Creutzfeldt-Jakob disease in a man surviving COVID-19: disentangling a casual or causal association by neuropathology.

BACKGROUND: Literature reporting the onset of Creutzfeldt-Jakob disease (CJD) immediately after COVID-19 infection has strengthened a possible causal link between infection and neurodegeneration. Here, we report a novel case undergoing detailed neuropathological assessment. CASE REPORT: Two months after he had contracted SARS-CoV-2 infection, a 54-year-old man manifested a subacute onset of ataxia, headache, anosmia, and hallucinations, followed by rapidly progressive cognitive decline. Electroencephalography documented unspecific slowing with periodic polyphasic delta waves. Brain MRI showed hyperintensities of basal ganglia and thalami on DWI/FLAIR. CSF tested positive for the 14-3-3 protein, and prion seeding activity was demonstrated by the real-time quaking-induced conversion assay. The patient died 2 months after the neurologic onset. The neuropathological examination confirmed the diagnosis of CJD and ruled out COVID-19-related encephalitis. DISCUSSION: To disentangle the link between COVID-19 infection and CJD, neuropathology is essential determining the extent of changes related to both conditions. In our patient, we did not find any specific abnormality related to COVID-19. Our conclusion is in line with the current worldwide epidemiological data that do not show an increase in CJD cases since the beginning of the COVID-19 pandemic.

Rapidly progressive dementia due to intravascular lymphoma: A prion disease reference center experience.

BACKGROUND: Intravascular large B-cell lymphoma (IVLBCL) is a rare extranodal lymphoma that is characterized by the selective growth of neoplastic cells in blood vessels, representing a potentially treatable cause of rapidly progressive dementia (RPD). Given its diverse clinical and instrumental presentation, it is often misdiagnosed with more common RPD causes, for example, Creutzfeldt-Jakob disease (CJD) or vascular dementia. METHODS: This study presents the clinical and histopathological characteristics of four IVLBCL cases that we diagnosed post-mortem over 20 years among over 600 brain samples received as suspected CJD cases at our prion disease reference center. RESULTS: Our patients exhibited various presenting symptoms, including behavioral disturbances, disorientation, and alertness fluctuations. The diagnostic tests performed at the time, including blood work, cerebrospinal fluid (CSF) analyses, electroencephalography, and neuroimaging, yielded nonspecific and occasionally misleading results. Consequently, the patients were repeatedly diagnosed as variably having CJD, epilepsy, vascular dementia, and encephalitis. The stored CSF samples of two patients tested negative at prion real-time quaking-induced conversion (RT-QuIC), which we performed afterwards for research purposes. Neuropathological analysis revealed a differential involvement of various brain areas, with frontotemporal neocortices being the most affected. CONCLUSIONS: Our results confirm the significant clinical and instrumental heterogeneity of IVLBCL. Neuropathological evidence of the preferential involvement of frontotemporal neocortices, potentially conditioning the clinical phenotype, could be relevant to reach an early diagnosis. Finally, given the therapeutic implications of its misdiagnosis with CJD, we emphasize the utility of prion RT-QuIC as a test for ruling out CJD in these patients.

Misfolded α-Synuclein Assessment in the Skin and CSF by RT-QuIC in Isolated REM Sleep Behavior Disorder.

