TheCaseforComorbidMyofascialPain—AQualitativeReview

Myofascial pain syndrome (MPS) is one of the most common pain conditions seen in both community settings and specialized pain clinics. While it often occurs in otherwise healthy people, growing evidence suggests that MPS may be even more prevalent in individuals with other medical conditions. This qualitative review examines the evidence for comorbid myofascial pain across a wide spectrum of diseases including cancer, osteoarthritis, neurological conditions, primary headaches, infectious and inflammatory diseases, and mental health disorders. The authors argue that recognizing comorbid MPS is clinically important because it can significantly contribute to patients' overall pain burden and may respond to targeted treatment.

The authors conducted a literature search of PubMed between March 20-31, 2020, using combinations of keywords related to MPS (myofascial, myalgia, muscle pain, torticollis) and various potential comorbid conditions. They searched for studies related to primary headaches, oncologic diseases, arthritis, infectious diseases, neurological diseases and chronic pain conditions, and mental health/insomnia. They excluded non-English manuscripts, reviews, case reports, and animal studies. The resulting evidence was synthesized qualitatively across six major categories of comorbid conditions, with the authors extracting prevalence data and clinical observations from each study.

In cancer patients, MPS contributes substantially to pain burden. Among head and neck cancer patients after treatment, 52% had severe pain, of which 13% was attributed to MPS. In breast cancer patients undergoing surgery, 44.8% developed MPS, making it the most common cause of pain in this cohort. Among patients with advanced cancer receiving palliative care, 65% reported pain, of which 45% were diagnosed with MPS using the Rivers criteria and 90% using the Simons criteria.

In osteoarthritis, multiple studies found higher numbers of trigger points in patients compared to controls. In patients awaiting total knee arthroplasty, all 25 patients had MPS of the muscles surrounding the knee. In a cross-sectional study of 114 patients with knee osteoarthritis, active myofascial trigger points were detected in 75% of participants' vastus medialis muscles and 65% of their vastus lateralis muscles.

In neurological conditions, active myofascial trigger points were documented in up to 50% of examined infraspinatus muscles in 50 post-stroke individuals with shoulder pain. In central post-stroke pain, MPS was observed in 67.5% of 40 patients. In complex regional pain syndrome (CRPS), 56% of 134 individuals had a myofascial component to their pain, and in another study of 41 CRPS patients, myofascial dysfunction was found in 61%. In lumbosacral radicular pain, gluteal myofascial trigger points were present in 76% of 271 patients versus only 1.9% of 152 healthy controls.

In primary headaches, 55.4% of 296 patients evaluated for head and neck pain exhibited trigger points attributable to their pain. Among 50 migraine sufferers studied by Tfelt-Hansen et al., all but two had tenderness in head and neck muscles, and 73% demonstrated referred pain characteristics. Patients with tension-type headaches showed increased incidence of myofascial trigger points in neck musculature, with referred pain reproducing headache patterns.

In mental health conditions, Croatian war veterans with PTSD and depression showed MPS of the upper body in 58% of 101 patients. In a prospective study of 7895 participants from the Taiwan National Health Insurance Research Database, individuals with insomnia had a twofold risk of developing MPS over 10 years of follow-up.

This review establishes that comorbid MPS is not merely an epiphenomenon but a clinically significant contributor to pain across numerous medical conditions. For patients, this means that persistent pain in conditions like cancer, arthritis, or after stroke may have a treatable muscular component that is often overlooked. For clinicians, the key message is that diagnosing a primary condition does not end the diagnostic process—actively seeking comorbid MPS may reveal additional sources of pain that respond to targeted therapies like trigger point injections, dry needling, or manual therapy.

The authors emphasize several important clinical implications. First, treating the myofascial component can significantly improve symptomatic burden without necessarily escalating treatment for the primary condition. Second, comorbid MPS may be more resistant to treatment than primary MPS because the underlying medical condition serves as a perpetuating factor. Third, in pain clinic settings, MPS is extraordinarily common—the authors previously reported that 82% of patients at a secondary pain clinic were diagnosed with MPS, many with other comorbid pain conditions.

Finally, mental health conditions, particularly anxiety, depression, PTSD, and insomnia, appear to predispose individuals to developing MPS, suggesting these should be evaluated and addressed in MPS patients.