Supratentorial intracerebral hemorrhage volume and other CT variables predict the neurological pupil index

•ICH volume and shift of midline structures correlate with the NPi.•Intracerebral hemorrhage volume predicts the NPi.•Certain CT markers of ICH severity are independent predictors of NPi.•There are differences between the pupil contralateral and ipsilateral to ICH in predicting NPi. There is growing interest in the ability of automated infrared pupillometry to assess severity of neurological illness. We studied the correlation between computed tomography (CT) indicators of intracerebral hemorrhage (ICH) severity with objective measures of the pupillary light reflex (PLR), and hypothesized that hemorrhage volume would predict the Neurological Pupil index™ (NPi™), an indicator of pupillary reactivity. This study examined data from patients with supratentorial ICH who underwent serial pupillometer evaluations. CT images were examined to determine the location and laterality of the hemorrhage, along with hematoma volume (using the simplified ABC/2 method), midline shift, hydrocephalus score, and modified Graeb score (indicating interventricular hemorrhage). Demographics were examined with standard measures of central tendency, hypotheses with logistic regression, categorical data with Fisher’s Exact X2, and multivariate modeling with constructed MAX-R models. Data were gathered from 44 subjects. ICH volume exhibited the strongest correlation with NPi (ipsilateral [r2 = 0.48, p < 0.0001, contralateral [(r2 = 0.39, p < 0.0001]). Horizontal midline shift of the septum pellucidum also correlated with NPi (ipsilateral [r2 = 0.25, p = 0.0006], contralateral [r2 = 0.15, p = 0.0106]), as did shift of the pineal gland (ipsilateral [r2 = 0.21, p = 0.0017], contralateral[r2 = 0.11, p = 0.0328]). ICH volume was the most predictive of abnormal NPi (AUC = 0.85 for ipsilateral and 0.88 for contralateral NPi), and multivariate modeling identified additional independent predictors of NPi. ICH volume and shift of midline structures correlate with NPi, and abnormalities in NPi can be predicted by hematoma volume and other CT indicators of ICH severity. Future studies should explore the role of NPi in detecting early hematoma expansion and worsening midline shift.