Assessment of Midline Lingual Point-Pressure Somatosensation Using Von Frey Hair Monofilaments

Abstract

Detection and discrimination threshold estimates for oral point pressure are assessed using Von Frey Hair monofilaments. Consistent with previously published protocols, threshold estimates are determined using a two-interval forced choice (2-IFC) paradigm with a three down/ one up approach. Detection threshold estimates determine the mean force in which a participant can identify the presence of pressure. During the detection threshold procedure, the participant is instructed to choose which of two sequentially presented observation intervals contained the tactile test stimulus. If the participant performs three correct detections in a row (i.e., 3 'hits'), the researcher decreases the stimulus to the next lower target force level. With one incorrect detection (a 'miss'), the researcher increases the force delivered to the next higher level. This threshold estimation approach is known as a 3-down/1-up adaptive staircase. Reponses are recorded on a paper ballot, and a participant's estimated threshold is defined as the geometric mean of five reversals. During the discrimination threshold procedure, the participant is asked to make a choice between two serially presented stimuli as to which is the "harder" or "stronger" pressure. The same scoring of 'hits', 'misses', and stopping points are used. Detection and discrimination testing for oral point pressure at tongue midline takes approximately 20 min to complete. Using these commercially-available clinical tools, individual touch sensation profiles for the midline tongue can be achieved in a relatively time and cost effective means.

Methodological approaches to assess tactile sensitivity in the food context—A scoping review

“…A methodological study estimated the time to measure thresholds (detection or discrimination) to 20 min per respondent, also providing test protocol recommendation such as rewetting the tongue continuously in order to maintain sensitivity (Etter et al, 2020). Further, the authors of the study concluded a floor effect for measuring detection thresholds where the majority of respondents could detect the lowest filament weight that is commercially available (0.008 g) as limitation, a result found in several other studies as well (Breen et al, 2019; Lv et al, 2020; Santagiuliana et al, 2019).…”

“…Correspondingly, the detection measurement via R Index with lowest filament weight showed a better discrimination between respondents than the next heavier filament (Appiani et al, 2020; Zhou et al, 2021); distributions being; however, still skewed toward a high fraction of detecting respondents (Appiani et al, 2020). Two studies measured discrimination thresholds additionally to detection thresholds and concluded a better discrimination between individuals with this procedure (Breen et al, 2019; Etter et al, 2020). Some studies further found that measurement place had an effect on sensitivity; Aktar et al (2015b) (but not Aktar et al (2015a)) found a lower detection thresholds on the tongue than fingertip, Yackinous and Guinard (2001) found a higher detection rate (R‐Index) on the front tongue than mid tongue and Chamberlain et al (2007) a higher perceived intensity on the anterior tongue than the posterior tongue and velum.…”

“…For letter recognition, most studies referred to a common test protocol by (Essick et al, 1999) leading to a more homogenous implementation. In this review two recent methodological studies were identified, for one‐point pressure (Etter et al, 2020) and grating orientation (Rabitti et al, 2021) could guide further harmonization of methods. Etter et al (2020) described a one‐point pressure test protocol based on discrimination instead of detection which showed a higher discriminability between respondents.…”

“…In this review two recent methodological studies were identified, for one‐point pressure (Etter et al, 2020) and grating orientation (Rabitti et al, 2021) could guide further harmonization of methods. Etter et al (2020) described a one‐point pressure test protocol based on discrimination instead of detection which showed a higher discriminability between respondents. The same protocol was used in a second study where discrimination but not detection threshold was significantly associated to particle texture sensitivity in a food model (Breen et al, 2019).…”

Assessment of Spatial Lingual Tactile Sensitivity using a Gratings Orientation Test

“…9. Repeat each grating as many times as deemed necessary for the R-Index cut-off selected, for instance, 6 times, 3 horizontally, and 3 vertically (Supplemental 10. Sterilize each grating after testing each participant (refer to section 4).…”