What is the appropriate initial management for an acute pectoralis major muscle spasm?

Treatment of Pectoral Muscle Spasm

For acute pectoralis muscle spasm, initiate treatment with rest, ice application, NSAIDs (if no contraindications), and a short course (2-3 weeks maximum) of cyclobenzaprine as an adjunct to physical therapy. 1, 2

Initial Conservative Management (First-Line)

• Rest and activity modification are fundamental components of the conservative protocol 1
• Ice application should be used for acute symptom management 1
• NSAIDs (ibuprofen or acetaminophen) for pain control if no contraindications exist 1
• Cyclobenzaprine (muscle relaxant) is FDA-approved as an adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions, but should only be used for short periods (up to 2-3 weeks) 2

Physical Therapy Protocol

• Gentle stretching and mobilization should begin once acute pain subsides, focusing on restoring range of motion 3
• Progressive strengthening exercises should be introduced gradually, targeting the rotator cuff, periscapular muscles, and scapular stabilizers 1, 3
• Address biomechanical factors including scapular dyskinesis and posterior shoulder girdle weakness 3

Critical Assessment Points

Before proceeding with treatment, evaluate for:

• Intramuscular hematoma requiring aspiration if causing significant pain or functional limitation 1
• Compartment syndrome signs: severe pain disproportionate to examination, pain with passive stretch, paresthesias, pallor, or weakness 1
• Anticoagulation status if hematoma is present, as this significantly increases risk of complications 1

Refractory Cases (Second-Line)

If symptoms persist beyond 6-12 weeks despite conservative management:

• Botulinum toxin A injections are effective for trauma-induced myospasms secondary to α-γ dysfunction, with successful resolution reported in multiple case series 4, 5
• Initial lidocaine injection can be performed to observe treatment response before proceeding with botulinum toxin 4
• Most patients respond to 1-2 botulinum toxin sessions 5

Surgical Options (Third-Line)

For intractable spasms failing conservative and botulinum toxin therapy:

• Medial and lateral pectoral neurectomy provides dramatic improvement in symptoms with no significant musculoskeletal sequelae 6, 7
• This is particularly effective for post-traumatic or post-surgical myospasms 6, 7

Common Pitfalls to Avoid

• Do not use cyclobenzaprine beyond 2-3 weeks, as adequate evidence of effectiveness for prolonged use is not available 2
• Avoid overhead pulley exercises during acute phase, as they can worsen shoulder pathology 8
• Do not overlook hematoma formation, as meticulous hemostasis is critical and changes can complicate physical examination and imaging interpretation 1
• Ensure complete resolution of symptoms before returning to full activity 3