The acute effects of stellate ganglion block on circulation in human ocular fundus

Purpose: To study the acute effects of local-anesthetic stellate ganglion b lock (SGB) on tissue circulation in the human fundus, Methods: Eleven patients with Bell's palsy (age 56+/-6 y, mean+/-SD) who un derwent SGB for its treatment participated in the study. Using the laser sp eckle method, normalized blur (NB) value, a quantitative index of tissue bl ood velocity, was measured every 0.125 s over an area located halfway betwe en the macula and the optic nerve head (ONH) with no discrete visible vesse ls and averaged over 3 pulses when fixation was satisfactory (NBch-ret) NBc h-ret and intraocular pressure (IOP) in both eyes, blood pressure (BP), and pulse rate (PR) were measured before, and 10, 20, 30, and 60 min after SGB , SGB was induced by injecting 1% mepivacaine hydrochloride (5 ml) into the vicinity of the seventh cervical vertebra on the paralyzed side. Results: The IOP in the blocked side significantly decreased between 20 and 60 min following SGB, compared to the baseline, while IOP in the unblocked side remained unchanged. The NBch-ret was significantly increased after 10 min by about 8% in the blocked side, but its effect almost disappeared at 60 min. There was no significant change in NBch-ret in the unblocked side, BP or PR throughout the experimental period. Conclusion: SGB increased tissue circulation in the fundus in the blocked s ide, bat its effect was thought to be small and transient.