Economy class stroke syndrome: case report and review of the literature

Emerging Stroke Risk Factors: A Focus on Infectious and Environmental Determinants

This review focuses on emerging risk factors for stroke, including air pollution and climate change, gut microbiota, high altitude, and systemic infection. Up to 14% of all stroke-associated mortality is attributed to air pollution and is more pronounced in developing countries. Fine particulate matter and other air pollutants contribute to an increased stroke risk, and this risk appears to increase with higher levels and duration of exposure. Short term air pollution exposure has also been reported to increase the stroke risk. The gut microbiota is a complex ecosystem of bacteria and other microorganisms that reside in the digestive system and affect multiple body systems. Disruptions in the gut microbiota may contribute to stroke development, possibly by promoting inflammation and atherosclerosis. High altitudes have been associated with erythrocytosis and cerebrovascular sinus thrombosis, but several studies have reported an increased risk of thrombosis and ischemic stroke at high altitudes, typically above 3000 m. Systemic infection, particularly infections caused by viruses and bacteria, can also increase the risk of stroke. The risk seems to be greatest in the days to weeks following the infection, and the pathophysiology is complex. All these emerging risk factors are modifiable, and interventions to address them could potentially reduce stroke incidence.

The secret enemy during a flight: Economy class syndrome

Deep venous thrombosis (DVT) and pulmonary thromboembolism (PTE) are the major causes of morbidity and mortality in immobile patients. There is observational evidence that intercontinental air travel is associated with a high incidence of DVT and PTE during or within 48 hours of long-distance flights. This situation is known as the economy class syndrome and can affect both the cabin crew and passengers. The term "economy class syndrome" refers to the occurrence of thrombotic events that mainly occur in passengers in the economy class of the aircraft during long-haul flights. This syndrome results from several factors related to the aircraft cabin and the passenger, acting together to predispose to excessive blood coagulation, which can result in venous thromboembolism. In this review, we have shared the relationship between air travel and the formation of DVT and PTE.

Economy class syndrome: what is it and who are the individuals at risk?

The term ‘economy class syndrome’ refers to the occurrence of thrombotic events during long-haul flights that mainly occur in passengers in the economy class of the aircraft. This syndrome results from several factors related to the aircraft cabin (immobilization, hypobaric hypoxia and low humidity) and the passenger (body mass index, thrombophilia, oral contraceptives or hormone replacement therapy, cancer), acting together to predispose to excessive blood coagulation, which can result in venous thromboembolism. Several risk factors, both genetic and acquired, are associated with venous thromboembolism. The most important genetic risk factors are natural anticoagulant deficiencies (antithrombin, protein C and protein S), factor V Leiden, prothrombin and fibrinogen gene mutations and non-O blood group individuals. Acquired risk factors include age, pregnancy, surgery, obesity, cancer, hormonal contraceptives and hormone replacement therapy, antiphospholipid syndrome, infections, immobilization and smoking. People who have these risk factors are predisposed to hypercoagulability and are more susceptible to suffer venous thromboembolism during air travel. For these individuals, a suitable outfit for the trip, frequent walks, calf muscle exercises, elastic compression stockings and hydration are important preventive measures. Hence, it is essential to inform about economic class syndrome in an attempt to encourage Brazilian health and transport authorities to adopt measures, in partnership with the pharmaceutical industry, to prevent venous thromboembolism.

Airplane stroke syndrome

Only 37 cases of stroke during or soon after long-haul flights have been published to our knowledge. In this retrospective observational study, we searched the Royal Melbourne Hospital prospective stroke database and all discharge summaries from 1 September 2003 to 30 September 2014 for flight-related strokes, defined as patients presenting with stroke within 14days of air travel. We hypothesised that a patent foramen ovale (PFO) is an important, but not the only mechanism, of flight-related stroke. We describe the patient, stroke, and flight characteristics. Over the study period, 131 million passengers arrived at Melbourne airport. Our centre admitted 5727 stroke patients, of whom 42 (0.73%) had flight-related strokes. Flight-related stroke patients were younger (median age 65 versus 73, p<0.001), had similar stroke severity, and received intravenous thrombolysis more often than non-flight-related stroke patients. Seven patients had flight-related intracerebral haemorrhage. The aetiology of the ischaemic strokes was cardioembolic in 14/35 (40%), including seven patients with confirmed PFO, one with atrial septal defect, four with atrial fibrillation, one with endocarditis, and one with aortic arch atheroma. Paradoxical embolism was confirmed in six patients. Stroke related to air travel is a rare occurrence, less than one in a million. Although 20% of patients had a PFO, distribution of stroke aetiologies was diverse and was not limited to PFO and paradoxical embolism.

Concomitant submassive pulmonary embolism and paradoxical embolic stroke after a long flight: which is the optimal treatment?

