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J Thorac Cardiovasc Surg 2000;119:1295-1296
© 2000 The American Association for Thoracic Surgery

LETTERS TO THE EDITOR

Paraplegia after coronary artery bypass operations: Relationship to severe hypertension and vascular disease

Department of Cardiothoracic Surgery, North Staffordshire Royal Infirmary, Stoke on Trent, United Kingdom

To the Editor:

Thomas and Harvey ¹ are to be congratulated on their article concerning the rare occurrence of paraplegia arising during isolated coronary artery bypass grafting (CABG), but their conclusion that hypertension and peripheral vascular disease are related needs further analysis.

Paraplegia in cardiac surgery is most commonly associated with repairs of descending or thoracoabdominal aortic aneurysms and dissection where there is ischemic injury to the spinal cord through disruption of the artery of Adamkiewicz at T9 through T12. ^2,3 However, increases in the intraspinal pressure and systemic hypotension in the perioperative period may also be potential mechanisms of injury. ^4-6 Other etiologic factors such as central disk prolapse, cord hemorrhage, or epidural hematomas ⁷ have not been reported after cardiac surgery.

Isolated CABG with cardiopulmonary bypass is an exceptional cause of paraplegia. It is known to occur as a result of aortic dissection produced by aortic crossclamping, cannulation of the aorta, the creation of an aortotomy for the aorto–saphenous vein anastomosis, or the use of an intra-aortic balloon pump (IABP). ^3,8 An IABP may by itself produce paraplegia by disrupting fragile plaques in the descending aorta and causing spinal cord emboli. ⁹ This mechanism of spinal cord injury has also been reported when IABP is used during CABG. ⁸ An IABP was used in one of the two cases reported by Thomas and Harvey, and since no evidence of aortic dissection was found, embolism into the radicular arteries of the spinal cord may be a contributory factor. Thus the literature seems to support the assertion that peripheral vascular disease is a significant risk factor in the absence of aortic dissection.

Thomas and Harvey also suggested that hypertension is a risk factor by causing plaque rupture, the raising of an intimal flap, or embolization of debris into the spinal cord circulation. However, this contention is not supported by any study. On the contrary, acute hypertension is usually well tolerated for short periods of time, and cerebral injury arises from acute hemorrhage. ¹⁰

In the cases reported, antihypertensive treatment was instituted at a mean arterial blood pressure of 100 mm Hg. This may not be abnormally high in patients with chronic hypertension and may be necessary for normal organ perfusion in these patients. However, in hypertensive patients, sudden lowering of blood pressure could cause strokes and paraplegia in watershed areas, ^11,12 and this is implicated as a mechanism of paraplegia in thoracoabdominal aortic surgery. ¹³

It is also interesting that sodium nitroprusside has been shown to be detrimental to spinal cord perfusion, ¹⁴ and sodium nitroprusside was used as the antihypertensive agent in the authors’ study.

Thus the occurrence of neurologic levels in watershed regions in both case reports may be compatible with hypoperfusion. Therefore postoperative hypertension may be necessary to maintain spinal cord perfusion in some patients and may not be an etiologic factor in paraplegia after CABG.

12/8/105461 doi:10.1067/mtc.2000.105461

References

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2. Wadouh F, Lindemann EM, Arndt CF, Hetzer R, Borst HG. The arteria radicularis magna anterior as a decisive factor influencing spinal cord damage during aortic occlusion. J Thorac Cardiovasc Surg 1984;88:1-10. [Abstract]
   
3. Archer AG, Choyke PL, Zeman RK, Green CE, Zuckerman M. Aortic dissection following coronary bypass surgery: diagnosis by CT. Cardiovasc Intervent Radiol 1986;9:142-5. [Medline]
   
4. Miyamoto K, Ueno A, Wada T, Kimoto S. A new and simple method of preventing spinal cord damage following temporary occlusion of the thoracic aorta by draining the cerebral spinal fluid. J Cardiovasc Surg 1960;1:188-97. [Medline]
   
5. Blaisdell FW, Cooley DA. The mechanism of paraplegia after temporary thoracic aortic occlusion and its relationship to spinal fluid pressure. Surgery 1962;51:351. [Medline]
   
6. Bevendes JN, Bredee JJ, Schipperheyn JJ, Mashhour YAS. Mechanism of spinal cord injury after cross clamping of the descending thoracic aorta. Circulation 1982(Suppl);66:I-1-112.
   
7. Hejazi N, Thaper PY. Nine cases of nontraumatic spinal epidural hematoma. Neurol Med-Chir 1998;38:718-23.
   
8. Harris RE, Reimer KA, Crain BJ, Becsey DD, Oldham HN. Spinal cord infraction following balloon support. Ann Thorac Surg 1986;42:206-7. [Abstract]
   
9. Rose DM, Jacobowitz IJ, Acinapura AJ, Cunningham JN Jr. Paraplegia following percutaneous insertion of an intra-aortic balloon. J Thorac Cardiovasc Surg 1984;87:788-9. [Abstract]
   
10. Garcia JH, Lassen NA. Ischemic stroke and incomplete infarction. Stroke 1986;27:761-5. [Abstract/Free Full Text]
    
11. Singh U, Silver JR, Welply NC. Hypotensive infarction of the spinal cord. Paraplegia 1994;32:314-22. [Medline]
    
12. Attar S, Hankins JR. Paraplegia after thoracotomy: report of five cases and review of the literature. Ann Thorac Surg 1995;59:1410-5. [Abstract/Free Full Text]
    
13. Crawford ES, Rubio PA. Reappraisal of adjuncts to avoid ischemia in the treatment of aneurysms of the descending thoracic aorta. J Thorac Cardiovasc Surg 1973;66:693-704. [Medline]
    
14. Marini CP, Grubbs PE, Toporoff B, Woloszyn TT, Coons MS, Acinapura AJ, et al. Effect of sodium nitroprusside on spinal cord perfusion and paraplegia during aortic cross-clamping. Ann Thorac Surg 1989;47:379-83. [Abstract]
    

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This Article Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Carl Wong Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wong, C. Search for Related Content PubMed PubMed Citation Articles by Wong, C.