Rapidly Progressive Dementia: Causes Found in a Greek Tertiary Referral Center in Athens

The Effectiveness of an Exercise Program on Muscle Strength and Range of Motion on Upper Limbs, Functional Ability and Depression at Early Stage of Dementia

Background: Dementia involves the loss of cognitive abilities and represents a decline from the prior level of function, which impairs functional abilities in day-to-day life. The purpose of the present study is to examine the effectiveness of an exercise program on the muscle strength and range of motion of the upper limbs, the functional status, and the depression of elderly people with early stage dementia. Methods: The sample consisted of 60 elderly people with early stage dementia who were randomly divided into a control and an experimental group of 30 participants each. The experimental group received a 12-week Otago exercise program with 45 min duration of each session. The control group received usual care without doing exercise. The outcome measures of muscle strength and range of motion of the upper limbs, the functional status, and the depression were assessed by valid instruments and tests at the beginning and at the end of the intervention program. Repeated measures one-way ANOVA and Mann-Whitney tests examined the differences between the two groups at the end of the 12-week exercise program. Results: Statistically significant differences were found between the experimental and control groups in the entire outcome measures (functional ability F = 9.35 p < 0.05; muscle strength right hand F = 32.33, p < 0.05 left hand U = 95.50 p < 0.01; e.g., range of motion shoulder extension U = 104.00 p < 0.01), except depression. Conclusions: Both muscle strength and range of motion of the upper limbs, as well as the functional ability, were improved by the exercise program. Further research is needed to investigate the present results, in particular to explore the long-term cognitive, behavioral, and functional status outcomes of exercise in the early stages of dementia.

Diagnostic Utility of Cerebrospinal Fluid Biomarkers in Patients with Rapidly Progressive Dementia

OBJECTIVE

This 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.

METHODS

Biomarkers 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.

RESULTS

Alzheimer 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.

INTERPRETATION

Selected 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.

Improving Early Recognition of Treatment-Responsive Causes of Rapidly Progressive Dementia: The STAM3 P Score

OBJECTIVE

To improve the timely recognition of patients with treatment-responsive causes of rapidly progressive dementia (RPD).

METHODS

A 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.

RESULTS

A 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, STAM3 P), captured 82 of 86 (95.3%) cases of treatment-responsive RPD. The presence of ≥3 STAM3 P features had a positive predictive value of 100%.

INTERPRETATION

Selected features at presentation reliably identified patients with potentially treatment-responsive causes of RPD. Adaptation of the STAM3 P 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.

The Etiology of Rapidly Progressive Dementia: A 3-Year Retrospective Study in a Tertiary Hospital in China

Background

Rapidly progressive dementia (RPD), characterized by a rapid cognitive decline leading to dementia, comprises a diverse range of disorders. Despite advancements in diagnosis and treatment, research on RPD primarily focuses on Western populations.

Objective

This study aims to explore the etiology and demographics of RPD in Chinese patients.

Methods

We retrospectively analyzed 323 RPD inpatients at Huashan Hospital from May 2019 to March 2023. Data on sociodemographic factors, epidemiology, clinical presentation, and etiology were collected and analyzed.

Results

The median onset age of RPD patients was 60.7 years. Two-thirds received a diagnosis within 6 months of symptom onset. Memory impairment was the most common initial symptom, followed by behavioral changes. Neurodegenerative diseases accounted for 47.4% of cases, with central nervous system inflammatory diseases at 30.96%. Autoimmune encephalitis was the leading cause (16.7%), followed by Alzheimer's disease (16.1%), neurosyphilis (11.8%), and Creutzfeldt-Jakob disease (9.0%). Alzheimer's disease, Creutzfeldt-Jakob disease, and frontotemporal dementia were the primary neurodegenerative causes, while autoimmune encephalitis, neurosyphilis, and vascular cognitive impairment were the main non-neurodegenerative causes.

Conclusions

The etiology of RPD in Chinese patients is complex, with neurodegenerative and non-neurodegenerative diseases equally prevalent. Recognizing treatable conditions like autoimmune encephalitis and neurosyphilis requires careful consideration and differentiation.

Prevalence and outcomes of rapidly progressive dementia: a retrospective cohort study in a neurologic unit in China

BACKGROUND

Rapidly progressive dementia (RPD) is a syndrome originating from various diseases. Recent advances have allowed a better understanding of its categories and spectrum; however, it remains challenging to make an accurate differential diagnosis and prognosis prediction.

METHODS

This study was a retrospective evaluation of all participants admitted to the neurology department of a single center in China from January 2015 to December 2019. The screened patients met the RPD criteria and their characteristics were collected to explore a diagnostic pattern of RPD. In addition, outcomes of RPD were evaluated with the Glasgow Outcome Scale (GOS), activities of daily living scale (ADL), and simplified Mini-Mental State Examination (MMSE), and different prognostic analysis methods were performed to determine the prognostic factors of RPD.

RESULTS

A total of 149 RPD patients among 15,731 inpatients were identified with an average MMSE value of 13.0 ± 4.6 at baseline. Etiological epidemiology revealed infectious, neurodegenerative and toxic/metabolic diseases as the three largest groups, accounting for 26.2%, 20.8% and 16.8% of all cases, respectively. In particular, prevalence rates of Creutzfeldt-Jakob disease (13.4%), Alzheimer's disease (11.4%), carbon monoxide poisoning (8.1%), neurosyphilis (5.4%) and dementia with Lewy bodies (5.4%) were highest in this series. A recommended diagnostic framework for RPD etiology was thus established. Follow-up evaluations showed a negative correlation between age and GOS scores (r=-0.421, P < 0.001), as well as age and simplified MMSE scores (r_s =- 0.393, P < 0.001), and a positive correlation between age and ADL scores (r_s =0.503, P < 0.001), and significantly different GOS, ADL and simplified MMSE scores across various etiologies (P = 0.003; F = 9.463, P < 0.001; F = 6.117, P < 0.001).

