Background/Purpose:

Prevailing linear-reductionist medical model seems unable to explain complex diseases like fibromyalgia (FM) and similar maladies. As consequence of this divorce, some physicians disparage the fibromyalgia concept. Paradigms derived from the new complexity theory may provide a coherent framework for these elusive illnesses. Along these lines is the proposal that FM represents a degradation of our main complex adaptive system (the autonomic nervous system), in a failed effort to adjust to a hostile environment (Semin Arthritis Rheum 2008;37:260).

Resilient complex systems have fractal structures (fractal is defined as an object or quantity that displays self-similarity at different scales). Fractality loss would signal degradation of a given system. Heart rate variability (HRV) fractal scaling index (alpha) is a novel non-linear method to assess autonomic nervous system resilience: high vagal influence produces less auto-correlated behavior (alpha values below 1.0) while increased sympathetic activity produces more auto-correlated and stiffer behavior (alpha greater than 1.0). Alpha values close to 1.0 indicate resilient fractal-like behavior (Open Cardiovasc Med J 2009;3:110).

The objective of this study was to estimate the HRV fractal scaling index in FM patients, and to correlate this scaling index with clinical symptoms.

Methods:

We studied 30 women with FM (1990 ACR criteria) that were free from any medication that may affect the autonomic nervous system. Thirty age – matched healthy women served as controls.  HRV was measured during 24 hrs with a Meigaoyi DSM-3 Holter monitor, while subjects were doing their routine activities. The fractal scaling index was estimated with the detrended fluctuation analysis method using custom computer programs which were previously validated. The scaling index was estimated in short-term scales or alpha 1 (4 to 11 heartbeats) and long-term scales or alpha 2 (greater than 11 heartbeats). Mean values between groups were compared with Student t test. Correlations between alpha indexes and symptoms scales were calculated with Pearson´s or Spearman´s correlations.

Results:

Demographic features and main results are shown in the table. The short-term fractal scaling index (alpha1) was higher in FM patients when compared to controls (1.22 +/-0.10 vs. 1.16 +/- 0.10 p =0.035). There was a positive correlation of fractal scaling index alpha 1 with total FIQ score (Rho=0.322, p=0.012).

Conclusion:

The short-term HRV fractal scaling index is altered in FM patients with values indicating stiffer autonomic behavior. This fractal index correlated with total FIQ score.  This tangible non-linear finding supports the notion that FM represents a degradation of our main complex adaptive system, namely the autonomic nervous system.

 

	Group
	FM n =30		Controls n = 30
	Mean	Standard Deviation	Mean	Standard Deviation	P
Age	31	8	31	8	0.856 NS
BMI	23.8	4.4	24.4	3.2	0.550 NS
FIQ score	63.24	16.38	10.30	10.05	<0.0001
Fractal scaling index alpha 1 Fractal scaling index alpha 2	1.22 0.93	0.10 0.04	1.16 0.95	0.10 0.05	0.035 0.143

---

« Back to 2013 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/autonomic-nervous-system-decomplexification-in-fibromyalgia-a-proof-of-concept-study-looking-at-the-fractality-of-heart-rhythms/