Pupillary ultrasonography vs Horner's syndrome to evaluate efficacy of stellate ganglion block in patients

Abstract

Stellate ganglion block (SGB) is not only used for treating cervical thoracic, and upper limb pain-related diseases but also for treating sympathetic nervous system dysfunction-related diseases, and it is a widely used clinical treatment method. This study has demonstrated that utilizing ultrasound to measure pupillary diameter (PD) changes and significant inter-eye differences offers a more objective assessment of stellate ganglion block (SGB) efficacy compared to the traditional subjective evaluation based on Horner’s syndrome (HS). However, there is currently no objective standard to evaluate the efficacy of SGB. Pupillary ultrasonography can observe precise dynamic changes in the pupils, and is less affected by peripheral light, non-invasive, and convenient. We performed SGB under ultrasound guidance, and evaluated the effectiveness of SGB according to HS in 60 patients. All patients were scored using a visual analogue scale (VAS) before and 24 h after stellate ganglion block treatment. We compared the changes in pupil diameter (PD) and pupillary constriction ratio during pupil light reflex (PLR) in the blocked side and the opposite side. Then we calculated the inter-eye difference of PD before and after SGB, and the inter-eye difference of PD in the blocked side and the opposite side (BO-IED) at each time point. We found that the area under the curve (AUC) for evaluating the effectiveness of SGB was statistically significant at each time points for BO-IED and blocked side inter-eye difference. Additionally, the BO-IED at 15 min after SGB has the largest AUC, when the BO-IED is greater than 0.5 mm, which shows a sensitivity of 86.5 %, and a specificity of 100 %. Our findings suggested an association between pupil reduction and symptom reduction in patients, with the degree of pupil reduction serving as a reference for evaluating the effectiveness of SGB and the degree of symptom relief.