Uncovering the Forgotten Effect of Superior Cervical Ganglia on Pupil Diameter in Subarachnoid Hemorrhage: an Experimental Study

Abstract

AIm: To investigate the relationship between neuron density of the superior cervical sympathetic ganglia and pupil diameter in subarachnoid hemorrhage. mATERIAl and mEThODS: This study was conducted on 22 rabbits; 5 for the baseline control group, 5 for the SHAM group and 12 for the study group. Pupil diameters were measured via sunlight and ocular tomography on day 1 as the control values. Pupil diameters were re-measured after injecting 0.5 cc saline to the SHAM group, and autologous arterial blood into the cisterna magna of the study group. After 3 weeks, the brain, superior cervical sympathetic ganglia and ciliary ganglia were extracted with peripheral tissues bilaterally and examined histopathologically. Pupil diameters were compared with neuron densities of the sympathetic ganglia and ciliary ganglia which were examined using stereological methods. RESulTS: Baseline values were; normal pupil diameter 7.180±620 µm and mean neuron density of the superior cervical sympathetic ganglia 6.321±510/mm3, degenerated neuron density of ciliary ganglia was 5±2/mm3 after histopathological examination in the control group. These values were measured as 6.850±578 µm, 5.950±340/mm3 and 123±39/mm3 in the SHAM group and 9.910±840 µm, 7.950±764/mm3 and 650±98/mm3 in the study group. A linear relationship was determined between neuron density of the superior cervical sympathetic ganglia and pupil diameters (p