Brain biopsy in dementia: clinical indications and diagnostic approach

Clinical considerations in early-onset cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is an important cerebral small vessel disease associated with brain haemorrhage and cognitive change. The commonest form, sporadic amyloid-β CAA, usually affects people in mid- to later life. However, early-onset forms, though uncommon, are increasingly recognized and may result from genetic or iatrogenic causes that warrant specific and focused investigation and management. In this review, we firstly describe the causes of early-onset CAA, including monogenic causes of amyloid-β CAA (APP missense mutations and copy number variants; mutations of PSEN1 and PSEN2) and non-amyloid-β CAA (associated with ITM2B, CST3, GSN, PRNP and TTR mutations), and other unusual sporadic and acquired causes including the newly-recognized iatrogenic subtype. We then provide a structured approach for investigating early-onset CAA, and highlight important management considerations. Improving awareness of these unusual forms of CAA amongst healthcare professionals is essential for facilitating their prompt diagnosis, and an understanding of their underlying pathophysiology may have implications for more common, late-onset, forms of the disease.

Alzheimer's Disease Blood Biomarkers Associated With Neuroinflammation as Therapeutic Targets for Early Personalized Intervention

The definitive diagnosis of Alzheimer's Disease (AD) without the need for neuropathological confirmation remains a challenge in AD research today, despite efforts to uncover the molecular and biological underpinnings of the disease process. Furthermore, the potential for therapeutic intervention is limited upon the onset of symptoms, providing motivation for studying and treating the AD precursor mild cognitive impairment (MCI), the prodromal stage of AD instead. Applying machine learning classification to transcriptomic data of MCI, AD, and cognitively normal (CN) control patients, we identified differentially expressed genes that serve as biomarkers for the characterization and classification of subjects into MCI or AD groups. Predictive models employing these biomarker genes exhibited good classification performances for CN, MCI, and AD, significantly above random chance. The PI3K-Akt, IL-17, JAK-STAT, TNF, and Ras signaling pathways were also enriched in these biomarker genes, indicating their diagnostic potential and pathophysiological roles in MCI and AD. These findings could aid in the recognition of MCI and AD risk in clinical settings, allow for the tracking of disease progression over time in individuals as part of a therapeutic approach, and provide possible personalized drug targets for early intervention of MCI and AD.

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.

Pathological Gait Signatures of Post-stroke Dementia With Toe-Off and Heel-to-Ground Angles Discriminate From Alzheimer's Disease

Given the limited power of neuropsychological tests, there is a need for a simple, reliable means, such as gait, to identify mild dementia and its subtypes. However, gait characteristics of patients with post-stroke dementia (PSD) and Alzheimer’s disease (AD) are unclear. We sought to describe their gait signatures and to explore gait parameters distinguishing PSD from post-stroke non-dementia (PSND) and patients with AD. We divided 3-month post-stroke patients into PSND and PSD groups based on the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), and the activity of daily living (ADL). Thirty-one patients with AD and thirty-two healthy controls (HCs) were also recruited. Ten gait parameters in one single and two dual-task gait tests (counting-backward or naming-animals while walking) were compared among the groups, with adjustment for baseline demographic covariates and the MMSE score. The area under the receiver operating characteristic curve (AUC) was used to identify parameters discriminating PSD from individuals with PSND and AD. Patients with PSD and patients with AD showed impaired stride length, velocity, stride time, and cadence while patients with PSD had altered stance and swing phase proportions (all p ≤ 0.01, post hoc). Patients with AD had smaller toe-off (ToA) and heel-to-ground angles (HtA) (p ≤ 0.01) than HCs in dual-task gait tests. Individuals with PSD had a shorter stride length, slower velocity, and altered stance and swing phase percentages in all tests (p ≤ 0.01), but a higher coefficient of variation of stride length (CoV_SL) and time (CoV_ST) only in the naming animals-task gait test (p ≤ 0.001) than individuals with PSND. ToA and HtA in the naming animals-task gait test were smaller in individuals with AD than those with PSD (p ≤ 0.01). Statistical significance persisted after adjusting for demographic covariates, but not for MMSE. The pace and the percentage of stance or swing phase in all tests, CoV_ST in the dual-task paradigm, and CoV_SL only in the naming animals-task gait test (moderate accuracy, AUC > 0.700, p ≤ 0.01) could distinguish PSD from PSND. Furthermore, the ToA and HtA in the naming animals-task gait paradigm discriminated AD from PSD (moderate accuracy, AUC > 0.700, p ≤ 0.01). Thus, specific gait characteristics could allow early identification of PSD and may allow non-invasive discrimination between PSD and AD, or even other subtypes of dementia.