BACKGROUND AND OBJECTIVES: Real-time quaking-induced conversion (RT-QuIC) assay detects misfolded α-synuclein (AS) in the skin and CSF of patients with the synucleinopathies Parkinson disease and dementia with Lewy bodies. Isolated REM sleep behavior disorder (IRBD) constitutes the prodromal stage of these synucleinopathies. We aimed to compare the ability of RT-QuIC to identify AS in the skin and CSF of patients with IRBD. METHODS: This was a cross-sectional study where consecutive patients with polysomnographic-confirmed IRBD and age-matched controls without RBD underwent skin biopsy and lumbar puncture the same day. Three-millimeter skin punch biopsies were obtained bilaterally in the cervical region from dorsal C7 and C8 dermatomes and in distal legs. RT-QuIC assessed AS in these 6 skin sites and the CSF. RESULTS: We recruited 91 patients with IRBD and 41 controls. In the skin, sensitivity to detect AS was 76.9% (95% CI 66.9-85.1), specificity 97.6% (95% CI 87.1-99.9) positive predictive value 98.6% (95% CI 91.0-99.8), negative predictive value 65.6% (95% CI 56.6-73.6), and accuracy 83.3% (95% CI 75.9-89.3). In the CSF, the sensitivity was 75.0% (95% CI 64.6-83.6), the specificity was 97.5% (95% CI 86.8-99.9), the positive predictive value was 98.5% (95% CI 90.5-99.8), the negative predictive value was 63.9% (95% CI 55.2-71.9), and the accuracy was 82.0% (95% CI 74.3-88.3). Results in the skin and CSF samples showed 99.2% agreement. Compared with negative patients, RT-QuIC AS-positive patients had a higher likelihood ratio of prodromal Parkinson disease (p < 0.001) and showed more frequently hyposmia (p < 0.001), dopamine transporter imaging single-photon emission CT deficit (p = 0.002), and orthostatic hypotension (p = 0.014). No severe or moderate adverse effects were reported. There was no difference between the percentage of participants reporting mild adverse events secondary to skin biopsy or lumbar puncture (9.1% vs 17.2%; p = 0.053). One hundred and ten (83%) and 104 (80%) participants, respectively, stated they would accept to undergo skin biopsy and lumbar puncture again for research purposes. DISCUSSION: Our study in IRBD shows that (1) RT-QuIC detects AS in the skin and CSF with similar high sensitivity, specificity, and agreement, (2) AS RT-QuIC positivity is associated with supportive features and biomarkers of synucleinopathy, and (3) skin punch biopsy and lumbar puncture have comparable mild adverse effects, tolerance, and acceptance. RT-QuIC in the skin or CSF might represent a patient selection strategy for future neuroprotective trials targeting AS in IRBD. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that RT-QuIC-detected AS in the skin and CSF distinguishes patients with IRBD from controls.

In vivo assessment of Lewy body and beta-amyloid copathologies in idiopathic normal pressure hydrocephalus: prevalence and associations with clinical features and surgery outcome.

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is a clinico-radiological syndrome of elderly individuals likely sustained by different neurodegenerative changes as copathologies. Since iNPH is a potentially reversible condition, assessing neurodegenerative pathologies in vitam through CSF biomarkers and their influence on clinical features and surgical outcome represents crucial steps. METHODS: We measured α-synuclein seeding activity related to Lewy body (LB) pathology by the real-time quaking-induced conversion assay (RT-QuIC) and Alzheimer disease core biomarkers (proteins total-tau, phospho-tau, and amyloid-beta) by immunoassays in the cerebrospinal fluid (CSF) of 293 iNPH patients from two independent cohorts. To compare the prevalence of LB copathology between iNPH participants and a control group representative of the general population, we searched for α-synuclein seeding activity in 89 age-matched individuals who died of Creutzfeldt-Jakob disease (CJD). Finally, in one of the iNPH cohorts, we also measured the CSF levels of neurofilament light chain protein (NfL) and evaluated the association between all CSF biomarkers, baseline clinical features, and surgery outcome at 6 months. RESULTS: Sixty (20.5%) iNPH patients showed α-synuclein seeding activity with no significant difference between cohorts. In contrast, the prevalence observed in CJD was only 6.7% (p = 0.002). Overall, 24.0% of iNPH participants showed an amyloid-positive (A+) status, indicating a brain co-pathology related to Aß deposition. At baseline, in the Italian cohort, α-synuclein RT-QuIC positivity was associated with higher scores on axial and upper limb rigidity (p = 0.003 and p = 0.011, respectively) and lower MMSEc scores (p = 0.003). A+ patients showed lower scores on the MMSEc (p = 0.037) than A- patients. Higher NfL levels were also associated with lower scores on the MMSEc (rho = -0.213; p = 0.021). There were no significant associations between CSF biomarkers and surgical outcome at 6 months (i.e. responders defined by decrease of 1 point on the mRankin scale). CONCLUSIONS: Prevalent LB- and AD-related neurodegenerative pathologies affect a significant proportion of iNPH patients and contribute to cognitive decline (both) and motor impairment (only LB pathology) but do not significantly influence the surgical outcome at 6 months. Their effect on the clinical benefit after surgery over a more extended period remains to be determined.

