About posterior interosseous nerve palsy
The posterior interosseous nerve is a branch of the radial nerve. It passes through the forearm muscles just below the elbow and controls the muscles that straighten the fingers and thumb. When it is compressed or injured, those muscles become weak, but feeling in the hand is usually normal.
People often notice that they cannot fully straighten their fingers at the knuckles, or that the wrist drifts toward the thumb side when they lift it. Because sensation is spared, it can be mistaken for a tendon problem or a stroke, so careful testing is important.
Common symptoms
- Weakness straightening the fingers at the knuckles
- Difficulty lifting the thumb away from the hand
- Wrist that tilts toward the thumb side when raised
- Aching in the upper forearm, sometimes without numbness
Common causes and risk factors
- Compression under a band of muscle near the elbow, called the arcade of Frohse
- Fractures or dislocations around the elbow
- Masses such as a cyst or a benign fatty lump pressing on the nerve
- Inflammation from elbow arthritis or repetitive forearm rotation
How we diagnose it
Dr. Chen examines each finger and wrist muscle to see exactly which ones are weak and checks that sensation is normal, which helps separate this condition from other radial nerve problems or a tendon rupture. An EMG and nerve conduction study confirms which nerve branch is affected and how severely, and ultrasound can show the nerve itself, including swelling, a cyst, or another mass pressing on it. Imaging such as MRI may be recommended if a mass is suspected.
How Propel treats posterior interosseous nerve palsy
Treatment starts with protecting the hand and keeping it useful. A splint can hold the wrist and fingers in a functional position, and therapy keeps the joints flexible while strengthening the muscles that still work. We adjust the tasks and training that aggravate the forearm so you can stay active during recovery.
Repeat nerve testing helps show whether the nerve is recovering. When a cyst, mass, or tight band is compressing the nerve, or strength does not improve over time, surgery to relieve the pressure is often the right answer, and we help coordinate a referral to a hand or nerve surgeon.
What to expect at your visit
- 1.
We listen first
Your visit opens with a real conversation: how the problem started, what you have already tried, and the activity you want back.
- 2.
Exam and in-office ultrasound
A hands-on exam, then ultrasound at the exam table, often while you move, so your physician can see the tendon, joint, or nerve involved.
- 3.
A clear diagnosis and plan
You leave knowing what is wrong and what your options are, from strength-based rehab to procedures, and why we recommend each one.
- 4.
Treatment and follow-through
Most procedures happen here in the office. We coordinate with your physical therapist and check progress against the goals you set.
Questions about posterior interosseous nerve palsy
- Why is my hand weak but not numb?
- The posterior interosseous nerve mainly controls muscles and carries very little skin sensation. That is why this condition typically causes weakness in the fingers and thumb without numbness.
- Will the weakness go away on its own?
- Sometimes it does, particularly when the cause is temporary inflammation. When a structure keeps pressing on the nerve, recovery is less likely without surgery. Follow-up testing helps guide that decision.
- Is sudden hand weakness ever an emergency?
- Yes. Sudden weakness in the hand or arm, especially with facial drooping, trouble speaking, or weakness on one side of the body, can signal a stroke and needs emergency care immediately.