Case of the Month
Section Editor: Nicholas Stence, MD
Children's Hospital Colorado, Aurora, CO
January 8, 2019
Left MCA Infarction Secondary to Missile Embolus
- Background
- Missile embolus is an uncommon cause of embolic stroke.
- Paradoxical shotgun pellet embolus from infra-diaphragmatic circulation to the intracranial circulation is exceedingly rare.
- No evidence of a patent foramen ovale was detected on our patient’s contrast enhanced transesophageal echocardiogram (TEE).
- Clinical Presentation
- Missile emboli have been reported in 0.3-1.1% patients with penetrating vascular trauma in military conflict settings.1
- The rate may be higher in the civilian population due to the association with lower velocity weapons and lower kinetic energy injuries.1
- Missile emboli to intracranial circulation have been previously reported in the setting of gunshot injuries to the neck and chest.2,3,4,5
- Patent foramen ovale (PFO)6, or the much less likely patent ductus arteriosus, or a pulmonary arterio-venous malformation can explain the paradoxical nature of the embolus, which may have been transient as it was not detected on TEE.
- Key Diagnostic Features
- Sudden onset of a central nervous system deficit in a patient with a gunshot injury should raise suspicion of cerebral missile embolization.
- Non-contrast head CT demonstrates a metallic object, without associated evidence of skull penetration and in the setting of known gunshot vascular injury.
- CTA can provide information about the specific location of the embolus within the blood vessels.
- Early detection may not be associated with findings of a completed infarct, and should prompt further evaluation with a CT perfusion study and/or consideration of immediate intervention.
- Missiles can migrate through vasculature or through brain parenchyma7, and previously-demonstrated locations should not be assumed to be static.
- Although 30% of adults have a probe-patent PFO at autopsy, only 10-18% of routine adult transesophageal echocardiograms will detect a PFO5, and thus may not identify the most common underlying abnormality to explain the paradoxical nature of the embolus.
- Differential Diagnosis
- Fat embolism
- Embolic or hypoperfusion stroke from carotid or aortic dissection
- Underlying atherosclerotic disease of carotid and/or cerebral circulations
- Atrial myxoma
- Embolized cardiac thrombus, from paroxysmal atrial fibrillation, valvular disease, or underlying cardiomyopathy
- Treatment
- Successful open surgical treatment with direct pellet removal from intracranial circulation5, and the use of internal carotid flow-reversal technique2 have been reported.
- Results from attempted endovascular approaches have been mixed, and have not been attempted recently.5
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