CONCLUSION

Infectious, neurodegenerative and toxic-metabolic entities were the most common RPD categories, and establishing a practical approach to RPD etiology would allow better disease management.

Rapidly Progressive Dementia

PURPOSE OF REVIEW

This article presents a practical approach to the evaluation of patients with rapidly progressive dementia.

RECENT FINDINGS

The approach presented in this article builds upon the standard dementia evaluation, leveraging widely available tests and emergent specific markers of disease to narrow the differential diagnosis and determine the cause(s) of rapid progressive decline. The discovery of treatment-responsive causes of rapidly progressive dementia underscores the need to determine the cause early in the symptomatic course when treatments are most likely to halt or reverse cognitive decline.

SUMMARY

A pragmatic and organized approach to patients with rapidly progressive dementia is essential to mitigate diagnostic and therapeutic challenges and optimize patient outcomes.

Rapidly progressive dementias - aetiologies, diagnosis and management

Rapidly progressive dementias (RPDs) are a group of heterogeneous disorders that include immune-mediated, infectious and metabolic encephalopathies, as well as prion diseases and atypically rapid presentations of more common neurodegenerative diseases. Some of these conditions are treatable, and some must be diagnosed promptly because of their potential infectivity. Prion disease is considered to be the prototypical RPD, but over the past two decades, epidemiological reports and the identification of various encephalitis-mediating antibodies have led to a growing recognition of other encephalopathies as potential causes of rapid cognitive decline. Knowledge of RPD aetiologies, syndromes and diagnostic work-up protocols will help clinicians to establish an early, accurate diagnosis, thereby reducing morbidity and mortality, especially in immune-mediated and other potentially reversible dementias. In this Review, we define the syndrome of RPD and shed light on its different aetiologies and on secondary factors that might contribute to rapid cognitive decline. We describe an extended diagnostic procedure in the context of important differential diagnoses, discuss the utility of biomarkers and summarize potential treatment options. In addition, we discuss treatment options such as high-dose steroid therapy in the context of therapy and diagnosis in clinically ambiguous cases.

The term ‘rapidly progressive dementia’ (RPD) describes a cognitive disorder with fast progression, leading to dementia within a relatively short time. This Review discusses the wide range of RPD aetiologies, as well as the diagnostic approach and treatment options.

Definitions of rapidly progressive dementia (RPD) vary according to the aetiological background and relate to the speed of cognitive decline, time from first symptom to dementia syndrome and/or overall survival.

RPD can occur in rapidly progressive neurodegenerative diseases, such as prion diseases, or in primarily slowly progressive diseases as a consequence of intrinsic factors or concomitant pathologies.

Besides neurodegenerative diseases, inflammatory (immune-mediated and infectious), vascular, metabolic and neoplastic CNS diseases are important and frequent causes of RPD.

To identify treatable causes of RPD, the technical diagnostic work-up must include MRI and analyses of blood and cerebrospinal fluid, and further diagnostics might be indicated in unclear cases.

Therapeutic options for many non-neurodegenerative causes of RPD are already available; disease-modifying therapies for neurodegenerative RPDs are an important focus of current research and could become a treatment option in the near future.

Normal pressure hydrocephalus: an update

Normal pressure hydrocephalus (NPH) has been a topic of debate since its introduction in publications. More frequent in the elderly population, it is characterized by gait disturbance, urinary urge incontinence and cognitive decline. Therefore, it is a clinical-radiological entity with relatively common findings for the age group, which together may have greater specificity. Therefore, its diagnosis must be careful for an adequate selection of patients for treatment with ventricular shunt, since the symptoms are potentially reversible. The tap test has a high positive predictive value as a predictor of therapeutic response, but a negative test does not exclude the possibility of treatment. Scientific efforts in recent years have been directed towards a better understanding of NPH and this narrative review aims to compile recent data from the literature in a didactic way for clinical practice.

Glioblastoma with Gliomatosis Cerebri Growth Pattern Presenting as Rapidly Progressive Dementia

The differential diagnosis of rapidly progressive dementia includes neurodegenerative, toxic/metabolic, infectious, inflammatory, vascular, and malignant etiologies. This case highlights a patient with rapidly progressive cognitive decline that remained a diagnostic dilemma due to nonspecific symptoms of disorientation that progressed to persistent alteration in mental status over the span of three months. Routine laboratory testing did not help clarify the diagnosis and initial brain imaging showed only subtle abnormalities that were not commensurate with the patient’s neurologic examination. As imaging findings evolved over time to reveal a multifocal process, a biopsy was pursued, with histology consistent with infiltrating glioma and molecular testing consistent with glioblastoma. Glioblastoma with gliomatosis cerebri growth pattern should be considered on the differential diagnosis of rapidly progressive dementia in patients with multifocal imaging findings.

Evolving Causes of Rapidly Progressive Dementia: A 5-Year Comparative Study

BACKGROUND

Rapidly progressive dementia (RPD) is a clinical syndrome developing in <1 to 2 years. Recent progress in RPD evaluation is significant, so RPD's prevalence may change over time. The aim of our new case series was to estimate the relative frequency of RPDs' causative entities, considering the recent advances in RPDs' diagnosis, and compare the results with those of our previous report.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 47 patients who were referred to Attikon University Hospital during a 5-year period for a suspected RPD.

RESULTS

Neurodegenerative diseases were the most frequent causes (38%), followed by prion disease (19%) and autoimmune encephalopathy (AE, 17%). AE cases were by far more common than in our previous report, while other than AE secondary causes were significantly decreased. Mean time to dementia was 9 months in neurodegenerative diseases and 5 months in non-neurodegenerative. Main clinical findings across all patients were memory impairment (66%) and behavioral-emotional disturbances (48%).

