Monday, May 6, 2013


Neurophysiological study of thin myelinated and unmyelinated fibers.
Espinosa ML, Santiago S, Guzman JJ, Prieto J, Ferrer T; Laboratorio de SNA, Hospital General
La Paz, Madrid, Espana.

INTRODUCTION: Standard neurophysiological techniques evaluate thick myelinated fibers. Yet,
peripheral nerves are equally composed of thin myelinated and unmyelinated fibers. The latter are
responsible for autonomic function as well as temperature and pain perception.

DEVELOPMENT:
Microneurographic studies are restricted to investigation laboratories. Since the techniques are complex
and invasive, their performance is still poor for clinical purposes and some of the components to be
analyzed, such as cardiovagal, cannot be directly recorded. The clinical need to evaluate the functions
regulated by the autonomic nervous system (ANS) had led to devising a series of tests which, in most
cases, rely on reflex responses evoked by already known standardize stimuli. The battery chosen has to
be non invasive, reproducible, specific, providing relevant data to the investigated function, with a readily
available technology, which has to be managed being aware of the physiological and pathological factors
that might bear an influence on the results. The recent development of heart rate blood pressure power
spectral analysis, provides a new interesting insight for quantification of ANS abnormalities. The study of
thermography and thermometry of body surface brings forward evidence on the activity of other thin and
unmyelinated fibers components of the peripheral nerve spectrum.

CONCLUSION: The adequate
management of the above mentioned tests gives rise to a more extensive and appropriate knowledge of
the whole peripheral nerve fiber spectrum.

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