An Unusual Case of HACE?

Nick Haslam / Post-Foundation Doctor / UK

In July and August 2014, Nick Haslam was one of three doctors who joined a British Exploring Society Expedition to Ladakh, India; a remote high altitude desert. Nearing the end of their expedition, Nick found himself in a diagnostic conundrum, looking after a 17 year old girl with atypical high altitude cerebral oedema (HACE).

Background

The expedition was nearing an end. The first four weeks had seen a constant flow of minor medical complaints but thankfully nothing serious had come our way. We had spent 25 days sleeping above 4850m and were now well acclimatised to the high altitude. Most had climbed to 5800m or higher without medical difficulties and our symptoms of acute mountain sickness, present earlier in the expedition, were but a faint memory.

There were 48 people taking part in the expedition. Fourteen were leaders with a body of expertise in glacial and mountainous travel. Almost all the leaders had previous high altitude experience. The expedition participants were between the ages of 16-22 and had limited travelling experience, though about a fifth had been up to high altitude before.

We set our base camp at the mouth of the Zara valley: a remote location accessible by off-road vehicle thirty minutes from the Leh-Manali “Highway” (in reality, another dirt road). The nearest public hospital was in Leh, five hours drive away over the Tanglang La Pass (5328m) – the second highest motorable pass in India. A military base in Leh could provide helicopter evacuation if aircraft were available but RIMO, our in country contact, estimated a 24 hour response time due to the bureaucracy.

The expedition was equipped with several EPIRBs, two 2-wheel drive vehicles at base camp, three cylinders of oxygen (2 x 680 litres, 1x 1880 litres), two Gamow bags and a significant quantity of medication and resuscitation equipment.

All expedition members were required to return a structured medical questionnaire signed by their GP prior to departure.

We first flew to Leh (3500m) from Delhi and rested there for two nights. We then began a steady ascent profile via road over a period of three nights (Camp 1 3800m, Camp 2 4100m, Camp 3 4350m) before arriving at base camp (4851m GPS – N33 26′ 36.0 E077 47′ 05.3.). At this point the expedition was divided into three equal groups. During the expedition each group made several 3-4 day excursions from base camp over a period of three weeks and most managed to climb to above 6000m.

The Case

SC was a 17 year old girl with no previous high altitude experience. Her only regular medication was the progesterone-only pill and she had no current medical problems. Past medical history included pneumonia as a neonate requiring ITU admission, a benign heart murmur and two episodes of probable reactive arthritis. SC was physically fit (a fell runner) and had no history of migraines. During the expedition SC had suffered from only mild symptoms of acute mountain sickness on arrival at base camp, and one brief episode of blurred vision.

Twenty-five days after reaching base camp (4581m) we made an attempt on our last summit of the expedition – a glaciated peak of approximately 5900m. Prior to this SC had spent two comfortable nights sleeping at 5400m and ascended to 5880m without difficulties. That morning, she ate a normal breakfast and reported that she had slept well, with no headache, dizziness, nausea or visual disturbance.

SC now takes up the story in this recording made four days after the evacuation:

Evacuation

Once off the glacier, we continued our evacuation on foot to a temporary camp at 5100m where oxygen was available. We got there at 7pm, at which point SC had improved considerably and was able to walk on her own with two poles. She received intermittent oxygen (4l/min) through the night that appeared to give her some symptomatic relief, alongside oral dexamethasone (4mg QDS) and simple analgesia. In general, her condition remained stable although she began to describe the headaches as explosive and mostly retro-orbital.

Measurement of SC’s oxygen saturations at all stages of the evacuation demonstrated readings above 90%. And whilst her respiratory rate was variable throughout the evacuation her lung fields were clear and there was no evidence to suggest that SC was suffering from High altitude pulmonary oedema (HAPE).

At 6am the next morning we continued our descent to base camp at 4900m (Fig. 4). At basecamp, SC’s ataxia became more prominent and we decided to evacuate with oxygen by road to Leh hospital via the Taglangla pass (5,328m) (Fig. 5 & 6).

After arrival in Leh (3500m) SC was treated with intermittent oxygen therapy, oral dexamethasone 8mg BD, regular analgesia and rest. Over the following four days SC’s fatigue, ataxia, appetite and working memory all improved to some extent. However, as this video from four days after the event demonstrates, her headache, dizziness, cerebellar signs and diplopia remained despite treatment:

Aftermath

On arrival at Heathrow, five days after the event, SC was still mildly ataxic, fatigued and complained of a constant headache and sensation of dizziness. She also had retrograde amnesia.

We arranged for her to be followed up in the UK by a consultant neurologist fourteen days after the original event. At that point, her neurological signs had resolved. Her bloods were normal apart from a mild neutrophilia and a raised ALT. An MRI head and venogram were also normal. However, her headache and dizziness persisted, particularly at night and her parents (both physicians) reported that SC was still not ready for school 23 days after the event. In fact, it took six months for the symptoms to fully resolve and now, nearly a year later, she remains well.

So Was It HACE?

Ataxia at altitude is HACE until proven otherwise (2) and this was certainly the rule we used to treat SC on the mountain. However, in other ways the case fails to fit the classical description of HACE. For example it has been suggested that:

“Onset of illness after 3 days at a stable altitude, abrupt onset, trauma, focal neurological signs, high fever, stiff neck, and lack of response to treatment should all mandate consideration of other diagnoses.”

Hackett & Roach (2)

SC fulfilled three of these criteria. Her illness began after considerably more than three days at a stable altitude. It came on abruptly and didn’t really respond to treatment.

