Trigger Points in the Deltoid Muscle
Yes, trigger points can and do occur in the deltoid muscle, and they are clinically relevant in patients with chronic shoulder pain, including those with fibromyalgia.
Prevalence and Clinical Significance
The deltoid muscle commonly harbors myofascial trigger points (MTrPs) in patients with chronic shoulder pain:
- Latent trigger points were found in the anterior deltoid in 38% of patients with chronic non-traumatic shoulder pain, making it one of the most frequently affected muscles 1
- The deltoid is comprised of three distinct portions (anterior/clavicular, middle/acromial, and posterior/spinal), each of which can develop trigger points independently 2
- All patients (100%) in one observational study of chronic shoulder pain had at least one muscle with trigger points, with a median of 6 muscles containing active MTrPs per patient 1
Trigger Points in Fibromyalgia Context
For patients with fibromyalgia specifically, the relationship between trigger points and symptoms is important to understand:
- Fibromyalgia involves central sensitization with dysfunction of neuro-circuits that process nociceptive stimuli, manifesting predominantly as musculoskeletal pain 3
- The pathogenesis includes inflammatory, immune, endocrine, genetic, and psychosocial factors beyond just peripheral pain generators 3
- Myofascial trigger points can produce a symptom complex that overlaps with other shoulder pathologies like subacromial impingement or rotator cuff tendinopathy 4
Clinical Assessment Approach
When evaluating deltoid trigger points in a patient with chronic pain:
- Palpate all three portions of the deltoid systematically (anterior, middle, posterior) for taut bands and localized tenderness 1
- Distinguish between active trigger points (spontaneously painful) and latent trigger points (painful only on palpation) 1
- The number of muscles with active MTrPs shows only moderate correlation with functional disability scores, so trigger point presence doesn't always predict symptom severity 1
Treatment Considerations
Physical therapy modalities targeting trigger point inactivation can be considered as part of a comprehensive treatment plan:
- Manual techniques, stretching, and mobilization can address MTrPs in shoulder muscles 4
- For fibromyalgia patients specifically, treatment requires simultaneous application of pharmacological and nonpharmacological approaches, as either alone is typically unsuccessful 5
- Patient education about the condition is the essential first step before implementing other interventions 5
Important Caveats
- The deltoid can be affected by various other pathologies including enthesitis, calcific tendinitis, myositis, infection, tumors, and chronic avulsion injury—trigger points are just one potential source of pain 2
- Deltoid contracture from repeated intramuscular injections can cause progressive abduction deformity and scapular winging 2
- Axillary nerve injury can cause deltoid dysfunction and must be excluded, as it has disastrous functional consequences 2