Dunham, Steven

AbstractBackgroundThe causes of rapidly progressive dementia are heterogeneous, including neurodegenerative, vascular, and autoimmune/inflammatory diseases. Overlap in presenting symptoms and signs, results of cognitive testing, and findings on brain imaging and other common diagnostic tests confounds the etiologic diagnosis, contributing to diagnostic delays, missed opportunities for treatment, and poorer outcomes in patients with RPD. New tools and approaches are needed to improve diagnostic accuracy, with particular emphasis on improving early recognition of patients with potentially treatable causes of RPD.MethodsEstablished and emerging biomarkers of Alzheimer disease neuropathology (Aβ42/40, p‐tau181, p‐tau231), neuroaxonal and neuronal injury (neurofilament light [NfL], VILIP‐1, total tau), neuroinflammation (YKL‐40, sTREM2, GFAP, MCP‐1), and synaptic dysfunction (SNAP‐25, neurogranin) were measured in cerebrospinal fluid obtained at presentation from 78 prospectively accrued patients with RPD due to neurodegenerative (n = 35), vascular (n = 9), and autoimmune/inflammatory (n = 34) diseases, and 72 age‐ and sex‐similar cognitively normal individuals (controls). Causes of RPD were further classified as potentially treatment‐responsive or nonresponsive, referencing the extant literature. Biomarker levels were compared across etiologic diagnoses and by treatment responsiveness, referencing control values. Analyses were adjusted for the effects of age (ANCOVA).ResultsAlzheimer disease biomarkers (low Aβ42/40 and elevated p‐tau181 and p‐tau231) were associated with neurodegenerative causes of RPD (ANCOVA, p = 0.02 p = 0.30, p = 0.15), while high NfL (p = 0.61), low VILIP‐1 (p = 0.009), and elevated markers of inflammation (sTREM2, p = 0.009; YKL‐40, p<0.001) identified patients with autoimmune/inflammatory diseases (Figure). MCP‐1 levels were highest in patients with vascular causes of RPD (p = 0.08). 44 patients (56.4%) had potentially treatment‐responsive causes of RPD. Treatment responsiveness was associated with higher levels of CSF Aβ42/40 (p = 0.003), NfL (p<0.001), sTREM2 (p<0.001) and YKL‐40 (p<0.001); and lower levels of p‐tau‐181 and p‐tau231 (p<0.001, p<0.001) and VILIP‐1 (p<0.001).ConclusionSelected biomarkers measured in CSF at presentation associate with etiologic diagnosis and treatment responsiveness in patients with neurodegenerative, vascular, and autoimmune/inflammatory causes of RPD. Biomarker panels may be adapted to improve recognition of patients with treatment‐responsive causes of RPD early in the symptomatic course when treatments may be most effective.

ObjectiveThis study was undertaken to apply established and emerging cerebrospinal fluid (CSF) biomarkers to improve diagnostic accuracy in patients with rapidly progressive dementia (RPD). Overlap in clinical presentation and results of diagnostic tests confounds etiologic diagnosis in patients with RPD. Objective measures are needed to improve diagnostic accuracy and to recognize patients with potentially treatment‐responsive causes of RPD.MethodsBiomarkers of Alzheimer disease neuropathology (amyloid‐β 42/40 ratio, phosphorylated tau [p‐tau181, p‐tau231]), neuroaxonal/neuronal injury (neurofilament light chain [NfL], visinin‐like protein‐1 [VILIP‐1], total tau), neuroinflammation (chitinase‐3‐like protein [YKL‐40], soluble triggering receptor expressed on myeloid cells 2 [sTREM2], glial fibrillary acidic protein [GFAP], monocyte chemoattractant protein‐1 [MCP‐1]), and synaptic dysfunction (synaptosomal‐associated protein 25kDa, neurogranin) were measured in CSF obtained at presentation from 78 prospectively accrued patients with RPD due to neurodegenerative, vascular, and autoimmune/inflammatory diseases; 35 age‐ and sex‐matched patients with typically progressive neurodegenerative disease; and 72 cognitively normal controls. Biomarker levels were compared across etiologic diagnoses, by potential treatment responsiveness, and between patients with typical and rapidly progressive presentations of neurodegenerative disease.ResultsAlzheimer disease biomarkers were associated with neurodegenerative causes of RPD. High NfL, sTREM2, and YKL‐40 and low VILIP‐1 identified patients with autoimmune/inflammatory diseases. MCP‐1 levels were highest in patients with vascular causes of RPD. A multivariate model including GFAP, MCP‐1, p‐tau181, and sTREM2 identified the 44 patients with treatment‐responsive causes of RPD with 89% accuracy. Minimal differences were observed between typical and rapidly progressive presentations of neurodegenerative disease.InterpretationSelected CSF biomarkers at presentation were associated with etiologic diagnoses and treatment responsiveness in patients with heterogeneous causes of RPD. The ability of cross‐sectional biomarkers to inform upon mechanisms that drive rapidly progressive neurodegenerative disease is less clear. ANN NEUROL 2024;95:299–313

