Creutzfeldt-Jakob Disease-Like Periodic Sharp Wave Complexes in Voltage-Gated Potassium Channel-Complex Antibodies Encephalitis: A Case Report

Clinical Use of Improved Diagnostic Testing for Detection of Prion Disease

Prion diseases are difficult to recognize as many symptoms are shared among other neurologic pathologies and the full spectra of symptoms usually do not appear until late in the disease course. Additionally, many commonly used laboratory markers are non-specific to prion disease. The recent introduction of second-generation real time quaking induced conversion (RT-QuIC) has revolutionized pre-mortem diagnosis of prion disease due to its extremely high sensitivity and specificity. However, RT-QuIC does not provide prognostic data and has decreased diagnostic accuracy in some rarer, atypical prion diseases. The objective of this review is to provide an overview of the current clinical utility of fluid-based biomarkers, neurodiagnostic testing, and brain imaging in the diagnosis of prion disease and to suggest guidelines for their clinical use, with a focus on rarer prion diseases with atypical features. Recent advancements in laboratory-based testing and imaging criteria have shown improved diagnostic accuracy and prognostic potential in prion disease, but because these diagnostic tests are not sensitive in some prion disease subtypes and diagnostic test sensitivities are unknown in the event that CWD transmits to humans, it is important to continue investigations into the clinical utility of various testing modalities.

Challenges and Advances in Antemortem Diagnosis of Human Transmissible Spongiform Encephalopathies

Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, arise from the structural conversion of the monomeric, cellular prion protein (PrPC) into its multimeric scrapie form (PrPSc). These pathologies comprise a group of intractable, rapidly evolving neurodegenerative diseases. Currently, a definitive diagnosis of TSE relies on the detection of PrPSc and/or the identification of pathognomonic histological features in brain tissue samples, which are usually obtained postmortem or, in rare cases, by brain biopsy (antemortem). Over the past two decades, several paraclinical tests for antemortem diagnosis have been developed to preclude the need for brain samples. Some of these alternative methods have been validated and can provide a probable diagnosis when combined with clinical evaluation. Paraclinical tests include in vitro cell-free conversion techniques, such as the real-time quaking-induced conversion (RT-QuIC), as well as immunoassays, electroencephalography (EEG), and brain bioimaging methods, such as magnetic resonance imaging (MRI), whose importance has increased over the years. PrPSc is the main biomarker in TSEs, and the RT-QuIC assay stands out for its ability to detect PrPSc in cerebrospinal fluid (CSF), olfactory mucosa, and dermatome skin samples with high sensitivity and specificity. Other biochemical biomarkers are the proteins 14-3-3, tau, neuron-specific enolase (NSE), astroglial protein S100B, α-synuclein, and neurofilament light chain protein (NFL), but they are not specific for TSEs. This paper reviews the techniques employed for definite diagnosis, as well as the clinical and paraclinical methods for possible and probable diagnosis, both those in use currently and those no longer employed. We also discuss current criteria, challenges, and perspectives for TSE diagnosis. An early and accurate diagnosis may allow earlier implementation of strategies to delay or stop disease progression.

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

Distinguishing treatable causes for rapidly progressive dementia from those that are incurable is vital. Creutzfeldt-Jakob disease (CJD) and voltage-gated potassium channel complex-associated autoimmune encephalitis (VGKC AE) are 2 such conditions with disparate outcomes and response to treatment. To determine the differences in electroencephalography between CJD and VGKC AE, we performed a retrospective review of medical records and examined clinical data, neuroimaging, and electroencephalographs performed in patients admitted for evaluation for rapidly progressive dementia diagnosed with CJD and VGKC AE at the Johns Hopkins Hospital and Bayview Medical Center between January 1, 2007 and December 31, 2015. More patients in the VGKC AE group had seizures (12/17) than those with CJD (3/14; P = .008). Serum sodium levels were lower in those with VGKC AE (P = .001). Cerebrospinal fluid (CSF) white blood cell count was higher in VGKC AE (P = .008). CSF protein 14-3-3 (P = .018) was more commonly detected in CJD, and tau levels were higher in those with CJD (P < .006). On neuroimaging, diffusion restriction in the cortex (P = .001), caudate (P < .001), and putamen (P = .001) was more frequent in CJD. Periodic sharp wave complexes (P = .001) and generalized suppressed activity (P = .008) were more common on initial EEG in CJD. On serial EEGs, generalized periodic discharges (P = .004), generalized suppressed activity (P=0.008), and periodic sharp wave complexes (P < .001) were detected more in CJD. This study shows that there are a number of differentiating features between CJD and VGKC AE, and electroencephalography can aid in their diagnoses. Performing serial EEGs better delineates these conditions.

