Regional cerebral blood flow and metabolic rate in persistent Lyme encephalopathy

Dynamic contrast-enhanced MRI shows altered blood-brain barrier function of deep gray matter structures in neuroborreliosis: a case-control study

BACKGROUND

Main aim was assessment of regional blood-brain barrier (BBB) function by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in patients with neuroborreliosis. Secondary aim was to study the correlation of BBB function with biochemical, clinical, and cognitive parameters.

METHODS

Regional ethical committee approved this prospective single-center case-control study. Within 1 month after diagnosis of neuroborreliosis, 55 patients underwent DCE-MRI. The patient group consisted of 25 males and 30 females with mean age 58 years, and the controls were 8 males and 7 females with mean age 57 years. Pharmacokinetic compartment modelling with Patlak fit was applied, providing estimates for capillary leakage rate and blood volume fraction. Nine anatomical brain regions were sampled with auto-generated binary masks. Fatigue, severity of clinical symptoms and findings, and cognitive function were assessed in the acute phase and 6 months after treatment.

RESULTS

Leakage rates and blood volume fractions were lower in patients compared to controls in the thalamus (p = 0.027 and p = 0.018, respectively), caudate nucleus (p = 0.009 for both), and hippocampus (p = 0.054 and p = 0.009). No correlation of leakage rates with fatigue, clinical disease severity or cognitive function was found.

CONCLUSIONS

In neuroborreliosis, leakage rate and blood volume fraction in the thalamus, caudate nucleus, and hippocampus were lower in patients compared to controls. DCE-MRI provided new insight to pathophysiology of neuroborreliosis, and can serve as biomarker of BBB function and regulatory mechanisms of the neurovascular unit in infection and inflammation.

RELEVANCE STATEMENT

DCE-MRI provided new insight to pathophysiology of neuroborreliosis, and can serve as biomarker of blood-brain barrier function and regulatory mechanisms of the neurovascular unit in infection and inflammation.

KEY POINTS

• Neuroborreliosis is an infection with disturbed BBB function. • Microvessel leakage can be studied with DCE-MRI. • Prospective case-control study showed altered microvessel properties in thalamus, caudate, and hippocampus.

Neuropsychiatric Lyme Disease and Vagus Nerve Stimulation

Lyme disease, the most common tick-borne disease in the United States, is caused by infection with the spirochete Borrelia burgdorferi. While most patients with acute Lyme disease recover completely if treated with antibiotics shortly after the onset of infection, approximately 10-30% experience post-treatment symptoms and 5-10% have residual symptoms with functional impairment (post-treatment Lyme disease syndrome or PTLDS). These patients typically experience pain, cognitive problems, and/or fatigue. This narrative review provides a broad overview of Lyme disease, focusing on neuropsychiatric manifestations and persistent symptoms. While the etiology of persistent symptoms remains incompletely understood, potential explanations include persistent infection, altered neural activation, and immune dysregulation. Widely recognized is that new treatment options are needed for people who have symptoms that persist despite prior antibiotic therapy. After a brief discussion of treatment approaches, the article focuses on vagus nerve stimulation (VNS), a neuromodulation approach that is FDA-approved for depression, epilepsy, and headache syndromes and has been reported to be helpful for other diseases characterized by inflammation and neural dysregulation. Transcutaneous VNS stimulates the external branch of the vagus nerve, is minimally invasive, and is well-tolerated in other conditions with few side effects. If well-controlled double-blinded studies demonstrate that transcutaneous auricular VNS helps patients with chronic syndromes such as persistent symptoms after Lyme disease, taVNS will be a welcome addition to the treatment options for these patients.

Neuropsychiatric Symptoms and Tick-Borne Diseases

In North America, Lyme disease (LD) is primarily caused by the spirochetal bacterium Borrelia burgdorferi, transmitted to humans by Ixodes species tick bites, at an estimated rate of 476,000 patients diagnosed per year. Acute LD often manifests with flu-like symptoms and an expanding rash known as erythema migrans (EM) and less often with neurologic, neuropsychiatric, arthritic, or cardiac features. Most acute cases of Lyme disease are effectively treated with antibiotics, but 10-20% of individuals may experience recurrent or persistent symptoms. This chapter focuses on the neuropsychiatric aspects of Lyme disease, as these are less widely recognized by physicians and often overlooked. Broader education about the potential complexity, severity, and diverse manifestations of tick-borne diseases is needed.

