UltrasoundImagingandGuidanceforCervicalMyofascialPain:ANarrativeReview

Cervical myofascial pain syndrome (MPS) is one of the most common conditions seen by musculoskeletal physicians, accounting for more than 90% of chronic non-specific neck pain cases. The hallmark of MPS is the myofascial trigger point (MTrP), a palpable hard nodule within a taut band of skeletal muscle that produces local and referred pain upon palpation. Currently, diagnosis relies heavily on manual examination, which has high variability between operators. This has led to growing interest in ultrasound (US) imaging as a tool to better identify MTrPs and guide interventions.

However, cervical MPS is clinically complex, involving not just muscle trigger points but also fascial structures and neural elements that can generate or perpetuate pain. Understanding this complexity is essential for effective treatment.

The authors conducted a narrative review of the scientific literature on ultrasound assessment and ultrasound-guided interventions for cervical myofascial pain. Their approach was organized in three phases: first, reviewing the anatomical, histological, biochemical, and sonographic features of MTrPs; second, expanding to pain generators beyond MTrPs, including fascial and neural structures in the cervical region; and third, proposing a practical "pain generator-based approach" for ultrasound-guided procedures. They described sonographic techniques for identifying MTrPs, peripheral nerves (spinal accessory nerve and dorsal scapular nerve), and fascial structures, along with corresponding interventional techniques including trigger point injection/dry needling, interfascial plane blocks, and fascial hydro-dissection.

The typical sonographic appearance of an MTrP is a focal hypoechoic area with heterogeneous internal texture, which may appear spherical, elliptical, or band-like. The authors noted that Taheri et al. reported a sensitivity of 91% and specificity of 75% for US imaging to identify MTrPs within the upper fibers of the trapezius. Da Silva et al. found 100% agreement for intrarater reliability and 90% agreement for interrater reliability for gray-scale assessment of MTrPs in the upper trapezius. Beyond MTrPs, the review identified several other pain generators: the spinal accessory nerve and dorsal scapular nerve can become entrapped due to muscle spasm or poor posture, leading to neuropathic pain; superficial and deep fasciae contain rich neural networks and can develop densification with impaired gliding; and cutaneous branches of the dorsal rami of spinal nerves can be compressed or entrapped, particularly where they pierce muscular and fascial layers.

For interventions, the authors described that low-quality evidence suggests superior short-term effects of MTrP injections with local anesthetic compared to dry needling for decreasing cervical muscle pain. They proposed combining dry needling with anesthetic injection for synergistic effects—mechanical disruption plus pharmacological blockade of peripheral sensitization. For interfascial plane blocks, high volumes are recommended to "open" the plane and improve nerve kinematics. For fascial hydro-dissection, a "seeding technique" with slow, layer-by-layer injection is suggested to restore intrafascial gliding.

This review provides a practical framework for clinicians to move beyond a simplistic "trigger point only" approach to cervical myofascial pain. By using ultrasound systematically, clinicians can identify multiple interacting pain generators and tailor interventions accordingly. The pain generator-based approach allows for more precise, safer procedures—particularly important in the cervical region where vital structures are nearby. For patients with refractory pain, assessing for nerve entrapment or fascial involvement may reveal targets that respond to interfascial blocks or hydro-dissection when trigger point therapy alone fails.

The emphasis on power Doppler imaging before procedures enhances safety by identifying vascular structures. While the evidence base for some interventions remains limited (the authors note "low-quality evidence" for anesthetic superiority over dry needling), the technical guidance and anatomical detail provide valuable practical information for musculoskeletal physicians seeking to incorporate ultrasound into their practice.