eISSN: 2383-5699
Korean J Clin Geri 2017;18(2):118-121 https://doi.org/10.15656/kjcg.2017.18.2.118
CASE REPORT
Received: June 27, 2017 Accepted: October 19, 2017.
Corresponding author: In-Uk Song
Department of Neurology, Incheon St. Mary’s Hospital, 56 Donsu-ro, Bupyeong-gu, Incheon 21431, Korea Tel: +82-32-280-5010, E-mail: siuysiuy@naver.com
Copyright Ⓒ 2017 The Korean Academy of Clinical Geriatrics
This is an open access article distributed under the term s of the Creative Com m ons Attribution Non-Com m ercial License (http://creativecom m ons.org/licenses/by-nc/4.0) which perm its unrestricted non-com m ercial use, distribution, and reproduction in any m edium , provided the original work is properly cited.
Rare Cerebral Infarction in Patient with Type B Aortic Dissection
Sung-Jin Park, In-Uk Song, Sung-Woo Chung
Department of Neurology, College of Medicine, The Catholic University of Korea, Incheon, Korea
A 65 years old woman was admitted with sudden visual disturbance. She had a history of cerebral infarction which led to the diagnosis of type B aortic dissection. Transthoracic echocardiography revealed mobile echogenic mass in the false lumen of dissection. Thoracic aorta computed tomography angiography showed partial thrombosis with mild aneurysmal change of the false lumen at the proximal descending aorta. The patient was transferred to the department of thoracic surgery for surgical treatment of aortic dissection. The presented case is notable for rare atypical presentation of cerebral infarction resulting from type B aortic dissection.
Key Words: Infarction, Type B aortic dissection, Thrombosis, False lumen
INTRODUCTION
Aortic dissection (AD), a separation of the layers within the aortic wall, is a potentially fatal disease, with an esti- mated incidence of 5∼30 cases per million per year.1) Although it usually presents with sudden severe chest or upper back pain, neurological involvement is not in- frequently reported and ischemic stroke is known as the most common cause of neurologic complications occurring in 18∼30% of the cases.2) With use of Stanford classi- fication, type A dissection which involves the ascending aor- ta may cause ischemic stroke through extension of dissection into common carotid arteries, thromboembolism, or hypoper- fusion. It accounts for a high proportion of ischemic strokes associated with AD, compared with type B dissection which involves descending aorta distal to left subclavian artery.
Here we report a patient with posterior cerebral artery (PCA) infarction who had chronic type B dissection and aberrant right subclavian artery arising from descending thoracic aorta.
CASE REPORT
A 65 years old woman with hypertension visited emer- gency room due to sudden visual disturbance which devel- oped 2 hours ago. She had a history of left PCA infarction which led to the diagnosis of type B aortic dissection. On admission, her blood pressure was 193/87 mmHg. Neurologic examination revealed cortical blindness and left facial palsy with slight clumsiness of her left hand. Electrocardiogram revealed normal findings. Laboratory tests were within nor- mal limits apart from elevated creatinine level.
Sung-Jin Park, et al: Cerebral Infarction and Type B Aortic Dissection 119
Figure 1. (A) Magnetic resonance diffuse weight imaging and angiography show Acute infarction in right posterior cerebral artery territory and patent right vertebral artery from right subclavian artery arising from descending thoracic aorta. (B) Thoracic aorta computed tomography angiography show aortic dissection, aberrant right subclavian artery and partial thrombosis with mild aneurysmal change of the false lumen at the proximal descending aorta (arrow).
Diffusion weighted image of brain showed acute in- farction at right PCA territory. Magnetic resonance angiog- raphy showed non-visualization of left proximal vertebral ar- tery (VA) and patent right VA from right subclavian artery arising from descending thoracic aorta just distal to the ori- gin of left subclavian artery (Figure 1A). Transthoracic echo- cardiography revealed mobile echogenic mass in the false lu-
men of dissection. Thoracic aorta computed tomography an- giography showed partial thrombosis with mild aneurysmal change of the false lumen at the proximal descending aorta (Figure 1B). These findings suggest that thrombus from false lumen of dissected aorta may be the source of embo- lism, which caused PCA infarction passing through aberrant right subclavian artery. She was transferred to the depart-
120 Korean J Clin Geri 2017;18(2):118-121
ment of thoracic surgery for surgical treatment of aortic dissection.