Prevalence Estimates of Amyloid Abnormality Across the Alzheimer Disease Clinical Spectrum.

IMPORTANCE: One characteristic histopathological event in Alzheimer disease (AD) is cerebral amyloid aggregation, which can be detected by biomarkers in cerebrospinal fluid (CSF) and on positron emission tomography (PET) scans. Prevalence estimates of amyloid pathology are important for health care planning and clinical trial design. OBJECTIVE: To estimate the prevalence of amyloid abnormality in persons with normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia and to examine the potential implications of cutoff methods, biomarker modality (CSF or PET), age, sex, APOE genotype, educational level, geographical region, and dementia severity for these estimates. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional, individual-participant pooled study included participants from 85 Amyloid Biomarker Study cohorts. Data collection was performed from January 1, 2013, to December 31, 2020. Participants had normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia. Normal cognition and subjective cognitive decline were defined by normal scores on cognitive tests, with the presence of cognitive complaints defining subjective cognitive decline. Mild cognitive impairment and clinical AD dementia were diagnosed according to published criteria. EXPOSURES: Alzheimer disease biomarkers detected on PET or in CSF. MAIN OUTCOMES AND MEASURES: Amyloid measurements were dichotomized as normal or abnormal using cohort-provided cutoffs for CSF or PET or by visual reading for PET. Adjusted data-driven cutoffs for abnormal amyloid were calculated using gaussian mixture modeling. Prevalence of amyloid abnormality was estimated according to age, sex, cognitive status, biomarker modality, APOE carrier status, educational level, geographical location, and dementia severity using generalized estimating equations. RESULTS: Among the 19 097 participants (mean [SD] age, 69.1 [9.8] years; 10 148 women [53.1%]) included, 10 139 (53.1%) underwent an amyloid PET scan and 8958 (46.9%) had an amyloid CSF measurement. Using cohort-provided cutoffs, amyloid abnormality prevalences were similar to 2015 estimates for individuals without dementia and were similar across PET- and CSF-based estimates (24%; 95% CI, 21%-28%) in participants with normal cognition, 27% (95% CI, 21%-33%) in participants with subjective cognitive decline, and 51% (95% CI, 46%-56%) in participants with mild cognitive impairment, whereas for clinical AD dementia the estimates were higher for PET than CSF (87% vs 79%; mean difference, 8%; 95% CI, 0%-16%; P = .04). Gaussian mixture modeling-based cutoffs for amyloid measures on PET scans were similar to cohort-provided cutoffs and were not adjusted. Adjusted CSF cutoffs resulted in a 10% higher amyloid abnormality prevalence than PET-based estimates in persons with normal cognition (mean difference, 9%; 95% CI, 3%-15%; P = .004), subjective cognitive decline (9%; 95% CI, 3%-15%; P = .005), and mild cognitive impairment (10%; 95% CI, 3%-17%; P = .004), whereas the estimates were comparable in persons with clinical AD dementia (mean difference, 4%; 95% CI, -2% to 9%; P = .18). CONCLUSIONS AND RELEVANCE: This study found that CSF-based estimates using adjusted data-driven cutoffs were up to 10% higher than PET-based estimates in people without dementia, whereas the results were similar among people with dementia. This finding suggests that preclinical and prodromal AD may be more prevalent than previously estimated, which has important implications for clinical trial recruitment strategies and health care planning policies.

Detection of prions in skin punch biopsies of Creutzfeldt-Jakob disease patients.

Prion real-time quaking-induced conversion (RT-QuIC) is an ultrasensitive assay detecting pathological aggregates of misfolded prion protein in biospecimens. We studied 71 punch biopsy skin samples of 35 patients with Creutzfeldt-Jakob disease (CJD), including five assessed in vitam. The results confirmed the high value of skin prion RT-QuIC for CJD diagnosis (89% sensitivity and 100% specificity) and support its use in clinical practice. Preliminary data based on a limited number of cases suggest that prion-seeding activity in the skin varies according to the prion strain, being higher in sporadic CJD subtypes linked to the V2 strain (VV2 and MV2K) than in typical CJDMM1.

Recent advances in the histo-molecular pathology of human prion disease.

