Anesth Analg 2003;97:979-980
© 2003 International Anesthesia Research Society
CARDIOVASCULAR ANESTHESIA
Tetraplegia After Coronary Artery Bypass Grafting
Susumu Fujioka, MD*,
Yoshinari Niimi, MD
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Kazuo Hirata, MD*,
Itaru Nakamura, MD*, and
Shigeho Morita, MD
*Department of Anesthesia, Ageo Central General Hospital, Ageo, Saitama, Japan; and
Department of Anesthesiology, School of Medicine, Teikyo University, Itabashi, Tokyo, Japan
Address correspondence and reprint requests to Susumu Fujioka, MD, Department of Anesthesia, Ageo Central General Hospital, 1-10-10 Kashiwaza, Ageo, Saitama 362-8588, Japan. Address e-mail to susumu{at}db3.so-net.ne.jp
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Abstract
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The authors present a rare case of a cervical cord dysfunction after uncomplicated coronary artery bypass grafting. The preoperative neurological examination did not reveal any abnormalities; however, the postoperative magnetic resonance image showed significant spinal canal stenosis at the same levels as high signal lesions. Although the pathophysiological basis of the case was impossible to determine retrospectively, it seems probable that placing the neck in an extended position during surgery might have aggravated a preexisting spinal canal stenosis to produce cervical injury.
IMPLICATIONS: The authors present a rare case of tetraplegia after coronary artery bypass grafting. It is suggested that neck extension during surgery might have aggravated an occult preexisting cervical spinal canal stenosis to produce cervical injury.
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Introduction
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Paraplegia after coronary artery bypass grafting (CABG) is an uncommon complication. We present a case of cervical spinal cord dysfunction after CABG in the absence of preceding neurological findings.
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Case Report
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A 63-yr-old, 175-cm, 67-kg man underwent routine two-vessel CABG for unstable angina with use of bilateral internal thoracic arteries. His medical history included diabetes, hypertension, moderate aortic valve stenosis, and transient cerebral ischemic attack. Hypertension was well controlled with amlodipine 5 mg/d, and the systolic and diastolic blood pressures were 120–130 mm Hg and 70–80 mm Hg, respectively. He was dependent on hemodialysis three times a week for diabetic nephropathy. He had never reported upper extremity symptoms, and the preoperative neurological examination did not reveal any abnormalities.
Anesthesia was induced and maintained with midazolam, ketamine, propofol, and fentanyl. The trachea was intubated without trauma, and the lungs were ventilated with 33%–100% oxygen and air so that the PaCO2 was maintained between 35 and 40 mm Hg. A pulmonary arterial catheter and a double-lumen central venous catheter were both inserted via the right jugular vein without difficulty. The endotracheal intubation and two vascular catheter placements were technically easy and did not require neck extension.
Thereafter, the patient’s neck was placed in a position of extension, and a cylindrical sponge was positioned under his upper back to facilitate skin incision and sternotomy. This position was maintained for the duration of the surgery. The sponge was made of polyurethane, and the height was 14 cm before insertion and 10 cm with the weight of the patient compressing it.
During surgery, the mean blood pressure and the cardiac index were successfully maintained >60 mm Hg and 2.5 L · min-1 · m-2, respectively, by using phenylephrine and 3–5 µg · kg-1 · min-1 of dopamine. During cardiopulmonary bypass (CPB), a nonpulsatile pump flow rate of 2.2–2.4 L · min-1 · m-2 was maintained by using a membrane oxygenator and an arterial line filter. The nasopharyngeal temperature was maintained at approximately 35°C. PaCO2, uncorrected for temperature, was adjusted to a normocapnic level. Perfusion pressure was maintained >50 mm Hg with phenylephrine. Surgery, CPB, aortic cross-clamp, and anesthesia required 355, 165, 105, and 450 min, respectively.
In the postoperative intensive care unit (ICU), the patient was kept unconscious with a continuous infusion of propofol because relatively major bleeding (50–150 mL/h) continued for approximately 8 h (total of 780 mL). The patient was transfused 800 mL of blood. The mean blood pressure and the cardiac index were successfully maintained >60 mm Hg and 2.5 L · min-1 · m-2, respectively, by using 3–5 µg · kg-1 · min-1 of dopamine.
The patient awoke the next morning, after which he complained of weakness and sensory abnormalities in his limbs. Neurological examination revealed flaccid, areflexic paraplegia and anesthesia in his lower limbs and muscle weakness (graded 1–2 out of 5) with diminished reflexes and hypesthesia in his upper limbs. According to the Frankel classification, the patient was assessed as Grade B (preserved sensation only; i.e., voluntary motor function was absent). T2-weighted magnetic resonance imaging (MRI) on the fourth postoperative day showed high signal lesions at the C4-5 and C5-6 level and showed spinal canal stenosis (Fig. 1).
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Figure 1. The postoperative T2-weighted magnetic resonance imaging shows high signal lesions (arrows) at the C4-5 and C5-6 levels and shows spinal canal stenosis.
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The patient was given edaravone, a radical scavenger (Mitsubishi Pharma, Osaka, Japan), and rehabilitation. He improved over the next few weeks. By 3 mo, upper limb strength was graded 2–4 out of 5, and lower limb strength was graded 1 out of 5. His sensation had returned almost to normal, and he was assessed as Frankel Classification C (preserved motor; i.e., motor function that performs no useful purpose).
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Discussion
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Although the pathophysiological cause of the neurologic deficits was impossible to determine retrospectively, spinal cord ischemia, epidural hematoma, and spinal cord injury from direct compression or retraction are worth considering. Spinal cord ischemia could be attributed to absolute hypotension, relative hypotension (mild hypotension in a hypertensive patient), and blood pressure changes in a patient with severe atherosclerotic disease. In this case, blood pressure was successfully maintained during surgery and CPB and in the postoperative ICU. The cervical cord is not anatomically vulnerable to ischemia (1–3). In fact, in all previous case reports after cardiac surgery (4–12) spinal infarction occurred in the middle thoracic spinal cord, the watershed zone of upper and lower spinal arteries. In addition, these cases were suggested to be related to the use of an intraaortic balloon pump (4–10), aortic dissection during aortic cross-clamp (11), or severe postoperative hypertensive crisis (12). In this case, there was no evidence of a preceding event that might have precipitated spinal ischemia. The MRI images also excluded epidural hematoma.
The postoperative T2-weighted MRI showed high signal lesions and significant spinal canal stenosis at the same levels (C4-5 and C5-6). Bondurant et al. (13) classified T2-weighted MRI images after 37 cases of acute spinal cord injury into 3 categories. Type 1 (27% of patients) demonstrated a decreased signal intensity consistent with acute hemorrhage. Type 2 (43%) demonstrated a bright signal intensity consistent with acute edema. Type 3 (8%) demonstrated a mixed signal of hypointensity centrally and hyperintensity peripherally consistent with contusion. They reported that Type 2 patients had a better neurological prognosis than Type 1 patients and improved at least one Frankel classification, which is compatible with the neurological recovery course of our case. Taken together, it seems probable that placing the neck in an extended position, which is commonly done during cardiac surgery in Japan, might have aggravated a preexisting spinal canal stenosis to produce cervical injury in this case.
In summary, we present a rare case of cervical spinal cord dysfunction after CABG. Although the pathophysiological basis of this dysfunction was impossible to determine retrospectively, it seems probable that placing the neck in an extended position during surgery might have aggravated a preexisting spinal canal stenosis to produce cervical cord injury.
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References
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Accepted for publication May 7, 2003.
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Abstract
Introduction
