2026 Workshop Handout Bundle-W134G - Stimulated Jitter Analysis in Children

W134G - Stimulated Jitter Analysis in Children - Sakonju Verma

Pdf Summary

Stimulated jitter analysis (stim-JA) using a concentric needle electrode is a sensitive electrodiagnostic method for assessing neuromuscular junction (NMJ) disorders. It is particularly useful in children, who may have difficulty maintaining the steady voluntary muscle activation required for conventional jitter testing.<br /><br />The procedure is performed with the child awake and supine. A stimulating electrode is placed above the zygomatic arch to activate the facial nerve, and apparent single-fiber action potentials (ASFAPs) are recorded from the ipsilateral orbicularis oculi muscle with a concentric needle electrode. The examiner measures jitter—the variation in timing between successive ASFAPs—and assesses blocking, while also evaluating muscle activity for signs of neuropathy or myopathy. Careful technique is important: movement, inadequate stimulation, and poor signal selection can affect results.<br /><br />Adult upper limits for orbicularis oculi jitter are 36 μs for individual mean consecutive difference (MCD) values and 24 μs for the mean MCD. Limited pediatric data suggest abnormality when at least two ASFAPs exceed 39 μs and the mean MCD exceeds 24 μs.<br /><br />Stim-JA can help confirm suspected NMJ disease, including myasthenia gravis, congenital myasthenic syndromes, and infant botulism. A case example demonstrates markedly increased jitter and blocking in a child with a congenital myasthenic syndrome. The test is generally well tolerated and provides results promptly. Serial measurements may also help monitor disease severity and response to treatment, making stim-JA a potential neurophysiological biomarker for pediatric NMJ disorders.

Keywords

stimulated jitter analysis

stim-JA

concentric needle electrode

neuromuscular junction disorders

orbicularis oculi

jitter measurement

single-fiber action potentials

myasthenia gravis

congenital myasthenic syndromes

pediatric electrodiagnosis