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.

Exploring the association between oral tactile sensitivity measures and phenotypic markers of oral responsiveness

“…Participants were then asked to relax their dorsal and neck muscles, show their tongue and keep it relaxed. Participants were asked to close their eyes and to keep them closed during the test; a blindfold was not used during the test to avoid participants' distraction due the feeling of being blindfolded (Etter et al, 2020). Participants were invited to ask for a pause during the test every time they felt they lost their oral lubrication and to refresh their mouth with water.…”

“…One incorrect answer resulted in a presentation of the next higher groove width level. The test continued until the stopping point defined as "the point when a participant has crossed over or received the test stimulus from the same target force a total of five times" (Etter et al, 2020). GOT threshold for each participant was calculated as the geometric mean of all the grating's groove width values included between the first time the participant received the stimulus of the stopping point and the last (Etter et al, 2020).…”

“…The test continued until the stopping point defined as "the point when a participant has crossed over or received the test stimulus from the same target force a total of five times" (Etter et al, 2020). GOT threshold for each participant was calculated as the geometric mean of all the grating's groove width values included between the first time the participant received the stimulus of the stopping point and the last (Etter et al, 2020). Participants who gave correct answers at all levels and correctly identified the lowest force (five times according to the "stopping point" definition) showed a GOT of 0.2 mm.…”

“…Participants were asked to identify in which of the two trials they could feel the stimulus: one of the trials was a "real" touch and the other a "false" touch in a randomized order. A 3-down/1-up staircase method was used for threshold estimation (Etter et al, 2020). The test started with 1.0 g monofilament.…”

“…The current measures of oral tactile sensitivity convey information about specific functions of oral mechanoreceptors, such as the perception of touch, spatial resolution (Weinstein, 1968), and oral stereognosis (Lederman & Klatzky, 2009), indicating complexity of the oral somatosensory system. The most common methods are: the point‐pressure method by Von Fryer monofilaments (Breen, Etter, Ziegler, & Hayes, 2019; Etter, Breen, Alcala, Ziegler, & Hayes, 2020; Yackinous & Guinard, 2001; Zhou et al, 2021), the oral stereognosis assessment by the identification of letters and shapes (Essick, Chen, & Kelly, 1999; Essick, Chopra, Guest, & Mcglone, 2003; Lukasewycz & Mennella, 2012; Steel et al, 2014; Bangcuyo & Simons, 2017) and the spatial resolution assessment by the identification of two‐point distance (Olarte Mantilla et al, 2022) or the identification of grating orientation (Johnson & Phillips, 1981; Wohlert, 1996).…”