Epilepsy and prion diseases: A narrative review

Probable Sporadic Creutzfeldt-Jakob Disease Presenting as Refractory Status Epilepticus in a Poststroke Epilepsy Patient: A Case Report

In this study, we report on a case of probable sporadic Creutzfeldt-Jakob disease (sCJD) diagnosed after a difficult course of status epilepticus (SE) in a patient with poststroke epilepsy. The patient was admitted with progressive cognitive decline and convulsive SE; therefore, it was initially thought that the patient had developed SE due to nonadherence to antiseizure medication (ASM) use, but despite treatment with ASMs after admission, no improvement was noted in consciousness disturbance or lateralized periodic discharges (LPDs) on electroencephalogram (EEG) examination. After a refractory course, the progression of LPDs to generalized periodic discharges (GPDs) on EEG and abnormal magnetic resonance imaging (MRI) findings met the diagnostic criteria of sCJD. Even if the patient had epilepsy, such as poststroke epilepsy, as in this case, it is essential to consider other underlying causes, including CJD in cases of superrefractory SE.

The advances in the early and accurate diagnosis of Creutzfeldt-Jakob disease and other prion diseases: where are we today?

INTRODUCTION

Before the introduction of MRI diffusion-weighted images (DWI), the diagnosis of Creutzfeldt-Jakob disease (CJD) relied upon nonspecific findings including clinical symptoms, EEG abnormalities, and elevated levels of cerebrospinal fluid 14-3-3 protein. Subsequently, the use of DWI has improved diagnostic accuracy, but it sometimes remains difficult to differentiate CJD from encephalitis, epilepsy, and other dementing disorders. The revised diagnostic criteria include real-time quaking-induced conversion (RT-QuIC), detecting small amounts of CJD-specific prion protein, and clinically sensitive DWI. Combining these techniques has further improved diagnostic accuracy, enabling earlier diagnosis.

AREAS COVERED

Herein, the authors review the recent advances in diagnostic methods and revised diagnostic criteria for sporadic CJD. They also discuss other prion diseases, such as variant CJD and chronic wasting disease, where the emergence of new types is a concern.

EXPERT OPINION

Despite improvements in diagnostic methods and criteria, some subtypes of prion disease are still difficult to diagnose, and even the diagnosis using the most innovative RT-QuIC test remains a challenge in terms of accuracy and standardization. However, these revised criteria can be adapted to the emergence of new types of prion diseases. It is essential to continue careful surveillance and update information on the latest prion disease phenotypes.

[A case of Creutzfeldt-Jakob disease presenting with nonconvulsive status epilepticus in the early stages]

A 64-year-old Japanese woman presented with 1 week of recurrent convulsive seizures. At the time of admission, she was in a coma and did not present with convulsions. Intravenous diazepam administration improved her consciousness, although severe psychomotor excitement developed. Brain MRI demonstrated diffusion restriction in the cerebral cortex of the right hemisphere. Electroencephalography (EEG) showed periodic discharges centered around the parietal regions with right-sided dominance. Nonconvulsive status epilepticus (NCSE) was suspected, and the patient was actively treated with anti-epileptic drugs. She developed akinetic mutism and generalized myoclonus 1 month after admission. Follow-up EEG studies disclosed periodic synchronous discharges. Abnormal prion protein in the cerebral fluid was detected using a real-time quaking-induced conversion assay. The clinical diagnosis in the present case was sporadic Creutzfeldt-Jakob disease (CJD). Seizures as an initial symptom in patients with CJD are relatively rare. Our case suggests that CJD should be considered as a differential diagnosis when a patient presents with refractory NCSE.

Neuronal excitatory-to-inhibitory balance is altered in cerebral organoid models of genetic neurological diseases

The neuro-physiological properties of individuals with genetic pre-disposition to neurological disorders are largely unknown. Here we aimed to explore these properties using cerebral organoids (COs) derived from fibroblasts of individuals with confirmed genetic mutations including PRNP^E200K, trisomy 21 (T21), and LRRK2^G2019S, which are associated with Creutzfeldt Jakob disease, Down Syndrome, and Parkinson's disease. We utilized no known disease/healthy COs (HC) as normal function controls. At 3-4 and 6-10 months post-differentiation, COs with mutations showed no evidence of disease-related pathology. Electrophysiology assessment showed that all COs exhibited mature neuronal firing at 6-10 months old. At this age, we observed significant changes in the electrophysiology of the COs with disease-associated mutations (dCOs) as compared with the HC, including reduced neuronal network communication, slowing neuronal oscillations, and increased coupling of delta and theta phases to the amplitudes of gamma oscillations. Such changes were linked with the detection of hypersynchronous events like spike-and-wave discharges. These dysfunctions were associated with altered production and release of neurotransmitters, compromised activity of excitatory ionotropic receptors including receptors of kainate, AMPA, and NMDA, and changed levels and function of excitatory glutamatergic synapses and inhibitory GABAergic synapses. Neuronal properties that modulate GABAergic inhibition including the activity of Na-K-Cl cotransport 1 (NKCC1) in Cl^- homeostasis and the levels of synaptic and extra-synaptic localization of GABA receptors (GABARs) were altered in the T21 COs only. The neurosteroid allopregnanolone, a positive modulator of GABARs, was downregulated in all the dCOs. Treatment with this neurosteroid significantly improved the neuronal communication in the dCOs, possibly through improving the GABAergic inhibition. Overall, without the manifestation of any disease-related pathology, the genetic mutations PRNP^E200K, T21, and LRRK2^G2019S significantly altered the neuronal network communication in dCOs by disrupting the excitatory-to-inhibitory balance.