ObjectiveTo improve the timely recognition of patients with treatment‐responsive causes of rapidly progressive dementia (RPD).MethodsA total of 226 adult patients with suspected RPD were enrolled in a prospective observational study and followed for up to 2 years. Diseases associated with RPD were characterized as potentially treatment‐responsive or non‐responsive, referencing clinical literature. Disease progression was measured using Clinical Dementia Rating® Sum‐of‐Box scores. Clinical and paraclinical features associated with treatment responsiveness were assessed using multivariable logistic regression. Findings informed the development of a clinical criterion optimized to recognize patients with potentially treatment‐responsive causes of RPD early in the diagnostic evaluation.ResultsA total of 155 patients met defined RPD criteria, of whom 86 patients (55.5%) had potentially treatment‐responsive causes. The median (range) age‐at‐symptom onset in patients with RPD was 68.9 years (range 22.0–90.7 years), with a similar number of men and women. Seizures, tumor (disease‐associated), magnetic resonance imaging suggestive of autoimmune encephalitis, mania, movement abnormalities, and pleocytosis (≥10 cells/mm3) in cerebrospinal fluid at presentation were independently associated with treatment‐responsive causes of RPD after controlling for age and sex. Those features at presentation, as well as age‐at‐symptom onset <50 years (ie, STAM3P), captured 82 of 86 (95.3%) cases of treatment‐responsive RPD. The presence of ≥3 STAM3P features had a positive predictive value of 100%.InterpretationSelected features at presentation reliably identified patients with potentially treatment‐responsive causes of RPD. Adaptation of the STAM3P screening score in clinical practice may minimize diagnostic delays and missed opportunities for treatment in patients with suspected RPD. ANN NEUROL 2024;95:237–248

AbstractBackgroundOverlap in the presenting clinical features and test results in patients with rapidly progressive dementia (RPD) confounds the etiologic diagnoses of RPD, contributing to diagnostic delays, missed treatment opportunities, and poorer outcomes. There is a need to improve diagnostic accuracy in patients with RPD, with particular emphasis on identifying patients with potentially treatment‐responsive causes of RPD early in the symptomatic course.MethodPatients with RPD were prospectively enrolled and evaluated in inpatient settings and outpatient subspecialty (memory) clinics at Washington University (Saint Louis, MO; 2016–2019) and Mayo Clinic (Jacksonville, FL; 2020–2021). Etiologic diagnoses were independently assigned by two dementia specialists integrating clinical features and the results of widely accessible diagnostic testing and referencing established diagnostic criteria. Diagnostic disagreements were resolved via blinded review by a third specialist. Clinicopathologic correlation was evaluated using neuropathological and genetic data when available.Result160 patients with RPD were assessed, with average age‐at‐symptom onset 60.0±15.9 years; 50% were female. Diagnostic inter‐rater reliability (91% agreement; Cohen’s κ = 0.88, p<0.001) and clinicopathologic correlation were excellent (100% agreement in 24 patients with neuropathologic or genetic data). Autoimmune encephalitis was the leading cause of RPD (39%), followed by Alzheimer disease and related dementias (29%—i.e., frontotemporal dementia, Lewy body dementia, vascular cognitive impairment), Creutzfeldt‐Jakob disease (15%), and other causes (15%—e.g., neurosarcoid, metabolic disruptions, neoplastic disease). The average age of patients with potentially treatable causes (AE and selected “other” causes; 54.4±18.2) was younger than those with neurodegenerative dementing illnesses (67.3±9.5) or CJD (67.4±7.9; p<0.001). Patients with potentially treatable causes were more likely to present with altered level of consciousness and seizures (p<0.05). CSF pleocytosis (>5 WBC/hpf) was more common in AE patients (p<0.05).ConclusionEtiologic diagnoses can be reliably established in RPD patients using available clinical data. Treatment‐responsive causes of RPD are common warranting consideration, particularly in younger patients with altered consciousness, seizures, and CSF pleocytosis.

