dr. young- vascular supply to spinal cord

[bent]

Dr. Young-

I just read your article on vascular supply to spinal cord. Is the Pial Plexus a sheath surrounding the cord or is it actually tissue of the spinal cord? Would extended venous congestion for weeks mimic the manifestations of traumatic spinal cord injury? Does infarcted spinal tissue resemble tissue from any traumatic contusion or bruise, or cutting? Does a spinal avm actually block blood flow to the cord from the spinal arteries, or does the problem result from too much blood flow from spinal arteries without proper drainage? What would be the process to get to the anterior spinal cord if a therapy were to arrive? Is a atrophied spinal cord beyonf help? When proper bloodflow is restored, can tissue once damaged, reawake and maintain neural conductivity? How do researchers such as yourself see treatments being administered? I would imagine that for a chronically damaged spinal cord, an oral treatment would not be enough. Do you forsee actual surgical intervention, or laser guided surgical procedures?

[Wise Young]

Originally posted by bent:

I just read your article on vascular supply to spinal cord. Is the Pial Plexus a sheath surrounding the cord or is it actually tissue of the spinal cord?

• It is tissue surrounding the spinal cord.

Would extended venous congestion for weeks mimic the manifestations of traumatic spinal cord injury?

• Venous congestion means that the pressure in the venous system is high. Like the sewers of New York, when the pressure is high, flow is low. Therefore, extended venous congestion would result in ischemia (low blood flow) of the spinal cord. By the way, one of the most prominent manifestations of arteriovenous malformation (AVM) of the spinal cord, where arterial blood flows inadvertently directly into the venous system. AVM's cause problems because they slow down blood flow.

Does infarcted spinal tissue resemble tissue from any traumatic contusion or bruise, or cutting?

• Yes, infarcted spinal tissues look like contused spinal cord. Many scientists believe that ischemia is the same as trauma. I personally think that there are important differences between the two. Here are two differences. First, ischemia tends to damage smaller axons whereas contusion injury tends to damage larger axons. Second, ischemia turns on some genes that trauma does not. For example, ischemia turns on the heat shock proteins in the surrounding cord. These proteins are neuroprotective while trauma does not turn them to the same extent.

Does a spinal avm actually block blood flow to the cord from the spinal arteries, or does the problem result from too much blood flow from spinal arteries without proper drainage?

• AVMs reduce blood flow to the spinal cord in two ways. One is mentioned above. They increase venous congestion and thereby slow blood flow. The other is that it shunts blood from the artery to the veins, bypassing the capillaries that feed the blood to the tissue.

[QUOTE]What would be the process to get to the anterior spinal cord if a therapy were to arrive? [/url]
• The anterior spinal artery can be reached by inserting a catheter into the artery of Adamkiewicz from the thoracic aorta.

Is a atrophied spinal cord beyonf help?

• I don't think that an atrophied spinal cord is beyond help. It simply means that cells have died. The cells need to be replaced.

When proper bloodflow is restored, can tissue once damaged, reawake and maintain neural conductivity?

• It depends on how much tissue damage there is. If all the cells have died, restoring blood flow does not help. On the other hand, I have seen people who have been paralyzed for years due to AVM and they get function back within days when their AVM is embolized. This is too fast for regeneration and it is likely to be due to neurons that have not yet died. In 1985, I published a paper with Alex Berenstein, one of the first neuroradiologist to embolize AVMs of the spinal cord. I saw several people recover dramatically evoked potentials and function when their AVM's were embolized. It is a study that I was very proud to be part of because we did the evoked potential monitoring of the cases and were able to reduce the number of cases of neurological deficits after embolization from over 20% to less than 2%.

How do researchers such as yourself see treatments being administered? I would imagine that for a chronically damaged spinal cord, an oral treatment would not be enough. Do you forsee actual surgical intervention, or laser guided surgical procedures?

• Treatment of AVMs is currently done by interventional neuroradiology where they inject glue or little balls to block arteriovenous connection. If the damage to the spinal cord is not so severe, substantial functional recovery can occur. However, if the tissue damage is severe, other restorative therapies are necessary. Ischemia damage the following structures in order from most to least: neurons, oligodendroglia, astrocytes, small axons, large axons. There is evidence now that there are stem cells in the spinal cord that can replace glia, even oligodendroglia. There is less evidence that the stem cells produce neurons that can replace the neurons that have been damaged. Axons, of course will need regeneration.

Wise.