Opportunities afforded by the study of unmyelinated nerves in skin and other organs

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Abstract from Muscle Nerve. 2004 Jun;29(6):756-67.

Opportunities afforded by the study of unmyelinated nerves in skin and

other organs.

Kennedy WR.

Department of Neurology, University of Minnesota Hospital, MMC 187, 420

Delaware Street SE, Minneapolis, Minnesota 55455-0374, USA.

Neurological practice is mainly focused on signs and symptoms of

disorders that involve functions governed by myelinated nerves.

Functions controlled by unmyelinated nerve fibers have necessarily

remained in the background because of the inability to consistently

stain, image, or construct clinically applicable neurophysiological

tests of these nerves. The situation has changed with the introduction

of immunohistochemical methods and confocal microscopy into clinical

medicine, as these provide clear images of thin unmyelinated nerves in

most organs. One obvious sign of change is the increasing number of

reports from several laboratories of the pathological alterations of

cutaneous nerves in skin biopsies from patients with a variety of

clinical conditions. This study reviews recent methods to stain and

image unmyelinated nerves as well as the use of these methods for

diagnosing peripheral neuropathy, for experimental studies of

denervation and reinnervation in human subjects, and for demonstrating

the vast array of unmyelinated nerves in internal organs. The new

ability to examine the great variety of nerves in different organs opens

opportunities and creates challenges and responsibilities for

neurologists and neuroscientists.