Differential diagnosis with other rapid progressive dementias in human prion diseases

Prion diseases are unique in medicine as in humans they occur in sporadic, genetic, and acquired forms. The most common human prion disease is sporadic Creutzfeldt-Jakob disease (CJD), which commonly presents as a rapidly progressive dementia (RPD) with behavioral, cerebellar, extrapyramidal, and some pyramidal features, with the median survival from symptom onset to death of just a few months. Because human prion diseases, as well as other RPDs, are relatively rare, they can be difficult to diagnose, as most clinicians have seen few, if any, cases. Not only can prion diseases mimic many other conditions that present as RPD, but some of those conditions can present similarly to prion disease. In this article, the authors discuss the different etiologic categories of conditions that often present as RPD and also present RPDs that had been misdiagnosed clinically as CJD. Etiologic categories of conditions are presented in order of the mnemonic used for remembering the various categories of RPDs: VITAMINS-D, for vascular, infectious, toxic-metabolic, autoimmune, mitochondrial/metastases, iatrogenic, neurodegenerative, system/seizures/sarcoid, and demyelinating. When relevant, clinical, imaging, or other features of an RPD that overlap with those of CJD are presented.

The importance of recognizing faciobrachial dystonic seizures in rapidly progressive dementias

BACKGROUND

Creutzfeldt-Jakob Disease (CJD) is the prototypical cause of rapidly progressive dementia (RPD). Nonetheless, efforts to exclude reversible causes of RPD that mimic prion disease are imperative. The recent expanding characterization of neurological syndromes associated with antibodies directed against neuronal cell surface or sympathic antigens, namely autoimmune encephalitis is shifting paradigms in neurology. Such antigens are well known proteins and receptors involved in synaptic transmission. Their dysfunction results in neuropsychiatric symptoms, psychosis, seizures, movement disorders and RPD. Faciobrachial dystonic seizure (FBDS) is a novel characterized type of seizure, specific for anti-LGI1 encephalitis.

OBJECTIVE

In order to improve clinical recognition we report the cases of two Brazilian patients who presented with characteristic FDBS (illustrated by videos) and anti-LGI1 encephalitis.

METHODS

We have included all patients with FBDS and confirmed anti-LGI1 encephalitis and video records of FDBS in two tertiary Brazilian centers: Department of Neurology of Hospital das Clínicas, Sao Paulo University, Sao Paulo, Brazil and Hospital Geral de Fortaleza, Fortaleza, Brazil between January 1, 2011 and December 31, 2015.

RESULTS

Both patients presented with clinical features of limbic encephalitis associated with FBDS, hyponatremia and normal CSF. None of them presented with tumor and both showed a good response after immunotherapy.

CONCLUSION

FBDSs may be confounded with myoclonus and occurs simultaneously with rapid cognitive decline. Unawareness of FDBS may induce to misdiagnosing a treatable cause of RPD as CJD.

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

Autoimmune encephalitis associated with anti-voltage-gated potassium channel antibodies are most likely to be misdiagnosed as sporadic Creutzfeldt-Jakob disease (sCJD). Our goal was to delineate patients who were initially suspected to have CJD but were later found to have AE. We performed a retrospective clinical review of cases of individuals and made a comparison between groups of patients diagnosed with sCJD and AE. Patients who had rapidly progressing dementia and focal neurological impairment, such as aphasia, gait disturbance, visual disturbance, and depression, at onset were diagnosed with sCJD, whereas epilepsy, hyponatremia and dysautonomia were strong hints for AE. Fluoroscope-positron emission tomography (PET) of patients with AE revealed variable metabolism and normative and long-term immunosuppression were less likely to relapse.