Potassium channel antibody associated encephalopathy presenting with a frontotemporal dementia like syndrome.
OBJECTIVE
To describe a patient who presented with features suggestive of frontotemporal dementia (FTD) but with some atypical findings and antibodies to neuronal voltage-gated potassium channels (VGKC-Abs).


METHODS
Case report.


METHODS
Mater Misericordiae University Hospital, Dublin, Ireland.


RESULTS
An 82-year-old man presented with progressive changes in personality, social conduct, and executive function with preservation of memory, deteriorating from baseline to requiring acute hospitalization within 6 months. Transient deterioration (episodic speech arrest) with spontaneous recovery, atypical for frontotemporal dementia, was observed. The patient had an elevated VGKC-Ab titer (2624 pM [normal range, < 100 pM]), elevated protein levels in cerebrospinal fluid, and a negative evaluation for malignancy. Magnetic resonance imaging of brain was normal but [(18)F]-fluorodeoxyglucose positron emission tomographic imaging revealed bifrontal hypometabolism. A marked and sustained improvement with steroid therapy was observed.


CONCLUSIONS
Workup for a potentially reversible autoimmune-mediated encephalopathy, including a VGKC-Ab titer, should be considered in patients presenting with rapidly progressive behavioral and cognitive decline.
McKeon
Andrew
A
Department of Neurology, Mater Misericordiae University Hospital, Dublin, Ireland. mckeon.andrew@mayo.edu
Marnane
Michael
M
O'connell
Martin
M
Stack
John P
JP
Kelly
Peter J
PJ
Lynch
Timothy
T
D000369:Aged, 80 and over; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001323:Autoantibodies / Q000276:immunology*; D001925:Brain Damage, Chronic / Q000188:drug therapy / Q000276:immunology* / Q000523:psychology*; D003704:Dementia / Q000523:psychology*; D003937:Diagnosis, Differential; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000276:immunology; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography; D024642:Potassium Channels, Voltage-Gated / Q000276:immunology*; D011239:Prednisolone / Q000627:therapeutic use; D019275:Radiopharmaceuticals
D000893:Anti-Inflammatory Agents; D001323:Autoantibodies; D024642:Potassium Channels, Voltage-Gated; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D011239:Prednisolone