What is the treatment approach for myofascial pain syndrome secondary to shoulder dyskinesia?

Myofascial Pain Syndrome Secondary to Shoulder Dyskinesia: Comprehensive Analysis

Overview and Pathophysiology

Myofascial pain syndrome (MPS) secondary to shoulder dyskinesia results from abnormal scapular movement patterns that create sustained muscle contraction and trigger point formation in the periscapular and rotator cuff musculature, perpetuating a cycle of pain, altered biomechanics, and functional impairment. 1

Pathophysiologic Mechanism

The pathophysiology involves a cascade of biomechanical and neuromuscular dysfunction:

• Primary mechanism: Shoulder dyskinesia (abnormal scapular motion) creates sustained or repetitive muscle contraction in the scapular stabilizers, rotator cuff, and periscapular muscles, leading to trigger point formation within taut bands of skeletal muscle fibers 1, 2
• Trigger point characteristics: These are discrete, hyperirritable spots within taut bands that produce localized pain when palpated and can refer pain in characteristic patterns away from the trigger point site 1
• Perpetuating cycle: The dyskinesia causes muscle overuse or underuse patterns, which maintain trigger point activity; the trigger points then further impair normal scapulohumeral rhythm, worsening the dyskinesia 3
• Secondary complications: Chronic dyskinesia can lead to rotator cuff impingement, adhesive capsulitis, bursitis/tendonitis, and altered cervical-shoulder alignment 4

Key Anatomical Targets

The muscles most commonly affected in shoulder dyskinesia-related MPS include:

• Scapular stabilizers: Trapezius (upper, middle, lower), levator scapulae, rhomboids, serratus anterior 5
• Rotator cuff: Supraspinatus, infraspinatus, subscapularis, teres minor 4
• Posterior shoulder girdle: Posterior deltoid, teres major 4

Differential Diagnoses

Primary Shoulder Pathologies

Adhesive capsulitis (frozen shoulder): Distinguished by progressive loss of both active and passive range of motion in all planes, particularly external rotation and abduction, with a characteristic capsular pattern; MPS typically maintains passive ROM even when active ROM is limited 4

Rotator cuff pathology:

• Rotator cuff tear: Presents with weakness in specific planes (external rotation for infraspinatus/teres minor, internal rotation for subscapularis), positive drop arm test, and often night pain; imaging confirms diagnosis 4
• Rotator cuff tendinopathy/impingement: Painful arc between 60-120 degrees of abduction, positive Neer and Hawkins-Kennedy signs, but trigger points are secondary rather than primary pathology 4

Glenohumeral instability: History of subluxation or dislocation, positive apprehension and relocation tests, often in younger patients with trauma history 4

Neurologic Conditions

Cervical radiculopathy: Dermatomal pain distribution, sensory changes, reflex abnormalities, positive Spurling's test; pain radiates distally following nerve root distribution rather than myofascial referral patterns 4

Brachial plexopathy: Weakness in multiple muscle groups supplied by specific plexus divisions, sensory loss in non-dermatomal patterns, often with history of trauma or traction injury 4

Complex regional pain syndrome (CRPS): Disproportionate pain with autonomic changes (temperature, color, sweating abnormalities), edema, and trophic changes; may develop after shoulder trauma or surgery 4

Inflammatory and Systemic Conditions

Subacromial/subdeltoid bursitis: Localized tenderness over bursa, pain with overhead activities, but lacks discrete trigger points with referral patterns 4

Heterotopic ossification: Develops weeks to months after trauma or neurologic injury, progressive loss of ROM with firm end-feel, confirmed by imaging 4

Polymyalgia rheumatica: Bilateral shoulder and hip girdle pain and stiffness, elevated inflammatory markers (ESR, CRP), age >50 years, dramatic response to low-dose corticosteroids 1

Fibromyalgia vs. MPS

Critical distinction: Fibromyalgia presents with widespread, diffuse pain affecting multiple body regions with tender points (not trigger points) that do not produce referral patterns; MPS involves localized, regional pain with discrete trigger points that reproduce the patient's pain and refer in predictable patterns 1

Evidence-Based Physical Therapy Treatment Protocols

First-Line Conservative Management

Manual physical therapy techniques should be the cornerstone of initial treatment, focusing on trigger point resolution, muscle lengthening, and fascial restriction release. 6

Manual Therapy Techniques

Ischemic compression therapy: Apply sustained pressure (30-90 seconds) directly to trigger points until pain decreases, followed by passive stretching of the affected muscle; this technique has demonstrated efficacy in reducing trigger point sensitivity 7

Myofascial release: Use sustained, gentle pressure along fascial planes to release connective tissue restrictions and reduce trigger point activity; this is often necessary before patients can participate effectively in exercise programs 6, 7

Spray and stretch technique: Apply vapocoolant spray in parallel strokes over the muscle while passively stretching it to full length; this reduces trigger point activity and improves ROM 7

Scapular Stabilization Program

The core of treating shoulder dyskinesia-related MPS is a progressive strengthening program targeting scapular stabilizers and rotator cuff muscles, combined with postural retraining. 4

Specific Exercise Protocol

Phase 1 - Scapular awareness and control (Weeks 1-2):

• Scapular setting exercises: Retraction, depression, and upward rotation in pain-free ranges 4
• Postural correction exercises focusing on thoracic extension and cervical neutral positioning 4
• Gentle ROM exercises for shoulder external rotation and abduction to prevent adhesive capsulitis 4

