What condition can result in AIN symptoms and the inability to bring the thumb and tip of the finger together?

• A. Carpal Tunnel Syndrome
• B. Bell's Palsy
• C. Parsonage Turner Syndrome
• D. Thoracic Outlet Syndrome

Answer: (C)

The condition that can result in anterior interosseous nerve (AIN) symptoms along with the inability to bring the thumb and tip of the finger together is indeed Parsonage-Turner syndrome. This syndrome primarily affects the brachial plexus, which includes nerves that innervate the muscles of the shoulder and arm, including the anterior interosseous nerve, a branch of the median nerve.

In Parsonage-Turner syndrome, patients often experience sudden onset shoulder pain followed by weakness or paralysis in the affected arm. A classic symptom is difficulty with pinch grip, which is the action of bringing the thumb and index finger together; this weakness is typically attributed to impairment of the flexor pollicis longus and flexor digitorum profundus muscles—both of which are innervated by the AIN. The inability to perform this action is a direct result of muscle atrophy or weakness caused by nerve involvement in this condition.

The other options listed—Carpal Tunnel Syndrome, Bell's Palsy, and Thoracic Outlet Syndrome—do not directly produce AIN symptoms in the same way. Carpal Tunnel Syndrome primarily affects the median nerve's sensory functions and can lead to trouble with the thumb, but not typically the A