CONCLUSIONS

Neurodegenerative diseases are common causes of RPD and have a slower evolution than non-neurodegenerative. Diagnostic novelties enabled the recognition of AE, whereas more common secondary causes are probably now diagnosed in primary settings since the recognition of RPD as distinct clinical entity is continually increasing.

The Impact of Primary Progressive Aphasia on Picture Naming and General Language Ability

BACKGROUND

Primary progressive aphasia (PPA) is a clinical syndrome that is characterized by progressive deterioration of language while other cognitive domains remain relatively intact. The extent to which print exposure and cortical volume atrophy jointly influence picture naming and general language ability in individuals with PPA remains underexplored.

OBJECTIVE

To investigate the language performance of individuals with the nonfluent variant of primary progressive aphasia (nfvPPA) and to explore the impact of print exposure and cortical volume atrophy on their language ability.

METHOD

We compared 14 Greek individuals with nfvPPA and similar age, education, disease duration, and cognitive ability with age-, gender- and education-matched Greek controls on picture naming and on language tasks of the Boston Diagnostic Aphasia Examination-Short Form, including oral word reading, word and sentence repetition, complex ideational material, and reading comprehension. The effects of print exposure and left-hemisphere cortical volume on the individuals' language performance were estimated through stepwise regression models.

RESULTS

The language performance of the individuals with nfvPPA was affected by print exposure and cortical volume atrophy. Picture naming and word reading were affected by print exposure. The highest contributions of cortical volume atrophy were found for the repetition, complex ideational material, and reading comprehension tasks.

CONCLUSION

Print exposure and cortical volume atrophy may help explain variability in the language performance of nfvPPA individuals with similar age, education, disease duration, and cognitive ability.

Rapidly progressive dementia and Parkinsonism as the first symptoms of dural arteriovenous fistula. The Sapienza University experience and comprehensive literature review concerning the clinical course of 102 patients

BACKGROUND

Dementia is a chronic loss of neurocognitive function that is progressive and irreversible. Dural arteriovenous fistulas (DAVFs) are acquired lesions that account for 10-15% of intracranial vascular malformations that could present with a rapid decline in neurocognitive function with or without Parkinson-like symptoms and evolve in a rapidly progressive dementia (RPD). Often the DAVFs are not even included in the differential hypotheses of this type of dementia and are not present in any type of diagnostic algorithm for evaluating RPD.

METHODS

We performed a systematic review of the international literature and adding the cases coming from our institutional experience and we have collected all the reported cases of DAVFs that debut with ROD identifying the most frequent forms in terms of location and type, reporting the neurological characteristics and the outcome of each patient.

RESULTS

The exact pathogenesis for developing dementia in patients with DAVFs remains largely unknown. The imaging changes and pathologic findings support the hypothesis that the clinical course results from the delivery of excessive volumes of blood flow into a venous system with outflow obstruction and venous congestion. The large variety of clinical manifestations of DAVFs depends on its location but this is not exactly valid for the onset of dementia. It supposed that the highly variable clinical manifestation of DAVFs has been convincingly related to the pattern of venous drainage more than location.

CONCLUSIONS

Neurologists and clinicians generally are familiar with the differential diagnoses of slowly progressive neurodegenerative dementias, but the diagnosis of RPD entails a different diagnostic approach. Due to their curable nature, the diagnosis of DAVFs must be suspected when facing a RPD picture, even more so if it is associated with characteristic abnormalities of the hemispheric white matter.

TARDBP p.I383V, a recurrent alteration in Greek FTD patients

BACKGROUND

A significant proportion of FTD (Frontotemporal Degeneration) cases can be attributed to mutations in major genes such as GRN, MAPT and C9orf72. Our previous report on a Greek FTD cohort revealed the presence of the single nucleotide polymorphism (SNP) p.I383V (rs80356740) in the TARDBP gene in three unrelated patients. Our objective was to develop a novel, fast and accurate method for the detection of this particular SNP and evaluate the assay in a larger cohort.

METHODS AND RESULTS

A real-time qPCR-melting curve analysis method was developed, validated and tested in 142 FTD patients and 111 healthy control subjects. The SNP was detected in another two patients raising its yield in FTD patients to 3.5% (5 out of 142 patients) while one in 111 healthy controls was found to be a carrier. However, its frequency in the general population has been reported extremely low in international SNP databases (0.002%).

CONCLUSION

This fact along with the indicated pathogenicity of this SNP in some bioinformatics tools, suggest that TARDBP p.I383V is recurrent and likely pathogenic for the Greek FTD population. Our high-throughput method could be used for genotyping in other larger patient cohorts and in other populations. Additionally, functional in vitro studies are required for the final adjudication of this TARDBP alteration as a pathogenic alteration.

Nonconvulsive status epilepticus manifesting as rapidly progressive dementia and infarction in the splenium of the corpus callosum: A case report

RATIONALE

Nonconvulsive status epilepticus (NCSE) is a heterogeneous disease with multiple subtypes. NCSE poses great diagnostic and therapeutic challenges due to the lack of typical symptoms. Here, we report a case of NCSE manifesting as rapidly progressive dementia (RPD) and infarction in the splenium of the corpus callosum. Additionally, the relevant literature was reviewed.

PATIENT CONCERNS

A 63-year-old man presented with RPD. Electroencephalogram (EEG) revealed NCSE, and brain magnetic resonance imaging (MRI) showed an isolated infarction in the splenium of the corpus callosum. Mini-mental state examination showed moderate cognitive impairment (14/30 points).

DIAGNOSIS

A diagnosis of NCSE with RPD and infarction in the splenium of the corpus callosum was made.

INTERVENTIONS

The patient was treated with intravenous diazepam (10 mg), oral levetiracetam (1.0g twice daily), oral sodium valproate (0.2g twice daily), and intramuscular phenobarbital sodium (0.2g once daily).

