Which of the following is a common nerve pathology related to the brachial plexus that presents with AIN symptoms?

• A. Median Nerve Entrapment
• B. Parsonage Turner Syndrome
• C. Ulnar Nerve Compression
• D. Radial Nerve Palsy

Answer: (B)

The common nerve pathology related to the brachial plexus that presents with anterior interosseous nerve (AIN) symptoms is indeed linked to Parsonage Turner Syndrome. This condition involves an inflammatory process that affects the brachial plexus and can lead to weakness in the muscles innervated by the AIN, notably the flexor pollicis longus, flexor digitorum profundus to the index and middle fingers, resulting in a characteristic "pinch grip" difficulty.

Parsonage Turner Syndrome often presents with acute shoulder pain followed by muscle weakness and atrophy, particularly affecting the anterior forearm muscles, which aligns well with AIN symptoms. The underlying mechanism involves a neuropathy that stems from the broader implications of brachial plexus involvement, rather than isolated nerve compression or entrapment.

This stands in contrast to other mentioned conditions, which do not primarily involve the AIN. Median Nerve Entrapment can cause symptoms in the median nerve territory, including AIN symptoms but is primarily due to local compression rather than brachial plexus pathology. Ulnar Nerve Compression and Radial Nerve Palsy affect different nerve distributions and do not present with AIN symptoms specifically, further clarifying why