My Tryst with High Altitude Cerebral Edema (HACE)

Prayer Flags at Tsokha

“Descend Fast”.

Two words that I heard many times from my father when he would talk about the effects of high altitude on the human body and mind. He had been an instructor at HMI and a commandant at Indian Army’s High Altitude Warfare School, among the many things he did during his long and illustrious military career. The many documentaries I saw about mountaineering also drilled the same message in my head. Knowledge is power; it is also a saviour. It was this knowledge, not only on my part but on the part of my trekking partners and our trekking guide that helped save my life. I say this with absolutely no exaggeration and with a very high sense of dread for what could have been, and gratitude for how it all turned out.

Just as I learnt from the experiences of others, I am writing this so that my experience can help someone else make the right decisions at the right time when faced with a life-threatening high altitude condition.

Yuksom to Tsokha

On the 29th of April 2022, my sister, brother-in-law, and I set out on a trek to GoechaLa in west Sikkim. The trek, if we had completed it, would have taken us from 5,600 feet above msl to over 16,000. On day 1, we ascended from 5,600ft to almost 10,000ft and spent the night at Tsokha. On day 2, we went from 10,000 to 13,000ft to Dzongri. Dzongri was to be our acclimatisation stop and we were to spend 2 nights here. That same day, I developed a throbbing headache which I thought was a migraine, but I did have AMS (Acute Mountain Sickness) at the back of my mind. I took some painkillers and had some garlic soup, which is supposed to help with AMS.

The next day (trek day 3), the headache was gone but there was a heaviness in the head and a feeling that a throbbing headache was lurking just below the surface. I did a short acclimatisation walk (2h, 200m alt gain) with my sister, brother-in-law, and our guide, Tashi, in the morning and felt fine. The next morning (trek day 4), we left for Tangsing, which involved a short ascent, a long descent, and then a long ascent, to finally end up again at about 13,000ft. I was deliberately walking slowly to not get out of breath and to not trigger a throbbing headache. I wasn’t feeling better but it wasn’t getting worse either.

Cairns, showing us the way and carrying prayers to the gods

We reached Tangsing by the afternoon of that day and spent the rest of the day relaxing and chatting with other trekkers who we had joined up with. All through that evening I felt out of sorts but there was no further worsening.

Things took a turn for the worse late that night when, while turning over in my sleeping bag, I started feeling a sense of imbalance (like I was drunk). I found out later that this is called Ataxia. When I woke up (trek day 5, 3rd of May) and sat up, I was swaying. I knew from the documentaries I had seen that any kind of mental disorientation is very serious and is a symptom of HACE (High Altitude Cerebral Edema). The two magic words (Descend Fast) started going through my mind. Thankfully my thinking wasn’t impaired yet.

I told our trek leader/guide, my sister, and my brother-in-law about my symptoms and we all immediately agreed that we need to go back down. As I started packing my backpack, the one thought going through my mind was how will I get back down, through terrain that required me to walk on narrow ledges, rocks, and boulders, when I could not even walk a straight line on flat land (like being drunk). As there was no other option, the only thing to do was to put my head down (literally and figuratively), keep it steady (moving the head would make my body sway), use my two trekking poles to balance, and just keep walking. It was very comforting to have my sister, brother-in-law, and our guide Tashi with me. In the riskiest portions, Tashi would be right behind me and had to put a hand out to stop me from falling over a few times.

A photo with the group before we said our goodbyes. It’s only later I noticed how swollen my face was due to the cerebral edema
Not the easiest of terrains to walk on, even with full faculties
Don’t look down took on a whole new meaning

The first section (Tangsing to Phedang – 8km, 1,000ft descent) took us almost 5 hours and we took our first break there. Progress was much better after that as the terrain improved and we were able to do the remaining 6km to Tsokha in about 2.5 hours. By now we had descended 3,300ft and we rested for the night at Tsokha. The next morning (trek day 6), the Ataxia was a lot better but still hadn’t fully gone. We walked another 13km in about 6 hours that day to reach Yuksom at 5,600ft. The sense of relief I felt having reached civilisation (and facilities) is indescribable. We stayed a night at Yuksom and then descended further to Siliguri at about 500ft above msl the next day, and then on to Mumbai the day after that. Even at sea level and about a week after the Ataxia began, I was still feeling a sense of imbalance, albeit much milder and very infrequently.

Happy to be down

It is only after getting down and speaking to a military doctor with high-altitude experience, a neurosurgeon friend, chatting with a wilderness first responder, and reading up about HACE that I learnt a lot more and realised that I had dodged a bullet. I learnt that:

1. HAPE (High Altitude Pulmonary Edema) and HACE are considered advanced/end stages of AMS and need to be treated immediately.

2. I already knew this but the most urgent action is to descend very quickly, ideally to below 10k ft. It is also advised to continue going on to lower altitude.

3. While ascending as well as descending, where one spends the night is more important than the max/min height that is attained.

4. Symptoms of HACE can take a few days, and even a few weeks to completely disappear.

5. Having had HACE once, one is predisposed toward it and the next incident can be more severe.

6. Finally, and this accounted for the sense of dread and gratitude that I felt, both HAPE and HACE can be fatal within 24 hours. Spending another night at high altitude is not an option.

While discussing with some other trekkers at Yuksom, someone suggested that I could have waited at Tangsing (where I first developed Ataxia) while the rest of the group could have completed the remaining 2 days of the trek. It was this suggestion, and hearing of another trekker who developed HAPE at the same location (Tangsing) just a few weeks ago, spent the night at the rest stop (Phedang) that was at over 12k ft altitude, and sadly died overnight because he hadn’t descended enough, that I decided to write about my experience so that someone else does not make a fatal mistake, for themselves or for their fellow trekker.

I am immensely grateful that everyone I was trekking with was very aware of the risks and immediately decided to descend. The force was definitely with me that I survived to see the morning of May the 4th.

More information on AMS, HAPE, and HACE here, and here.