A Case of Decreased Neurological Pupil Index with No Change in rSO₂ during Selective Cerebral Perfusion

Abstract

We encountered a patient whose Neurological Pupil index（NPi）decreased to zero without change in rSO₂ when perfusion in the left subclavian artery was stopped for anastomosis during selective cerebral perfusion. INVOS^TM（Covidien, Boulder, CO, US）is mainly attached on the forehead and rSO₂ represents the local oxygen saturation. Because of these characteristics, it is reportedly unsuitable for detecting decreased perfusion in the basilar artery region. In contrast, NPi, an independent indicator of a pupil recorder（NPi^®-200, NeuroOptics）, objectively evaluates the pupillary light reflex and represents the function of the brain stem through the cranial nerves II and III. In the present case, stenosis of the right vertebral artery was originally present. Perfusion of the basilar artery was believed to have decreased when perfusion of the left subclavian artery was stopped for anastomosis. At that time, only NPi decreased. We report that NPi could be used to monitor perfusion of the basilar artery region.