Prevalence of Myofascial Pain Syndrome and Efficacy of Trigger Point Injection in Patients with Incurable Cancer: A Multicenter, Prospective Observational Study (MyCar Study).

OBJECTIVE: Myofascial pain syndrome (MPS) is caused by overload or disuse of skeletal muscles. Patients with cancer are often forced to restrict their movement or posture for several reasons. The study was conducted to investigate the prevalence and risks of MPS in patients with incurable cancer. The efficacy of trigger point injection (TPI) was also explored. METHODS: This was a multicenter, prospective observational study. Patients with incurable cancer who started receiving specialist palliative care were enrolled. We investigated the MPS in this population and accompanying risk factors for restricting body movement. Pre- and post-TPI pain was also evaluated using a Numerical Rating Scale (NRS) in patients who received TPI. The primary outcome was the prevalence of MPS. RESULTS: A total of 101 patients were enrolled from five institutions in Japan. Most of the patients (n = 94, 93.1%) had distant metastases, and half of the patients (50, 49.5%) received anticancer treatment. Thirty-nine (38.6%) patients had MPS lesions at 83 sites. Multivariate analysis revealed that the significant risk factor for MPS was poor Performance Status (PS) (odds ratio 3.26; 95% confidence interval [CI] 1.18-9.02, P = .023). We performed TPI for 40 out of 83 MPS lesions. Mean NRS for MPS before TPI was 7.95, which improved to 4.30 after TPI (P < .001). CONCLUSIONS: MPS was common in patients with incurable cancer and the risk factor identified in this study was poor performance status. TPI could be a treatment option.

Prevalence of myofascial pain syndrome in patients with incurable cancer.

BACKGROUND: Myofascial pain syndrome (MPS) is a condition that involves skeletal muscles. It is caused by overload or disuse of muscles and is characterized by extreme tenderness in the muscles with taut bands. Treatment for MPS is different from that for cancer-related pain. Cancer patients have many factors that cause restriction of body movement and posture. Although cancer patients appear to demonstrate risk factors for MPS, its prevalence has not been reported in patients with incurable cancer. This study was conducted to investigate the prevalence of MPS in patients with incurable cancer. METHODS: A retrospective chart review. The data for patients with incurable cancer who received palliative care at our department between September 2015 and March 2016 were investigated. We examined the prevalence of MPS, which was diagnosed on the basis of the Rivers criteria (RC) and Simons criteria (SC). We also examined the following factors associated with MPS: performance status (PS), use of medical devices, and primary cancer sites. The primary outcome was the prevalence of MPS based on RC. Secondary outcomes included the prevalence of MPS based on SC and the relationship between MPS and either PS or medical devices. RESULTS: Thirty-four patients with incurable cancer were identified. MPS based on RC or SC was detected in 10 (29%) and 20 (59%) patients, respectively. Twenty-two of 34 patients who complained of pain, 10 (45%) had MPS based on RC and 20 (90%) had MPS based on SC. Age and central venous port were risk factors for MPS by multivariate analysis. CONCLUSION: A very high prevalence of MPS was detected in our study population. MPS should be considered when patients with incurable cancer complain of pain.