What is the best treatment approach for a patient with left trapezius spasm one month after C3-T1 (cervical spine 3 to thoracic spine 1) decompression surgery?

Treatment of Left Trapezius Spasm After C3-T1 Decompression

Initiate cyclobenzaprine 5 mg three times daily for 2-3 weeks combined with physical therapy focused on cervical range of motion exercises and ischemic compression techniques, as muscle spasm following cervical decompression is typically self-limited and responds to conservative management. 1

Immediate Pharmacologic Management

• Cyclobenzaprine is FDA-approved specifically for relief of muscle spasm associated with acute, painful musculoskeletal conditions and should be used for short periods (up to 2-3 weeks). 1
• Start with 5 mg three times daily rather than 10 mg to minimize drowsiness while maintaining efficacy, as clinical trials demonstrate statistically significant superiority of the 5 mg dose for pain relief and functional improvement. 1
• Cyclobenzaprine can be safely combined with NSAIDs or aspirin without significant drug interactions, though drowsiness may be more pronounced with combination therapy. 1
• The medication works by reducing basal electrical activity of the trapezius muscle, which directly addresses the pathophysiology of muscle spasm. 2

Physical Therapy Interventions

• Ischemic compression techniques applied directly to trapezius trigger points produce immediate reduction in muscle spasm, decreased basal electrical activity, and improved cervical range of motion. 2
• Ultrasound therapy can be used as an alternative modality, though ischemic compression demonstrates superior improvement in active cervical range of motion compared to ultrasound alone. 2
• Physical therapy should begin immediately rather than waiting, as post-operative rehabilitation starting 2 months after spinal decompression shows no additional benefit compared to advising patients to "keep active" with self-directed physical activities. 3

Critical Differential Diagnosis Considerations

Rule out C5 nerve palsy immediately, as this is the most common post-operative neural complication after cervical spine surgery and presents with deltoid/biceps weakness that may be confused with trapezius dysfunction. 4

• C5 nerve palsy occurs more frequently in males, after posterior cervical approaches, and with OPLL, and may present immediately or several days after surgery. 4
• If weakness is present rather than pure spasm, obtain urgent MRI to evaluate for residual compression at C4-5, as this changes management from conservative to potentially surgical. 4
• Parsonage-Turner syndrome (idiopathic brachial plexopathy) presents with severe neuropathic shoulder/neck pain followed by delayed neurological deficits involving the upper brachial plexus, typically days after pain onset. 4

Anatomical Considerations Specific to Your Case

• The trapezius muscle receives dual innervation: the descending (superior) portion is supplied by a single fine branch of the spinal accessory nerve, while the transverse and ascending portions receive innervation from both the spinal accessory nerve and cervical plexus branches. 5
• Your C3-T1 decompression may have caused traction injury or irritation to the cervical plexus branches (C3-C4) that contribute to trapezius innervation, explaining the spasm pattern. 5
• True trapezius palsy (weakness rather than spasm) from spinal accessory nerve injury would require nerve repair within 20 months or muscle transfer procedures, but this is unlikely given your presentation of spasm rather than paralysis. 6

Expected Timeline and Red Flags

• Muscle spasm associated with acute musculoskeletal conditions is generally of short duration, and symptoms should improve within 2-3 weeks with conservative management. 1
• If symptoms persist beyond 3 weeks or worsen, obtain flexion-extension cervical radiographs to rule out iatrogenic instability from the extensive decompression (C3-T1 is a long segment). 7
• Progressive weakness, new sensory deficits, or severe neuropathic pain (rather than muscular pain) warrant urgent re-evaluation with MRI to exclude residual compression or hematoma. 4

Common Pitfalls to Avoid

• Do not prescribe cyclobenzaprine beyond 2-3 weeks, as adequate evidence of effectiveness for prolonged use is not available and may delay recognition of underlying structural problems. 1
• Avoid attributing all shoulder/neck symptoms to "muscle spasm" without first ruling out C5 nerve palsy, as the latter requires evaluation for residual compression and has different management. 4
• Do not assume spasm is benign if it occurs in the context of extensive multilevel decompression (C3-T1), as this creates risk for iatrogenic instability that may require fusion if conservative management fails. 7