Economy class stroke syndrome consists of ischemic stroke due to paradoxical embolism through patent foramen ovale after a long flight. Few cases have been described in the literature to date. The treatment choice could be tricky. We present the case of a 65-year-old woman, admitted for submassive pulmonary embolism after a long flight, that presented a paradoxical embolic stroke through patent foramen ovale shortly after. The patient was treated with intravenous thrombolysis within 1 h of stroke onset with a definite symptoms improvement. Afterwards, intravenous unfractioned heparin was started with strict partial thromboplastin time monitoring. Cerebral computed tomography scan, obtained after 24 and 72 h, ruled out hemorrhage. Warfarin was started after 72 h. Patent foramen ovale was percutaneously closed 3 months after. In the reported case, the treatment with thrombolysis and subsequent heparin infusion was effective and safe. We discuss the rationale for this treatment in the light of literature data.

First-ever Ischemic Stroke after a Flight in a Patient with Prior Poliomyelitis

Survivors of poliomyelitis sometimes travel by air with mobility assistance. However, prolonged seating during long-haul flights may also possibly produce stroke events on polio-inflicted patients. A 48-year-old polio-inflicted male suffered a stroke after an extended flight. A two-dimensional echocardiography was normal without detected patent foramen ovale or dyskinetic segment. The venodynamic variables were all within normal limits. MR Imaging studies revealed acute cerebral infarction in the distribution of the right middle cerebral artery and posterior watershed area. Hematological examination revealed positive anti-cardiolipin IgG antibody which might contribute to the risk of thrombosis as an underlying condition in addition to immobilization. This is the first presentation of ischemic stroke after a flight in a patient with prior poliomyelitis. In addition to decompression sickness, economy class stroke syndrome and postpoliomyelitis syndrome, the physician should also take other coagulation disorders into consideration during the investigation.

Increased frequency of cardioembolism and patent foramen ovale in patients with stroke and a positive travel history suggesting economy class stroke syndrome

OBJECTIVE

To investigate the frequency of acute stroke in patients with a recent travel history and to analyse risk factors, stroke patterns and presence of a patent foramen ovale (PFO) in this patient group.

DESIGN

One-year prospective observational study.

SETTING

Single-centre study.

METHODS

Enrolling all patients presenting with a first cerebral ischaemia and complementing the usual history with a standardised travel history.

RESULTS

Of 338 patients with acute stroke, 42 had a positive travel history (PTH) (12.4%). Patients with a PTH were significantly younger (56.6 (SD 13) years) than patients (66.9 (13.2) years, p = 0.0001) with a negative travel history (NTH). Frequency of PFO in the PTH group (13; 44.8%) was significantly higher than in the NTH group (7; 10.8%) (p = 0.0001), even after patients were dichotomised into two age groups (younger and older than median of all

PATIENTS

31% v 6.1%, p = 0.007 and 13.8% v 4.6%, p = 0.022, respectively). PTH patients had fewer stroke risk factors (2.2 (1.4) v 3.3 (1.6), p = 0.0001) and a different risk profile with a lower frequency of diabetes (11.9% v 31.4%, p = 0.009), hypertension (52.4% v 78.7%, p = 0.0001), atrial fibrillation (7.1% v 22%, p = 0.025) and others (16.7% v 38.9%, p = 0.005). In contrast, PTH patients had significantly more cardioembolic (35.7% v 19.3%, p = 0.023) and cryptogenic strokes (50% v 19.9%, p = 0.0001) and more often ischaemia in the territory of the posterior cerebral artery (29.6% v 6.3%, p = 0.0001).

CONCLUSIONS

The finding that more PTH patients had a PFO and a cardioembolic stroke pattern but that fewer had other typical stroke risk factors led to the hypothesis that PFO is a risk factor for economy class stroke syndrome.

Stroke and pulmonary thromboembolism after a long flight

In the economy class syndrome (ECS) the patient presents a deep venous thrombosis (DVT) with or without pulmonary thromboembolism (PTE) during or after a long trip as a result of prolonged immobilization. Economy class stroke syndrome is an infrequent ECS variant in which ischemic stroke is associated with a patent foramen ovale (PFO). Few cases have been published in the literature to date. We present a patient who suffered a PTE and an ischemic stroke immediately after a transoceanic flight. A 36-year-old woman with no significant medical or familial history flew economy class from Lima, Peru, to Madrid, Spain. On disembarkation she presented sudden dyspnea and a depressed level of consciousness, global aphasia, and right hemiparesis. A pulmonary scintigraphy showed a PTE and a cranial MRI revealed an ischemic infarct in the left middle cerebral artery territory. We simultaneously performed a transesophageal echocardiography and a transcranial Doppler and observed a massive right-to-left shunt through a PFO. The patient was a heterozygous carrier of the C46T mutation of coagulation factor XII. The appearance of a stroke following a long trip is suggestive of paradoxical embolism through a PFO, mainly if it is associated with a DVT and/or a PTE. The cause of the initial event, the DVT, could be a prothrombotic state.