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Epilepsy Surgery – Wada Test — SCE Neurology MCQ

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HardClinical NeurophysiologyEpilepsy Surgery – Wada TestSCE Neurology

A commercial paraneoplastic line blot reports low-positive Yo and SOX1 bands in a man with subacute ataxia, normal CSF and no cancer found on initial imaging. The phenotype is not typical for either antibody. What is the most defensible next laboratory step before antibody-directed treatment?

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Correct answer: E — Confirm paired serum and CSF using an independent method

Explanation lettering: D = shown as A · C = shown as B · B = shown as C · A = shown as D

E is correct: commercial line blots generate clinically important false positives, especially low-intensity results that do not fit the phenotype. Unexpected findings should be confirmed in a reference laboratory using an independent assay, ideally with paired serum and CSF and appropriate tissue-based testing. A second band does not rescue a poorly fitting result. Repeating the identical method reproduces its limitations. CSF alone on the same platform is not genuinely independent, while dismissing the results without confirmation or proportionate tumour follow-up is also unsafe.

Reference: Paraneoplastic neurological syndromes: a practical approach: https://pn.bmj.com/content/22/1/19