Evaluation of pupil diameter for pain assessment in interventional headache management

Pain is a subjective experience. Besides, sensory, affective and behavioral responses, and autonomic response are part of pain response to noxious stimuli. Evaluation of pupil diameter by pupillometry has been used as an alternative method for pain assessment. In algologic procedures like interventional headache management have not been addressed in the literature. Herein, we investigated changes in pupil diameter during interventional headache management as an objective method for pain assessment.

Demographic data of the patients were collected before the bilateral major occipital nerve blockage (MONB) procedure. Numeric rating score (NRS) and pupil diameter measurements by pupillometer were recorded before MONB. Standard MONB procedure was applied to all patients. Pain assessment and pupillary diameter measurements were obtained after nerve blockage.

Twenty-eight patients were included in this study. Mean age was 41.03+-12.63 years. There is no difference between the hemodynamic parameters before and after the procedure. Post-procedure NRS and pupil diameter values were significantly lower than pre-procedure values. There was a positive correlation between changes in NRS scores and changes in the right and left pupil diameters.

There was a significant correlation between NRS score and pupil diameter in patients who underwent MONB. Monitoring of pupil diameter can be used for pain assessment during headache treatment. Evaluation of pupil diameter is a new approach in pain palliation. Future research is needed to study the effect of other parameters, that is, gender, age, origin of pain, acute, and chronic pain on pupil diameter and to evaluate its application in different algological procedures.