Checkpoint: RNS and Blink Reflex: Deeper Understanding for the NCS Technologist-Session recording

Video Transcription

Video Summary

The session focused on the “deeper understanding” of repetitive nerve stimulation (RNS) and blink-reflex testing: understanding not only how to perform each study, but why, to improve accuracy and efficiency.<br /><br />For RNS, Dr. Bandy reviewed testing for myasthenia gravis and Lambert–Eaton myasthenic syndrome, emphasizing medication review, warming, suitable nerve–muscle selection, immobilization, supramaximal stimulation, and slow stimulation rates. He explained how presynaptic and postsynaptic disorders affect responses differently, why baseline CMAP amplitude and post-exercise changes matter, and how technical errors can create misleading results. RNS has limited sensitivity, especially in ocular myasthenia; single-fiber EMG is more sensitive but does not distinguish these disorders.<br /><br />Dr. Kaur explained blink-reflex pathways: trigeminal sensory input and facial motor output. R1 is an early, usually stable response on the stimulated side; R2 is a later, variable, bilateral response that can habituate. Response patterns can help localize trigeminal, facial, brainstem, or generalized demyelinating abnormalities. Blink-reflex testing offers localization beyond a routine facial motor study, though it is not routinely used to assess CIDP or autonomic neuropathy.<br /><br />The demonstrations showed practical electrode placement and stimulation for RNS and blink reflex. Presenters stressed careful interpretation, adequate intervals between blink stimuli, and attention to artifacts, movement, and co-stimulation.

Keywords

repetitive nerve stimulation

RNS

blink reflex testing

myasthenia gravis

Lambert-Eaton myasthenic syndrome

single-fiber EMG

CMAP amplitude

presynaptic disorder

postsynaptic disorder

trigeminal nerve

facial nerve

brainstem localization

neuromuscular junction

nmj

electrode placement

nerve conduction study

ncs

ncv