ICD-11

The brachial plexus is formed by ventral rami of five spinal nerves (C5-T1), which have motor, sensory and preganglionic sympathetic fibres innervating the upper limb. These five rami join to form three trunks (upper-C5-C6; middle-C7; lower-C8-T1) which again divide into six divisions to become three cords (lateral, medial and posterior). The plexus is vulnerable to trauma at various levels and can be affected by a variety of diseases because of its close proximity to lymph nodes, blood vessels and lung parenchyma; diabetes mellitus and vasculitis can also cause brachial plexus dysfunction. Some cases are considered as an idiopathic brachial plexopathy. Clinical features depend on whether the entire plexus or a portion of it is involved. In panplexopathy, the arm hangs lifelessly by the side, the limb is flaccid and areflexic with complete sensory loss below a line extending from the shoulder diagonally downward and medially to the middle of upper arm. In lesions of the upper trunk, the arm hangs at the side, internally rotated at the shoulder, with the elbow extended and the forearm pronated in a “waiter`s tip” posture. The biceps and brachioradialis reflexes are absent and sensory loss is found over the lateral aspect of the arm, forearm and thumb. In lesions of the lower trunk, there is weakness of the intrinsic hand muscles, the finger flexion reflex is diminished or absent, and there is sensory loss over the two medial fingers as well as the medial aspect of forearm and hand.