Brachial plexus injuries

1. What is Erb's palsy, how does it present, what are common causes of it, and how is the NCS done?
2. What is Klumpke's palsy and how does it present?
3. What is vascular thoracic outlet syndrome (TOS) and how does it present?
4. What is neurogenic TOS?
5. What is Adson's test?

Answers:
1. Erb's palsy involves the upper trunk (C5-6) nerve roots, resulting in a "waiter's tip" position in which the arm is adducted (deltoid, supraspinatus), internally rotated (teres minor, infraspinatus), extended (biceps, brachioradialis), pronated (supinator, brachioradialis), with wrist flexed (ECR). It commonly results from obstetrical injury or a sports related Stinger. NCS involves stimulating at the tip of the C6 transverse process over the trunks of the brachial plexus to assess Erb's point.
2. Klumpke's palsy involves the lower trunk (C8-T1) and can also occur from an obstetrical traction injury. The patient may have wasting of small hand muscles and a "claw hand deformity". It is commonly associated with a nerve root avulsion, which is indicated by the preservation of the SNAP.
3. Vascular TOS involves an injury to the subclavian artery or vein, or the axillary vein. Presentation inovles limb ischemia, necrosis, vague pain, fatigue with decreased color and temperature.
4. Neurogenic TOS is a rare condiction that occurs from compression of the lower trunk of the brachial plexus between a cervical rib, fibrous band, or muscular entrapment. Presentation is with pain and numbness along the medial forearm and hand that increases with overhead activity. Median CMAP and ulnar SNAP/CMAP may be abnormal and there may be spontaneous activity in median and ulnar hand muscles. Rehab involves ROM and strengthening of traps/rhom, postural mechanics.
5. Adson's test for TOS: abduct, extend, and ext rotate patient's arm. If decrease or loss of pulse (due to subclavian compression) is noted when patient turns head toward arm, this is positive for TOS.