AIN Syndrome/Pronator Syndrome

Also known as: anterior interosseous syndrome, Kiloh-Nevin syndrome, pronator syndrome, AIN compressive neuropathy

What is AIN syndrome and pronator syndrome?

AIN syndrome and pronator syndrome are two related conditions that involve nerve dysfunction in the area of the elbow and forearm that cause pain and other symptoms. Both are related to the nerve being compressed or entrapped.

What causes AIN syndrome and pronator syndrome?

Oftentimes, the exact cause of these sydromes is not known. Traumatic injuries, repetitive movements and anatomical issues can contribute to the development of AIN syndrome and pronator syndrome. The source of symptoms is usually related to pressure or compression on nerves in the arm.

How can AIN syndrome and pronator syndrome affect children?

Symptoms of AIN syndrome include weakness of grip and pinch, especially in the thumb, index and middle fingers. The patient may not be able to make a normal OK sign. There are usually no complaints of pain.

Symptoms of pronator syndrome include numbness and tingling in the thumb, index and middle fingers (as seen in carpal tunnel syndrome).  There may be aching pain in the proximal forearm, and symptoms may be made worse with repetitive pronosupination.

How can AIN syndrome and pronator syndrome affect children?

AIN syndrome and pronator syndrome are more common in adults than they are in children.  Pronator syndrome may be seen occasionally in weightlifters with muscular forearms. 

What are AIN syndrome and pronator syndrome treatments?

Treatment for AIN syndrome and pronator syndrome begins with rest, splinting, and non-steroidal anti-inflammatory medications. Patients who do not demonstrate improvement with conservative measures, require imaging and nerve conduction studies to help determine the cause of nerve dysfunction. If nonoperative treatment fails, surgical decompression of the nerve may be recommended.

Reviewed by: Aaron Berger, MD

This page was last updated on: March 29, 2021 03:37 PM

Learn more about

Carpal Tunnel Syndrome

The median nerve is a mixed (motor and sensory) nerve of the upper extremity. If it becomes compressed as it travels through the wrist, the result can be carpal tunnel syndrome, which causes a number of symptoms in hand. Learn more

Peripheral Neuropathy

The peripheral nerves are the vast network of nerves that transmits messages from the central nervous system (brain and spinal cord) to the rest of the body. When these nerves don’t function normally it is known as a peripheral neuropathy. Learn more

Nerve Conduction Study

May be performed same day of EMG, electrodes are applied to the skin to measure speed of signals traveling between nerves and muscles. Learn more


Short for non-steroidal anti-inflammatory drugs, refers to a class of medications that reduce inflammation, pain and fever. Learn more