Pulmonary arteriovenous malformations (PAVMs) are structurally abnormal vessels that provide direct capillary-free communications between the pulmonary and systemic circulations, and hence, right-to-left shunts [1]. Due to impaired gas exchange, hypoxaemia is common but exercise tolerance is usually preserved through haematological (erythrocytotic) and cardiovascular compensations [2, 3], and patients are frequently asymptomatic [1–3]. Treatment of PAVMs is recommended to prevent paradoxical embolic sequelae such as ischaemic strokes [4] and brain abscess [5], commonly improves migraine headaches [6], and is a successful emergency treatment for haemorrhage.

ObjectiveTo evaluate if injection of intravenous particles may provoke migraines in subjects with right‐to‐left shunts due to pulmonary arteriovenous malformations (AVMs).BackgroundMigraine headaches commonly affect people with hereditary hemorrhagic telangiectasia (HHT), especially those with pulmonary AVMs that provide right‐to‐left shunts. In our clinical practice, patients occasionally reported acute precipitation of migraine headaches following injection of technetium‐labeled albumin macroaggregates for nuclear medicine scans.MethodsSelf‐reported migraine features and exacerbations were examined in HHT subjects with and without pulmonary AVMs, for a series of noninvasive and invasive investigations, using an unbiased online survey.ResultsOne hundred and sixty‐six subjects were classified as having both HHT and migraines. HHT subjects with migraines were more likely to have pulmonary AVMs (P < .0001). HHT subjects with pulmonary AVMs were more likely to report photophobia (P = .010), “flashes of light” (P = .011), or transient visual loss (P = .040). Pulse oximetry, x‐rays, ultrasound, and computerized tomography (CT) scans without intravenous contrast medium rarely, if ever, provoked migraines, but unenhanced magnetic resonance imaging (MRI) was reported to exacerbate migraines by 14/124 (11.2%) subjects. One hundred and fourteen subjects had both enhanced and unenhanced CT examinations: studies with contrast media were more commonly reported to start (9/114 [7.8%]), and/or worsen migraines (18/114 [15.7%]), compared to those undertaken without contrast medium (P < .01), or after simple blood tests (P < .05). Additionally, migraine exacerbation was reported by 9/90 (10%) after contrast echocardiography, 2/44 (4.5%) after nuclear medicine scans, and 10/154 (6.5%) after blood tests.ConclusionsHHT subjects frequently report migraine exacerbation following blood tests, contrast echocardiograms, MRI imaging, and CT studies performed with intravenous contrast medium. Since air emboli are recognized to complicate intravenous injections, particularly those given by a pressurized pump during contrast enhanced CT, future studies should re‐evaluate whether particulate emboli provoke migraines.

Introduction and objectivesPulmonary arteriovenous malformations (PAVMs) are an example of a right-to-left shunt resulting in deoxygenated, unfiltered venous blood bypassing the pulmonary capillaries to re-enter the systemic arterial circulation. Patients with PAVMs are known to have an increased incidence of migraines, reducing following PAVM treatment by embolisation. This study aimed to examine if paradoxical embolism of particulate matter through PAVMs may precipitate migraines.MethodsA structured survey was designed for online completion by people with hereditary haemorrhagic telangiectasia (HHT), the most common cause of PAVMs. Question logic directed participants through a series of unbiased questions that asked about HHT features including presence of PAVMs; variables in relation to migraines; and whether participants had undergone imaging tests. Stratified by whether contrast had been given, participants reporting migraines were asked whether any difference in migraines had been noted following scans, by ticking that “migraines were no different really”; “seemed a bit better”; “seemed a bit worse”; “seemed to bring on a migraine”; “seemed to stop a migraine”. Participants were recruited from 26/07/2013- 21/04/2015, yielding 702 consented responses. Data were downloaded to an Excel spreadsheet for participant stratifications, and statistical analyses using GraphPad Prism 6.0 and STATA 13.1 (Statacorp LP).ResultsOverall, 557 participants had HHT, of whom 180 (32.3%) reported features consistent with migraines. HHT participants with migraines more commonly reported PAVMs than those without migraines (62.8% vs 38.5%, p < 0.00001). For computerised tomography (CT) scans, images “with injection of contrast” were associated with a higher proportion of participants reporting worsening migraines than “without injection of contrast” CT scans (11.7% vs 3.4%, p = 0.0065). This association strengthened following paired analysis of participants who had undergone both methods (13.6% vs 3.2%, p = 0.0032). In multiple regression analyses, there was no additional contribution from other participant demographics such as alcohol consumption or smoking habit. Analysis of magnetic resonance imaging (MRI), contrast echocardiography and ultrasound data is ongoing.ConclusionThis study strongly indicates that an association between injecting contrast media and the worsening of migraines, in participants with right-to-left shunts due to PAVMs, exists. Further research is required to establish the exact mechanism responsible for this phenomenon.*S1- BTS Medical Student Award Highly Commended.

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