Tuesday, 13 November 2012

Spinal cord ischemia in a case of Aortic Dissection

A young male admitted with sudden onset both lower limb weakness with an associated severe backache. Motor loss more than sensory. Advised MRI whole spine screening for spinal cord. 
Day 1 MRI
Findings:
Sagittal T2w images of spine show faint abnormal intramedullary T2 hyper intensity confined to anterior cord in dorsal region.

Day 2 MRI with axial T2
Sagittal T2w image of cervico dorsal region spine with axial T2w images at the level of signal abnormality of spinal cord show same abnormal intramedullary T2 hyper intensity confined to anterior half of cord in dorsal region becoming more obvious on this follow up MRI.

Radio logical diagnosis: Acute Spinal cord Ischemia.
Further evaluation revealed an thoraco abdominal Aortic Dissection on CT Angiography. 


Discussion:

The differential diagnosis of acute onset paraplegia includes spinal cord injury, tumor, infection, Disc herniation, Demyelination or aortic dissection - occlusion. Aortic dissection in acute paraplegia is missed in up to 50% of cases.
Aortic dissection is uncommon, accounts for approximately 1 in 10,000 hospital admissions. The mortality rate is as high as 80% without aggressive treatment. Clinical presentation is commonly a severe painful tearing sensation usually located interscapular or mid-back area. Other common signs and symptoms include cardiovascular collapse, acute myocardial infarction, oliguria, syncope and cold extremities.

Classification of aortic dissection; DeBakey classification divides dissections into 3 types. Type I involves the ascending aorta, aortic arch and descending aorta. Type II involves only the ascending aorta. Type III involves the descending aorta distal to the left subclavian artery.
Stanford classification Type A includes involvement of the ascending aorta and Type B excludes it.

Neurologic sequelae of aortic dissection occur in ~ one third of cases. These sequelae fall into 3 categories: cerebral ischemia, spinal cord ischemia and ischemic peripheral neuropathy.
When the ascending aorta is involved, cerebral ischemia may result, present as a stroke or encephalopathy. Paraplegia with or without sensory loss is a rare phenomenon, occurs in about 2% to 8% of patients, results from dissection of the descending aorta. The clinical picture of motor loss without complete loss of sensation is known as anterior artery syndrome. Painful peripheral neuropathy result when the iliac arteries are involved.

The artery of Adamkiewicz arises from the posterior aspect of the aorta and supplies the anterior aspect of the major portion of spinal cord. This artery is can be involved in the aortic dissection. When involves most areas of the spinal cord receive additional blood flow from the collateral flow. In the thoracic spinal cord, there is a “watershed” area which is especially prone to ischemia.

Conclusion: Acute aortic dissection to be considered in the differential diagnosis of acute onset paraplegia. 

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