OUTCOMES

After the treatment, the symptoms were improved. The patient could answer questions. Repeated EEG showed that the background a rhythm was slightly overdeveloped, and no clinical or electrical seizures were observed. After discharge, the patient was treated with oral levetiracetam (1.0g twice daily) and oral sodium valproate (0.2g twice daily) for 6 months. At the last follow-up, the patient had clear consciousness, sensitive response, and fluent answering ability. Repeated mini-mental state examination showed that his cognitive function was significantly improved (28/30 points); nevertheless, the lesion in the splenium of corpus callosum remained unchanged on MRI.

LESSONS

NCSE manifesting as RPD and infarction in the splenium of the corpus callosum is extremely rare. Epileptic events and focal infarction are usually overlooked in patients with dementia, and the diagnostic value of MRI and EEG should be highlighted.

Diagnosis of Rapidly Progressive Dementia in a Referral Center in Argentina

INTRODUCTION

Rapidly progressive dementia (RPD) is a broadly defined clinical syndrome. Our aim was to describe clinical and ancillary study findings in patients with RPD and evaluate their diagnostic performance for the identification of nonchronic neurodegenerative rapidly progressive dementia (ncnRPD).

METHODS

We reviewed clinical records and ancillary methods of patients evaluated for RPD at our institution in Buenos Aires, Argentina from 2011 to 2017. We compared findings between chronic neurodegenerative RPD and ncnRPD and evaluated the diagnostic metrics using receiver operating characteristic curves.

RESULTS

We included 104 patients with RPD, 29 of whom were chronic neurodegenerative RPD and 75 of whom were ncnRPD. The 6-month time to dementia cutpoint had a sensitivity of 89% and specificity of 100% for ncnRPD, with an area under the receiver operating characteristic curve of 0.965 (95% confidence interval=0.935-0.99; P<0.001). A decision tree that included time to dementia, brain magnetic resonance imaging, and cerebrospinal fluid analysis identified ncnRPD patients with a sensitivity of 100%, specificity of 79%, positive predictive value of 93%, and negative predictive value of 100% overall.

DISCUSSION

RPD is a clinical syndrome that comprises different diagnoses, many of them for treatable diseases. Using the time to dementia, brain magnetic resonance imaging, and cerebrospinal fluid analysis when triaging these patients could help identify those diseases that need to be studied more aggressively.

Reversible Dementias

PURPOSE OF REVIEW

This article describes the clinical features that suggest a reversible cause of dementia.

RECENT FINDINGS

Substantial variability exists in the presenting features and clinical course of patients with common neurodegenerative causes of dementia, but the response to available therapies and eventual outcomes are often poor. This realization has influenced the evaluation of patients with dementia, with diagnostic approaches emphasizing routine screening for a short list of potentially modifiable disorders that may exacerbate dementia symptoms or severity but rarely influence long-term outcomes. Although a standard approach to the assessment of dementia is appropriate in the vast majority of cases, neurologists involved in the assessment of patients with dementia must recognize those rare patients with reversible causes of dementia, coordinate additional investigations when required, and ensure expedited access to treatments that may reverse decline and optimize long-term outcomes.

SUMMARY

The potential to improve the outcome of patients with reversible dementias exemplifies the need to recognize these patients in clinical practice. Dedicated efforts to screen for symptoms and signs associated with reversible causes of dementia may improve management and outcomes of these rare patients when encountered in busy clinical practices.

Treatable causes of adult-onset rapid cognitive impairment

OBJECTIVES

Acute and subacute cognitive decline, defined collectively as rapid cognitive impairment (RCI), is attributed to diverse disorders and brings great challenges for differential diagnosis. In this study we investigated the RCI patients to determine the underlying causes and the cognitive outcome of the treatable RCI.

PATIENTS AND METHODS

We reviewed medical records of consecutively hospitalized patients (n = 346) with significant and new cognitive dysfunction between January 2014 and December 2015. Based on the duration of their cognitive dysfunction, patients were divided into two groups with the RCI (< 12 months) and the chronic cognitive impairment (CCI, ≥ 12 months), respectively. Etiologies of the RCI and the CCI were analyzed; the cognitive outcomes of the RCI patients with the treatable disorders were assessed in the follow-up visits.

RESULTS

Potentially treatable or reversible causes were identified in 134 (72%) of 187 RCI patients and in 34 (21%) of 159 CCI patients. The causes in the 134 (72%) RCI patients were immune/inflammation (50, 37%), infection (30, 22%), vascular diseases (29, 22%), neoplasm (16, 12%), metabolic/toxic disorders (7, 5%), and others (2, 1%). The treatable disorders found in both the RCI and the CCI patients were vascular diseases, autoimmune encephalitis, viral encephalitis, inflammatory demyelinating diseases, Hashimoto encephalopathy, neurosyphilis, hydrocephalus, and Vitamin B12 deficiency. Total 114 RCI patients with the treatable disorders were followed up for 6∼39 (median 21) months. Poor cognitive outcomes were found in 24 (21%) of the 114 followed-up patients, comprising patients with infection (1, 3%), immune/inflammation (12, 25%), vascular diseases (8, 28%), and metabolic/toxic disorders (3, 43%).

CONCLUSIONS

Treatable or reversible causes are common underlying RCI. Poor outcomes with severe cognitive deficits are considerably present in the treatable RCI patients and result in permanent dementia.

Rapidly Progressive Dementia in the Outpatient Clinic: More Than Prions

BACKGROUND

Published approaches to the evaluation and management of patients with rapidly progressive dementia (RPD) have been largely informed by experience at academic hospitals and national centers specializing in the diagnosis of Creutzfeldt-Jakob disease. Whether these approaches can be applied to patients assessed within lower-acuity outpatient settings is unknown.

METHODS

A total of 96 patients with suspected RPD were assessed within the Washington University School of Medicine (Saint Louis, MO) outpatient memory clinic from February 2006 to February 2016. Consensus etiologic diagnoses were established following independent review of clinical data by 2 dementia specialists.

