Lake Louise Questionnaire for the Symptoms of Acute Mountain Sickness

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Introduction

Acute Mountain Sickness

Acute Mountain Sickness (AMS) is the most common acute altitude illness that can occur in unacclimatized individuals at altitudes >2500m. Risk factors include, rate of ascent, altitude of ascent, and individual physical characteristics. However, even if omeone has AMS, or mild AMS, it does not mean that they must descend immediately.

AMS must not be interchanged with high-altitude cerebral edema (HACE). It is not a neurological condition, and is known to be self-limited. Contrarily, HACE may occur between 24-72 hours after ascent, has characteristics of an altered mental state and/or ataxia. It usually occurs in conjunction with AMS or high-altitude pulmonary edema, and would be characterized as a medical emergency.

Introduction to the Lake Louise Acute Mountain Sickness scale

The Lake Louise Acute Mountain Sickness (AMS) scale was created to assess adults of AMS. It was first developed in 1991. It is a very useful scale to help diagnose and score the severity of AMS.

The symptoms measured on the initial test included,

• Headache
• Gastrointestinal Upset
• Fatigue/Weakness
• Dizziness/Light-Headedness
• Sleep Disturbance

*the double words are for general feelings and descriptions

These were rated with an intensity level of 0-3. A score that is ≥3, with a headache, was indicative of AMS.

Of the five symptoms assessed for AMS, disturbed sleep is the most likely symptom to occur due to altitude hypoxia. However, this symptom was seen to be poorly related to the other symptoms, and AMS. It was questioned if sleep disturbance was a symptom of AMS or an effect of hypoxia. Considering this fact, a revised scoring system does not include disturbed sleep as a symptom. Comparing daytime vs. night time effects of altitude was also a factor.

About the Test

Since the 'sleep disturbance' symptom was removed, a scoring of ≥3 from the four symptoms, including a headache, is indicative of AMS.

If someone wanted a more detailed scoring system, they could categorize intensity values as:

• 3-5 points as Mild
• 6-9 points as Moderate
• 10-12 points as Severe

Despite symptoms being able to develop within 6 hours of ascent to altitude, it is recommended that the score be assessed subsequent to 6 hours, to bypass any symptoms of travel or effects of acute hypoxia via vagal responses.

Characteristics of the Test - (What it looks like)

The AMS Clinical Functional Score can be used if someone wanted to assess the effect of AMS symptoms on overall health, function, and performance.

The scoring system looks like the following:

2018 Lake Louise Acute Mountain Sickness Score

Headache

• 0 - None at all
• 1 - A mild headache
• 2 - Moderate headache
• 3 - Severe headache, incapacitating

Gastrointestinal Symptoms

• 0 - Good appetite
• 1 - Poor appetite or nausea
• 2 - Moderate nausea or vomiting
• 3 - Severe nausea and vomiting, incapacitating

Fatigue and/weakness

• 0 - Not tired or weak
• 1 - Mild fatigue/weakness
• 2 - Moderate fatigue/weakness
• 3 - Sever fatigue/weakness, incapacitating

Dizziness/light-headedness

• 0 - No dizziness/light-headedness
• 1 - Mild dizziness/light-headedness
• 2 - Moderate dizziness/light-headedness
• 3 - Severe dizziness/light-headedness

AMS Clinical Functional Score - Overall, if you had AMS symptoms, how did they affect your activities?

• 0 - Not at all
• 1 - Symptoms present, but did not force any change in activity or itinerary
• 2 - My symptoms forced me to stop the ascent or to go down on my own power
• 3 - Had to be evacuated to a lower altitude

How to Conduct the Test

According to Roach et al, 2018, this test is only to be conducted by investigators, and not Clinicians, Professional Outdoor Guides, and general individuals, for the diagnosis and management of AMS. On the mountain, Guides will conduct an assessment twice a day, which includes the LLSS, pulse oximetry, and other criteria, to check for health and fitness on the mountain.

The Lake Louise AMS score can be administered as:

• A self-report tool
• Completed by researcher asking about the symptoms
• Individual filling in the score, and researcher reading it back to the individual

Diagnosis of AMS encompasses the following conditions:

• Ascent in altitude within the previous 4 days
• Presence of a headache
• Presence of atleast one other symptom, listed above
• A score of ≥3 from the entire test

What the Results Mean

The total AMS score would be the sum of scores for each of the four symptoms, listed again:

• Headache
• Nausea/Vomiting
• Fatigue
• Dizziness/Light-Headedness

To be categorized as having AMS, one would need to have atleast 1 point for a headache, and ≥3 points in total.

*For research purposes, the AMS score must include a headache, while for clinical purposes a headache may not need to be included for categorizing AMS.

*A severe headache of 3 point, with no other AMS symptoms, would be categorized as AMS.

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