A Neurologist's Practical Approach to Cognitive Impairment

The global prevalence of dementia is expected to triple by the year 2050. This impending health care crisis has led to new heights of public awareness and general concern regarding cognitive impairment. Subsequently, clinicians are seeing more and more people presenting with cognitive concerns. It is important that clinicians meet these concerns with a strategy promoting accurate diagnoses. We have diagramed and described a practical approach to cognitive impairment. Through an algorithmic approach, we determine the presence and severity of cognitive impairment, systematically evaluate domains of function, and use this information to determine the next steps in evaluation. We also discuss how to proceed when cognitive impairment is associated with motor abnormalities or rapid progression.

The standardization of cerebrospinal fluid markers and neuropathological diagnoses brings to light the frequent complexity of concomitant pathology in Alzheimer's disease: The next challenge for biochemical markers?

During the last two decades, neuropathological examination of the brain has evolved both technically and scientifically. The increasing use of immunohistochemistry to detect protein aggregates paralleled a better understanding of neuroanatomical progression of protein deposition. As a consequence, an international effort was achieved to standardize hyperphosphorylated-Tau (phospho-TAU), ßAmyloid (Aß), alpha syncuclein (alpha-syn), phosphorylated transactive response DNA-binding protein 43 (phospho-TDP43) and vascular pathology detection. Meanwhile harmonized staging systems emerged in order to increase inter rater reproducibility. Therefore, a refined definition of Alzheimer's disease was recommended., a clearer picture of the neuropathological lesions diversity emerged secondarily to the systematic assessment of concomitant pathology highlighting finally a low rate of pure AD pathology. This brings new challenges to laboratory medicine in the field of cerebrospinal fluid (CSF) markers of Alzheimer's disease: how to further validate total Tau, phospho-TAU, Aß40 and Aß42 and new marker level cut-offs while autopsy rates are declining?

Brain biopsy in suspected non-neoplastic neurological disease

Brain biopsy has a well-established role in the diagnosis of CNS neoplasia. Nevertheless, despite being essential for the diagnosis of some benign neurological diseases, little consensus exists regarding its indications for disease diagnosis and patient orientation. Our aim was to assess brain biopsy diagnostic yield in patients with neurological deterioration of unknown etiology, to identify the clinical characteristics associated with an increased likelihood of achieving a diagnostic biopsy as well as the characteristics linked to a particular diagnosis.

METHODS

A retrospective analysis of 62 consecutive brain biopsies performed at a single tertiary care center between January 2004 and December 2015 for suspected non-neoplastic neurological disease was performed. The clinical presentation, imaging, and laboratory results were collected and compared between diagnostic groups.

RESULTS

Sixty-eight percent of the biopsies led to a definitive diagnosis. The most common histological diagnosis was central nervous system lymphoma (eight cases), followed by astrocytoma, demyelinating disease, and progressive multifocal leukoencephalopathy (four cases each). No clinical characteristics were found to predict a diagnostic biopsy or to correlate with a specific diagnosis. Importantly, a distinct diagnosis from the initially suspected was achieved in 52% of cases and biopsy findings led to a change of therapeutic orientation in 78% of the cases.

CONCLUSIONS

Our results suggest that brain biopsies have a significant impact on patient management and should be considered early in selected cases in which less invasive testing was unable to reach a definitive diagnosis.

Review: Fluid biomarkers in the human prion diseases

The human prion diseases are a diverse set of often rapidly progressive neurodegenerative conditions associated with abnormal forms of the prion protein. We review work to establish diagnostic biomarkers and assays that might fill other important roles, particularly those that could assist the planning and interpretation of clinical trials. The field now benefits from highly sensitive and specific diagnostic biomarkers using cerebrospinal fluid: detecting by-products of rapid neurodegeneration or specific functional properties of abnormal prion protein, with the second generation real time quaking induced conversion (RT-QuIC) assay being particularly promising. Blood has been a more challenging analyte, but has now also yielded valuable biomarkers. Blood-based assays have been developed with the potential to screen for variant Creutzfeldt-Jakob disease, although it remains uncertain whether these will ever be used in practice. The very rapid neurodegeneration of prion disease results in strong signals from surrogate protein markers in the blood that reflect neuronal, axonal, synaptic or glial pathology in the brain: notably the tau and neurofilament light chain proteins. We discuss early evidence that such tests, applied alongside robust diagnostic biomarkers, may have potential to add value as clinical trial outcome measures, predictors of future disease course (including for asymptomatic individuals at high risk of prion disease), and as rapidly accessible and sensitive markers to aid early diagnosis.

