Clinical StudyAirplane stroke syndrome
Introduction
Almost 2 billion people travel by air every year. The age of travellers is increasing and long-haul aircraft such as the Airbus A380 and Boeing 777 are now capable of extending flight times to 18–20 hours [1]. As such, an appreciation of the associations between air travel and illness is important.
There is no standard definition of a long-haul flight. However, flight durations longer than 8 hours or distance greater than 5000 km have been shown to significantly increase the risk of deep venous thrombosis (DVT) and pulmonary embolism (PE) [1], and this association could be driven by various factors including comorbidities and dehydration.
The association between air travel and DVT, with or without PE, was labeled “economy class syndrome” by Symington et al. in 1977, based on the theory that highly congested seating arrangements put passengers at risk [2]. Although this term has been used subsequently, the exact mechanism of the association remains unclear. The first description of stroke as a complication of long-haul air travel was in 1968 by Beighton and Richards who described a 48-year-old woman who developed a lower limb DVT during a long-haul flight and had a fatal stroke soon after landing [2]. Although this condition was called “economy class stroke syndrome”, it seems to affect business class travellers equally [2]. It may, therefore, be more accurate to call it “airplane stroke syndrome”. Although airplane stroke syndrome has been recognised for a long time, only a few cases have been described in the literature as single case reports or small case series (Table 1).
One of the potential explanations for an association between air travel and stroke is paradoxical embolism through a patent foramen ovale (PFO), which is proposed as the aetiology in 17 of 29 published ischaemic strokes (Table 1). However, the relevance of PFO in the pathogenesis of ischaemic stroke is somewhat unclear. It has been estimated that the prevalence of PFO in the general population is 25%. In ischaemic stroke patients with no other identifiable cause the prevalence is 40%, and many of these are likely to be incidental [3].
To further understand airplane stroke syndrome, we describe all identified patients, flights, and stroke characteristics in patients with flight-related stroke at the Royal Melbourne Hospital, Australia. We also report the underlying aetiology of stroke and the presence of a PFO. We hypothesised that PFO is an important, but not the sole, underlying aetiology of flight-related strokes.
Section snippets
Methods
In this retrospective, observational, single centre study, we manually searched our local prospective stroke database and all discharge summaries from the Royal Melbourne Hospital Stroke Unit from 1 September 2003 to 30 September 2014 for flight-related stroke admissions. We employed a standardised search methodology using a keyword search for the following terms: “stroke”, “plane”, “airplane”, “travel”, “flight”, “trip”, “holiday”, “PFO”, and “airport”. We subsequently manually reviewed the
Results
Over the study period we had 5727 stroke admissions. Of those, a total of 42 patients (0.73%) had flight-related strokes. Table 2 shows the baseline clinical characteristics, stroke characteristics, and outcomes in patients with and without flight-related stroke. Median patient age in the flight-related stroke group was 65 years and 22 were males. Median baseline NIHSS was 9 (1–25), indicating moderate stroke severity. The stroke subtype was ischaemic stroke in 35 patients and intracerebral
Discussion
Although airplane travel is a very common experience, flight-related stroke is fortunately uncommon. We identified 42 flights-related strokes during a period with >100 million passengers landing in Melbourne. Therefore flight-related strokes are probably a less than a one in a million occurrence.
Still, in our enriched population, 0.7% of stroke admissions were flight-related and the present series of 42 patients is by far the largest published to our knowledge (Table 1). Unlike the previous
Conflicts of Interest/Disclosures
The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
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