Sensory findings after stimulation of the thoracolumbar fascia with hypertonic saline suggest its contribution to low back pain

Abstract

Injection of hypertonic saline into deep tissues of the back (subcutis, muscle, or the surrounding fascia) can induce acute low back pain (LBP). So far, no study has analyzed differences in temporal, qualitative, and spatial pain characteristics originating from these tissues. The current study aimed to investigate the role of the thoracolumbar fascia as a potential source of LBP. In separate sessions, 12 healthy subjects received ultrasound-guided bolus injections of isotonic saline (0.9%) or hypertonic saline (5.8%) into the erector spinae muscle, the thoracolumbar fascia (posterior layer), and the overlying subcutis. Subjects were asked to rate pain intensity, duration, quality, and spatial extent. Pressure pain thresholds were determined pre and post injection. Injections of hypertonic saline into the fascia resulted in significantly larger area under the curve of pain intensity over time than injections into subcutis (P<0.01) or muscle (P<0.001), primarily based on longer pain durations and, to a lesser extent, on higher peak pain ratings. Pressure hyperalgesia was only induced by injection of hypertonic saline into muscle, but not fascia or subcutis. Pain radiation and pain affect evoked by fascia injection exceeded those of the muscle (P<0.01) and the subcutis significantly (P<0.05). Pain descriptors after fascia injection (burning, throbbing, and stinging) suggested innervation by both A- and C-fiber nociceptors. These findings show that the thoracolumbar fascia is the deep tissue of the back that is most sensitive to chemical stimulation, making it a prime candidate to contribute to nonspecific LBP but not to localized pressure hyperalgesia.

A novel human surrogate model of noninjurious sharp mechanical pain

“…In addition, each pain modality was rated with respect to the sensory and affective components after the respective block was completed. We used an extended German version of the Pain Sensation Questionnaire (Schmerz-Empfindungsskala, SES), 16,19,41 containing items describing affective or sensory pain components. It yielded sensory and affective pain scores derived from a list of 28 pain-related items each of which was rated on a 0 to 3 ordinal scale (0 5 does not apply, 1 5 applies somewhat, 2 5 applies mostly, 3 5 applies fully).…”

Clavicle pain and reduction of incisional and fascial pain after posterior cervical surgery

“…The idea of fascial nociception is old and has led the way to a number of different treatments for neck pain. 1,7,10,11 This idea needs to be transferred to postoperative care. Anatomically, during a posterior cervical spine exposure, the surgeon must pass 2 different fascia layers while dissecting through the posterior cervical space: the trapezius muscle and the deep cervical fasciae, which lie over the deeper cervical muscles.…”

Fascia–Current knowledge and future directions in physiatry: Narrative review

“…Injections into tendon and tendon-bone junction sites were found to be more sensitive than injections into the muscle belly [38]. Sensitivity to pain was not found to be a strictly volume-driven process because ultrasound-guided injections of isotonic saline into fascia resulted in less pain than hypertonic saline injections even though both fluids distended the fascia [39]. The innervation profile of fascia may partially explain why these injections result in pain.…”

“…Studies have shown that intense local and referred pain occurs with injection of hypertonic saline into the tendons and fascia [38][39]. Injections into tendon and tendon-bone junction sites were found to be more sensitive than injections into the muscle belly [38].…”