Creutzfeldt-Jakob Disease Presenting as Expressive Aphasia and Nonconvulsive Status Epilepticus

Creutzfeldt-Jakob disease (CJD), the most common form of human prion diseases, is a fatal condition with a mortality rate reaching 85% within one year of clinical presentation. CJD is characterized by rapidly progressive neurological deterioration in combination with typical electroencephalography (EEG) and magnetic resonance imaging (MRI) findings and positive cerebrospinal spinal fluid (CSF) analysis for 14-3-3 proteins. Unfortunately, CJD can have atypical clinical and radiological presentation in approximately 10% of cases, thus making the diagnosis often challenging. We report a rare clinical presentation of sporadic CJD (sCJD) with combination of both expressive aphasia and nonconvulsive status epilepticus. This patient presented with slurred speech, confusion, myoclonus, headaches, and vertigo and succumbed to his disease within ten weeks of initial onset of his symptoms. He had a normal initial diagnostic workup, but subsequent workup initiated due to persistent clinical deterioration revealed CJD with typical MRI, EEG, and CSF findings. Other causes of rapidly progressive dementia and encephalopathy were ruled out. Though a rare condition, we recommend consideration of CJD on patients with expressive aphasia, progressive unexplained neurocognitive decline, and refractory epileptiform activity seen on EEG. Frequent reimaging (MRI, video EEGs) and CSF examination might help diagnose this fatal condition earlier.

EBV driven natural killer cell disease of the central nervous system presenting as subacute cognitive decline

Brain biopsy in patients presenting with subacute encephalopathyis never straightforward and only undertaken when a ‘treatable condition’ is a realistic possibility.

This 63 year old right handed, immunocompetent Caucasian woman presented with an 8 month history of rapidly progressive right-sided hearing impairment, a 4 month history of intermittent headaches, tinnitus, ‘dizziness’, dysphagia, nausea and vomiting, with the subsequent evolution of progressive gait ataxia and a subacute global encephalopathy. The possibility of CJD was raised. Brain biopsy was carried out. Western blot for prion protein was negative. She died 9 days later and autopsy brain examination confirmed widespread subacute infarction due to an EBV positive atypical NK/T-cell infiltrate with positivity for CD3, CD56, granzyme B, perforin and EBER with absence of CD4, CD5 and CD8 expression. Molecular studies for T-cell clonality were attempted but failed due to insufficient DNA quality. Serology was consistent with past EBV infection (EBV VCA and EBNA IgG Positive). There was no evidence of disease outside the CNS. Primary central nervous system NK/T-cell lymphoma is extremely rare. The rare reported cases all present with a discrete intracranial mass, unlike the diffuse infiltrative pattern in this case. Whilst the diffuse interstitial pattern is reminiscent of chronic active EBV infection (CAEBV) seen in other organ systems such as the liver and bone marrow, the clinical presentation and epidemiologic profile are not typical for CAEBV.

Brain biopsies requiring Creutzfeldt-Jakob disease precautions in the Republic of Ireland 2005-2016

AIMS

Creutzfeldt-Jakob disease (CJD) risk precautions are required when performing brain biopsies on patients with a dementing illness and in 'risk' groups. The impact on a diagnostic neuropathology service is considerable. We sought to determine if better case selection might reduce the necessity for application of CJD risk precautions.

METHODS

We reviewed the clinical information, contributory investigations and final neuropathologic diagnosis in a cohort of patients (n = 21), referred to the National CJD Surveillance Centre between January 1, 2005, and December 31, 2016.

RESULTS

Of this 21-patient cohort, five were positive for CJD, four belonged to the 'at risk of CJD' category requiring brain surgery, while the remaining 12 were referred to the National CJD Surveillance Unit with CJD as part of their differential diagnosis. CJD was confirmed in 5/21 (three sporadic [s]CJD, one variant [v]CJD and one iatrogenic [i] CJD). CJD was clinically probable in 4/5 proven CJD patients (80%). The patients (n = 4) in the 'at risk of CJD' group were diagnosed with tumour (n = 2), inflammation (n = 1) and non-specific changes (n = 1). Of the remaining 12 patients (in whom CJD was included in the differential diagnosis), the final neuropathologic diagnoses included tumour (n = 2), neurodegenerative (n = 2), inflammatory (n = 1), metabolic (n = 2), vascular (n = 2) and non-specific gliosis (n = 3).

CONCLUSIONS

More often than not, the clinical suspicion of CJD was not borne out by the final neuropathological diagnosis. Failure by clinicians to adhere to the recommended CJD investigation algorithm impacts adversely on the neuropathology workload and causes unnecessary concern among operating theatre, laboratory and nursing personnel.

Intravascular large B-cell lymphoma presenting clinically as rapidly progressive dementia

BACKGROUND

In patients presenting with rapidly progressive dementia, prion disease may enter the differential diagnosis. The commonest malignancies masquerading as prion disease are primary CNS lymphoma and intravascular large B-cell lymphoma, both rare and difficult to diagnose without brain biopsy.

CASE PRESENTATION

This 82-year-old lady with a past history of hypertension, presented with rapidly progressive cognitive impairment and ataxia. The possibility of sCJD was raised. Brain biopsy was carried out. Western blot for prion protein was negative. Brain biopsy showed intravascular large B-cell lymphoma. She died shortly afterwards.

CONCLUSION

The clinical presentation of intravascular large B-cell lymphoma is diverse. Patients may present as in this case with dementia, seizures, and myoclonus leading to a clinical diagnosis of sCJD. The diagnosis here was made at biopsy but is made at autopsy in over 50% of cases.