Prion diseases are progressive neurodegenerative disorders affecting humans and other mammalian species. The term prion, originally put forward to propose the concept that a protein could be infectious, refers to PrPSc , a misfolded isoform of the cellular prion protein (PrPC ) that represents the pathogenetic hallmark of these disorders. The discovery that other proteins characterized by misfolding and seeded aggregation can spread from cell to cell, similarly to PrPSc , has increased interest in prion diseases. Among neurodegenerative disorders, however, prion diseases distinguish themselves for the broader phenotypic spectrum, the fastest disease progression and the existence of infectious forms that can be transmitted through the exposure to diseased tissues via ingestion, injection or transplantation. The main clinicopathological phenotypes of human prion disease include Creutzfeldt-Jakob disease, by far the most common, fatal insomnia, variably protease-sensitive prionopathy, and Gerstmann-Sträussler-Scheinker disease. However, clinicopathological manifestations extend even beyond those predicted by this classification. Because of their transmissibility, the phenotypic diversity of prion diseases can also be propagated into syngenic hosts as prion strains with distinct characteristics, such as incubation period, pattern of PrPSc distribution and regional severity of histopathological changes in the brain. Increasing evidence indicates that different PrPSc conformers, forming distinct ordered aggregates, encipher the phenotypic variants related to prion strains. In this review, we summarize the most recent advances concerning the histo-molecular pathology of human prion disease focusing on the phenotypic spectrum of the disease including co-pathologies, the characterization of prion strains by experimental transmission and their correlation with the physicochemical properties of PrPSc aggregates.

Prion-related peripheral neuropathy in sporadic Creutzfeldt-Jakob disease.

OBJECTIVE: To assess whether the involvement of the peripheral nervous system (PNS) belongs to the phenotypic spectrum of sporadic Creutzfeldt-Jakob disease (sCJD). METHODS: We examined medical records of 117 sCJDVV2 (ataxic type), 65 sCJDMV2K (kuru-plaque type) and 121 sCJDMM(V)1 (myoclonic type) subjects for clinical symptoms, objective signs and neurophysiological data. We reviewed two diagnostic nerve biopsies and looked for abnormal prion protein (PrPSc) by western blotting and real-time quaking-induced conversion (RT-QuIC) in postmortem PNS samples from 14 subjects. RESULTS: Seventy-five (41.2%) VV2-MV2K patients, but only 11 (9.1%) MM(V)1, had symptoms or signs suggestive of PNS involvement occurring at onset in 18 cases (17 VV2-MV2K, 9.3%; and 1 MM(V)1, 0.8%) and isolated in 6. Nerve biopsy showed a mixed predominantly axonal and demyelinating neuropathy in two sCJDMV2K. Electromyography showed signs of neuropathy in half of the examined VV2-MV2K patients. Prion RT-QuIC was positive in all CJD PNS samples, whereas western blotting detected PrPSc in the sciatic nerve in one VV2 and one MV2K. CONCLUSIONS: Peripheral neuropathy, likely related to PrPSc deposition, belongs to the phenotypic spectrum of sCJDMV2K and VV2 and may mark the clinical onset. The significantly lower prevalence of PNS involvement in typical sCJDMM(V)1 suggests that the PNS tropism of sCJD prions is strain dependent.

Two novel PRNP truncating mutations broaden the spectrum of prion amyloidosis.

Truncating mutations in PRNP have been associated with heterogeneous phenotypes ranging from chronic diarrhea and neuropathy to dementia, either rapidly or slowly progressive. We identified novel PRNP stop-codon mutations (p.Y163X, p.Y169X) in two Italian kindreds. Disease typically presented in the third or fourth decade with progressive autonomic failure and diarrhea. Moreover, one proband (p.Y163X) developed late cognitive decline, whereas some of his relatives presented with isolated cognitive and psychiatric symptoms. Our results strengthen the link between PRNP truncating mutations and systemic abnormal PrP deposition and support a wider application of PRNP screening to include unsolved cases of familial autonomic neuropathy.

Identification of rare genetic variants in Italian patients with dementia by targeted gene sequencing.

