Ipsilateral brachial plexus block and hemidiaphragmatic paresis as adverse effect of a high thoracic paravertebral...

Thoracic paravertebral block is regularly used for unilateral chest and abdominal surgery and is associated with a low complication rate.

We describe 2 patients with an ipsilateral brachial plexus block with Horner syndrome after a high continuous thoracic paravertebral block at T2-3. One patient also developed an ipsilateral hemidiaphragmatic paresis, an adverse effect that has not been reported before. Subsequent radiologic examination revealed a limited thoracic cephalad spread of the radiopaque dye and a laterally ascending spread from the thoracic paravertebral space toward and around the brachial plexus. We offer potential explanations for these phenomena.

Brachial plexus block can occur by a route parallel to a nerve connecting the second intercostal nerve and T1 nerve, that is, Kuntz nerve. The hemidiaphragmatic paresis was attributed to the ascending spread of local anesthetic toward the area where the phrenic nerve bypasses the subclavian artery and vein.