Creutzfeldt–Jakob Disease–Like Periodic Sharp Wave Complexes in Voltage-Gated Potassium Channel–Complex Antibodies Encephalitis

Abstract

Introduction Voltage-gated potassium channel-complex antibodies (VGKC-cAbs) encephalitis, a treatable autoantibody encephalopathy, has been previously reported to clinically mimic sporadic Creutzfeldt-Jacob disease (sCJD). Among available clinical clues to distinguish them, periodic sharp wave complexes (PSWC), a typical finding in sCJD, have never been reported in association with VGKC-cAbs encephalitis. Case presentation A 76 years old man was transferred to a tertiary neurology center with a clinical history of six-month weight loss, cognitive disturbance and non specific generalized weakness. He had two seizures the month before transfer and then evolved to severe encephalopathy, requiring mechanical ventilation. PSWC every 1–2 seconds over slowed background were found on EEG, and MRI showed cerebellar and bifrontal cortical T2/FLAIR/DWI hypersignal without restricted diffusion on ADC mapping. Pancorporal PET-scan was negative. An immunotherapy trial did not improve the patient condition. Therefore, he died after life support withdrawal. Brain autopsy revealed mononuclear neocortex infiltrate without significant spongiosis, and the anti-VGKC test showed a seropositivity of 336 pmol/L (normal: 0–31), three month after the patient deceased. Conclusion This is the first reported case of VGKC-cAbs encephalitis associated with PSWC on EEG, which further confuse the differential diagnosis with sCJD. However, the cortical DWI hypersignal without restriction seem to remain a way to discriminate these two entities appropriately, when present. These clues are of paramount importance since VGKC-cAbs encephalitis is a treatable disease.

Autoimmune encephalitis mimicking sporadic Creutzfeldt–Jakob disease: A retrospective study

“…However, PSWC can also occur in other rapidly progressive dementia like Alzheimer's disease and Vascular dementia (Steinhoff et al, 2004). There is a reported case of VGKC encephalitis presenting PSWC on EEG (Savard et al, 2016). This finding indicates that some cases involving PSWC may not be sCJD.…”

The importance of recognizing faciobrachial dystonic seizures in rapidly progressive dementias

“…Ancillary tests can be deceiving in CJD. For example, despite the specificity for sCJD, periodic sharp wave complexes were recently reported in a case of VGKC encephalitis 7 and can be present in patients with other etiologies (i.e. Alzheimer disease and vascular dementia).…”

EEG Differences in Two Clinically Similar Rapid Dementias: Voltage-Gated Potassium Channel Complex–Associated Autoimmune Encephalitis and Creutzfeldt-Jakob Disease

“…2,9 EEG findings in CJD are welldescribed, and include slowing of the background frequencies, FIRDA, and PSWCs. 2,5,[10][11][12][13] Conversely, EEG characteristics of VGKC AE are not well described but up to 85% are abnormal, 3 and they also have been noted to have diffuse slowing [14][15][16] and FIRDA. 4 Focal temporal lobe slowing or epileptiform discharges have been described as well 4,15,[17][18][19] and do feature in the diagnostic criteria for definite autoimmune limbic encephalitis.…”

“…21,23 Though PSWCs are considered specific for CJD, they can be seen in up to 10% of dementing illnesses, including VGKC AE. 2,9,14 Therefore, a better way to differentiate the cause of periodic discharges (PDs) in these conditions is needed.…”