FMS is the most common rheumatologic disease after osteoarthritis . There is not an effective treatment strategy for all patients because of uncertain etiopathogenesis. FMS affects quality of life and causes severe chronic pain, emotional disturbances including anxiety, depression.
According to 1990 ACR classification criteria, all FMS patients should have pain bilaterally in the neck-shoulder region and in the lumbosacral-hip region, with radiation of pain to the extremities. In addition, all the pain should be perceived as more severe in one-half of the body . In 2002 Crofford and colleagues criticized to ACR classification crtiteria because of focusing the pain and ignoring fatigue, cognitive disorders, sleep disturbance and psychological disorders. They explained that neuroendocrine axis anomalies may be the cause of painless symptoms in patients with FMS . Wilke et al., was noted low specificity (% 81) in the ACR classification criteria . In our study, nonrestorative sleep, fatigue, morning stiffness was the most common painless symptoms. We found that particularly nonrestorative sleep, morning stiffness and paresthetic complaint were correlated with decreased quality of life and depressed mood. Therefore, pain is important for the diagnosis of FMS but for assessing quality of life we should attach importance to painless symptoms. The cause of these symptoms is still unknown.
We investigated the subgroups of FMS patients accordingly to the study of Muller et al., in 2007 . But we did not find a significant difference between subgroups and grip strength. Howewer, SF-36 total scores was higher in non-depressive group. At the same time nonrestorative sleep and morning stiffness was a less common presenting symptom in non-depressive patients. This also showed that nondepressive patients had better life quality compared with depressive patients. For appropriate treatment program of FMS patients, morning stiffness and sleep patterns should be questioned.
Evaluation of hand grip strength between FMS patients and normal healthy subjects was the main aim of this study. Measuring maximal voluntary isometric muscle contraction is the oldest method to assess muscle strength. Jacobsen et al., found that measurement of isometric muscle strength is equivalent with isokinetic muscle strength in patients with FMS . In present study, muscle strength was evaluated with isometric measurement. FMS patients were likely to reduce isometric muscular strength compared with control group. In a similar study, Maquet et al., had found statistically significant difference between patient group and control group for hand grip strength (20 ± 9 kg/force, 27 ± 7 kg/force, p<0.01). In this study, isokinetic muscle strength were measured in FMS group and % 56 lower results were obtained . Sahin et al., had found decreased hand grip strength in FMS group and the results were correlated with pulmonary muscles strength . Mannerkorpi et al., had evaluated physical performance in FMS and healthy controls with physical performance tests. As a result, patients with FMS had reduced at physical performance capabilities .
All this studies indicated that hand grip strength is reduced in patients with FMS and this reduction is influenced by neither the intensity of pain nor the motivation of patients. Also many studies have shown that patients with FMS have impaired physical performance and mental health compared with other painful disease [18,19]. We have found significantly less physical functioning and mental health SF-36 scores in FMS. This reduction should be secondary to deterioration of physical condition or reduction to physical performance. Low maximum voluntary muscle strength in patients with FMS are not diagnostic. It can be seen together myofascial pain syndrome, rheumatoid arthritis and other rheumatic conditions.
Hand grip strength measurement should be used for assessment of quality of life with FMS rather than diagnosis crtiteria. Indeed, we did not find any correlation with tender points, FIQ scores and BDI scores with grip strength but SF36 total scores was significantly correlated with decreased grip strength.
FMS patients often have many disability in activities of daily living. Psychological factors may play an important role on this situation. In many studies was shown significant deterioriation in quality of life and mental health in patients with FMS [20,21]. This situation impacted on their social and business lives, and significant economic burden is due to loss of labor in addition health care costs . Verbunt et al., suggested that disability of FMS patients was appeared in clinic like deteroriation of mental health. At the same time, patients with FMS were significantly higher rates of psychological stress compared with complex regional pain syndrome and chronic low back pain. Effect on the quality of life is very high compared to other diseases .
Hoffmann et al., were found significantly lower mental and physical SF-36 scores in FMS patients compared to other diseases . We have achieved similar results with our study. FMS patients had lower mental health, physical health and general health SF-36 scores compared with control group. As noted other studies, FMS is characterized low mental health scores.
Being a cross-sectional study that consists of a small population size are some of the important limitations of our study. Still the results are worth discussing. Also, ACR 2010 criteria for FMS could be more valuable for this study. But we had designed this study between 2009 and 2011.
As a result, decreasing hand grip strength was influenced by neither the intensity of pain nor the motivation of patients. Consequently muscle weakness can be linked to peripheral and central mechanisms . Several studies found no correlation in muscle histopathologically and muscle metabolism in FMS etiopathogenesis [24,25]. Muscle weakness in FMS patients can be responsible for blood flow changes in the central nervous system, physical inactivity due to the pain and physical decondition of muscles . We suggested that hand grip strength can be used for as a marker of quality of life not for diagnostic evaluation.