Median nerve palsy
Nerve disorder causing thumb paralysis and hand deformity.
Median nerve palsy is a nerve disorder resulting from injuries to the arm, forearm, or wrist. The median nerve controls the majority of the muscles in the forearm, including thumb abduction, wrist flexion, and finger flexion, and provides sensation to the first three fingers. Due to its major role, it is called the eye of the hand. Damage to this nerve can cause loss of thumb opposition and abduction, leading to ape-hand deformity, and may be treated through surgery and tendon transfers.
- field
- Neurology, Orthopedics
- known_for
- Causing ape-hand deformity and loss of thumb opposition
- common_causes
- Deep penetrating injuries, blunt force trauma, neuropathy
- subsections
- High MNP (elbow/forearm) and Low MNP (wrist)
- key_syndrome
- Carpal tunnel syndrome
Lore & Background
Median nerve palsy can be caused by deep penetrating injuries to the arm, forearm, or wrist, as well as blunt force trauma or neuropathy. It is divided into high median nerve palsy, involving lesions at the elbow and forearm, and low median nerve palsy, resulting from lesions at the wrist. Compression can occur at several anatomical sites, including under Struthers' ligament, at the bicipital aponeurosis, between the two heads of the pronator teres, or in the carpal tunnel, the latter causing carpal tunnel syndrome.
Reader's Guide
Median nerve palsy is significant because the median nerve is essential for hand function, controlling most forearm muscles and providing sensation to the thumb, index, middle, and part of the ring fingers. Its damage leads to ape-hand deformity, where the thumb becomes adducted and laterally rotated due to thenar muscle paralysis. Diagnosis involves motor and sensory testing, nerve conduction studies, and specific physical tests like the Phalen maneuver for carpal tunnel syndrome or the pronator teres test. Treatment ranges from rest, splints, and anti-inflammatory drugs to surgery and tendon transfers, which have been very successful in restoring motor function and improving functional outcomes. The condition highlights the importance of the median nerve as the 'eye of the hand' and the need for prompt intervention to prevent permanent deformity.
Did You Know?
- The median nerve is called the eye of the hand because of its major role in controlling forearm muscles.
- Ape-hand deformity results from paralysis of the thenar muscles, causing the thumb to become adducted and laterally rotated.
- Carpal tunnel syndrome is caused by compression of the median nerve as it passes under the carpal tunnel.
- The Anterior Interosseus Nerve syndrome accounts for less than 1% of neuropathies in the upper limb.
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