Genetics is intricately involved in the etiology of neurodegenerative dementias. The incidence of monogenic dementia among all neurodegenerative forms is unknown due to the lack of systematic studies and of patient/clinician access to extensive diagnostic procedures. In this study, we conducted targeted sequencing in 246 clinically heterogeneous patients, mainly with early-onset and/or familial neurodegenerative dementia, using a custom-designed next-generation sequencing panel covering 27 genes known to harbor mutations that can cause different types of dementia, in addition to the detection of C9orf72 repeat expansions. Forty-nine patients (19.9%) carried known pathogenic or novel, likely pathogenic, variants, involving both common (presenilin 1, presenilin 2, C9orf72, and granulin) and rare (optineurin, serpin family I member 1 and protein kinase cyclic adenosine monophosphate (cAMP)-dependent type I regulatory subunit beta) dementia-associated genes. Our results support the use of an extended next-generation sequencing panels as a quick, accurate, and cost-effective method for diagnosis in clinical practice. This approach could have a significant impact on the proportion of tested patients, especially among those with an early disease onset.

Is the Epworth Sleepiness Scale a useful tool for screening excessive daytime sleepiness in commercial drivers?

The significant social and economic impact of excessive daytime sleepiness makes sleep evaluation a primary medical need in commercial drivers. However, the best screening tool is still matter of debate. In our cohort of 221 commercial drivers, only ten (4.5%) had Epworth Sleepiness Scale scores indicative of excessive daytime sleepiness. These findings and the lack of concordance in estimating excessive daytime sleepiness among commercial drivers in previous studies using the same psychometric measure indicate that the Epworth Sleepiness Scale is not a reliable tool. This may be due to the low internal consistency of the scale in non-clinical samples and the possible intentional underscoring of sleepiness due to a perceived threat of driver's license suspension. Moreover, the reliability of the Epworth Sleepiness Scale results may be strongly influenced by the administration setting. The clinical application of inexpensive less time-consuming new tools like performance tests should be considered for the objective evaluation of excessive daytime sleepiness in commercial drivers.

Multiple variants in families with amyotrophic lateral sclerosis and frontotemporal dementia related to C9orf72 repeat expansion: further observations on their oligogenic nature.

The C9orf72 repeat expansion (RE) is one of the most frequent causative mutations of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, it is still unclear how the C9orf72 RE can lead to a heterogeneous phenotype. Several reports have shown the coexistence of mutations in multiple ALS/FTD causative genes in the same family, suggesting an oligogenic etiology for ALS and FTD. Our aim was to investigate this phenomenon in an Italian group of ALS/FTD pedigrees carrying the C9orf72 RE. We included 11 subjects from 11 pedigrees with ALS/FTD and the C9orf72 RE. Mutation screening of FUS, SOD1 and TARDBP genes was performed by direct sequencing. A dementia-specific custom-designed targeted next-generation sequencing panel was used for screening dementia-associated genes mutations. We found genetic variants in additional ALS or dementia-related genes in four pedigrees, including the p.V47A variant in the TYROBP gene. As a group, double mutation carriers displayed a tendency toward a younger age at onset and a higher frequency of positive familiar history and of parkinsonism. Our observation supports the hypothesis that the co-presence of mutations in different genes may be relevant for the clinical expression of ALS/FTD and of their oligogenic nature.

Technique and Preliminary Analysis of Drug-Induced Sleep Endoscopy With Online Polygraphic Cardiorespiratory Monitoring in Patients With Obstructive Sleep Apnea Syndrome.

