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moderate levels of other symptoms or moderate pain and high levels of other symp-
toms are present. Symptoms must be steadily present for at least 3 months and no
disorder should explain the pain, hence, FMS remained an exclusion diagnosis. In
2011, the diagnostic criteria were revised to include 19 specifi c pain locations, and 6
self-administered symptoms questionnaires including sleep diffi culty, fatigue, head-
ache, depression, abdominal pain, and poor cognitive status [ 6 ].
The prevalence of FMS is remarkably high; it affects 2–5 % of the general popu-
lation, mainly women—the men to women ratio being 1–9—and mostly people in
their 40s, although cases among teenagers are increasing [ 7 – 11 ]. However, on using
the 2010 classifi cation, with a higher weight of somatic symptoms, the prevalence
of FMS was reported to be even higher, particularly in men [ 10 ]. Not surprisingly,
FMS is a costly condition, with an estimated cost of 10,000 Euros per patient per
year [ 12 , 13 ].
Some authors believe that FMS is a primary psychogenic disorder, as depression
is commonly found in patients with FMS [ 14 ]. In their study, Hauser et al. [ 15 ]
noted that psychological trauma caused by sexual abuse in childhood, as well as
complex personalities, may both be risk factors for the development of FMS; fur-
thermore, depression and posttraumatic stress disorder (PTSD) were depicted to
have a negative impact on the outcome of FMS. In addition to psychosocial causes,
genetic studies reported an association between FMS and some single nucleotide
polymorphisms of genes encoding proteins involved in the neural synapse [ 16 ].
Other research work assessing genome-wide analysis and epigenetic modifi cations
in FMS are currently under study [ 17 ].
In view of such a wide range of FMS symptoms , a multidisciplinary treatment
approach has been recommended, including pharmacology, psychology, sport and
physical medicine, nutrition, and alternative therapies such as acupuncture and
balneotherapy.
Challenges in the Assessment of Fibromyalgia
Fibromyalgia is one of the most common forms of chronic pain disorders. Pain in
FMS patients has been attributed to aberrant nociception due to altered central or
peripheral control and a positive feedback mechanism that amplifi es the sensation
of pain [ 16 ]. Patients with FMS show signs of hyperalgesia and allodynia; often,
simple things such as shopping or house chores cause an intense pain. Alterations in
brain levels of substances such as growth hormone—which is secreted during the
deeper stages of rapid eye movement (REM) sleep—are below normal limits.
Serotonin, melatonin, substance P, and nerve growth factor may all be involved in
sleep quality and clinical symptoms observed in FMS [ 18 ]. Plasma cytokines also
may be associated with increased sensitivity to pain, fatigue, depression, and poor
quality sleep [ 19 ]. However, all these “objective measures” are not specifi c to FMS
and show high interindividual variability.
L. Carmona et al.