A 64-year-old man developed cognitive dysfunction and generalized seizures, followed by episodes of transient speech and gait disturbances lasting several minutes, occurring multiple times per day; the events were not associated with any triggers. Neurologic examination during one of his episodic symptoms (video 1) showed transient ataxic dysarthria. Testing for neural autoantibodies revealed evidence of voltage-gated potassium channel complex antibodies by radioimmunoprecipitation assay; CASPR2-IgG was positive in serum and CSF by cell-based assay. Brain MRI was normal; CSF analysis showed an elevated protein level at 101 mg/dL, but it was otherwise normal. Oncologic evaluation was negative. The cognitive symptoms improved; seizures and episodic ataxia resolved after 12 weeks of treatment with IV methylprednisolone. Episodic ataxia is a manifestation of CASPR2 autoimmunity;1 patients can have normal MRI, and immunotherapy is beneficial.
Video 1
Neurologic examination of the patient showing transient ataxic dysarthria.Download Supplementary Video 1 via http://dx.doi.org/10.1212/000536_Video_1
Author contributions
A.S. Lopez-Chiriboga and S. Pittock contributed to the conception and design of the study; collection, analysis, and interpretation of the data; drafting and critical revision of the manuscript; and generation/collection of the figures. Both authors gave final approval of the manuscript.
Study funding
No targeted funding reported.
Disclosure
A.S. Lopez-Chiriboga reports no disclosures. S. Pittock has a patent pending for GFAP, Septin-5 and MAP1B autoantibodies as biomarkers of neurological autoimmumity; received research support from Grifols, MedImmune, Alexion, AEA, and NIH; had compensation for consulting activities paid to Mayo Clinic from Alexion and MedImmune; and has a financial interest with Mayo Clinic in patents that relate to functional AQP4/NMO-IgG assays and NMO-IgG as a cancer marker. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/NN.
Footnotes
The Article Processing Charge was funded by the authors.
Funding information and disclosures are provided at the end of the article. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/NN.
- Received September 27, 2018.
- Accepted in final form November 8, 2018.
- Copyright © 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.
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Reference
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