Multisensory Sensitivity is Related to Deep-Tissue but Not Cutaneous Pain Sensitivity in Healthy Individuals

Figures & data

Figure 1 The schematic study design framework of the pain sensitivity assessments and associated sample sizes.

Abbreviations: PPT, pressure pain threshold; HPT, heat pain threshold; TSP, temporal summation of pain; CPM, conditioned pain modulation.

Table 1 Seven Items (Unshaded) from the 10-Item Somatosensory Amplification Scale (SSAS) Used to Assess Multisensory Sensitivity

Individual Items of SSAS
When someone else coughs, it makes me cough too.
I cannot stand smoke, smog, or pollutants in the air.
I am often aware of various things happening within my body.
When I bruise myself, it stays noticeable for a long time.
Sudden loud noises really bother me.
I can sometimes hear my pulse or my heartbeat throbbing in my ear.
I hate to be too hot or too cold.
I am quick to sense the hunger contractions in my stomach.
Even something minor, like an insect bite or a splinter, really bothers me.
I cannot stand pain.

Notes: Grey highlighted items were not included in the non-noxious somatosensory amplification score for the current study. Reprinted from Journal of Psychiatric Research, 24(4), Barsky AJ, Wyshak G, Klerman GL, The somatosensory amplification scale and its relationship to hypochondriasis, 323-334, Copyright (1990), with permission from Elsevier.²⁶

Table 2 Characteristics of Study Participants Overall and by MSS Sex-Specific Quartiles

	All (N=465)		MSS Sex-Specific Quartiles				Quartile P-value
	Mean (SD) or N (%)	Range	Q1 (n=129)	Q2 (n=127)	Q3 (n=107)	Q4 (n=102)
Age	26.2 (7.7)	18–54	28.1^a,b,c (9.0)	26.0^a,b,c (7.6)	25.6^b,c (6.7)	24.9^b,c (6.8)	0.01
BMI (kg/m^2)	24.6 (3.8)	17–41.3	25.1^a (4.3)	24.4^a (3.5)	24.8^a (4.0)	24.0^a (3.2)	0.17
Female	236 (50.8)	-	60 (46.5)	77 (60.6)	50 (46.7)	49 (48.0)	0.08
Caucasian	404 (86.9)	-	105 (81.4)	116 (91.3)	94 (87.9)	89 (87.3)	0.39
7-item SSAS	18.3 (4.2)	9–30	13.3^a (1.9)	17.4^b (1.0)	19.9^c (1.2)	24.1^d (2.3)	<0.0001
EPQ-R Neuroticism	9.1 (5.1)	0–23	7.3^a (5.0)	8.8^b (5.0)	9.6^b,c (4.6)	11.3^d (5.1)	<0.0001

Notes: Values with same upper letter (a, b, c, d) indicated no difference with each other. False discovery rate was used for multiple comparisons between MSS sex-specific quartiles (4th = highest sensory sensitivity; 1st = lowest sensory sensitivity). Mean (SD) or N (%) were presented if appropriate. The significant values for the ANOVA model were highlighted in bold (p≤0.05).

Abbreviations: MSS, multisensory sensitivity; SSAS, somatosensory amplification scale; EPQ-R Neuroticism, Eysenck Personality Questionnaire-Revised Neuroticism.

Figure 2 Boxplots showing median (black bars) and 25th–75th percentiles (IQR boxes) of each pain sensitivity outcome by sex-specific MSS quartiles: (A) local pain ratings from 4 intramuscular infusion conditions; (B) pressure pain thresholds (PPT) at 3 sites; (C) heat pain thresholds (HPT); (D) temporal summation of pain (TSP) using 3 different stimuli; (E) condition pain modulation using PPTs as the test stimulus (pressure CPM); and (F) CPM using HPTs as the test stimulus (heat CPM). Significant differences between MSS quartiles (eg, 4th = highest sensory sensitivity) and the referent MSS quartile (1st, lowest) are indicated (**p≤0.01 *p≤0.05) based on transformed data but graphs show original data for clarity.

Figure 3 Boxplots showing median (black bars) and 25th–75th percentiles (IQR boxes) of (A) local pain ratings between men and women from the saline infusion at 80 mL/hr and (B) pressure pain thresholds (PPT) at the deltoid muscle are shown by sex-specific MSS quartiles. Significant sex-MSS interactions were observed for both conditions; yet the follow-up stratified analyses by sex only show the significant difference on saline infusion at 80 mL/hr in women between MSS quartiles (eg, 4th = highest sensory sensitivity) and the referent MSS quartile (1st, lowest) (*p≤0.05).

Figure 4 Odds ratios (ORs) and their associated 95% confidence intervals (CI) for experiencing: referred pain from the 4 intramuscular infusions, the presence of temporal summation (TSP (+)), and the absence of conditioned pain modulation (CPM (-)) to each stimulus in people with high (4th quartile) versus low (1st quartile) MSS. All ORs were adjusted for age, sex, BMI, and neuroticism. Orange symbols and lines highlight significant ORs (p≤0.05).

Barsky AJ, Wyshak G, Klerman GL. The somatosensory amplification scale and its relationship to hypochondriasis. J Psychiatr Res. 1990;24(4):323–334. doi:10.1016/0022-3956(90)90004-A

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