View Full Version : Die back of neurons above POI
11-24-2003, 10:34 AM
I'm one year post injury, T11 complete. Recurrent mental fog and distractability eventually led me to a brain MRI. My neurologist says the MRI indicates that there is "die back" of neurons above my point of injury, all the way to cervical and brain levels. I'm told this is to be expected in SCI.
My questions: What are the implications of this die back, both in terms of my general health and in terms of potential return/recovery? Are there any treatments, experimental or othewise, to address this phenomenon?
02-14-2004, 04:50 AM
Neurons situated in the brain send axons down to the spinal cord. Neurons situated in the spinal cord send axons up the spinal cord to the brain.
The term that your doctor used, i.e. "dieback", is not strictly correct. The axons (nerve fibers) that have been separated from their neurons by the injury die. Since about half of the axons in the spinal cord are going up and half of them are going down, you would expect loss of those axons. This is not dieback per se.
Dieback refers to the dying back of axons that are still connected to the neurons. There is indeed some dieback, generally for a couple of centimeters from the injury site, usually back to the first branch point of the axon. However, in general, over time, those axons will often sprout back to the injury edge.
Let me give an example to make sure that you understand. A neuron in your brain sends an axon down through the T11 injury site. The part of the axon below T11 will die (because it has been separated from the neuron). The part of axon that is close to the injury site will dieback a few centimeters and then tend to grow back towards the injury edge.
In the opposite direction, a sensory neuron in your spinal cord below the injury site or in the dorsal root sensory ganglion just outside of your spinal cord will send axons to the brain. Your injury damaged those axons. The part of the axon in the spinal cord above the injury and separated from the neurons below the injury site will die.
The process of regeneration is to get the axons to grow back across the injury site and all the way back to their original connection points. This is of course the goal of many of the therapies.
Please keep asking if the above is confusing.
02-14-2004, 07:38 PM
Dr. Young, my understanding of this is that sensory and motor neurons would be involved, but not those of the higher centers of cognition, correct? If that is correct, then it would not explain Lyena's symptoms.
02-14-2004, 10:44 PM
KLD, I share your understanding of the situation. The changes in the spinal cord would not explain "recurrent mental fog and distractability".
Lyena, are you taking any medication? Sometimes the symptoms that you describe can result from taking antispasticity (baclofen), bladder spasticity (ditropan) drugs, and others.
02-15-2004, 06:48 AM
Have you had blood work done lately?
Maybe you should, as imbalances of certain components of blood can sometimes do this. Dan had very low blood sugar and it affected his mental clarity.
Just a thought,