Patients with fibromyalgia may experience hypersensitivity to not only painful stimuli but also to sound and heat, which suggests that mechanisms of fibromyalgia augmentation are operant in both the spinal cord and in the brain, a study in The Journal of Pain suggests.
This study included 23 patients with fibromyalgia (mean age, 46.2 years) and 28 age-matched healthy control group participants (mean age, 49.6 years) who were recruited from north central Florida. All patients with fibromyalgia were tapered off their psychotropic and pain medications, but they continued on stable doses of medications for other comorbid conditions.
Participants were asked to rank their overall pain intensity, depression, and anxiety on a 0-to-10 visual analogue scale (VAS). A 0-to-100 electronic VAS (eVAS) was used to rate participants’ experimental painless and painful heat or mechanical sensations.
Audiometry testing was also performed, including testing of auditory thresholds for air conduction and testing of loudness sensitivity. Tests of mechanical and heat pain sensitivity included quantitative sensory testing, mechanical stimuli placed on the back of the hands or legs, and heat stimuli placed on the skin.
The mean clinical pain ratings were 1.5 VAS in healthy control group participants and 4.6 VAS in patients with fibromyalgia (P <.001). A lower average peak pressure required for pain ratings of 50 (±10) eVAS at the upper extremities was observed in patients with fibromyalgia (309.5 vs 584.4 kPa; P <.001). A similar finding was reported for pressure sensitivity at the lower extremities (490.0 vs 729.3 kPa; P <.001).
Patients with fibromyalgia also required significantly lower peak heat stimulus temperatures to reach pain ratings of 50 (±10) eVAS at the upper extremities (44.1 vs 48.8 °C; P <.001) and lower extremities (44.6 vs 47.6 °C; P <.001). The researchers wrote that these findings suggest heat hyperalgesia is widespread in people with fibromyalgia.
In addition, the mean sound pressure ratings of mild loudness were 36.6 dB in patients with fibromyalgia vs 52.9 in healthy control group participants. For moderate loudness, the mean sound pressures were 52.3 and 63.9 dB, while the mean sound pressures for intense loudness were 61.1 and 71.6 dB (P <.001 for both groups). Bivariate correlation analyses found that depression scores were significantly associated with sound pressures used for high-intensity stimuli (P <.012).
A limitation of this study included its small sample size and the recruitment of participants from a single geographic region.
The investigators added that “additional studies are needed to explore whether these findings extend to other sensory domains such as sight and smell, and whether responses to innocuous and painful stimuli are modulated by similar or different central mechanisms.”
Staud R, Godfrey MM, Robinson ME. Fibromyalgia patients are not only hypersensitive to painful stimuli but also to sound stimuli. J Pain. Published online February 23, 2021. doi:10.1016/j.jpain.2021.02.009