Table 2.

Differences between fibromyalgia syndrome and small fiber neuropathy.

Parameter	FMS	SFN	References
Age at onset (median, range)	35 (4–65)	47 (12–67)	31
Pain localization	Proximal, generalized	Distal, feet	31
Accompanying symptoms	IBS, sleep disturbance	IGT, numbness	31
Pattern of small fiber loss	Generalized	Length-dependent	31
QST	Mild deficits in temperature detection	Strong deficits in temperature detection	40
Activity-induced slowing (MN)	Increased	Regular	52
Gene expression in keratinocytes	Not different from controls	Inflammatory genes upregulated	33

FMS, fibromyalgia syndrome; IBS, irritable bowel syndrome; IGT, impaired glucose tolerance; MN, microneurography; QST, quantitative sensory testing; SFN, small fiber neuropathy.