Evaluation of optic nerve sheath diameter and hemodynamic effects by ultrasonography in patients undergoing stellate ganglion block

Stellate ganglion block (SGB) is an invasive procedure that provides temporary blockade of the sympathetic innervation of the head, neck, and upper extremity by interrupting the cervical sympathetic chain. In the literature, it has been reported that SGB affects not only the peripheral but also the central nervous system and may increase cerebral blood flow. The optic nerve sheath diameter (OSKÇ) is used as a noninvasive indicator of increased intracranial pressure (ICP). This study aimed to evaluate the changes in OSKÇ after SGB using ultrasonography and to investigate the relationship between these changes and clinical parameters reflecting sympathetic block efficacy. Eighteen cooperative volunteers aged between 20 and 70 years, diagnosed with complex regional pain syndrome or postherpetic neuralgia, were included in the study. At the C6 level, 5 mL of 1% lidocaine and 2 mL of dexamethasone were administered under ultrasound guidance for SGB. Bilateral arm skin temperature, capnography, perfusion index (PI), numeric rating scale (NRS) for pain, vital signs, and ONSD measurements in both horizontal and vertical planes from both eyes were recorded before and after the procedure, and the average values were calculated. Post-procedurally, an average increase of 2.21 °C in skin temperature and a significant increase in the perfusion index were observed on the blocked side (p < 0.001). Similarly, a significant decrease in NRS pain scores was detected (p < 0.001). A significant increase in ONSD was observed on both the ipsilateral and contralateral sides (p < 0.001 and p = 0.001, respectively), suggesting that the changes may be related not only to local but also to systemic hemodynamic effects. The mean post-procedural ONSD increased from 0.57 ± 0.08 cm to 0.63 ± 0.08 cm. In conclusion, ultrasound-guided SGB appears to induce changes not only in peripheral sympathetic activity but also in central hemodynamic parameters. ONSD measurements may serve as a potential noninvasive marker for monitoring the effects of SGB on cerebral circulation.