Importance: Drug-induced sleep endoscopy is a diagnostic technique that allows dynamic evaluation of the upper airway during artificial sleep. The lack of a standardized procedure and the difficulties associated with direct visual detection of obstructive events result in poor intraobserver and interobserver reliability, especially when otolaryngology surgeons not experienced in the technique are involved. Objectives: To describe a drug-induced sleep endoscopy technique implemented with simultaneous polygraphic monitoring of cardiorespiratory parameters (DISE-PG) in patients with a diagnosis of obstructive sleep apnea syndrome and discuss the technique's possible advantages compared with the standard procedure. Design, Setting, and Participants: This prospective cohort study included 50 consecutive patients with obstructive sleep apnea syndrome who underwent DISE-PG from March 1, 2013, to June 30, 2014. A standard protocol was adopted, and all the procedures were carried out in an operation room by an experienced otolaryngology surgeon under the supervision of an anesthesiologist. Endoscopic and polygraphic obstructive respiratory events were analyzed offline in a double-blind setting and randomized order. Main Outcomes and Measures: The feasibility and safety of the DISE-PG technique, as well as its sensitivity in detecting respiratory events compared with that of the standard drug-induced sleep endoscopy procedure. Results: All 50 patients (43 men and 7 women; mean [SD] age, 51.1 [12.1] years) underwent DISE-PG without technical problems or patient difficulties regarding the procedure. As expected, polygraphic scoring was more sensitive than endoscopic scoring in identifying obstructive events (mean [SD] total events, 13.3 [6.8] vs 5.3 [3.6]; mean [SD] difference, 8.8 [5.6]; 95% CI, 7.3 to 10.4; Cohen d, -1.5). This difference was most pronounced in patients with a higher apnea-hypopnea index (AHI) at baseline (mean [SD] difference for AHI >30, 27.1% [31.0%]; 95% CI, -36.2% to 90.4%; Cohen d, 0.2; for AH I >40, 76.0% [35.5%]; 95% CI, 4.6% to 147.4%; Cohen d, 0.5; for AHI >50, 92.2% [37.2%]; 95% CI, 17.3% to 167.1%; Cohen d, 0.6) and a high percentage of hypopneas (≥75% of all obstructive events) at baseline (mean [SD] difference, 20.2% [5.4%]; 95% CI, 9.2% to 31.3%; Cohen d, 1.1). No other anthropomorphic or polygraphic features at baseline were associated with the differences between the DISE-PG and baseline home sleep apnea test. Conclusions and Relevance: The DISE-PG technique is feasible, safe, and more sensitive at detecting an obstructed breathing pattern than is drug-induced sleep endoscopy alone. The DISE-PG technique could be helpful for accurate comprehension of upper airway obstructive dynamics (ie, degree of obstruction and multilevel pattern) and a nonobstructive breathing pattern (ie, central apneas).

Prion-specific and surrogate CSF biomarkers in Creutzfeldt-Jakob disease: diagnostic accuracy in relation to molecular subtypes and analysis of neuropathological correlates of p-tau and Aß42 levels.

The differential diagnosis of Creutzfeldt-Jakob disease (CJD) from other, sometimes treatable, neurological disorders is challenging, owing to the wide phenotypic heterogeneity of the disease. Real-time quaking-induced prion conversion (RT-QuIC) is a novel ultrasensitive in vitro assay, which, at variance with surrogate neurodegenerative biomarker assays, specifically targets the pathological prion protein (PrPSc). In the studies conducted to date in CJD, cerebrospinal fluid (CSF) RT-QuIC showed good diagnostic sensitivity (82-96%) and virtually full specificity. In the present study, we investigated the diagnostic value of both prion RT-QuIC and surrogate protein markers in a large patient population with suspected CJD and then evaluated the influence on CSF findings of the CJD type, and the associated amyloid-ß (Aß) and tau neuropathology. RT-QuIC showed an overall diagnostic sensitivity of 82.1% and a specificity of 99.4%. However, sensitivity was lower in CJD types linked to abnormal prion protein (PrPSc) type 2 (VV2, MV2K and MM2C) than in typical CJD (MM1). Among surrogate proteins markers (14-3-3, total (t)-tau, and t-tau/phosphorylated (p)-tau ratio) t-tau performed best in terms of both specificity and sensitivity for all sCJD types. Sporadic CJD VV2 and MV2K types demonstrated higher CSF levels of p-tau when compared to other sCJD types and this positively correlated with the amount of tiny tau deposits in brain areas showing spongiform change. CJD patients showed moderately reduced median Aß42 CSF levels, with 38% of cases having significantly decreased protein levels in the absence of Aß brain deposits. Our results: (1) support the use of both RT-QuIC and t-tau assays as first line laboratory investigations for the clinical diagnosis of CJD; (2) demonstrate a secondary tauopathy in CJD subtypes VV2 and MV2K, correlating with increased p-tau levels in the CSF and (3) provide novel insight into the issue of the accuracy of CSF p-tau and Aß42 as markers of brain tauopathy and ß-amyloidosis.