Are unresponsive dilated pupils an indicator for brain death? an evaluation of Edinger Westphal nucleus in rabbits with brain death

Abstract

Aim: To investigate a relationship between unresponsive pupils and severity of neurodegeneration in Edinger Westphal nucleus(EWN) of animals diagnosed with brain death.Material and Methods: A total of 24 New Zealand white rabbits were used. The animals were divided into three groups, as controlgroup (n=5), sham (n=5) and subarachnoid hemorrhage (SAH) group (n=14). Pupil diameters were measured after giving 2 mL ofphysiological saline for sham and 2 ml non‑heparinized autologous arterial blood for the study group into the cisterna magna. Braindeath was diagnosed in 10 rabbits in the SAH group. Then all animals were sacrificed. The brains, oculomotor nerves of all animalswere extracted and stored in 10% formalin solutions for histopathological examination.Results:TThe mean neuron numbers of Edinger Westphal nucleus was 253±43/mm3 in the control group; 244±12/mm3 in the shamgroup and 236±12/mm3 in dead unresponsive animals. Pupil diameters and degenerated neuron density of EWN in control, shamand SAH groups were found as follows, respectively: 8960±990µm-3±1/mm3; 10543±1.123µm-13±4/mm3 and 13540±1.356µm63±11/mm3 (P