What are the main trigger points for shoulder injections in a patient with chronic musculoskeletal pain, including fibromyalgia?

Main Trigger Points for Shoulder Injections

For shoulder injections in patients with chronic musculoskeletal pain including fibromyalgia, target trigger points located in the upper trapezius muscle, which are the most commonly affected areas in the shoulder region and respond well to injection therapy. 1, 2

Anatomical Location of Shoulder Trigger Points

The primary trigger points for shoulder injections are found in:

• Upper trapezius muscle: This is the most frequently documented location for shoulder-related trigger points and is consistently identified in patients with myofascial pain syndrome 1, 2
• Taut bands within skeletal muscle: Trigger points manifest as discrete, focal, hyperirritable spots within these bands, producing both local and referred pain patterns 1
• Muscles maintaining body posture: The neck and shoulder girdle muscles are particularly susceptible to trigger point formation due to their postural stabilization role 1

Physical Examination Findings

When identifying trigger points for injection, look for these specific characteristics:

• Palpable hypersensitive nodule: A bundle of muscle fiber with harder than normal consistency that is tender to touch 1
• Local twitch response: Palpation of the trigger point elicits a visible or palpable contraction of the taut band 1
• Referred pain pattern: Pressure on the trigger point causes radiation of pain toward a predictable zone of reference, not just local tenderness 1

Critical Distinction: Trigger Points vs. Tender Points

Trigger points are NOT the same as tender points, despite common confusion:

• Trigger points: Occur in a restricted regional pattern, generate referred pain, contain taut bands, and are characteristic of myofascial pain syndrome 3
• Tender points: Occur in a widespread distribution throughout the body and are characteristic of fibromyalgia 3
• Overlap syndromes: Patients with fibromyalgia can simultaneously have myofascial trigger points requiring injection 2, 3

Special Considerations for Fibromyalgia Patients

Patients with both fibromyalgia and myofascial pain respond differently to trigger point injections compared to those with myofascial pain alone:

• Delayed response: Fibromyalgia patients experience significant but delayed pain relief following trigger point injection compared to patients without fibromyalgia 2
• Attenuated immediate benefit: Immediate post-injection improvement in pain intensity, pain threshold, and range of motion is significantly less in fibromyalgia patients 2
• Equivalent long-term benefit: Two weeks after injection, improvement in pain threshold and range of motion becomes comparable between fibromyalgia and non-fibromyalgia patients 2
• Increased post-injection soreness: Fibromyalgia patients experience more severe, earlier-onset, and longer-lasting post-injection soreness (distinct from myofascial pain) 2

Injection Technique Recommendations

When performing trigger point injections in the shoulder region:

• Use 0.5% lidocaine (xylocaine) as the standard injectate for trigger point deactivation 2
• Trigger point injection is one of the most effective modalities for inactivating trigger points and providing prompt symptom relief 1
• Combine injection therapy with a comprehensive exercise and rehabilitation program for optimal outcomes 3

Common Pitfall to Avoid

Do not confuse trigger point injections with corticosteroid injections for shoulder pathology - these are distinct interventions with different indications. Corticosteroid injections target joint spaces or bursae for inflammatory conditions 4, 5, while trigger point injections target discrete muscle nodules for myofascial pain 1. After any shoulder corticosteroid injection, avoid overhead pulley exercises as they can worsen shoulder pathology 5, 6.