – before it progresses to HACE. Some people might also develop high altitude pulmonary edema (HAPE), which is a buildup of fluid in the lungs due to high altitude.
It’s uncommon to see cases of HACE without these accompanying symptoms or conditions, but just because someone doesn’t show AMS or HAPE, doesn’t mean we can rule out the possibility of HACE.
Risk Factors and Frequency for High Altitude Cerebral Edema
HACE, or High Altitude Cerebral Edema, is a condition that occurs at high altitudes. It is more common in younger males who often ignore early symptoms, but it can affect anyone, regardless of age or gender. Certain factors are known to increase the risk of HACE. These include a history of high-altitude illness, a lack of acclimatization, heavy physical exertion, a rapid ascent, and a sudden climb from a lower altitude.
- The chance of getting HACE is 0.5-1% when you are 4000-5000 meters above sea level.
- It can affect anyone, regardless of age or gender.
- Younger males are at a slightly higher risk, particularly if they ignore early symptoms or climb too quickly.
- Your risk of HACE increases if you have had high altitude sickness before, do not acclimatize, exert yourself physically, or ascend rapidly or from a lower altitude.
Signs and Symptoms of High Altitude Cerebral Edema
High Altitude Cerebral Edema (HACE) often occurs as a progression of Acute Mountain Sickness (AMS). People experiencing AMS may typically complain of symptoms like headache, fatigue, nausea, insomnia, and lightheadedness after going to a higher altitude quickly. Some people might also show symptoms of High Altitude Pulmonary Edema (HAPE). When these conditions advance to HACE, the individual may start showing signs of brain damage, such as difficulty walking (usually the earliest clinical sign) and changes in mental state (ranging from mild to severe).
- Complaints of headache, fatigue, nausea, insomnia, and lightheadedness after a quick rise in altitude
- Possibility of symptoms of HAPE
- Difficulty walking (usually the earliest clinical sign)
- Changes in mental state (ranging from mild to severe)
- Severe headache
- Difficulty speaking
- Lassitude (extreme tiredness)
- Decline in the level of consciousness
- Occurrence of focal neurological deficits or seizures
Testing for High Altitude Cerebral Edema
High Altitude Cerebral Edema (HACE) is a condition diagnosed by observing certain symptoms and signs. It usually begins with signs and symptoms of Acute Mountain Sickness. This can then progress to more serious neurological symptoms like a decline in thinking or mental abilities, decreased ability to stay alert or awake, issues with coordination, unclear speech, and more fatigue. These are signs that Acute Mountain Sickness has transitioned to HACE.
Early symptoms of HACE may be mistaken for general tiredness, so it’s important to recognize these symptoms and rule out other conditions that could cause similar symptoms, like dehydration, low blood sugar levels (hypoglycemia), low body temperature (hypothermia), or lower than normal sodium levels in the blood (hyponatremia).
Laboratory tests, though rarely available, may show a high white blood cell count in patients with HACE, indicating an immune response by the body. Metabolic (related to the body’s process of breaking down food and its functions) abnormalities could also be seen in conditions that have overlapping symptoms with HACE.
A Lumbar puncture, a procedure where a needle is inserted into the lower spine to collect fluid, may show an increased pressure but otherwise normal results in people with HACE. A CT scan (a type of X-ray) might reveal swelling in the brain (cerebral edema), but an MRI (which uses strong magnets and radio waves to create images of the inside of the body) could give a more detailed image of this swelling. The abnormalities seen in MRI scans can remain for several days, or even weeks. However, the severity of the swelling does not necessarily correlate with how severe the patient’s symptoms are, or their recovery outcome.
Treatment Options for High Altitude Cerebral Edema
The best way to treat this condition is to immediately reduce your altitude by at least 1000m or until you start feeling better. You should never try to do this alone, and you should try to avoid physical exertion, which could potentially make your condition worse. If you can’t reduce your altitude, you may be able to temporarily improve your symptoms using a portable device that mimics the conditions at lower altitude (a hyperbaric chamber) and/or by using supplemental oxygen. However, these measures should never take the place of getting to a lower altitude and evaluation by a medical professional.
If available, a medication called dexamethasone can help cope with the symptoms. This medication, which can be given by mouth, through an injection, or intravenously, is typically used to reduce inflammation. However, please speak with your doctor for the correct dosage and frequency.
Another medication called acetazolamide may also be used, there is only one clinical study suggesting that it could be beneficial. This medication, which is usually given by mouth, is typically used to reduce the production of fluid in the body which helps to improve breathing and reduce discomfort at high altitudes.
Remember, while all these treatments can help to temporarily manage symptoms, they do not replace the need to descend to a lower altitude as soon as possible to resolve your condition. It’s always crucial to immediately seek medical attention when dealing with this condition.
What else can High Altitude Cerebral Edema be?
When someone experiences sudden changes in behavior or mental state, several factors could be at the root of these changes. Here are some of the potential causes:
- Acute psychosis
- Brain tumour
- Carbon monoxide poisoning
- Infections of the central nervous system
- Bleeding or blockage in the blood vessels of the brain (cerebrovascular bleed or infarct)
- Sudden narrowing of blood vessels in the brain (cerebrovascular spasm)
- Diabetic ketoacidosis, a serious diabetes complication
- Low blood sugar levels (hypoglycemia)
- Low sodium levels in the blood (hyponatremia)
- Taking certain drugs
- Seizure disorder
It’s important to see a doctor immediately if any of these situations apply, as these conditions can be serious and require immediate treatment.
