Sudden Shoulder Pain, Then Weakness: Brachial Neuritis

Brachial neuritis (Parsonage-Turner syndrome) usually starts with sudden, severe pain in the shoulder or upper arm, often at night and on one side. The pain typically lasts days to a few weeks. As it fades, weakness appears in some shoulder or arm muscles, sometimes with a shoulder blade that sticks out. Any new weakness needs a medical assessment, ideally soon after it appears. Recovery is often slow: months, and for some people 2 to 3 years.

It is an inflammation of nerves in the brachial plexus, the network of nerves running from the neck to the arm. It is also called neuralgic amyotrophy. The cause is not fully understood; the immune system is thought to play a part. It can follow an infection, a vaccination, surgery, childbirth or unusually hard exercise, and often follows nothing obvious at all.

Key takeaways

Pattern: brachial neuritis typically starts with sudden, severe shoulder or upper arm pain, followed by weakness as the pain eases.
Muscles affected: the muscles around the shoulder blade and shoulder are most often affected, so the shoulder blade may stick out and lifting the arm may be hard.
Assessment: new weakness in the shoulder or arm needs a doctor’s assessment; nerve tests and scans help rule out other causes.
Recovery time: nerves regrow slowly, so recovery usually takes months, and for some people 2 to 3 years.
Outcome: many people regain much of their strength; some are left with ongoing weakness, fatigue or ache.

Where are you right now?

Severe pain started in the last few days: see a doctor. Read the three safety sections at the end first, because sudden arm or shoulder pain has other causes that need ruling out.
The pain is fading and weakness has appeared: read “Month by month” and “Is this normal?”. If you can’t lift your arm above your head, that page covers the other common causes.
It started after surgery, a vaccine or an infection: tell the doctor who looked after you about the timing. The recovery pattern is usually the same.
Getting back to work or sport: use the “When can I…” table, and expect the arm to tire sooner than it used to.

Month by month

First days to 2 weeks: severe, constant pain, often worse at night, that ordinary painkillers may not touch. A doctor may prescribe stronger pain relief and sometimes a short course of steroids.
Weeks 2 to 6: the pain usually eases. Weakness becomes obvious, often with thinning of muscles over the shoulder blade or shoulder. Nerve conduction studies are often done from around three weeks.
Months 2 to 6: the goal is keeping the shoulder moving and the muscles ready. Some people notice the first flickers of strength returning; others do not yet.
Months 6 to 12: strength often builds gradually. The arm commonly tires with repeated or overhead tasks.
Years 1 to 3: many people keep improving through this period. Some reach a plateau with some lasting weakness or ache.

Where else this could be coming from

Pinched nerve in the neck: a pinched nerve in the neck usually brings neck pain, arm pain that changes with neck movement, and tingling along one nerve path. Pain and weakness tend to come together rather than one after the other.
Rotator cuff tear: a torn rotator cuff often follows a fall or a lift, or builds slowly with age. Pain comes with arm use, and the muscle wasting is usually not spread across several muscle groups.
Calcific tendinitis: calcific tendinitis can also cause sudden, severe shoulder pain, but strength usually returns as the pain settles.
Frozen shoulder: in frozen shoulder the arm is stiff even when someone else lifts it. In brachial neuritis the arm usually moves freely when lifted for you, but you cannot lift it yourself.
Winged shoulder blade: brachial neuritis is one of the common causes of a winged shoulder blade, through the nerve to the serratus anterior muscle.
Heart: left shoulder or arm pain with chest pain, breathlessness or sweating needs urgent care. See left shoulder pain: heart or shoulder?

Nerves regrow at around a millimeter a day, so progress is measured in months, not weeks.

Is this normal?

The pain went, then the weakness came: this is the typical order. Weakness often becomes noticeable as the pain fades.
The arm tires quickly: fatigue with repeated use is common for months, even once strength has improved.
A patch of skin feels numb: small areas of numbness on the shoulder or arm can occur. Mention them to your doctor.
Feeling low: severe pain and a slow recovery can wear on mood and sleep. That is common and worth raising with your doctor.

If it isn’t going to plan

It is month four. The pain went weeks ago, but you still cannot lift a mug onto the top shelf without your shoulder hitching up toward your ear. The thought in your head: the pain has gone, so it should be getting stronger by now.

The belief that is failing is “once the pain goes, the strength comes back on its own.” The nerve has to regrow to reach the muscle, and that takes time. Meanwhile the joint can stiffen and nearby muscles take over in awkward patterns, like shrugging to lift. Pushing weak muscles hard tends to bring fatigue and ache rather than speed.

What recovery usually needs is the shoulder kept moving, the shoulder blade supported and controlled, and strength rebuilt gradually as the nerve supply returns. Get assessed by your doctor and a physical therapist. Ask which nerves are involved, whether a repeat nerve study would help, what to do while waiting for the nerve, and how much exercise is too much.

When can I…

Activity	Typical range
Sleep on that side	Once the severe pain settles, often 2 to 6 weeks after onset
Drive	When pain is controlled and you can steer and turn safely with both arms; weeks to months
Reach overhead	Varies with the muscles affected; often months, and for some people 1 to 2 years
Lift	Light loads close to the body once pain settles; heavier loads built up over months
Desk work	Often 2 to 6 weeks after onset, once pain is controlled
Manual work or sport	Often 6 to 12 months or longer, especially for overhead or heavy work

If you have had surgery, your surgeon’s protocol comes first.

Call your local emergency number or go to the emergency department if

Heart signs: shoulder or arm pain with chest pain, breathlessness, sweating or nausea.
Stroke signs: sudden weakness of the face, arm or leg, or slurred speech.
Breathing: severe breathlessness, or breathlessness that is getting worse.
Spinal signs: weakness in both arms or both legs, unsteady walking, or loss of bladder or bowel control.

See a doctor today if

New weakness: new weakness in the shoulder or arm, with or without pain.
Severe pain: sudden, severe shoulder or arm pain with no injury that painkillers do not ease.
Lying flat: breathlessness that comes on when you lie flat.
Fever: shoulder pain with fever or a hot, swollen joint.

Get it checked soon if

Other arm: pain or weakness starts in the other arm.
Spreading: numbness or weakness is spreading rather than holding steady.
No change: there is no sign of any returning strength by about six months.
Stiffening: the shoulder is getting stiffer as well as weaker.