GENERAL NEUROLOGY

• manual pupil measurements (performed using a penlight or ophthalmoscope) are subjective, inaccurate, and not repeatable or consistent
• Neurological Pupil index (NPi) provides a standardized, objective measure of pupillary reactivity
• requires specialized equipment – automated pupillometer (e.g., NeurOptics)
• low NPi scores are associated with poor neurological outcome in various conditions (e.g., traumatic brain injury, stroke, cardiac arrest,  status epilepticus)
  • the NPi and automated pupillometry have recently been included in the updated 2020 American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation (CPR) and Emergency Cardiovascular Care (ECC) as an object measurement supporting brain injury prognosis in patients following cardiac arrest  (Panchal, 2020)
• results may be affected by certain medications or eye conditions

• a patient’s pupil measurement is obtained using a pupillometer, and the measurement is compared against a normative model of pupil reaction to light and automatically graded by the NPi on a scale of 0 to 4.9
• a score equal to or above 3 means that the pupil measurement falls within the boundaries of normal pupil behavior as defined by the NPi
• a value closer to 4.9 is more normal data than a value closer to 3
• an NPi score below 3 means the reflex is abnormal, i.e., weaker than a normal pupil response, and values closer to 0 are more abnormal than values closer to 3
  • abnormal NPi (< 3) have higher mortality and worse short-term and long-term neurologic and functional outcomes as compared to those with normal NPi (≥ 3)  (Oddo, 2023)  (Jiang, 2023)
• a difference in NPi between right and left pupils of greater than or equal to 0.7 may also be considered an abnormal pupil reading

• monitoring intracranial pressure changes
• early detection of neurological deterioration
• assessing brainstem function in comatose patients
• evaluating the effectiveness of treatments and prognosis