[Comparison of clinical characteristics of patients with riboflavin responsive lipid storage myopathy versus polymyositis].

OBJECTIVE

To compare the clinical characteristics of riboflavin responsive lipid storage myopathy (RR-LSM) versus polymyositis (PM).

METHODS

The clinical data were collected and analyzed for 26 RR-LSM and 15 PM patients from 2003 to 2011 at Peking University First Hospital .

RESULTS

The mean onset ages of RR-LSM and PM were (29 ± 10) and (43 ± 15) years while the durations before definite diagnosis were (8.2 ± 8.0) and (2.6 ± 3.7) years respectively. There were significant inter-group differences in onset age (P = 0.001) and duration before definite diagnosis (P = 0.003). No significant inter-group difference existed in the frequency of limb weakness, dysphagia, neck weakness, dyspnea or myalgia. Dysmasesia occurred in 65.38% of RR-LSM and 26.67% of PM patients and significant inter-group difference existed (P = 0.017). All RR-LSM patients had exercise intolerance with a fluctuating course. Both groups had extra-muscular symptoms and it was more obvious in PM. Mean creatine kinase (CK) level was (1475 ± 1796) U/L in RR-LSM and (4062 ± 3448) U/L in PM patients with significant inter-group difference (P = 0.017).

CONCLUSION

Comparing with PM patients, RR-LSM patients tend to have an earlier onset, a longer diagnosis delay time, fluctuating weakness, a higher frequency of dysmasesia. But there are fewer extra-muscular symptoms and a smaller elevation of CK level.