RESULTS

In total, 67/90 (70%) patients manifested with faster-than-expected cognitive decline leading to dementia within 2 years of symptom onset. Female sex (42/67, 63%), median patient age (68.3 y; range, 45.4 to 89.6), and years of education (12 y; range, 6 to 14) were consistent with clinic demographics. Atypical presentations of common neurodegenerative dementing illnesses accounted for 90% (60/67) of RPD cases. Older age predicted a higher odds of amnestic Alzheimer disease dementia (OR, 2.1 per decade; 95% CI, 1.1-3.8; P=0.02). Parkinsonism (OR, 6.9; 95% CI, 1.6-30.5; P=0.01) or cortical visual dysfunction (OR, 10.8; 95% CI, 1.7-69.4; P=0.01) predicted higher odds of another neurodegenerative cause of RPD, including sporadic Creutzfeldt-Jakob disease.

CONCLUSIONS AND RELEVANCE

The clinical environment influences the prevalence of RPD causes. The clinical evaluation should be adapted to promote detection of common causes of RPD, specific to the practice setting.

Incidence and characteristics of uncommon dementia subtypes: Results from 10 years of clinical surveillance by the Registry of Dementia of Girona

INTRODUCTION

Age- and sex-stratified incidence rates of uncommon dementia subtypes are imprecise and scarce.

METHODS

We used data from 7357 newly diagnosed individuals aged between 30.6 and 101.0 years from the Registry of Dementia of Girona during 2007-2016 to determine the incidence rates of uncommon dementia subtypes stratified by sex and age groups and to describe their clinical characteristics.

RESULTS

Uncommon dementia subtypes were classified according to their etiology. The incidence rate of uncommon dementia subtypes was 27.8 cases per 100,000 person-years for those aged 30 years and older, 3.7 cases per 100,000 person-years for people aged less than 65 years, and 110.9 per 100,000 person-years for those aged 65 years and older. Age, sex, dementia severity, and medical comorbidities were different depending on the dementia subtype.

DISCUSSION

There are differences in the incidence rates and the demographic and clinical characteristics among uncommon dementia subtypes for age and sex groups.

Diagnostic challenges in rapidly progressive dementia

INTRODUCTION

Rapidly progressive dementia is a syndrome caused by numerous disease entities. Accurate diagnosis is crucial as substantial proportion of these diseases is highly treatable. Others might implicate specific hygienic problems. Still, differential diagnosis remains challenging because of a huge overlap of clinical presentations. Areas covered: The paper reviews PubMed-listed research articles with a focus on diagnosis and treatment of diseases showing rapid cognitive decline such as inflammatory diseases, rapidly progressive neurodegenerative diseases, toxic-metabolic encephalopathies and prion diseases. The literature was interpreted in the light of experience in clinically differentiating rapid progressing dementia in the framework of Creutzfeldt-Jakob-Disease (CJD) surveillance activities. An overview of relevant differential diagnoses and diagnostic pitfalls as well as therapeutic protocols is presented. Expert commentary: Over the last years, more and more neurologic disorders causing cognitive symptoms, in particular various types of immune-mediated diseases have been discovered. To identify treatable conditions and to enhance knowledge of differential diagnosis and epidemiology, we suggest an extended diagnostic work up in cases with rapidly progressing dementia. Besides standard methods, this should include the search for neoplasia as well as atypical encephalitis. High-dose steroid therapy should be considered in certain clinical situations even when no evidence for inflammation is present.

Rapidly Progressive Dementia: Prevalence and Causes in a Neurologic Unit of a Tertiary Hospital in Brazil

BACKGROUND

Rapidly progressive dementia (RPD) is usually associated with Creutzfeldt-Jakob disease, a fatal condition. Current advances in the understanding of immune-mediated diseases allow the diagnosis of previously unrecognized treatable RPDs.

OBJECTIVE OF THE STUDY

The objective of the study was to describe the prevalence and causes of RPD in a neurology service, identifying potentially reversible causes.

METHODS

We carried out a cross-sectional evaluation of all patients admitted to the neurology unit of a tertiary hospital in Brazil between March 2012 and February 2015. We included patients who had progressed to moderate or severe dementia within a few months or up to 2 years at the time of hospitalization, and used multivariable logistic regression analysis to identify factors associated with a favorable outcome.

RESULTS

We identified 61 RPD (3.7%) cases among 1648 inpatients. Mean RPD patients' age was 48 years, and median time to progression was 6.4 months. Immune-mediated diseases represented the most commonly observed disease group in this series (45.9% of cases). Creutzfeldt-Jakob disease (11.5%) and nonprion neurodegenerative diseases (8.2%) were less common in this series. Outcome was favorable in 36/61 (59.0%) RPD cases and in 28/31 (89.3%) of immune-mediated cases. Favorable outcome was associated with shorter time from symptom onset to diagnosis and abnormal cerebrospinal fluid findings.

CONCLUSIONS

Immune-mediated diseases were the most common cause of RPD in this series. Timely evaluation and diagnosis along with institution of appropriate therapy are required in RPD, especially in view of potentially reversible causes.

Rapidly progressive dementia: An eight year (2008-2016) retrospective study

BACKGROUND AND PURPOSE

Rapidly progressive dementia (RPD) is an emergency in cognitive neurology, defined as cognitive impairment affecting the daily living activities developed over less than 1 year. This study investigated the profile of patients with rapidly progressive dementia at first presentation.

METHODS

Retrospective case analysis was done in 187 patients with rapidly progressive dementia who presented to the Postgraduate Institute of Medical Education and Research, Chandigarh, India from January 2008 to August 2016. Patients were divided into three groups: (1) Reversible (treatable) secondary dementia group, (2) Prion dementia group (sporadic Creutzfeldt-Jakob disease), (3) Non-prion Neurodegenerative and vascular dementias (primary neurodegenerative and vascular dementia). Cases presenting with delirium secondary to metabolic, drug induced or septic causes and those with signs of meningitis were excluded.

