Checkpoint: RNS and Blink Reflex: Deeper Understanding for the NCS Technologist-Dr. Divpreet Kaur Presentation

Dr. Divpreet Kaur Presentation

Pdf Summary

The blink reflex is a brainstem-mediated response assessed by stimulating the supraorbital branch of the ophthalmic division of the trigeminal nerve (CN V1) and recording activity in the orbicularis oculi muscles, supplied by the facial nerve (CN VII). Trigeminal sensory input reaches interneurons in the pons and lateral medulla, which activate the facial nuclei and produce a blink response.<br /><br />The reflex has two components: an early R1 response, which is ipsilateral to stimulation, and a later R2 response, which is bilateral. R1 is generally stable and reproducible, while R2 is typically more variable and polyphasic.<br /><br />For testing, the patient lies relaxed and supine. Responses are recorded simultaneously from both sides using electrodes over the inferior orbicularis oculi muscles, with reference electrodes near the lateral canthi and a ground electrode on the forehead or chin. The medial supraorbital ridge is stimulated, usually with supramaximal current of 15–25 mA. The shortest-latency, highest-amplitude response is recorded, allowing several seconds between stimuli to reduce habituation.<br /><br />The presentation outlines the anatomy and testing procedure but does not provide details of specific abnormal response patterns.

Keywords

blink reflex

brainstem

trigeminal nerve

facial nerve

orbicularis oculi

R1 response

R2 response

supraorbital stimulation

electromyography

EMG

neurological testing

pons

electrodiagnostic testing