Shoulder impingement: the tendon has a story, and so does the alarm.

Reaching and lifting hurt, physio has not worked, and the scan shows what everyone's scan shows. Here is what else may be keeping the pain going.

This page is about understanding the condition and the role the brain and nervous system can play in it. It is not a diagnosis. Your own clinicians know your case.

What shoulder impingement is

Shoulder impingement describes pain thought to arise when one of the rotator cuff tendons, usually the supraspinatus, rubs against the underside of the acromion, the bony roof formed by the shoulder blade, as the arm is raised. The tendon and the bursa (a fluid cushion) become irritated and inflamed. Pain is felt at the top and outside of the shoulder, worse with lifting, reaching overhead or behind the back, and often at night when lying on that side.

It is the most common shoulder diagnosis in adults. Treatment usually starts with activity modification, physiotherapy to strengthen the cuff and improve shoulder-blade control, anti-inflammatory medication and sometimes a steroid injection. Most people improve within a few months. Surgery to shave the acromion, called subacromial decompression, was once common.

The name is now in question. Studies show that the bony shape of the acromion is similar in people with and without pain, that MRI findings such as tendon wear are common in pain-free shoulders, and that removing the 'impinging' bone adds nothing over sham surgery. Many clinicians now prefer the term subacromial pain syndrome, which describes the pain without claiming the mechanism.

The neuroplastic contribution

Neuroplastic symptoms are real physical symptoms produced by learned pathways in the brain and nervous system, a sensitized alarm system, rather than by ongoing damage or disease. They are not imaginary, and because the brain can change, they are reversible.

The ATNS Index of Neuroplastic Symptoms states that shoulder impingement is not caused by neuroplastic symptoms. Tendon irritation is real and usually settles. The index adds that if the symptoms are not typical, or if the course over time or the response to treatment is not as expected, neuroplastic symptoms should be assessed as part of a complete evaluation. That describes a large group: people whose pain has lasted well beyond the expected healing time, who have done the exercises and had the injection, and who still cannot lift the arm without bracing.

• Learned pain. After months of pain with reaching, the brain predicts pain with reaching and produces it, whether or not the tendon is still irritated. This is central sensitization.
• Fear and guarding. Protecting the arm, avoiding overhead movement and tensing before every lift keep the nervous system on alert and the shoulder stiff, the loop described in the fear-avoidance cycle.
• The label itself. Being told a bone is pinching your tendon every time you lift makes lifting feel dangerous. Our article on hurt versus harm addresses exactly this.
• Life context. Shoulder pain that began during a stressful period, or that spread to the neck and the other shoulder, points toward the nervous system.

What the research shows

The FIMPACT trial, published in the BMJ in 2018, randomised people with shoulder impingement to arthroscopic subacromial decompression or to diagnostic arthroscopy alone, a placebo surgery in which nothing was removed. At both six months and one year, decompression offered no benefit over the placebo procedure; both groups improved substantially in pain and function. The authors note that the parallel CSAW trial in the Lancet reached the same conclusion. If the bone is not the problem, the explanation for the pain, and for the improvement, lies elsewhere.

A 2025 study of the pathophysiology of subacromial pain syndrome concluded that pain and disability tracked more closely with central sensitization than with structural findings on MRI, and that imaging findings such as tendon tears and narrowed subacromial space did not reliably match reported pain.

A secondary analysis of long-term outcomes after physiotherapy for subacromial pain syndrome found that fear-avoidance beliefs and patient expectations predicted outcomes about as strongly as baseline pain and disability did. In other words, what people believe about their shoulder shapes how it recovers.

Signs the brain may be part of the picture

• Pain that has lasted far beyond the three to six months in which tendon irritation usually settles.
• Physiotherapy, injections or surgery that gave brief relief and then the pain returned.
• Pain that has spread to the neck, upper back, the other shoulder or down the arm.
• Pain that flares with stress and fatigue and eases on relaxed, absorbed days.
• Bracing before movement, and fear that lifting will damage the shoulder.

A solution that addresses it

Alongside physiotherapy, there is an approach that addresses the brain's contribution. Pain and symptom reprocessing includes education about neuroplastic symptoms and the evidence that your shoulder is not being pinched, somatic tracking of the ache with curiosity instead of alarm, reducing fear and guarding, a graded return to reaching, lifting and sleeping on that side, emotional awareness and expression, and acceptance and commitment skills so life does not shrink around the arm. Trained clinicians deliver it, and digital programs increasingly make it available every day.

Cindra is a daily AI companion built around these approaches, with daily check-ins, short practices and plain-language lessons for people whose symptoms have a neuroplastic component. If your shoulder pain has outlasted its diagnosis, join the waitlist.

What to do next

Have the shoulder properly assessed by a clinician or physiotherapist to exclude a full-thickness rotator cuff tear, a frozen shoulder, arthritis, or referred pain from the neck. Seek prompt attention for shoulder pain after a fall with sudden weakness, for a hot swollen joint with fever, or for shoulder pain with chest pain or breathlessness. Do not stop any prescribed medication on your own.

Then ask whether your course has been typical. If treatment has not worked as expected, ask for a neuroplastic assessment as the index recommends, and start learning and practising. A graded return to movement, with fear addressed directly, is what most people with persistent shoulder pain have not yet tried.

This article is for general education and is not medical advice, and it does not diagnose or treat any condition. Persistent symptoms deserve a proper medical assessment to rule out disease or injury before a neuroplastic explanation is considered. If your symptoms are new, changing, or come with red-flag signs such as fever, unexplained weight loss, numbness or weakness, chest pain, or loss of bladder or bowel control, see a clinician promptly.