Extent of sympathetic blockade after stellate ganglion block with bupivacaine.

A study of the extent of sympathetic blockade after stellate ganglion block was assessed using liquid crystal thermography. Two volumes (10 and 20 ml) of bupivacaine 0.5% plain were used. Irrespective of the volume used cranial sympathetic block always occurred and thoracic sympathetic block never occurred. While upper cervical block was present in all patients, lower cervical sympathetic block was present only in the 20-ml group (P less than 0.05). The larger volume was associated with a significant incidence of hoarseness due to spread of local anaesthetic onto adjacent laryngeal nerves.