Quantitative analysis of nailfold capillary morphology in patients with fibromyalgia

Background/Aims: Nailfold capillaroscopy (NFC) has been used to examine morphological and functional microcirculation changes in connective tissue diseases. It has been demonstrated that NFC patterns reflect abnormal microvascular dynamics, which may play a role in fibromyalgia (FM) syndrome. The aim of this study was to determine NFC patterns in FM, and their association with clinical features of FM. Methods: A total of 67 patients with FM, and 30 age- and sex-matched healthy controls, were included. Nailfold capillary patterns were quantitatively analyzed using computerized NFC. The parameters of interest were as follows: number of capillaries within the central 3 mm, deletion score, apical limb width, capillary width, and capillary dimension. Capillary dimension was determined by calculating the number of capillaries using the Adobe Photoshop version 7.0. Results: FM patients had a lower number of capillaries and higher deletion scores on NFC compared to healthy controls ($17.3{\pm}1.7$ vs. $21.8{\pm}2.9$, p < 0.05; $2.2{\pm}0.9$ vs. $0.7{\pm}0.6$, p < 0.05, respectively). Both apical limb width (${\mu}m$) and capillary width (${\mu}m$) were significantly decreased in FM patients ($1.1{\pm}0.2$ vs. $3.7{\pm}0.6$; $5.4{\pm}0.5$ vs. $7.5{\pm}1.4$, respectively), indicating that FM patients have abnormally decreased digital capillary diameter and density. Interestingly, there was no difference in capillary dimension between the two groups, suggesting that the length or tortuosity of capillaries in FM patients is increased to compensate for diminished microcirculation. Conclusions: FM patients had altered capillary density and diameter in the digits. Diminished microcirculation on NFC may alter capillary density and increase tortuosity.