Long-term utility and complication profile of open craniotomy for biopsy in patients with idiopathic encephalitis

Neurosurgeons are often asked to perform open biopsy for diagnosis of encephalitis after medical investigations are non-diagnostic. These patients may be critically ill with multiple comorbidities. Patients and their families often request data regarding the success rates and complication profile of biopsy, but minimal literature exists in this area. Retrospective chart review of all patients undergoing open brain biopsy (burr hole or craniotomy) for encephalitis refractory to medical diagnosis between January 2009 and December 2013 was undertaken. Pathology records and outpatient follow-up were reviewed to determine most recent clinical status of each patient. A total of 59 patients were included with mean follow up of 20months. The average age at biopsy was 55years. The most common unconfirmed diagnoses leading to biopsy were vasculitis (44%), neoplasm (27%), infection (12%), autoimmune (12%), amyloidosis (5%). Tissue pathology was diagnostic in 42% of all cases. Overall, biopsy confirmed the preoperative diagnosis in 46% of cases and refuted the preoperative leading diagnosis in 25% of cases. At last follow-up, the tissue pathology resulted in a medical treatment change in 25% of cases. There was a 14% major neurological complication rate (postoperative stroke, hemorrhage, or neurological deficit) and 9% cardiopulmonary complication rate (delayed extubation and re-intubation) attributable to surgical intervention. In this limited series, diagnostic utility of biopsy in patients with idiopathic encephalitis is less than 50% and the major complication rate is 23%. Patients and providers must be counseled accordingly and weigh the risks and benefits of open biopsy for encephalitis cautiously.

Neuronavigation-assisted trajectory planning for deep brain biopsy with susceptibility-weighted imaging

BACKGROUND

Susceptibility-weighted imaging (SWI) exploits susceptibility differences between tissues to enhance contrast in magnetic resonance imaging to enable the visualization of small blood vessels that are difficult to detect by other contrast agents. This study explored the value of SWI-based planning for neuronavigation-guided deep brain biopsies to reduce the incidence of post-surgical complications.

METHODS

The cohort of 84 patients was divided into 41 biopsies performed aided by SWI (SWI group) and 43 biopsies based on conventional T1w-Gd-based imaging (T1w-Gd group). Biopsy targets were determined using magnetic resonance spectroscopy (MRS) before the operation, and the safest trajectory was selected based on preoperative images of blood vessels.

RESULTS

Within 24 h of surgery, there was no radiographically identified bleeding, no blood extravasation and no clinical intracranial hypertension in the SWI group. Only one patient (2.5 %) with basal ganglia lymphoma developed transient hemiparesis after biopsy, who later recovered after undergoing symptomatic treatment. Complication rates in the SWI group were lower than in the T1w-Gd group, where a 7 % morbidity rate was encountered with one patient developing a permanent neurological deficit and two showing biopsy-associated hemorrhages. SWI imaging yielded a better visualization of subcortical vessels and deep-seated brain structures.

CONCLUSIONS

SWI-based imaging revealed significantly better visualization of small-caliber vasculature that was not detectable on conventional T1w-Gd imaging, minimizing damage to the brain and reducing postoperative complications. Furthermore, MRS can contribute significantly to target selection to improve the yield of image-guided biopsies.

Diagnostic Value and Safety of Brain Biopsy in Patients With Cryptogenic Neurological Disease: A Systematic Review and Meta-analysis of 831 Cases

BACKGROUND

The role of brain biopsy in patients with cryptogenic neurological disease is uncertain.

OBJECTIVE

To determine the risks and benefits of diagnostic brain biopsy for nonneoplastic indications in immunocompetent patients.

METHODS

Appropriate studies were identified by searching electronic databases.

RESULTS

We screened 3645 abstracts and included 20 studies with a total of 831 patients. Indications for biopsy were: (1a) severe neurological disease of unknown etiology in adults (n = 7) and (1b) in children (n = 2); (2) suspected primary angiitis of the central nervous system (PACNS) (n = 3); (3) chronic meningitis of unknown cause (n = 3); (4) atypical dementia (n = 4); and (5) nonneoplastic disease (n = 1). Diagnostic success rates calculated for subgroups were 51.3% (34.5-68.1) for 1a, 53.8% (42.9-64.5) for 1b, 74.7% (64.0-84.1) for 2, 30.3% (17.2-45.4) for 3, and 60.8% (41.2-78.8) for 4. Clinical impact rates were 30.5% (13.6-50.6) for 1a (n = 6), 67.1% (42.8-87.3) for 1b (n = 2), 8.3% (2.3-20.0) for 3 (n = 1), and 14.2% (6.5-24.3) for 4 (n = 2). Lymphoma (n = 32) and Creutzfeldt-Jakob disease (n = 30) were the most common diagnoses on the final histopathology reports of positive brain biopsies in 1a. In 1b, encephalitis (n = 7), PACNS (n = 6), and demyelination (n = 6) were the most common. The odds ratio for achieving a diagnostic biopsy when there was a radiological target was 3.70 (P = .014, 95% confidence interval, 1.31-10.42).