Phase 2 - Strengthening (Weeks 3-6):

• Low-resistance, high-repetition exercises for scapular stabilizers: rows, scapular push-ups, wall slides 6
• Rotator cuff strengthening emphasizing external rotation and posterior cuff (infraspinatus, teres minor) 4
• Progressive resistance training for rhomboids, middle/lower trapezius, and serratus anterior 4

Phase 3 - Functional integration (Weeks 7-12):

• Sport or activity-specific exercises incorporating proper scapulohumeral rhythm 4
• Proprioceptive and balance training for upper extremity 4
• Ergonomic modifications and activity pacing strategies 3

Physical Modalities

Transcutaneous electrical nerve stimulation (TENS): Apply as part of multimodal pain management; demonstrated efficacy in reducing myofascial pain 8, 7

Heat and cold therapy: Use heat before stretching to improve tissue elasticity; apply cold after exercise to reduce inflammation and pain 4, 6

Avoid overhead pulleys: These encourage uncontrolled abduction and can exacerbate shoulder pain and dyskinesia 4

Breathing and Neuromuscular Re-education

Diaphragmatic breathing exercises: Incorporate to reduce accessory respiratory muscle (upper trapezius, scalenes) overactivity that perpetuates trigger points 4

Scapular proprioceptive training: Use tactile cueing and mirror feedback to retrain normal scapular positioning and movement patterns 4

Pharmacological Management

First-Line Medications

NSAIDs: Provide symptomatic relief; diclofenac patches have demonstrated significant benefit for myofascial pain and can be applied directly over affected areas 6, 7

Topical agents: Lidocaine patches and topical diclofenac offer localized pain relief without systemic side effects 6, 7

Muscle relaxants: Thiocolchicoside has shown efficacy for myofascial pain; use for documented muscle spasm 5, 7

Second-Line Options

Tricyclic antidepressants or SNRIs: Consider for persistent pain, particularly when sleep disturbance or central sensitization is present 6

Anticonvulsants (gabapentin, pregabalin): Reserve for refractory cases with neuropathic pain features 6

Interventional Procedures

Trigger Point Injections

Trigger point injections should only be considered after 3+ months of failed conservative treatment and must be part of a comprehensive multimodal program, not standalone therapy. 5

Protocol:

• Identify trigger points by palpation in trapezius, levator scapulae, rhomboids, and subscapularis 5
• Limit to 4 sets of injections maximum to assess therapeutic response 5
• Continue concurrent physical therapy as injections alone are insufficient 5
• Use local anesthetic (lidocaine) or dry needling; both have demonstrated efficacy 7, 3

Corticosteroid Injections

Intra-articular triamcinolone injections: Consider for concomitant adhesive capsulitis or glenohumeral joint pathology; these have shown significant pain reduction and ROM improvement 4

Subacromial injections: Use when impingement syndrome coexists with MPS 4

Botulinum Toxin

OnabotulinumtoxinA injections: Supported by randomized controlled trials for persistent myofascial pain; provides 8-12 weeks of relief when other treatments fail 8, 9

Adjunctive Therapies

Behavioral Interventions

Cognitive behavioral therapy: May benefit patients with chronic pain, addressing pain catastrophizing and maladaptive coping strategies 6

Relaxation techniques and breathing exercises: Reduce muscle tension and autonomic arousal that perpetuate trigger points 6

Patient education: Provide information on posture, ergonomics, activity modification, and self-management strategies 3

Alternative Modalities

Acupuncture: Can be incorporated as part of multimodal treatment; mechanism may overlap with trigger point dry needling 9

Kinesiology taping: May provide proprioceptive feedback and support for scapular positioning 1

Low-level laser therapy and extracorporeal shockwave therapy: Emerging evidence supports use for refractory cases 1

Treatment Algorithm

Step 1 (Weeks 0-4): Manual physical therapy (myofascial release, ischemic compression, spray and stretch) + scapular stabilization exercises Phase 1 + NSAIDs or topical analgesics + patient education on posture and ergonomics 6, 7

Step 2 (Weeks 4-8): Continue manual therapy + progress to strengthening exercises Phase 2 + add TENS or heat/cold modalities + consider muscle relaxants if spasm persists 6, 7

Step 3 (Weeks 8-12): Functional integration exercises Phase 3 + continue strengthening + add behavioral interventions if needed + reassess for underlying perpetuating factors 3

Step 4 (After 12+ weeks if refractory): Consider trigger point injections (maximum 4 sets) OR botulinum toxin injections + continue all conservative measures + evaluate for surgical causes of dyskinesia (labral tears, instability) 5, 8

Critical Pitfalls to Avoid

Treating trigger points without addressing underlying dyskinesia: The most important strategy is treating the underlying scapular dyskinesia; trigger points cannot be permanently inactivated if the biomechanical cause persists 3

Using overhead pulleys: These encourage uncontrolled abduction and have the highest incidence of developing hemiplegic shoulder pain; avoid this modality 4

Relying on injections alone: Trigger point injections must be part of multimodal treatment with concurrent physical therapy; standalone injections are insufficient and not supported by guidelines 5

Neglecting perpetuating factors: Address postural abnormalities, ergonomic issues, cervical pathology, and behavioral factors that maintain trigger point activity 3

Passive modalities without active exercise: Active, supervised exercise programs are superior to passive interventions like massage or ultrasound alone 6

Delaying treatment: MPS becomes increasingly refractory as it enters the chronic stage; early intervention with conservative measures yields better outcomes 1