ImportanceAutoimmune encephalitis misdiagnosis can lead to harm.ObjectiveTo determine the diseases misdiagnosed as autoimmune encephalitis and potential reasons for misdiagnosis.Design, Setting, and ParticipantsThis retrospective multicenter study took place from January 1, 2014, to December 31, 2020, at autoimmune encephalitis subspecialty outpatient clinics including Mayo Clinic (n = 44), University of Oxford (n = 18), University of Texas Southwestern (n = 18), University of California, San Francisco (n = 17), Washington University in St Louis (n = 6), and University of Utah (n = 4). Inclusion criteria were adults (age ≥18 years) with a prior autoimmune encephalitis diagnosis at a participating center or other medical facility and a subsequent alternative diagnosis at a participating center. A total of 393 patients were referred with an autoimmune encephalitis diagnosis, and of those, 286 patients with true autoimmune encephalitis were excluded.Main Outcomes and MeasuresData were collected on clinical features, investigations, fulfillment of autoimmune encephalitis criteria, alternative diagnoses, potential contributors to misdiagnosis, and immunotherapy adverse reactions.ResultsA total of 107 patients were misdiagnosed with autoimmune encephalitis, and 77 (72%) did not fulfill diagnostic criteria for autoimmune encephalitis. The median (IQR) age was 48 (35.5-60.5) years and 65 (61%) were female. Correct diagnoses included functional neurologic disorder (27 [25%]), neurodegenerative disease (22 [20.5%]), primary psychiatric disease (19 [18%]), cognitive deficits from comorbidities (11 [10%]), cerebral neoplasm (10 [9.5%]), and other (18 [17%]). Onset was acute/subacute in 56 (52%) or insidious (&amp;gt;3 months) in 51 (48%). Magnetic resonance imaging of the brain was suggestive of encephalitis in 19 of 104 patients (18%) and cerebrospinal fluid (CSF) pleocytosis occurred in 16 of 84 patients (19%). Thyroid peroxidase antibodies were elevated in 24 of 62 patients (39%). Positive neural autoantibodies were more frequent in serum than CSF (48 of 105 [46%] vs 7 of 91 [8%]) and included 1 or more of GAD65 (n = 14), voltage-gated potassium channel complex (LGI1 and CASPR2 negative) (n = 10), N-methyl-d-aspartate receptor by cell-based assay only (n = 10; 6 negative in CSF), and other (n = 18). Adverse reactions from immunotherapies occurred in 17 of 84 patients (20%). Potential contributors to misdiagnosis included overinterpretation of positive serum antibodies (53 [50%]), misinterpretation of functional/psychiatric, or nonspecific cognitive dysfunction as encephalopathy (41 [38%]).Conclusions and RelevanceWhen evaluating for autoimmune encephalitis, a broad differential diagnosis should be considered and misdiagnosis occurs in many settings including at specialized centers. In this study, red flags suggesting alternative diagnoses included an insidious onset, positive nonspecific serum antibody, and failure to fulfill autoimmune encephalitis diagnostic criteria. Autoimmune encephalitis misdiagnosis leads to morbidity from unnecessary immunotherapies and delayed treatment of the correct diagnosis.

AbstractBackgroundDiagnostic criteria emphasize the use of real‐time quaking‐induced conversion (RT‐QuIC) assays in cerebrospinal fluid (CSF) to identify patients with rapidly progressive dementia (RPD) due to for Creutzfeldt‐Jakob disease (CJD; CDC Diagnostic Criteria; Oct‐2018). Yet, this test is often performed in specialized centers, leading to delays in return of results. There is a need to leverage clinical features and the results of readily available tests to distinguish patients with CJD from those with other causes (‘CJD mimics’), including patients with potentially treatment‐responsive RPD.MethodPatients with definite (pathology‐confirmed) or probable CJD (clinical features with positive RT‐QuIC) were identified through retrospective review of Mayo Clinic Enterprise (n=91) and Washington University in St. Louis records (n=14; Jan‐2014 to Dec‐2020). Demographic, clinical details and results of common investigations (e.g., neuroimaging, CSF analyses and electroencephalogram) were compared between CJD cases and ‘mimics’ who met clinical criteria for probable CJD but did not have CJD.ResultCJD mimics were diagnosed with autoimmune encephalitis (n=8), neurosarcoidosis (n=1), FTLD/MND (n=1) and unknown dementia (n=1), comprising 11/155 (7%) patients enrolled with RPD at study sites. Median [range] ages‐at‐presentation (65.6 [21.9‐81.5] vs 62.4 [32.8‐76.4] years; p=0.09), % females (51% vs 46%; p>0.99) and symptoms/signs were similar between groups, with the exception of motor complaints (e.g., spasms, focal weakness), which were more common in mimics (11/11 vs 55/105; p<0.01). Electroencephalogram findings did not differ between groups. MRI findings compatible with CJD (i.e., restricted diffusion within deep nuclei/cortical ribbon) predominated in cases (80/105 vs 4/11; p<0.01), while elevations in CSF leukocytes (>5 cells/hpf: 6/11 vs 5/103; p<0.01) and protein >45 mg/dL (10/11 vs 43/103; p<0.01) were more common in mimics. Total‐tau levels >1150 pg/mL (76/84 vs 2/10; p<0.01) and ‘positive’ 14‐3‐3 (67/98 vs 3/10; p=0.03) were frequent in cases. Autoantibodies associated with autoimmune encephalitis were detected in 5/10 mimics but 0/87 cases (p<0.01). Immunosuppressant therapies were provided to 10 mimics and 24 cases, with response limited to mimics.ConclusionsAutoimmune encephalitis, neurosarcoidosis and select neurodegenerative diseases may mimic CJD at presentation. Findings from brain MRI and commonly available CSF tests may facilitate early recognition of mimics, providing an opportunity for early treatment.