Spinal Subarachnoid Hemorrhage Induced Intractable Miotic Pupil. a Reminder of Ciliospinal Sympathetic Center Lschemia Based Miosis: an Experimental Study

Abstract

Aim: To examine ischemic neurodegeneration of the ciliospinal center on permanent miosis following subarachnoid hemorrhage (SAH). MATERIAL and METHODS: Nineteen rabbits were examined in this study. The animals were divided into three groups, as control (GI, n=5), sham (GII, n=5) and study group (GIII, n=9). Pupil diameters were measured after giving 0.5 mL physiological saline for sham and autologous arterial blood for the study group into the cervico-thoracic subarachnoid space. After three weeks of follow up, the cervico-thoracic cord and bilateral superior cervical sympathetic ganglia were removed. The pupil diameter values were compared with degenerated neuron volumes of sympathetic ganglia and degenerated neuron densities of thoracic sympathetic nuclei which were studied by stereological methods. RESULTS: The mean pupil diameter was 5180 +/- 370 pm and the mean degenerated neuron density of the ciliospinal center was 4 +/- 1/mm(3) in animals of the control group (GI). These values were 9850 +/- 610 mu m, 10 +/- 3/mm(3) in sham (GII), and 7.010 +/- 440 mu m and 98 +/- 21/mm(3) in the study (GIII) groups. There was an inverse relationship between degenerated neuron density of the ciliospinal nuclei and pupil diameters. CONCLUSION: Although there is a widespread belief that the main cause of miosis is oculomotor nerve injury during SAH, we showed and reported for the first time that ciliospinal sympathetic center ischemia-induced neurodegeneration may have been responsible for permanent miosis following SAH.