Reliability of pain tolerance threshold testing by applying an electrical current stimulus to the alveolar ridge

Measurement reliability of current perception threshold and pain threshold in parallel with blood sampling

The irritation and pain associated with oral blood sampling necessary to monitor glycemic control can alter oral sensation, but no studies have measured the reliability of oral sensation testing when performed concurrently with blood sampling. The primary and secondary aims of this study were to verify the measurement reliability of current perception threshold (CPT) and pain threshold (PT) tests performed before and after blood sampling and to investigate the differences in CPTs/PTs obtained from the oral cavity, hand, and foot, respectively. CPT/PT measurements were obtained from the oral mucosa and the tips of fingers and toes of 18 volunteers (10 males and 8 females, average age = 26.3 years) using electrical stimulation at frequencies of 5, 250, and 2,000 Hz. Participants also provided blood samples by pricking their own index fingers with a small needle. All subjects completed the following 3 conditions at once-weekly intervals as follows: (a) sensory measurements followed by blood sampling (SB block); (b) blood sampling followed by sensory measurements (BS block); (c) sensory measurements without blood sampling (CO control block). Cronbach's α coefficients were over 0.78 for the SB, BS, and CO blocks, and are considered to be acceptable for assuring measurement reliability. The oral cavity had significantly lower CPT/PTs than both hands and feet, such that the threshold increased in the order oral cavity < hand < foot. CPT and PT measurements performed concurrently with blood sampling are both reliable and region specific, and for which the oral cavity is the most sensitive testing region.

Pain threshold reflects psychological traits in patients with chronic pain: a cross-sectional study

Background

Chronic pain enhances sensory sensitivity and induces the biased development of psychological traits such as depression and pain catastrophizing, leading to the formation of heterogeneous conditions. Fluctuations in the sensory-related thresholds of non-injured sites (with normal peripheral tissue) in patients with chronic pain are thought to be related to central sensitization. The objectives of this study were to analyze the association between pain tolerance thresholds (PTTs) in non-injured sites and the psychological traits of patients with chronic pain and to evaluate the usefulness of PTT measures in assessments of pathological conditions related to chronic pain.

Methods

This study included 57 patients with chronic pain. The PTTs were measured in non-injured sites with quantitative sensory testing (QST) with electrical stimulation and then classified with cluster analysis. The Short-Form McGill Pain Questionnaire was used to subjectively assess pain in the injured sites. The Minnesota Multiphasic Personality Inventory (MMPI) was used to assess the patients’ psychological traits.

Results

Based on the cluster analysis of PTTs, the patients were classified into a High-Sensitivity group and an Others group consisting of the remaining patients. The results of the MMPI profiles showed that the High-Sensitivity group included significantly more patients with the Neurotic Triad pattern and no patients with the Conversion V pattern. The scores of the hypochondriasis and hysteria scales were significantly lower in the High-Sensitivity group than in the Others group.

Conclusions

This study indicated that patients with chronic pain can be classified according to PTTs in non-injured sites and suggests that patients with High-Sensitivity have characteristic psychological traits. Assessment of PTTs in non-injured sites would be useful for evaluating the psychological condition of patients with chronic pain.

Characteristics of the pain tolerance threshold induced by electrical stimulation of the alveolar ridge

The purpose of this study was to determine the characteristics of the pain tolerance threshold (PTT) induced by electrical stimulation of the alveolar ridge. A total of 100 healthy volunteers studying or working at Nihon University School of Dentistry at Matsudo and patients from Nihon University School of Dentistry at Matsudo Affiliated Hospital, including 51 men (58.7 ± 17.6 years old) and 49 women (60.7 ± 17.1 years old), participated in this study. The volunteers were enrolled after obtaining written informed consent. PTT measurements were obtained using a Neurometer CPT/C® device to deliver electrical stimulation around the left greater palatine foramen at frequencies of 5 and 250 Hz. When the stimulus could no longer be tolerated, the participant released a button to automatically discontinue the stimulus. After the distribution of the PTT values was analyzed, the influence of gender, age, and Eichner index on PTT was analyzed. The Eichner index values were divided into three categories: group A (four supporting zones), group B (less than four supporting zones but with anterior tooth contact), and group C (no occlusal contact). The PTT values did not show a normal distribution. There were no significant differences in PTT between men and women. PTT was significantly associated with age (P = 0.017) at 5 Hz in men. There were no significant differences in PTT among the Eichner index groups. The characteristics of the PTT of the alveolar ridge are as follows: (1) age and PTT at 5 Hz are significantly associated with men but not with women, and (2) the Eichner index has no influence on the PTT.