Altered Sensitivity to Sound in Fibromyalgia

It is not only pain sensitivity that is altered in Fibromyalgia. This problem may occur with many kinds of sensation. These 2 new studies show that even how we handle sound is altered.

The first study shows that Fibromyalgia patients have increased sensitivity to sound as well as to pressure. As the others aptly note:

“The findings of this study and others suggest that persons with FM (Fibromyalgia) display sensitivity to a number of sensory stimuli. These findings suggest that FM is associated with a global central nervous system augmentation (amplification) of sensory information. These findings may also help to explain why persons with FM display a number of comorbid (additional) physical symptoms other than pain."

Following this is a second study showing that people with Fibromyalgia have trouble processing sensory input (again, using hearing as a model). And some fools out there still say Fibromyalgia is not real and all in the mind…

Study 1—A Psychophysical Study of Auditory and Pressure Sensitivity in Patients With Fibromyalgia and Healthy Controls

Michael E Geisser, Jennifer M Glass, Ljubinka D Rajcevska, Daniel J Clauw, David A Williams, Paul R Kileny, and Richard H Gracely
J Pain, February 14, 2008
Chronic Pain and Fatigue Research Center, Department of Internal Medicine, Division of Rheumatology, University of Michigan, Ann Arbor; Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor.

Fibromyalgia (FM) is characterized by widespread tenderness. Studies have also reported that persons with FM are sensitive to other stimuli, such as auditory tones. We hypothesized that subjects with FM would display greater sensitivity to both pressure and auditory tones and report greater sensitivity to sounds encountered in daily activities. FM subjects (n = 30) and healthy control subjects (n = 28) were administered auditory tones and pressure using the same psychophysical methods to deliver the stimuli and a common way of scaling responses. Subjects were also administered a self-report questionnaire regarding sensitivity to everyday sounds. Participants with FM displayed significantly greater sensitivity to all levels of auditory stimulation (Ps < .05). The magnitude of difference between FM patients' lowered auditory sensitivity (relative to control subjects) was similar to that seen with pressure, and pressure and auditory ratings were significantly correlated in both control subjects and subjects with FM. FM patients also were more sensitive to everyday sounds (t = 8.65, P < .001). These findings support that FM is associated with a global central nervous system augmentation in sensory processing. Further research is needed to examine the neural substrates associated with this abnormality and its role in the etiology and maintenance of FM.

PERSPECTIVE: Muscle tenderness is the hallmark of FM, but the findings of this study and others suggest that persons with FM display sensitivity to a number of sensory stimuli. These findings suggest that FM is associated with a global central nervous system augmentation of sensory information. These findings may also help to explain why persons with FM display a number of comorbid physical symptoms other than pain.

Study 2—Absence of Contralateral Suppression of Transiently Evoked Otoacoustic Emissions in Fibromyalgia Syndrome

J Laryngol Otol. 2008 Mar 4;:1-5 (Epub ahead of print)
Gunduz B, Bayazit YA, Celenk F, Sarýdoðan C, Guclu AG, Orcan E, Meray J.
Department of Audiology, Faculty of Medicine, Gazi University, Besevler, Ankara, Turkey.
PMID: 18318918

Objective: To assess contralateral suppression of transiently evoked otoacoustic emissions in patients with Fibromyalgia syndrome and normal hearing.

Methods: Twenty-four female patients with Fibromyalgia syndrome and 24 healthy female controls with normal hearing were assessed using pure tone audiometry and transiently evoked otoacoustic emissions.

Results: All patients with fibromyalgia syndrome and all controls had normal hearing on pure tone audiometry. In the patients with fibromyalgia syndrome, the mean transiently evoked otoacoustic emission amplitude was 15.5 +/- 4.8 dB. The mean transiently evoked otoacoustic emission amplitudes after contralateral suppression was 15.5 +/- 4.9 dB. There was no statistically significant difference between the transiently evoked otoacoustic emission amplitudes measured before and after contralateral suppression (p > 0.05). In the controls, the mean transiently evoked otoacoustic emission amplitude was 12 +/- 5 dB. The mean transiently evoked otoacoustic emission amplitudes after contralateral suppression was 11 +/- 4.7 dB. There was a statistically significant decrease in transiently evoked otoacoustic emission amplitudes after contralateral suppression (p < 0.01).

Conclusion: The mechanisms related to contralateral suppression of transiently evoked otoacoustic emissions seem dysfunctional in Fibromyalgia syndrome. This dysfunction may be at the brain stem level, where the medial superior olivary complex is located, or at the synapses of medial superior olivary complex fibres with the outer hair cells in the cochlea. Demonstration of lack of contralateral suppression of transiently evoked otoacoustic emissions can be used as a diagnostic tool in patients with Fibromyalgia syndrome.