Case Description:
A 73-year-old woman with history of chronic renal failure was taken to
the emergency department for suspected acute aortic syndrome. During
transfer, she suffered sudden neurological deterioration with a Glasgow
Coma Score of 4. On arrival, and after orotracheal intubation, a
contrast-enhanced total body computed tomography (CT-scan) confirmed the
diagnosis of type A acute aortic dissection (TAAD) (Supplemental figure
1). Both carotid arteries were occluded without any antegrade flow (the
vertebral arteries remained patent) (Figure 1, Central picture, Video 1)
and the Near Infrared Spectroscopy (NIRS) indicated regional oxygen
saturation around 20 in the prefrontal region bilaterally. This
aggressive presentation raised the suspicion of massive ischemic stroke
and questioned the benefits of TAAD surgical management. To guide
decision-making, an emergency magnetic resonance imaging (MRI) was
performed 4 hours after the onset of neurological symptoms. The patient
was hemodynamically stable and transthoracic echocardiography showed
minimal pericardial effusion. MRI revealed a small-sized, focal, recent
cortical stroke in the right internal carotid territory (Figure 2).
Brain viability in the remaining territories associated with a permeable
Willis polygon with blood flow provided from vertebral arteries was
demonstrated, allowing antegrade flow in both sylvian arteries
(Supplemental figure 2) (Video 2). Surgical management was therefore
performed. Surgery began 5 hours after the onset of neurological
symptoms. After right axillary cannulation and institution of
cardiopulmonary bypass (CPB), we observed an immediate and bilateral
improvement in the NIRS score. The intimal tear was located at the
medial part of the ascending aorta. Supracoronary ascending aortic
replacement and hemiarch replacement under moderately hypothermic (25°C)
circulatory arrest (HCA) and bilateral antegrade cerebral perfusion were
performed. Disruption of the right coronary artery required a bypass
graft, and the native aortic valve was repaired. The CPB time was four
hours including forty-four minutes of HCA.
The neurological postoperative course was satisfactory, the patient
awakened from anesthesia without any deficit and was extubated on day 3
due to respiratory failure. Later, she presented a confusion episode
which recovered spontaneously. Postoperative renal failure required
temporary dialysis. She was transferred to another hospital on
postoperative day 14 and provided consent for use of data.
Discussion :
Cerebral malperfusion occurs in 6 to 14% of TAAD patients (1,2). The
benefit of emergency surgery in patients with comatose TAAD is
controversial, as it may be futile if massive ischemic cerebral lesion
has occurred. It also carries the risk of cerebral reperfusion oedema or
hemorrhagic conversion. In the international registry of aortic
dissection (IRAD), ischemic brain injury clearly influenced patient
management. Surgery was not performed in 24.1% of patients with stroke
and 33.3% of comatose patients, compared to 11% of patients without
neurological symptoms (1). On the other hand, comatose patients
medically managed have a 0% survival rate. Surgery appeared to be a
protective factor, resulting in a 55.6% survival rate (1,2). Some
authors established a decision-making algorithm considering the
predictive factors of neurological recovery to orient the patient
towards immediate, delayed or no surgical management (3).
To our knowledge, this is the first case description of emergency brain
MRI used for decision-making in TAAD complicated by coma. Patients
presenting with impaired consciousness and/or neurological deficits are
usually assessed by contrast-enhanced CT-scan, promptly providing
morphological information about the vessels, including the supra-aortic
trunks. The role of cerebral MRI in this context is unknown. MRI not
only can assess cerebral perfusion and the patency of the polygon of
Willis, but also can discriminate since a very early phase from symptoms
onset, between massive ischemic stroke and brain viability. Such
assessment is rapidly reliable and prognostically valuable, since few
hours after the onset of symptoms. MRI is also useful to exclude
intracranial hemorrhage and predict hemorrhagic transformation through
blood-brain barriers rupture (4).
Additionally, delayed neurological reassessment has also been proposed
in patients affected by TAAD complicated by coma. Nonetheless, Tsukube
et al. observed significantly different survival between comatose
patients who underwent immediate repair and those who were initially
administered medical treatment before later clinical reevaluation
(P = .0008) (5). In this perspective, MRI could also allow
gaining time by avoiding delayed reassessment and identifying eligible
comatose patients to immediate surgery.