RESULTS

Secondary reversible causes formed the most common cause for RPD with immune mediated encephalitides, neoplastic and infectious disorders as the leading causes. The patients in this series had an younger onset of RPD. Infections presenting with RPD accounted for the most common cause in our series (39%) with SSPE (41%) as the leading cause followed by neurosyphilis (17.9%) and progressive multifocal leukoencephalopathy (15.3%). Immune mediated dementias formed the second most common (18.1%) etiologic cause for RPD. The neurodegenerative dementias were third common cause for RPD in our series. Neoplastic disorders and immune mediated presented early (< 6 months) while neurodegenerative disorders presented later (> 6 months).

CONCLUSIONS

Rapidly progressive dementia is an emergency in cognitive neurology with potentially treatable or reversible causes that should be sought for diligently.

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.

Spectrum of noncerebrovascular rapidly progressive cognitive deterioration: a 2-year retrospective study

Purpose

The number of cognitive deterioration patients has been steadily increasing as the population ages in China. Patients with cognitive deterioration demonstrated diverse patterns, often making the diagnosis difficult, especially in rapidly progressive cognitive deterioration (RPCD) patients. The purpose of this study was to exhibit the disease spectrum and frequency of noncerebrovascular RPCD in patients from a medical college hospital of southeastern China.

Materials and methods

We performed a 2-year retrospective cohort study including 310 RPCD patients who had been admitted to the Department of Neurology, Second Affiliated Hospital, Zhejiang University School of Medicine, from January 1, 2015 to December 31, 2016. RPCD patients’ information on epidemiologic data and clinical aspects were collected. All the data were analyzed using SPSS.

Results

Of a total of 310 patients hospitalized for RPCD diagnosis, mean age of onset was 55.92±18.89 years. The most common cause of RPCD was viral encephalitis, accounting for 21.9% (68) of the cases, followed by Alzheimer’s disease and autoimmune encephalitis, accounting for 14.5% (45) and 9.0% (28) of the cases, respectively. Creutzfeldt–Jakob disease accounted for 7.1% (22) of the cases. Patients in the secondary RPCD group tended to be younger than those in the primary RPCD group and experienced a more rapid progression course.

Conclusion

Our study suggests that the most common causes of RPCD are secondary neurological diseases and most of them are potentially reversible under appropriate treatment of the underlying disease. The spectrum and frequency of RPCD in our cohort is comparable with a previous study performed in the European population.

CJD mimics and chameleons

Rapidly progressive dementia mimicking Creutzfeldt–Jakob disease (CJD) is a relatively rare presentation but a rewarding one to become familiar with, as the potential diagnoses range from the universally fatal to the completely reversible. Patients require urgent decisions about assessment and investigation and have quickly evolving needs for treatments and support, through symptom management and end-of-life care in most cases. We have based this pragmatic review on the experiences of a specialist prion referral centre in the UK, which, unsurprisingly, is strongly biased towards seeing patients with CJD. Cases eventually proven not to have prion disease might be described as ‘CJD-mimics’; being referred from UK neurologists, these are the most challenging cases. CJD in its classical presentation is very rarely mimicked; however, it is highly heterogeneous, and atypical forms can mimic virtually all common neurodegenerative syndromes. Warning features of a mimic include generalised seizures, hyponatraemia, fever, a facial movement disorder, a normal neurological examination and a modestly rapid presentation. Contrast-enhancing lesions or MRI signal hyperintensity outside the striatum, thalamus or cortex and a cerebrospinal fluid pleocytosis are key investigation pointers to a CJD mimic.

Rapidly Progressive Dementia

PURPOSE OF REVIEW

This article presents a practical and informative approach to the evaluation of a patient with a rapidly progressive dementia (RPD).

RECENT FINDINGS

Prion diseases are the prototypical causes of RPD, but reversible causes of RPD might mimic prion disease and should always be considered in a differential diagnosis. Aside from prion diseases, the most common causes of RPD are atypical presentations of other neurodegenerative disorders, curable disorders including autoimmune encephalopathies, as well as some infections, and neoplasms. Numerous recent case reports suggest dural arterial venous fistulas sometimes cause RPDs.

SUMMARY

RPDs, in which patients typically develop dementia over weeks to months, require an alternative differential than the slowly progressive dementias that occur over a few years. Because of their rapid decline, patients with RPDs necessitate urgent evaluation and often require an extensive workup, typically with multiple tests being sent or performed concurrently. Jakob-Creutzfeldt disease, perhaps the prototypical RPD, is often the first diagnosis many neurologists consider when treating a patient with rapid cognitive decline. Many conditions other than prion disease, however, including numerous reversible or curable conditions, can present as an RPD. This chapter discusses some of the major etiologies for RPDs and offers an algorithm for diagnosis.

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.

Pathologically confirmed autoimmune encephalitis in suspected Creutzfeldt-Jakob disease

Objective:

To determine the clinical features and presence in CSF of antineuronal antibodies in patients with pathologically proven autoimmune encephalitis derived from a cohort of patients with suspected Creutzfeldt-Jakob disease (CJD).

Methods:

The Dutch Surveillance Centre for Prion Diseases performed 384 autopsies on patients with suspected CJD over a 14-year period (1998–2011). Clinical information was collected from treating physicians. Antineuronal antibodies were tested in CSF obtained postmortem by immunohistochemistry on fresh frozen rat brain sections, by Luminex assay for the presence of well-characterized onconeural antibodies, and by cell-based assays for antibodies against NMDAR, GABA_BR1/2, GABA_AR GLUR1/2, LGI1, Caspr2, and DPPX.