CONCLUSION

Brain biopsy in cryptogenic neurological disease was associated with the highest diagnostic yield in patients with suspected PACNS. The greatest clinical impact was seen in children with cryptogenic neurological disease. The presence of a radiological target was associated with a higher diagnostic yield.

Clinical Perspectives on Targeting Therapies for Personalized Medicine

Expected benefits from new technology include more efficient patient selection for clinical trials, more cost-effective treatment pathways for patients and health services and a more profitable accelerated approach for drug developers. Regulatory authorities expect the pharmaceutical and biotechnology industries to accelerate their development of companion diagnostics and companion therapeutics toward the goal of safer and more effective personalized medicine, and expect health services to fund and prescribers to adopt these new therapeutic technologies.

This review discusses the importance of a range of new approaches to developing new and reprofiled medicines to treat common and serious diseases, and rare diseases: new network pharmacology approaches, adaptive trial designs with enriched populations more likely to respond safely to treatment, as assessed by companion diagnostics for response and toxicity risk and use of “real world” data.

Case studies are described of single and multiple protein drug targets in several important therapeutic areas. These case studies also illustrate the value and complexity of use of selective biomarkers of clinical response and risk of adverse drug effects, either singly or in combination.

Feasibility Study: Comparison of Frontal Cortex Needle Core Versus Open Biopsy for Detection of Characteristic Proteinopathies of Neurodegenerative Diseases

The clinical diagnosis and classification of neurodegenerative diseases based on clinical examination or available biomarkers are currently insufficiently accurate. Although histologic examination is considered the gold standard for diagnosis, brain biopsies have been avoided because of the high risk-benefit ratio. However, brain biopsies have previously been performed with a craniotomy and excision of approximately 1 cm of cerebral cortex tissue, and it is possible that needle core brain biopsies would have a lower morbidity and mortality risk. Here, we compared the ability of simulated needle core biopsy versus simulated open biopsy to detect the frontal cortex histopathology associated with common neurodegenerative diseases in the elderly using 144 autopsy-proven cases. Simulated needle core biopsy, as compared with simulated open biopsy, gave close to 90% sensitivity and specificity for identifying graded densities of β-amyloid and neuritic plaques, neurofibrillary tangles, phosphorylated α-synuclein, and phosphorylated TDP-43 pathology. This study shows that the presence and densities of the most common molecular pathologies may be histopathologically assessed in simulated frontal cortex needle biopsies, with accuracy very close to that obtained by open cortical biopsy. An accurate estimation of the morbidity and mortality risk associated with cortical needle core biopsy will require specifically designed clinical trials in appropriate subjects.

Creutzfeldt-Jakob disease: updated diagnostic criteria, treatment algorithm, and the utility of brain biopsy

Creutzfeldt-Jakob disease (CJD) is a rare neurodegenerative condition with a rapid disease course and a mortality rate of 100%. Several forms of the disease have been described, and the most common is the sporadic type. The most challenging aspect of this disease is its diagnosis—the gold standard for definitive diagnosis is considered to be histopatho-logical confirmation—but newer tests are providing means for an antemortem diagnosis in ways less invasive than brain biopsy. Imaging studies, electroencephalography, and biomarkers are used in conjunction with the clinical picture to try to make the diagnosis of CJD without brain tissue samples, and all of these are reviewed in this article. The current diagnostic criteria are limited; test sensitivity and specificity varies with the genetics of the disease as well as the clinical stage. Physicians may be unsure of all diagnostic testing available, and may order outdated tests or prematurely request a brain biopsy when the diagnostic workup is incomplete. The authors review CJD, discuss the role of brain biopsy in this patient population, provide a diagnostic pathway for the patient presenting with rapidly progressive dementia, and propose newer diagnostic criteria.

The use of cerebrospinal fluid and neuropathologic studies in neuropsychiatry practice and research

The gold standard for diagnosis of neurodegenerative diseases (ie, Alzheimer disease, frontotemporal dementia, Parkinson disease, dementia with Lewy bodies, amyotrophic lateral sclerosis) is neuropathologic examination at autopsy. As such, laboratory studies play a central role in antemortem diagnosis of these conditions and their differentiation from the neuroinflammatory, infectious, toxic, and other nondegenerative etiologies (eg, rapidly progressive dementias) that are encountered in neuropsychiatric practice. This article summarizes the use of cerebrospinal fluid (CSF) laboratory studies in the diagnostic evaluation of dementia syndromes and emerging CSF biomarkers specific for underlying neuropathology in neurodegenerative disease research.

