I[NTRODUCTION]{.smallcaps} {#sec1-1}
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Patent foramen ovale (PFO) is a general abnormality detected in approximately one-fourth of the adult population.\[[@ref1][@ref2]\] In addition, it is well known that the abnormality is a cause of stroke, especially in younger individuals. Conversely, paradoxical embolism of stroke-related PFO is a cause of stroke in older individuals.\[[@ref3]\] However, a clinical case of an elderly patient with paradoxical embolism is lacking from the literature. We describe the case of a nonagenarian patient with paradoxical embolism of stroke-related PFO.

C[ASE]{.smallcaps} R[EPORT]{.smallcaps} {#sec1-2}
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A 95-year-old woman with hypertension and dyslipidemia was admitted to our hospital because of dysarthria. She had a history of hospitalization because of cerebral infarction 30 years previously. She was prescribed aspirin (100 mg), nifedipine (40 mg), telmisartan (20 mg), and atorvastatin (10 mg). On presentation, her consciousness was clear and she had no paralysis or paresthesia. However, she could not speak well. Her blood pressure was 193/103 mmHg, and the pulse rate was 85 beats/min. Electrocardiogram revealed a normal sinus rhythm, but laboratory data showed that the D-dimer level was increased (2.2 μg/ml). Emergency magnetic resonance imaging showed cerebral infarction of the left temporal lobe, and magnetic resonance angiography showed no significant stenosis of the major cerebral artery \[[Figure 1](#F1){ref-type="fig"}\]. After hospitalization in the neurosurgery department, she was treated by heparin and edaravone. There was no significant stenosis with plaque of the carotid artery by the carotid duplex. In addition, there was no evidence of an episode of arrhythmia during hospitalization. On the transthoracic echocardiogram, the ejection fraction was normal without abnormalities of wall motion, and there was no significant valvular disease. Consequently, she was tentatively diagnosed as having embolic strokes of undetermined source (ESUS). Transesophageal echocardiography (TEE) showed no sources of cardiac embolism, such as an atrial appendage thrombus, appendage stasis with reduced flow velocities, or significant aortic arch atherosclerotic plaque. However, PFO with spontaneous bidirectional shunt and the prevalence of PFO separation were detected, whereas the patient was at rest \[Figure [2a](#F2){ref-type="fig"} and [b](#F2){ref-type="fig"}\]. Furthermore, the Eustachian valve was found \[[Figure 2c](#F2){ref-type="fig"}\]. Ultrasonography of the leg vein revealed a thrombus in the deep vein. Finally, we diagnosed her as having cerebral infarction that occurred due to paradoxical embolism-related PFO.

![Diffusion-weighted magnetic resonance imaging revealed infarction of the left temporal lobe, and magnetic resonance angiography showed no significant stenosis at major cerebral artery](JCE-29-172-g001){#F1}

![(a) Transesophageal echocardiography showed patent foremen ovale with bidirectional shunt by color Doppler. (b) Transesophageal echocardiography revealed the prevalence of patent foramen ovale separation at rest. (c) The Eustachian valve was found by transesophageal echocardiography](JCE-29-172-g002){#F2}

Anticoagulant therapy (DOAC) was initiated 6 days after the acute ischemic event, as decided by the neurologist and cardiologist.

D[ISCUSSION]{.smallcaps} {#sec1-3}
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Most cases of cerebral infarction in elderly individuals are caused by atherosclerosis and cardioembolic sources, such as atrial fibrillation. Therefore, the possibility of ESUS-related PFO decreases with increasing age.\[[@ref4][@ref5]\] However, the prevalence of a venous thrombus increases with the advancement of age. TEE is the gold standard approach for detecting embolic sources, but it is difficult to accurately diagnose the type of stroke in very old patients with stroke because there is a tendency to avoid the use of TEE in these patients. The transcranial Doppler bubble test is a useful tool for detecting a right-to-left shunt, such as PFO, but the anatomy of PFO can be confirmed using the only TEE.

Little is known about elderly patients with ESUS-related PFO. A previous case report described an 85-year-old man who had multiple embolic infarcts associated with PFO.\[[@ref6]\] This present case is a very rare case in which ESUS-related PFO was diagnosed in a patient older than 90 years of age.

Percutaneous PFO closure in younger patients with ESUS-related PFO is more effective than conventional medical therapy alone to prevent cerebrovascular events.\[[@ref7][@ref8][@ref9]\] However, the standard treatment of elderly patients with ESUS-related PFO remains unclear. We previously reported that percutaneous PFO closure in elderly patients with anatomically high-risk PFO is safe and effective.\[[@ref10]\] In the present case, TEE revealed bidirectional shunt through the PFO and the prevalence of PFO separation with the patient at rest. These PFO findings are considered as high-risk morphology for the recurrence of embolic stroke. We treated our patient on a DOAC to prevent the recurrence of stroke. In the future, however, performing percutaneous PFO closure in elderly patients with ESUS-related PFO similarly to that in younger patients may be recommended. This treatment should be decided by a brain--heart team consisting of a neurologist and cardiologist and based on each individual case.

Meanwhile, atrial fibrillation increases with increasing age. The demonstration of a regular sinus rhythm during hospital monitoring does not absolutely exclude the occurrence of paroxysmal atrial fibrillation episodes. We consider that the implantation of a loop recorder might have eventually unmasked unrecognized episodes of atrial fibrillation.

In conclusion, we experienced a case of ESUS-related PFO in a very old patient. It demonstrated that regardless of age, PFO is the cause of paradoxical embolism of stroke.

Declaration of patient consent {#sec2-1}
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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship {#sec2-2}
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Nil.

Conflicts of interest {#sec2-3}
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There are no conflicts of interest.
