Quantitative Infrared Pupillometry in Nonconvulsive Status Epilepticus.

Area of Science:

• Neuroscience
• Critical Care Medicine
• Ophthalmology

Background:

• Nonconvulsive status epilepticus (NCSE) is a common yet challenging diagnosis in neurocritical care settings.
• Pupil function alterations are observed in NCSE patients, but their variability complicates diagnosis.
• Infrared pupillometry offers a sensitive method to detect subtle changes in pupil function, with the neurological pupil index (NPi) serving as a potential global marker.

Purpose of the Study:

• To investigate whether the neurological pupil index (NPi) is altered in patients with nonconvulsive status epilepticus (NCSE).
• To evaluate the diagnostic utility of NPi parameters in identifying NCSE.

Main Methods:

• A cross-sectional observational study involving 103 adult emergency patients with suspected seizures and EEG indication for NCSE exclusion.
• Pupillometry was performed before EEG recording, and NCSE diagnosis was established using Salzburg consensus criteria.
• Statistical analysis included group comparisons of NPi values (right, left, minNPi, diffNPi) and receiver operating characteristic (ROC) analysis for diagnostic cut-offs.

Main Results:

• Significantly lower NPi values (right, left, minNPi) and a higher difference between left and right NPi (diffNPi) were observed in patients with confirmed or possible NCSE compared to those without NCSE.
• ROC analysis identified optimal cut-offs: minNPi of 4.0 (AUC=0.93) and diffNPi of 0.2 (AUC=0.89) for NCSE diagnosis.
• No significant difference in minNPi or diffNPi was found between confirmed and possible NCSE groups.

Conclusions:

• Reduced NPi and increased inter-pupil NPi difference are significant indicators in confirmed NCSE.
• NPi values below 4.0 or an NPi difference greater than 0.2 may serve as potential diagnostic markers for NCSE.
• Infrared pupillometry, using NPi, shows promise as a valuable tool for NCSE assessment, warranting further investigation in larger cohorts.