Brain biopsy in neurologic decline of unknown etiology

Brain biopsies have an uncertain role in the diagnosis of patients with dementia or neurologic decline of unknown etiology. They are often performed only after an exhaustive panel of less invasive tests and procedures have failed to provide a definitive diagnosis. The objective of this study was to evaluate the sensitivity of brain biopsies in this patient group through the retrospective analysis of 53 brain biopsies performed for neurologic disease of unknown etiology at a single tertiary care institution between December 2001 and December 2011. Patients with known nonlymphomatous neoplasms thought to be associated with the neurologic symptoms or with immunodeficiency were excluded from the study. Furthermore, the clinical presentation, imaging and laboratory tests were compared between diagnostic groups to identify factors more likely to yield a diagnosis. Sixty percent of the biopsies were diagnostic (32 of 53), with the most common histologic diagnosis of central nervous system lymphoma in 14 of 53 patients (26% of total) followed by infarct in four subjects (7.5%). A few patients were found to have rare and unsuspected diseases such as lymphomatosis cerebri, neurosarcoidosis and neuroaxonal leukodystrophy. Complications from biopsy were uncommon and included hemorrhage and infection with abscess formation at the biopsy site. These results suggest that brain biopsies may be useful in difficult cases in which less invasive measures have been unable to yield a definitive diagnosis.

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.

Lymphomatosis cerebri mimicking iatrogenic Creutzfeldt-Jakob disease

Lymphomatosis cerebri (LC) is a rare variant of primary central nervous system lymphoma (PCNSL) whereby individual lymphoma cells infiltrate the cerebral white matter without causing a mass effect. The disease characteristically presents as a rapidly progressive dementia, which opens an ample differential diagnosis of toxic, metabolic, neurodegenerative and infective causes. Other presentations also include changes in personality, myoclonus and psychotic symptoms. Here we report a patient who presented with a rapidly progressive dementia with a unique surgical history of a dural mater graft in the 1970s. The diagnosis of iatrogenic Creutzfeldt-Jakob disease (iCJD) was initially considered. However, the patient's clinical status deteriorated rapidly with no response to symptomatic treatment and she died 2 months after symptom onset. A diagnosis of T-type LC was reached at autopsy.

Biopsy of the superficial cortex: predictors of effectiveness and outcomes

BACKGROUND

Brain biopsies of superficial cortex are performed for diagnosis of neurological diseases, but preoperative predictors of successful diagnosis and risks are lacking.

OBJECTIVE

We evaluated effectiveness and outcomes of superficial cortical biopsies and determined preoperative predictors of diagnosis, outcomes, morbidities, and mortality.

METHODS

A single-institution retrospective analysis of 170 patients who underwent open brain biopsies of superficial cortex was performed. Clinical predictors of effectiveness and outcomes were determined using univariate/multivariate analyses and a system for risk-benefit stratification was created and tested.

RESULTS

Brain biopsies led to successful diagnosis in 122 of 170 (71.8%) and affected management in 97 of 170 (57.1%) cases. Factors increasing the odds of diagnostic pathology included age older than 45 years (odds ratio [OR]: 2.67, 95% confidence interval [CI]: 1.34-5.27, P < .01), previous cancer diagnosis (OR: 3.64, 95% CI: 1.69-7.85, P < .001), focal (OR: 3.90, 95% CI: 1.91-8.00, P < .001) and enhancing (OR: 5.03, 95% CI: 2.41-10.52, P < .001) lesions on magnetic resonance imaging, biopsy of specific lesions on magnetic resonance imaging (OR: 9.34, 95% CI: 4.29-20.33, P < .001), and use of intraoperative navigation (OR: 6.59, 95% CI: 3.04-14.28, P < .001). Brain biopsies led to symptomatic intracranial hemorrhage, seizures, other significant morbidities, and perioperative mortality in 12.4%, 16.2%, 37.1%, and 8% of cases, respectively. Risk of postoperative intracranial hemorrhage was increased by a history of aspirin use (OR: 2.51, 95% CI: 1.23-5.28, P < .05) and age older than 60 years (OR: 2.66, 95% CI: 1.36-5.18, P < .01).

CONCLUSION

Effectiveness and risk of morbidity/mortality can be estimated preoperatively for patients undergoing open brain biopsies of the superficial cortex. Older age and specific imaging characteristics increase the odds of diagnostic biopsy. Conversely, older age and aspirin use increases the risk of postoperative complications.

Simulated surgical-type cerebral biopsies from post-mortem brains allows accurate neuropathological diagnoses in the majority of neurodegenerative disease groups

BACKGROUND

In theory, cerebral biopsies could provide the diagnosis in a significant proportion of patients with neurodegenerative diseases, however, there are considerable ethical barriers. Previous series of cerebral biopsies have shown variable diagnostic accuracy but have understandably suffered because of lack of post-mortem tissue with which to compare the diagnosis. To determine the accuracy of such biopsies in neurodegenerative disease we took small biopsy-sized samples of predominantly fresh post-mortem brain tissue from frontal and temporal lobes in 62 cases. These were processed as for a biopsy and stained for H&E, p62, tau, Aβ, α-synuclein, and TDP-43. The sections were assessed blind by 3 neuropathologists and the results compared with the final post-mortem diagnosis.

