Abstract
The use of von Frey filaments, originally developed by Maximilian von Frey, has become
the cornerstone for assaying mechanical sensitivity in animal models and is widely
used for human assessment. While there are certain limitations associated with their
use that make comparisons between studies not straightforward at times, such as stimulus
duration and testing frequency, von Frey filaments provide a good measurement of mechanosensation.
Here we describe the application of von Frey filaments to testing in animal models,
specifically with respect to determining changes in sensory thresholds in a pain state
using the Dixon up-down method. In a literature survey, we found that up to 75% of
reports using this method analyze the data with parametric statistical analysis and
of those that used nonparametric analysis, none took into account that mechanical
sensation is perceived on a logarithmic scale (Weber's Law) when calculating efficacy.
Here we outline a more rigorous analysis for calculating efficacy and ED50's from von Frey data that incorporates Weber's Law. We show that this analysis makes
statistical and biological sense and provide a specific example of how this change
affects data analysis that brings results from animal models more in line with clinical
observations.
Perspective
This focus article argues that analyzing von Frey paw withdrawal threshold data obtained
by using the Dixon up-down method without considering Weber's Law is inappropriate.
An analysis method that incorporates how mechanical sensation is perceived and how
its application brings results from animal models more in line with clinical data
is presented.
Key words
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References
- Quantitative assessment of tactile allodynia in the rat paw.J Neurosci Methods. 1994; 53: 55-63
- The up-and-down method for small samples.J Am Statist Assoc. 1965; 60: 967-978
- Efficient analysis of experimental observations.Ann Rev Pharmacol Toxicol. 1980; 20: 441-462
Mills CD; PubMed search: First 100 articles with key word search for spinal nerve ligation, run 9.12.11, and first 100 articles with key word chronic constriction injury, run 9.13.11. Limitations: English, free full text
- Predictive validity of animal pain models? A comparison of the pharmacokinetic-pharmacodynamic relationship for pain drugs in rats and humans.Neuropharm. 2008; 54: 767-775
Article info
Publication history
Published online: April 30, 2012
Footnotes
All authors are employees of Abbott Laboratories.
Identification
Copyright
© 2012 American Pain Society. Published by Elsevier Inc. All rights reserved.
