Studies of an amputated arm and leg have shed some light on the cause or effects of complex regional pain syndrome (CRPS). This painful condition of the extremities occurs after trauma to the area. It begins after something as minor as a mosquito bite. Major trauma such as injury or surgery for joint replacement can also bring it on.
Researchers took skin samples from the donated amputations. They compared them to skin biopsies from normal human skin. The authors carefully describe their exact chemical and biologic findings for the tissue samples. Nerve fiber type and number in the skin were compared from one group to the other.
Only the samples from the amputated arm and leg showed abnormalities. There were fewer nerves and blood vessels to the affected skin. The authors think the loss of nerve fibers supports the idea that CRPS is a neuropathic (nerve-related) condition. This is because other neuropathic diseases show the same kind of changes.
The authors say they can't be sure the changes weren't caused by the treatment these patients received before amputation. The disease may not have caused them at all. At the very least they know that CRPS-I is a neuropathic condition whether as a cause of the disease or an effect of the treatment.
Phillip J. Albrecht, et al. Pathologic Alterations of Cutaneous Innervation and Vasculature in Affected Limbs From Patients with Complex Regional Pain Syndrome. In Pain. February 2006. Vol. 120. No. 3. Pp. 244-266.'