RESULTS

The agreement and sensitivity in most cases was good especially: controls; Alzheimer's disease (AD); multiple system atrophy (MSA); frontotemporal lobar degeneration with TDP-43 positive inclusions and/or motor neurone disease (FTLD-TDP/MND); Huntington's disease (HD); corticobasal degeneration (CBD) / microtubular associated protein tau mutation cases with CBD-like features (CBD/MAPT); and combined AD- Dementia with Lewy Bodies (AD-DLB) where the sensitivity on assessing both brain regions varied between 75-100%. There was poor sensitivity for progressive supranuclear palsy (PSP) and amyotrophic lateral sclerosis (ALS) (both 0%), but moderate sensitivity for pure DLB (60%). The temporal lobe assessment was marginally more accurate than the frontal lobe but these were only slightly worse than both combined.

CONCLUSIONS

The study shows that with certain caveats the cerebral biopsy in life should be a viable method of accurately diagnosing many neurodegenerative diseases.

EFNS-ENS Guidelines on the diagnosis and management of disorders associated with dementia

BACKGROUND AND OBJECTIVES

The last version of the EFNS dementia guidelines is from 2007. In 2010, the revised guidelines for Alzheimer's disease (AD) were published. The current guidelines involve the revision of the dementia syndromes outside of AD, notably vascular cognitive impairment, frontotemporal lobar degeneration, dementia with Lewy bodies, corticobasal syndrome, progressive supranuclear palsy, Parkinson's disease dementia, Huntington's disease, prion diseases, normal-pressure hydrocephalus, limbic encephalitis and other toxic and metabolic disorders. The aim is to present a peer-reviewed evidence-based statement for the guidance of practice for clinical neurologists, geriatricians, psychiatrists and other specialist physicians responsible for the care of patients with dementing disorders. It represents a statement of minimum desirable standards for practice guidance.

METHODS

The task force working group reviewed evidence from original research articles, meta-analyses and systematic reviews, published by June 2011. The evidence was classified (I, II, III, IV) and consensus recommendations graded (A, B, or C) according to the EFNS guidance. Where there was a lack of evidence, but clear consensus, good practice points were provided.

RESULTS AND CONCLUSIONS

New recommendations and good practice points are made for clinical diagnosis, blood tests, neuropsychology, neuroimaging, electroencephalography, cerebrospinal fluid (CSF) analysis, genetic testing, disclosure of diagnosis, treatment of behavioural and psychological symptoms in dementia, legal issues, counselling and support for caregivers. All recommendations were revised as compared with the previous EFNS guidelines. The specialist neurologist together with primary care physicians play an important role in the assessment, interpretation and treatment of symptoms, disability and needs of dementia patients.

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.

The paradox of syndromic diversity in Alzheimer disease

Variant syndromes of Alzheimer disease (AD), led by deficits that extend beyond memory dysfunction, are of considerable clinical and neurobiological importance. Such syndromes present major challenges for both diagnosis and monitoring of disease, and serve to illustrate the apparent paradox of a clinically diverse group of disorders underpinned by a common histopathological substrate. This Review focuses on the most common variant AD phenotypes: posterior cortical atrophy, logopenic variant primary progressive aphasia and frontal variant AD. The neuroanatomical, molecular and pathological correlates of these phenotypes are highlighted, and the heterogeneous clinical presentations of the syndromes are discussed in the context of the emerging network paradigm of neurodegenerative disease. We argue that these apparently diverse clinical phenotypes reflect the differential involvement of a common core temporoparietofrontal network that is vulnerable to AD. According to this interpretation, the network signatures corresponding to AD variant syndromes are produced by genetic and other modulating factors that have yet to be fully characterized. The clinical and neurobiological implications of this network paradigm in the quest for disease-modifying treatments are also explored.

Post-mortem findings in 10 patients with presumed normal-pressure hydrocephalus and review of the literature

AIMS

Neuropathological features of idiopathic normal-pressure hydrocephalus (iNPH) are poorly characterized. Brain biopsy during life may help in the differential diagnosis of dementia, but post-mortem validation of biopsy findings is scarce. Here we review and report brain biopsy and post-mortem neuropathological findings in patients with presumed NPH.

METHODS

We evaluated 10 patients initially investigated by intraventricular pressure monitoring and a frontal cortical biopsy for histological and immunohistochemical assessment as a diagnostic procedure for presumed NPH.

RESULTS

Out of the 10 patients, eight were shunted and seven benefited. Until death, six had developed severe and two mild cognitive impairment. One was cognitively unimpaired, and one was mentally retarded. Three subjects displayed amyloid-β (Aβ) aggregates in their frontal cortical biopsy obtained at the initial procedure. One of these patients developed Alzheimer's disease during a follow-up time of nearly 10 years. One patient with cognitive impairment and NPH suffered from corticobasal degeneration. In six patients various vascular lesions were seen at the final neuropathological investigation. Five of them were cognitively impaired, and in four vascular lesions were seen sufficient in extent to be considered as causative regarding their symptoms.