Results:

In 203 patients, a diagnosis of definite CJD was made, while in 181 a variety of other conditions were diagnosed, mainly neurodegenerative. In 22 of these 181, the neuropathologist diagnosed autoimmune encephalitis. One patient was excluded because of lack of clinical information. Inflammatory infiltrates were predominantly perivascular and consisted mainly of T cells. The predominant locations were basal ganglia and thalamus (90%) and temporal lobes and hippocampus (81%). In 6 patients (29%), antineuronal antibodies were detected in postmortem CSF, directed against Hu, NMDAR, GABABR1/2, Caspr2, and an unidentified synaptic antigen in 2. The most frequent symptoms were dementia (90%), gait disturbance (86%), cerebellar signs (67%), and neuropsychiatric symptoms (67%). Immunopathologic and clinical findings did not differ between autoantibody-negative patients and patients with antineuronal antibodies.

Conclusions:

It is important to consider immune-mediated disorders in the differential diagnosis of rapidly progressive neurologic deficits.

Clinicopathological Correlations and Concomitant Pathologies in Rapidly Progressive Dementia: A Brain Bank Series

BACKGROUND

Rapidly progressive dementia (RPD) is caused by a heterogeneous group of both neurodegenerative and non-neurodegenerative disorders. The presence of concomitant pathologies, mainly Alzheimer's disease (AD), may act as a confounding variable in the diagnostic process of this group of diseases.

OBJECTIVES

We aimed to describe clinicopathological features, including Alzheimer's co-pathology, and diagnostic accuracy in a postmortem series of RPD.

METHODS

Retrospective analysis of 160 brain donors with RPD (defined as 2 years of disease duration from the first symptom to death) registered at the Neurological Tissue Bank of the Biobanc-Hospital Clínic-IDIBAPS, from 2001 to 2011.

RESULTS

Prion diseases were the most frequent neuropathological diagnosis (67%), followed by non-prion neurodegenerative pathologies (17%), mostly AD and dementia with Lewy bodies, and non-neurodegenerative diseases (16%). We observed clinicopathological diagnostic agreement in 94% of the patients with prion RPD but only in 21% of those with non-prion RPD. Four patients with potentially treatable disorders were diagnosed, while still alive, as having Creutzfeldt-Jakob disease. Concomitant pathologies were detected in 117 (73%). Among all RPD cases, 51 presented moderate or frequent mature β-amyloid plaques (neuritic plaques), which are considered to be associated with positive amyloid biomarkers in vivo.

CONCLUSIONS

Prion diseases were accurately identified in our series. In contrast, non-prion RPD diagnosis was poor while the patients were still alive, supporting the need for better diagnostic tools and confirmatory neuropathological studies. The presence of concomitant AD pathology in RPD should be taken into account in the interpretation of amyloid biomarkers.

Hashimoto's encephalopathy: a brief review

Hashimoto's encephalopathy (HE) is a syndrome of altered mental status, hallucinations, delusional thinking, and often, epileptic seizures. It is diagnosed by the clinical syndrome, the presence of elevated titers of antithyroid antibodies, the lack of another diagnosis based on clinical evaluation, and the response to corticosteroid and other immunosuppressant treatment. This review discusses the symptoms, pathophysiology, and treatment of HE. The disorder is important to recognize because aggressive treatment may bring about a favorable clinical outcome. The disorder has a relatively benign prognosis, compared with many of the entities for which it can be mistaken.

When dementia progresses quickly: a practical approach to the diagnosis and management of rapidly progressive dementia

Making a diagnosis of rapidly progressive dementia requires practical adaptation of the skills used to assess patients with chronic causes of cognitive impairment. An expedited assessment, commensurate with the accelerated pace of the disease, is required to identify the cause of symptoms amidst a myriad of possibilities. Features upon history, physical examination and cognitive assessment that support specific diagnoses are reviewed, and a stratified approach to testing is presented. The use of readily-accessible investigations is prioritized, acknowledging the implications and applications of novel diagnostic tests. The coordinated use of clinical and laboratory measures are promoted as a means of facilitating rapid evaluation, with the ultimate goal of identifying patients with potentially reversible causes of rapidly progressive dementia.

Differential diagnosis of Jakob-Creutzfeldt disease

OBJECTIVES

To identify the misdiagnoses of patients with sporadic Jakob-Creutzfeldt disease (sCJD) during the course of their disease and determine which medical specialties saw patients with sCJD prior to the correct diagnosis being made and at what point in the disease course a correct diagnosis was made.

DESIGN

Retrospective medical record review.

SETTING

A specialty referral center of a tertiary academic medical center.

PARTICIPANTS

One hundred sixty-three serial patients over a 5.5-year period who ultimately had pathologically proven sCJD. The study used the subset of 97 patients for whom we had adequate medical records.

MAIN OUTCOME MEASURES

Other diagnoses considered in the differential diagnosis and types of medical specialties assessing patients with sCJD.

RESULTS

Ninety-seven subjects' records were used in the final analysis. The most common disease categories of misdiagnosis were neurodegenerative, autoimmune/paraneoplastic, infectious, and toxic/metabolic disorders. The most common individual misdiagnoses were viral encephalitis, paraneoplastic disorder, depression, vertigo, Alzheimer disease, stroke, unspecified dementia, central nervous system vasculitis, peripheral neuropathy, and Hashimoto encephalopathy. The physicians who most commonly made these misdiagnoses were primary care physicians and neurologists; in the 18% of patients who were diagnosed correctly at their first assessment, the diagnosis was almost always by a neurologist. The mean time from onset to diagnosis was 7.9 months, an average of two-thirds of the way through their disease course.

CONCLUSIONS

Diagnosis of sCJD is quite delayed. When evaluating patients with rapidly progressive dementia with suspected neurodegenerative, autoimmune, infectious, or toxic/metabolic etiology, sCJD should also be included in the differential diagnosis, and appropriate diagnostic tests, such as diffusion brain magnetic resonance imaging, should be considered. Primary care physicians and neurologists need improved training in sCJD diagnosis.