DISCUSSION
Neurologic complications have been reported to occur in 17∼40% of patients with AD and ischemic stroke is the most common among them.3) Presumptive mechanisms of ischemic stroke in AD patients are occlusion of the origin of the common carotid by dissection flap, artery-to-artery em- bolism from a thrombus developed on the intimal surface of the dissected artery and severe hypotension. According to previous report,4) strokes associated with AD are tend to be more common in Stanford type A dissections which involve ascending aorta. In addition, they are more frequently hemi- spheric compared with vertebro-basilar location, and pre- dominantly right-sided.4) Tendency to be right sided and commonly involving ascending aorta is accounted for the fact that carotid artery origins are much more vulnerable to the advancing dissection because of their proximity to the aortic arch. The proximal ascending aorta is vulnerable to dissection, because during systole, it expands the most and its convexity is repeatedly exposed to maximum arterial pressure.
On the other hand, our patient had type B aortic dis- section which occurs distal to the left subclavian artery, and her ischemic stroke involved vertebro-basilar arterial system.
Considering her dissection was chronic and the fact that the partial thrombosis was revealed on thoracic aorta computed tomography angiography, the cerebral infarction was esti- mated to be caused by artery-to-artery embolism, rather than the direct occlusion by dissection flap. Presumably, her aberrant right subclavian played a pivotal role in the stroke occurrence, delivering the thrombus from descending thora- cic aorta to intracranial arteries. Aberrant right subclavian artery (ARSA) is one of the most common congenital anom- aly of the aortic arch with the prevalence of 0.4% to 2.0%.5) As the ARSA is mostly asymptomatic, and often discovered incidentally, its clinical implications remain unclear.
A handful of authors previously speculated that ARSA in- duces aortic dissection as the acute angle of the ARSA
weakens the aortic wall.6) However, the coexistence of type B dissection and ARSA is extremely rare, and the correlation is still to be revealed.
Few considerations of the present case should be addressed. First, in terms of pathogenic mechanism, the pos- sibility that her stroke resulted from artery to artery embo- lism involving left vertebral artery cannot be excluded con- sidering her magnetic resonance angiography showed non-vis- ualization of left proximal vertebral artery. Namely, the non-visualization of left vertebral artery may be an evidence of its occlusion and the thrombus of the false lumen in dis- sected aorta is an incidental finding. Second, although she arrived emergency room within the time window of intra- venous thrombolysis of acute ischemic stroke, recombinant tissue plasminogen activator (rt-PA) was not applied. The decision came from the speculation that her stroke may be associated with aortic dissection, taking its relation with her previous left PCA infarction into account. Actually, there are numerous reports in literature of rt-PA therapy in pa- tients with acute aortic dissection starting with acute stroke, most of which showed deleterious results. Mortality rate in such patients is approximately 71%.7-12) Most of the re- ported patients received rt-PA therapy because aortic dis- section was overlooked initially. It may indicate the diffi- culties lying in the immediate detection of aortic dissection in the emergency setting. In fact, up to one-third f patients with aortic dissection give no history of significant pain in the early period, and half of patients who do not report typ- ical chest pain show neurological symptoms at the beginning.13)
In this context, the need for a proper and effective clin- ical evaluation of acute stroke patients who are in the suspi- cion of aortic dissection should be set out. While chest X-rays have limited sensitivity revealing no widening of su- perior mediastinum in 20% of cases, and chest computed tomography scanning is time consuming, a previous article emphasized a usefulness of transthoracic echocardiography as a rapid screening tool to exclude aortic dissection.13,14) They proposed the use of transthoracic echocardiography focused on aorta similarly to the one used in patients after trauma, in patients at increased risk of aortic dissection especially
Sung-Jin Park, et al: Cerebral Infarction and Type B Aortic Dissection 121
when thrombolysis is considered. Further study is required to validate the clinical utility of this approach.
In conclusion, we report an unusual case of PCA in- farction caused by thromboembolism through aberrant right subclavian artery in type B aortic dissection. Aortic dis- section has varied presentations and requires a high degree of suspicion for an early and accurate diagnosis.
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