BRACHIAL PLEXUS ANATOMY/Parsonage Turner Syndrome

BRACHIAL PLEXUS:

BRACHIAL PLEXUS

 

• The brachial plexus is composed of-- Three trunks (upper, middle, and lower)
• Two divisions (anterior and posterior) per trunk.
• The trunks divide into three cords -medial,lateral, and posterior.
• The anterior primary rami of C5 and C6 fuse to form the upper trunk;
• The anterior primary ramus of C7 continues as the middle trunk,
• The anterior rami of C8 and T1 join to form the lower trunk.

Immune-Mediated Brachial Plexus Neuropathy Immune-mediated brachial plexus neuropathy (IBPN) goes by various terms, including acute brachial plexitis, neuralgic amyotrophy, and Parsonage-Turner syndrome. IBPN usually presents with an acute onset of severe pain in the shoulder region. The intense pain usually lasts several days to a few weeks, but a dull ache can persist. Individuals who are affected may not appreciate weakness of the arm early in the course because the pain limits movement. However, as the pain dissipates, weakness and often sensory loss are appreciated. Attacks can occasionally recur. Clinical findings are dependent on the distribution of involvement (e.g., specific trunk, divisions, cords, or terminal nerves). The most common pattern of IBPN involves the upper trunk or a single or multiple mononeuropathies primarily involving the suprascapular, long thoracic, or axillary nerves. Additionally, the phrenic and anterior interosseous nerves may be concomitantly affected. Any of these nerves may also be

affected in isolation. EDx is useful to confirm and localize the site(s) of involvement. Empirical treatment of severe pain with glucocorticoids is often used in the acute period.

Extra Edge: 
Widening the angle between the neck and shoulder may stretch the C5 and C6 roots and/or superior trunk, thereby damaging the axillary, musculocutaneous, and suprascapular nerves .

An upper plexus injury results in Erb palsy, which is characterized by an adducted and medially rotated arm, extended elbow, and pronated hand (waiter’s tip sign).

The axillary nerve is at risk from fractures of the surgical neck of the humerus.
 

The musculocutaneous nerve supplies all the muscles of the anterior compartment of the arm.

An abnormal increase in the angle between the upper limb and thorax and/or severe abduction traction may stretch the C8 and T1 roots and/or the inferior trunk and, hence, affect the ulnar and median nerves

 A lower plexus injury may result in Klumpke palsy, which is characterized primarily by signs of ulnar nerve damage (claw hand).

The ulnar nerve innervates all but five muscles of the hand: the three thenar muscles and the lumbricals to the index and middle fingers.

In ulnar nerve palsies, the patent is unable to abduct and adduct the fingers.

A posterior cord injury results in signs of radial nerve damage (wrist drop).







Source: Harrison medicine and case file anatomy.