CONCLUSIONS

The frequent finding of vascular pathology in NPH is intriguing, suggesting that vascular alterations might be causative of cognitive impairment in a notable number of patients with NPH and dementia. Brain biopsy can be used to detect Aβ aggregates, but neuropathological characteristics of iNPH as a distinct disease still need to be discovered.

Cortical brain biopsy in long-term prognostication of 468 patients with possible normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) can be alleviated by cerebrospinal fluid shunting but the differential diagnosis and patient selection are challenging. Intraventricular intracranial pressure monitoring as part of the diagnostic workup as well as shunting enable to obtain cortical brain biopsies to detect amyloid-β (Aβ) and hyperphosphorylated tau (HPτ), the hallmark lesions of Alzheimer's disease (AD). In possible NPH, Aβ alone indicates an increased risk of AD and when present with HPτ probable AD, but the effect of those brain lesions on survival is not known. The aim of this study was to evaluate the predictive value of brain biopsy for the long-term outcome of possible NPH. Between 1991 and 2006, the Neurosurgery Department of the Kuopio University Hospital evaluated 468 patients for possible NPH by intraventricular intracranial pressure monitoring and frontal cortical brain biopsy immunostained against Aβ and HPτ. All patients were followed up until the end of 2008 (n = 201) or death (n = 267) with a median follow-up of 4.6 years (range 0-17). Logistic regression analysis with Cox models was applied. Out of the 468 cases, Aβ was detected in 197 (42%) cortical biopsies, and together with HPτ in 44 (9%). Aβ alone indicated increased risk of AD and with HPτ probable AD, but it did not affect survival. Vascular aetiology was the most frequent cause of death. Cortical biopsy findings indicate that NPH is at present a heterogeneous syndrome and has notable overlapping with AD. Brain biopsy did not predict survival but may open a novel research window to study the pathobiology of neurodegeneration.

Pathologic lesions in neurodegenerative diseases

This chapter will discuss two of the most widely used approaches to assessing brain structure: neuroimaging and neuropathology. Whereas neuropathologic approaches to studying the central nervous system have been utilized for many decades and have provided insights into morphologic correlates of dementia for over 100 years, accurate structural imaging techniques "blossomed" with the development and refinement of computerized tomographic scanning and magnetic resonance imaging (MRI), beginning in the late 1970s. As Alzheimer disease progresses over time, there is progressive atrophy of the hippocampus and neocortex--this can be quantified and regional accentuation of the atrophy can be evaluated using quantitative MRI scanning. Furthermore, ligands for amyloid proteins have recently been developed--these can be used in positron emission tomography studies to localize amyloid proteins, and (in theory) study the dynamics of their deposition (and clearance) within the brain over time. Neuropathologic studies of the brain, using highly specific antibodies, can demonstrate synapse loss and the deposition of proteins important in AD progression--specifically ABeta and phosphor-tau. Finally, neuropathologic assessment of (autopsy) brain specimens can provide important correlation with sophisticated neuroimaging techniques.

Simulated brain biopsy for diagnosing neurodegeneration using autopsy-confirmed cases

Risks associated with brain biopsy limit availability of tissues and the role of brain biopsy in diagnosing neurodegeneration is unclear. We developed a simulated brain biopsy paradigm to comprehensively evaluate potential accuracy of detecting neurodegeneration in biopsies. Postmortem tissue from the frontal, temporal and parietal cortices and basal ganglia from 73 cases including Alzheimer's disease (AD), Lewy body disease (LBD), frontotemporal lobar degeneration-TDP43 (FTLD-TDP), multiple system atrophy (MSA), Pick's disease (PiD), corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) were evaluated using H&E and immunostains. Brain biopsy was simulated in a blinded manner by masking each slide with opaque tape except for an area measuring 10 mm in diameter. Diagnoses obtained from frontal cortex only or all 4-brain regions were then compared with autopsy diagnoses. Diagnostic sensitivity in frontal cortex was highest in FTLD-TDP (88%), AD (80%) and LBD (79%); intermediate for MSA (71%), CBD (66%) and PiD (66%) and lowest for PSP (0%) (average 64%). Specificity was 43%. Sensitivities were enhanced with all 4-brain regions: FTLD-TDP (100%), AD (80%), LBD (100%), MSA (100%), CBD (83%), PiD (100%) and PSP (88%) (average 92%). Specificity was 71%. Simulated brain biopsy addressed limitations of standard brain biopsies such as tissue availability and lack of autopsy confirmation of diagnoses. These data could inform efforts to establish criteria for biopsy diagnosis of neurodegenerative disorders to guide care of individuals who undergo biopsy for enigmatic causes of cognitive impairment or when evidence of an underlying neurodegenerative disease may influence future therapy.