Eyeing up the injured brain: automated pupillometry and optic nerve sheath diameter

Multimodal monitoring has emerged as a novel paradigm of care in acute brain injury, and in this context the value of noninvasive devices is increasingly under scrutiny. This narrative review summarizes recent clinical investigation focused on the role of automated infrared pupillometry (AIP) and optic nerve sheath diameter (ONSD) ultrasound as novel techniques to monitor and manage neurocritical care patients.

AIP provides a quantitative measurement of the pupillary light reflex that is more precise and reliable than the traditional examination of the pupillary light reflex using manual flashlight lamps. AIP helps detect raised intracranial pressure (ICP) and brain herniation in patients with intracranial mass lesions. Using an automatically computed scalar index - the neurological pupil index - AIP has great accuracy to predict poor neurological outcome in patients in coma after cardiac arrest. Recent data indicate that ONSD may diagnose intracranial hypertension with better accuracy than other ultrasound-based methods.

Noninvasive AIP and ONSD appear useful complements to multimodality monitoring of acute brain injury, in particular in patients at risk of elevated ICP and for early neuroprognostication following cardiac arrest.