Influence of surface anesthesia on the pressure pain threshold measured with different-sized probes

Abstract

Transcutaneous pressure with pressure probes of arbitrary diameters have been commonly used for measuring the threshold and magnitude of muscle pain, yet this procedure lacks scientific validation. To examine the valid probe dimensions, we conducted physiological experiments using 34 human subjects. Pin-prick pain, pressure pain threshold (PPT) to pressure probes of various diameters, heat pain threshold, and electrical pain threshold of deep tissues were measured before and after application of surface lidocaine anesthesia to the skin surface over the brachioradial muscle in a double-blinded manner. The anesthesia neither affected PPT with larger probes (diameters: 1.6 and 15 mm) nor increased electric pain threshold of deep structures, whereas it diminished pain count in pin-prick test and PPT with a 1.0 mm diameter probe, suggesting that mechanical pain thresholds measured with 1.6 and 15 mm probes reflect the pain threshold of deep tissues, possibly muscle. Pain thresholds to heat did not change after application of the anesthesia. These results suggest that larger pressure probes can give a better estimation of muscular pain threshold.

Bradykinin and Nerve Growth Factor Play Pivotal Roles in Muscular Mechanical Hyperalgesia after Exercise (Delayed-Onset Muscle Soreness)

“…A probe of tip diameter 5 mm was used to measure the withdrawal threshold of the gastrocnemius muscle. Use of a probe with a tip diameter of Ն2.6 mm allows measurement of muscle mechanical nociceptive threshold (Takahashi et al, 2005;Nasu et al, 2010). The animals were restrained around the trunk with a towel to calm them and treated gently during the experiments.…”

A Human Experimental Bone Pain Model

“…They stimulated the brachial muscle before and after LA with lidocaine with probe sizes of 1, 1.6 and 15 mm in diameter. They observed no significant difference in PPT before and after LA with probe sizes 1.6 and 15 mm, suggesting that the role of skin component would be minimal with probe size >1.6 mm [14]. In the present study, probe sizes 2 mm were used, and therefore, the skin influence would be expected to be minimal.…”

“…Takahashi et al showed that subcutaneous tissue hinders the transmission of pressure to the muscle when tissue thickness is larger than 9 mm. Under these conditions, a probe size of 2 mm in diameter may be necessary to assess the extent of muscle pain [14]. In the present study, the thickness of the skin that covers tibia is expected to be <9 mm as none of the volunteers were obese.…”

“…Takahashi et al investigated the validity of probe size used for transcutaneous pressure stimulation to induce deep pain [14]. They stimulated the brachial muscle before and after LA with lidocaine with probe sizes of 1, 1.6 and 15 mm in diameter.…”

“…Mechanical stimulations using probes of different sizes have been utilized in several studies to evoke experimental pain from deeper tissues such as muscle, nerve and periost [7,[12][13][14][15]. As the sensory threshold and perceived intensity are affected by increased stimulation area, manifested as decreased pain threshold and increased pain intensity, it is important to investigate whether the stimulus duration could influence the threshold when using probes of different sizes [16].…”