This site is intended for healthcare professionals
Last reviewed dd mmm yyyy. Last edited dd mmm yyyy
Lower brachial plexus lesions involve C8 and T1. They are the result of traction on the arm in an abducted position - e.g. during a difficult labour; or at birth - Dejerine Klumpke's palsy.
The patient presents with a claw hand - the result of paralysis of the intrinsic hand muscles; sensory loss along the ulnar side of the hand and the forearm (first thoracic dermatome); and if the T1 root is affected, possibly, a Horner's syndrome from interruption of sympathetic innervation at that level.
Note that a combined ulnar and median nerve lesion produces a similar picture in the hand but with additional involvement of flexor carpi radialis and pronator teres.