NeuroTalk Support Groups - Skin biopsy information and posts:

There is some research in monkeys showing that damage to the dorsal roots PRECEDES damage to the end point sensory nerves.

This one:
http://www.ncbi.nlm.nih.gov/pubmed/21924225

Quote:

Performing your original search, dorsal root damage neuropathy, in PubMed will retrieve 111 records.

Am J Pathol. 2011 Nov;179(5):2337-45. Epub 2011 Sep 13.
Macrophage-mediated dorsal root ganglion damage precedes altered nerve conduction in SIV-infected macaques.
Laast VA, Shim B, Johanek LM, Dorsey JL, Hauer PE, Tarwater PM, Adams RJ, Pardo CA, McArthur JC, Ringkamp M, Mankowski JL.
Source

Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Abstract

Peripheral neuropathy is the most common neurological complication of HIV-1 infection, affecting over one-third of infected individuals, including those treated with antiretroviral therapy. To study the pathogenesis of HIV-induced peripheral nervous system disease, we established a model in which SIV-infected macaques developed changes closely resembling alterations reported in components of the sensory pathway in HIV-infected individuals. Significant declines in epidermal nerve fiber density developed in SIV-infected macaques, similar to that of HIV-infected individuals with neuropathy. Changes in dorsal root ganglia (DRG) included macrophage infiltration, SIV replication in macrophages, immune activation of satellite cells, and neuronal loss. To determine whether dorsal root ganglion damage was associated with altered nerve function, we measured unmyelinated C-fiber conduction velocities (CV) in nerves of SIV-infected macaques and compared CV changes with DRG alterations. Twelve weeks postinoculation, SIV-infected macaques had significantly lower C-fiber conduction velocity in sural nerves than uninfected animals and the magnitude of conduction velocity decline correlated strongly with extent of DRG macrophage infiltration. Thus, injury to neurons in the DRG-mediated by activated macrophages-preceded altered conduction of unmyelinated nerve fibers in SIV-infected macaques, suggesting that macrophage-mediated DRG damage may be the initiating event in HIV-induced sensory neuropathy.

Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

PMID:
21924225
[PubMed - indexed for MEDLINE]
PMCID:
PMC3204023
[Available on 2012/11/1]

The nervous system has a "balance" quality to it. Meaning if the balancing nerves are damaged, the whole system will fail eventually. When signals from "above" in the peripheral system, meaning here, dorsal roots and spinal cord, are compromised, then end points may atrophy over time. This is how muscle atrophy happens too. It is as if signals from above are interrupted, the lower levels stop working.

I am still searching this subject, but that is how our bodies were designed genetically. And this is why physical therapy is still done on spinal cord injury patients, to keep the lower systems still working.