Abstract Details

The Interplay of Sympathetic Hyperactivity and Small Fiber Damage in Fibromyalgia Patients
Pain
S11 - Pain (11:39 AM-11:51 AM)
003
FMS is associated with autonomic dysfunction, particularly cardiovascular dysautonomia, manifesting as chronic orthostatic intolerance, palpitations, and fatigue. Heart rate variability (HRV) studies indicate that FMS patients exhibit SNS hyperactivity while supine and impaired adaptation during orthostasis. Around 30-50% of FMS patients have small fiber pathology (SFP), characterized by reduced small intraepidermal nerve fiber density (IENFD). More recently, it has been observed that SFP also affects autonomic sympathetic fibers in the dermis, though the clinical significance of this remains unclear.

To evaluate the clinical and functional impact of autonomic denervation in fibromyalgia syndrome (FMS) by examining the role of small fiber pathology (SFP) in central sympathetic nervous system (SNS) hyperactivity and its contribution to symptoms of orthostatic intolerance.
A cohort of 43 fibromyalgia patients underwent cardiovascular reflex tests, including tilt testing, deep breathing, Valsalva maneuver, and HRV power spectral analysis. Patients were divided into two groups based on the presence or absence of SFP, and results were compared between these groups and with sex and age- matched healthy controls. We also explored the correlation between IENFD and central sympathetic activity.
FMS patients exhibited reduced HRV, SNS hyperactivity at rest, and diminished vagal activity. Impaired adaptation to orthostasis was noted, with 30% of patients experiencing transient orthostatic hypotension. All patients reported symptoms of orthostatic intolerance, which were more severe in those with SFP (p=0.0052). A linear correlation between IENFD and central SNS activity suggested that lower IENFD was associated with greater central sympathetic hyperactivity (p=0.0032, r2=0.1934). Seven patients met diagnostic criteria for postural orthostatic tachycardia syndrome (POTS), with higher prevalence among those with SFP (p=0.0398).
The study suggests that in FMS patients, central SNS hyperactivity is reflexively influenced by peripheral small fiber damage. This impaired autonomic regulation may contribute to chronic orthostatic intolerance symptoms in FMS, highlighting the role of autonomic denervation.
Authors/Disclosures
Pietro Falco, MD (Sapienza University of Rome)
PRESENTER 		Dr. Falco has nothing to disclose.
Eleonora Galosi (sapienza university) Eleonora Galosi has nothing to disclose.
Giuseppe Di Pietro Mr. Di Pietro has nothing to disclose.
Gianfranco De Stefano Mr. De Stefano has nothing to disclose.
Caterina Leone Caterina Leone has nothing to disclose.
Giulia Di Stefano (Sapienza University of Rome) Giulia Di Stefano has nothing to disclose.
Andrea Truini No disclosure on file