Determination of neuronal antibodies in suspected and definite Creutzfeldt-Jakob disease

IMPORTANCE

Creutzfeldt-Jakob disease (CJD) and autoimmune encephalitis with antibodies against neuronal surface antigens (NSA-abs) may present with similar clinical features. Establishing the correct diagnosis has practical implications in the management of care for these patients.

OBJECTIVE

To determine the frequency of NSA-abs in the cerebrospinal fluid of patients with suspected CJD and in patients with pathologically confirmed (ie, definite) CJD.

DESIGN, SETTING, AND PARTICIPANTS

A mixed prospective (suspected) and retrospective (definite) CJD cohort study was conducted in a reference center for detection of NSA-abs. The population included 346 patients with suspected CJD and 49 patients with definite CJD.

MAIN OUTCOMES AND MEASURES

Analysis of NSA-abs in cerebrospinal fluid with brain immunohistochemistry optimized for cell-surface antigens was performed. Positive cases in the suspected CJD group were further studied for antigen specificity using cell-based assays. All definite CJD cases were comprehensively tested for NSA-abs, with cell-based assays used for leucine-rich glioma-inactivated 1 (LGI1), contactin-associated protein-like 2 (CASPR2), N-methyl-d-aspartate (NMDA), and glycine (GlY) receptors.

RESULTS

Neuronal surface antigens were detected in 6 of 346 patients (1.7%) with rapid neurologic deterioration suggestive of CJD. None of these 6 patients fulfilled the diagnostic criteria for probable or possible CJD. The target antigens included CASPR2, LGI1, NMDAR, aquaporin 4, Tr (DNER [δ/notch-like epidermal growth factor-related receptor]), and an unknown protein. Four of the patients developed rapidly progressive dementia, and the other 2 patients had cerebellar ataxia or seizures that were initially considered to be myoclonus without cognitive decline. The patient with Tr-abs had a positive 14-3-3 test result. Small cell lung carcinoma was diagnosed in the patient with antibodies against an unknown antigen. All patients improved or stabilized after appropriate treatment. None of the 49 patients with definite CJD had NSA-abs.

CONCLUSIONS AND RELEVANCE

A low, but clinically relevant, number of patients with suspected CJD had potentially treatable disorders associated with NSA-abs. In contrast, none of 49 patients with definite CJD had NSA-abs, including NMDAR-abs, GlyR-abs, LGI1-abs, or CASPR2-abs. These findings suggest that cerebrospinal fluid NSA-abs analysis should be included in the diagnostic workup of patients with rapidly progressive central nervous system syndromes, particularly when they do not fulfill the diagnostic criteria of probable or possible CJD.

Rapidly progressive dementia: experience in a tertiary care medical center

Diagnosis of rapidly progressive dementia (RPD) poses a complex medical challenge that requires an exhaustive evaluation. Although prion diseases, in particular Creutzfeldt-Jakob disease (CJD), are often suspected, many other nonprion diseases may present as RPD. Our aim was to review the causes of RPD in our center to better understand the underlying conditions. We reviewed clinical, neuroimaging, and cerebrospinal fluid data from patients with RPD admitted to our hospital from 1994 to 2009. Forty-nine patients (mean age at onset 72.4 y) with RPD were admitted to our center during the study period. The mean interval between the onset of symptoms and admission was 4.6 months. The final clinical diagnoses were as follows: nonprion neurodegenerative diseases (36.8%), CJD (30.6%), vascular dementia (8.2%), toxic-metabolic conditions (8.2%), and other disorders (16.2%). Among cases with informed death (n = 19), the average survival time was 8.6 ± 9.5 months. Survival was shorter among patients with prion disease (n = 10) than in those with other diagnoses (n = 9, P = 0.004). In conclusion, nonprion neurodegenerative diseases are the most common cause of RPD in our center. Our results suggest that although CJD is often suspected as a cause of RPD, its frequency depends on the referral differences across specialized centers.

Diagnosis and treatment of rapidly progressive dementias

Rapidly progressive dementias are conditions that typically cause dementia over weeks or months. They are a particular challenge to neurologists as the differential diagnosis often is different from the more typical, slowly progressive dementias. Early and accurate diagnosis is essential, as many of the etiologies are treatable. The information in this review is in part based on experience through our rapidly progressive dementia program at the University of California San Francisco, Memory and Aging Center. As treatment of a rapidly progressive dementia is entirely dependent on the diagnosis, we present a comprehensive, structured, but pragmatic approach to diagnosis, including key clinical, laboratory, and radiologic features. For the 2 most common causes of rapid dementia, treatment algorithms for the autoimmune encephalopathies and symptomatic management for the neurodegenerative causes are discussed.

Rapidly progressive dementias and the treatment of human prion diseases

IMPORTANCE OF THE FIELD

Rapidly progressive dementia (RPD) has many possible etiologies and definitive treatment is reliant upon an accurate diagnosis from an appropriate diagnostic work-up. A large portion of the neurodegenerative causes of RPD are due to prion diseases (e.g., Creutzfeldt-Jakob disease). The study of prion diseases, for which there is no currently available treatment, has public health implications and is becoming increasingly more relevant to our understanding of other protein misfolding disorders including Alzheimer's disease, frontotemporal degeneration, and Parkinson's disease.

AREAS COVERED IN THIS REVIEW

This article begins with an overview of the etiologies and diagnostic work-up of RPD followed by a detailed review of the literature concerning the treatment of human prion diseases (1971 to present).

WHAT THE READER WILL GAIN

The reader will understand the differential diagnosis and work-up of RPD as it pertains to its treatment, as well as an in-depth understanding of treatments of human prion diseases.

TAKE HOME MESSAGE

An accurate diagnosis of the cause of RPD is of paramount importance when determining appropriate treatment. Most studies of the treatment for human prion diseases are case reports or case series, and results from only one randomized, placebo-controlled study have been reported in the literature (flupirtine). Studies have been hindered by disease heterogeneity and lack of standardized outcome measures. Although no effective prion disease treatment has been revealed through these studies, they provide important considerations for future studies.