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Isaac Syndrome — SCE Neurology MCQ

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HardClinical NeurophysiologyIsaac SyndromeSCE Neurology

A patient has continuous muscle-fibre activity, stiffness, cramps, myokymia and neuromyotonic discharges; CASPR2 antibodies are positive. Which diagnosis is most likely?

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Correct answer: C — Acquired neuromyotonia (Isaacs syndrome), given the imaging pattern

The best answer is “Acquired neuromyotonia (Isaacs syndrome), given the imaging pattern”. Peripheral nerve hyperexcitability with neuromyotonic discharges and CASPR2 antibodies defines autoimmune acquired neuromyotonia. “Stiff-person syndrome” can be reasonable in another presentation, but it does not account for the defining feature here. “Myotonic dystrophy type 2” can be reasonable in another presentation, but it does not account for the defining feature here. “Brody disease” can be reasonable in another presentation, but it does not account for the defining feature here. “Motor neurone disease” can be reasonable in another presentation, but it does not account for the defining feature here.

Reference: European guideline for autoimmune peripheral nerve hyperexcitability: https://pubmed.ncbi.nlm.nih.gov/38448130/