Pressure pain threshold mapping - a new imaging modality of muscle sensitivity to pain

The present paper investigated the importance of interpolation methods on pressure pain threshold maps in the neck- shoulder region. Thirty-two pressure pain threshold values measured at points covering the entire trapezius muscle were assessed in 8 healthy subjects. The measured values were interpolated by means of Shepard, Franke and Nielson and Clough and Tocher. The interpolated maps were then compared with respect to their mutual information and the role of spatial resolution was assessed by removing points from the original maps. The mutual information of the generated maps was highest when using Franke and Nielson method compared with Shepard and Clough and Tocher (P < 0.001). Moreover, the number of measured points played a significant role on the maps mutual information (P < 0.001). These results indicated that Franke and Nielson method should be preferred due to the relative high maps heterogeneity. The method may prove to be valuable in pain treatment.