It made me question the diagnosis. After all, the incidence of HACE is related to the rate of ascent and degree of acclimatisation (3). SCs ascent rate was extremely conservative in comparison to most trekkers and climbers. Our expedition had the luxury of time and wild camping. This makes HACE less likely, though there are several cases of sudden-onset HACE reported in climbers above 5000m (4), (5), so we can’t exclude it on that alone.

Some consider AMS and HACE to be a spectrum, with HACE as the end point of worsening AMS. Generally, most cases of HACE are preceded by 24-48 hours of progressive AMS symptoms (2). So, SC’s presentation wasn’t typical. Again though, a number of cases of potential HACE associated with an abrupt onset of ataxia in the absence of AMS symptoms have been reported (6). Of course whether these cases were due to the same underlying mechanism as classical HACE remains debatable.

“The usual course is rapid recovery if treatment is started at the first sign of HACE and slower recovery when treatment is delayed”

Hackett & Roach (2)

Rapid descent, oxygen and dexamethasone are the cardinal treatments for HACE (2). The time between disease onset and treatment is related to both the rate and success of recovery. SC was already descending when she first developed ataxia, the key symptom of HACE. Before this her symptoms were only really in keeping with moderate to severe AMS. Oral dexamethasone was given within hours if not minutes of her symptoms worsening. Oxygen at 4l/min was provided after descending 500m vertical meters and approximately 6-7 hours after diagnosis. However, despite prompt treatment SCs condition showed only brief episodes of moderate improvement in the first 24 hours. Indeed, by the second morning of the evacuation SC was considerably more ataxic and fatigued. This progressed despite descending to base camp and prompted further evacuation to Leh that day. Once in Leh, her recovery was slow and full recovery took six months.

We know from the literature of other cases similar to SC’s. Rightly or wrongly, these cases have been clinically diagnosed as atypical HACE and that is the only diagnosis we were left with for SC. She became ill at high altitude, had normal imaging in the UK and then a complete (albeit prolonged) recovery.

Is HACE Always Preventable?

SC’s case leaves me with the question – is HACE always preventable? Increasing travel to high altitude (9) makes this question ever more pertinent, especially for expedition medics on large, organised tours. Before I went to Ladakh, I was under the impression that we could mitigate the risk of HACE if we ascended appropriately and monitored one another judiciously. After all, this has been confidently stated in the literature:

“It (HACE) is 100% preventable if climbers ascend slowly and ‘‘listen to their bodies’’ and descend in the face of increasing symptoms of headache, nausea, and tiredness.”

Graham LE, Basnyat B (10)

However, I believe SC’s case forces us to reconsider. Maybe HACE is not always preventable? Indeed, some experts would agree:

“At extreme altitude, onset of HACE may be abrupt, and prevention is not always possible.”

Hackett & Roach (2)

Learning Points

I can only conclude that from a practical point of view it is always safer to ‘never say never’. In this vein, the following are three key points I learnt from SC’s case:

1 / HACE classically develops on a background of AMS, but it can also present acutely.

2 / When at very high altitude (>5000m) [?extreme] HACE can present in the well-acclimatised climber or trekker.

3 / Appreciate that it might not be preventable and can come on quickly. Vital facts for travellers, clinicians and our friends in the medico-legal fraternity.

Author’s Note

SC kindly provided written and verbal consent for all information, images and video presented in this report. Nick would like to thank all those on the BES expedition for their teamwork and support. Particular thanks to Dr William Davies, Dr Nicola Carroll, Soo Redshaw (Expedition Leader), Martin Stitt (Expedition Deputy Leader) and James Dyer (UK BES Operations Manager).

References

1 / Norboo T, Saiyed HN, Angchuk PT, Tsering P, Angchuk ST, Phuntsog ST, et al. Mini review of high altitude health problems in Ladakh. Biomed Pharmacother. 2004 May;58(4):220–5.

2 / Hackett PH, Roach RC. High Altitude Cerebral Edema. High Alt Med Biol. 2004 May;5(2):136–46.

3 / Zafren K. Prevention of high altitude illness. Travel Med Infect Dis. 2014 Feb;12(1):29–39.

4 / Clarke C. Neurology at high altitude. Pract Neurol. 2006 Jan 8;6(4):230–7.

5 / Thomassen O, Skaiaa SC. High-altitude cerebral edema with absence of headache. Wilderness Environ Med. 2007;18(1):45–7.

6 / Wu T, Ding S, Liu J, Jia J, Dai R, Liang B, et al. Ataxia: an early indicator in high altitude cerebral edema. High Alt Med Biol. 2006;7(4):275–80.

7 / Basnyat B, Wu T, Gertsch JH. Neurological Conditions at Altitude That Fall Outside the Usual Definition of Altitude Sickness. High Alt Med Biol. 2004 May;5(2):171–9.

8 / Firth PG, Bolay H. Transient High Altitude Neurological Dysfunction: An Origin in the Temporoparietal Cortex. High Alt Med Biol. 2004 Mar 1;5(1):71–5.

9 / Mieske K, Flaherty G, O’Brien T. Journeys to High Altitude—Risks and Recommendations for Travelers with Preexisting Medical Conditions. J Travel Med. 2010 Jan 1;17(1):48–62.

10 / Graham LE, Basnyat B. Cerebral edema in the Himalayas: too high, too fast! Wilderness Environ Med. 2001;12(1):62.

11 / Hackett PH, Rennie D, Levine HD. The incidence, importance, and prophylaxis of acute mountain sickness. Lancet Lond Engl. 1976 Nov 27;2(7996):1149–55.