Fibrotic and mechanical tissue changes may contribute to chronic neck-pain presentations. The direct human evidence is limited but noteworthy. An older surgical study found dense fibrosis around symptomatic trapezius muscle in four patients, and newer shear-wave elastography studies show the upper trapezius can be measurably stiffer in cervical myofascial pain. These findings support considering structural tissue change. Stiffness on imaging or under the hands does not, by itself, prove microscopic fibrosis in an individual patient.
What does "fibrosis" mean in skeletal muscle?
Fibrosis is excess, often disorganized collagen and connective tissue laid down within or around a muscle, usually after repeated strain, injury, or long-standing irritation. It changes how the tissue behaves mechanically. It is confirmed by looking at tissue directly, at surgery or under a microscope, not by feel or by a scan.
What did the Hagert surgical study find?
Hagert and Christenson, in Acta Orthopaedica Scandinavica (1990), measured pressure inside the trapezius muscle at rest and under load.
- Pressure: the 25 symptomatic trapezius muscles had higher intramuscular pressure than 32 pain-free muscles, both at rest and during load.
- Surgery: in 4 patients who had operations, surgeons found dense fibrosis around the muscle, including around the accessory nerve that supplies it.
- Outcome: releasing the fibrotic tissue relieved symptoms and brought pressure back to normal.
Only four patients had surgical confirmation, and the study is more than 30 years old. It is direct human evidence that clinically significant trapezius fibrosis can occur in symptomatic neck-shoulder pain. It is not evidence that most painful trapeziuses contain fibrosis.
What does modern elastography show?
Shear-wave elastography uses ultrasound to measure how stiff a tissue is. Hao and colleagues, in Quantitative Imaging in Medicine and Surgery (2023), measured the upper trapezius in 109 people with right-sided posterior neck pain: 51 diagnosed with cervical myofascial pain syndrome and 58 with other neck pain.
- The trapezius was significantly stiffer in the myofascial pain group (p < .001).
- The difference was driven by moderate and severe pain. People with mild myofascial pain had stiffness similar to the comparison group.
- As a screening measure, stiffness separated the groups moderately well (area under the curve 0.791).
This is a larger, modern sample showing that painful upper-trapezius tissue in myofascial pain can be mechanically different.
Does a stiff trapezius prove fibrosis?
No. Elastography measures mechanical stiffness. It does not sample tissue. Stiffness can reflect muscle tone, contraction, fluid, the state of the connective tissue, or collagen content, and these cannot be separated on a scan. Tenderness, muscle tone and stiffness are related but not interchangeable, and no examiner's hands can measure collagen deposition.
Taken together, the two studies point the same way from different directions. Hagert observed fibrosis directly, but in four people. Hao measured stiffness in over a hundred, but cannot say what the stiffness is made of. Together they make a structural component biologically plausible without proving one universal pathology.
The evidence side by side
| Study | What was measured | Finding | Key limitation |
|---|---|---|---|
| Hagert & Christenson, 1990 | Intramuscular pressure in 25 symptomatic vs. 32 pain-free muscles; surgery in 4 | Higher pressure; dense fibrosis seen at surgery | Only 4 surgical confirmations |
| Hao et al., 2023 | Shear-wave stiffness in 109 neck-pain patients (51 myofascial, 58 other) | Stiffer trapezius in myofascial pain; AUC 0.791 | Stiffness is not histology |
| Vasvit et al., 2025 | Stiffness before and after focused shockwave or sham in 64 patients | Stiffness fell 6.1 kPa at the trigger point | Does not show fibrosis was removed |
How do trigger points fit in?
A trigger point is a tender, irritable spot in a taut band of muscle that can refer pain elsewhere. It is usually described as a neuromuscular and sensitization phenomenon, while fibrosis is a structural change. Trigger points are common in the upper trapezius and in headache populations. A 2025 review of 77 studies found active trigger points and tenderness common in migraine and tension-type headache, especially chronic headache, though the certainty of those findings was very low.
Can a trigger point and structural tissue change coexist?
They may. Long-standing irritation and abnormal loading can, in principle, drive both, and the same small area of muscle can be tender, taut and stiff at once. The research has not established how often they overlap. We cover the distinction in more depth in trigger point or fibrous adhesion?
What about tension-type headache?
Tender neck and scalp muscles are a recognized feature of tension-type headache. The ICHD-3 headache classification divides it into forms with and without pericranial tenderness, and a 2021 meta-analysis of 1,200 patients found tenderness scores markedly higher than in healthy people in chronic tension-type headache (standardized mean difference 1.57). Tenderness was also higher in migraine (SMD 1.27), so it does not identify the headache type or show that the muscle is the cause.
Is posture to blame?
Not as a rule. Desk work, screen time and sustained postures are possible contributors to how the neck is loaded, not diagnoses on their own. They are part of the history we take, alongside everything else.
Can a clinician feel fibrosis?
Not with certainty. Palpation can find tenderness, taut bands, referred pain and tissue that resists movement, and those findings can guide treatment. Palpation cannot confirm microscopic fibrosis or measure collagen. We use soft-tissue restriction as a clinical finding, not a tissue diagnosis.
Does shockwave change measured stiffness?
In one randomized trial, yes. Four weekly sessions of focused shockwave lowered upper-trapezius stiffness by 6.1 kPa at the trigger point and 5.3 kPa in the underlying aponeurosis, and pain improved. Disability improved in both groups. That shows shockwave can change tissue mechanics. It does not show it removes fibrosis. The full trial evidence is in shockwave therapy for chronic neck pain, including how radial and focused shockwave compare.
What the research does not prove
- That fibrosis causes all, or most, chronic neck pain
- That a stiff trapezius on ultrasound contains fibrosis
- That palpation can identify fibrosis
- That trigger points are fibrosis
- That treatment removes fibrosis rather than changing pain and tissue mechanics
How Novo uses these findings
We examine the upper trapezius, levator scapulae and suboccipital muscles for tenderness, referred pain and tissue resistance, alongside neck motion, strength and endurance, the headache pattern, and neurologic signs when relevant. Restricted, sensitive tissue is one finding among several. When it fits the presentation, manual treatment and shockwave are options, usually alongside exercise. See how we approach chronic neck pain and tension headache, or book a new patient exam.
Sources
- Hagert CG, Christenson JT. Hyperpressure in the trapezius muscle associated with fibrosis. Acta Orthopaedica Scandinavica. 1990;61(3):263-265. PMID 2371824. (link)
- Hao CJ, Kang XY, Kang CS, et al. Upper trapezius muscle elasticity in cervical myofascial pain syndrome measured using real-time ultrasound shear-wave elastography. Quantitative Imaging in Medicine and Surgery. 2023;13(8):5168-5181. PMID 37581083. (link)
- Vasvit P, Klarod K, Sukkho O, et al. Therapeutic effect of focused-extracorporeal shockwave therapy on muscular and adjacent tissue stiffness and pain changes in myofascial pain syndrome: a randomized controlled trial study. Complementary Therapies in Medicine. 2025;92:103203. PMID 40609961. (link)
- Castien R, Duineveld M, Maaskant J, et al. Pericranial total tenderness score in patients with tension-type headache and migraine: a systematic review and meta-analysis. Pain Physician. 2021;24(8):E1177-E1189. PMID 34793636. (link)
- Pensri C, Liang Z, Treleaven J, et al. Cervical musculoskeletal impairments in migraine and tension-type headache and relationship to pain related factors: an updated systematic review and meta-analysis. Musculoskeletal Science and Practice. 2025;76:103251. PMID 39756244. (link)