Detecting Borrelia Spirochetes: A Case Study With Validation Among Autopsy Specimens

The complex etiology of neurodegenerative disease has prompted studies on multiple mechanisms including genetic predisposition, brain biochemistry, immunological responses, and microbial insult. In particular, Lyme disease is often associated with neurocognitive impairment with variable manifestations between patients. We sought to develop methods to reliably detect Borrelia burgdorferi, the spirochete bacteria responsible for Lyme disease, in autopsy specimens of patients with a history of neurocognitive disease. In this report, we describe the use of multiple molecular detection techniques for this pathogen and its application to a case study of a Lyme disease patient. The patient had a history of Lyme disease, was treated with antibiotics, and years later developed chronic symptoms including dementia. The patient's pathology and clinical case description was consistent with Lewy body dementia. B. burgdorferi was identified by PCR in several CNS tissues and by immunofluorescent staining in the spinal cord. These studies offer proof of the principle that persistent infection with the Lyme disease spirochete may have lingering consequences on the CNS.

Post-treatment Lyme Disease as a Model for Persistent Symptoms in Lyme Disease

It has long been observed in clinical practice that a subset of patients with Lyme disease report a constellation of symptoms such as fatigue, cognitive difficulties, and musculoskeletal pain, which may last for a significant period of time. These symptoms, which can range from mild to severe, have been reported throughout the literature in both prospective and population-based studies in Lyme disease endemic regions. The etiology of these symptoms is unknown, however several illness-causing mechanisms have been hypothesized, including microbial persistence, host immune dysregulation through inflammatory or secondary autoimmune pathways, or altered neural networks, as in central sensitization. Evaluation and characterization of persistent symptoms in Lyme disease is complicated by potential independent, repeat exposures to B. burgdorferi, as well as the potential for co-morbid diseases with overlapping symptom profiles. Antibody testing for B. burgdorferi is an insensitive measure after treatment, and no other FDA-approved tests currently exist. As such, diagnosis presents a complex challenge for physicians, while the lived experience for patients is one marked by uncertainty and often illness invalidation. Currently, there are no FDA-approved pharmaceutical therapies, and the safety and efficacy of off-label and/or complementary therapies have not been well studied and are not agreed-upon within the medical community. Post-treatment Lyme disease represents a narrow, defined, mechanistically-neutral subset of this larger, more heterogeneous group of patients, and is a useful definition in research settings as an initial subgroup of study. The aim of this paper is to review the current literature on the diagnosis, etiology, risk factors, and treatment of patients with persistent symptoms in the context of Lyme disease. The meaning and relevance of existing patient subgroups will be discussed, as will future research priorities, including the need to develop illness biomarkers, elucidate the biologic mechanisms of disease, and drive improvements in therapeutic options.

Neurocognition in Post-Treatment Lyme Disease and Major Depressive Disorder

OBJECTIVE

Neurocognitive dysfunction in patients with residual or emergent symptoms after treatment for Lyme Disease is often attributed to comorbid depression. In this study, patients with Post-Treatment Lyme Disease Syndrome (PTLDS) were compared to patients with Major Depressive Disorder (MDD), as well as healthy comparison subjects (HC), on neurocognitive measures administered through the same laboratory, to determine if patterns of performance were similar.

METHODS

Two analyses were conducted. First, performance on the Wechsler Adult Intelligence Scale (WAIS-III) and on subtests from the Wechsler Memory Scale (WMS-III) was compared among the groups. Second, comparable subgroups of PTLDS and MDD patients with at least one low WMS-III score were compared on an additional set of measures assessing motor function, psychomotor performance, attention, memory, working memory, and language fluency, to determine if the overall profile of performance was similar in the two subgroups.

RESULTS

In the first analysis, PTLDS patients performed more poorly than both MDD and HC on tasks assessing verbal abilities, working memory, and paragraph learning. Processing speed in the two patient groups, however, was equally reduced. In the second analysis, MDD patients with low WMS-III exhibited concomitantly greater difficulties in psychomotor speed and attention, while low-WMS-III PTLDS patients exhibited greater difficulties in language fluency.

CONCLUSIONS

MDD and PTLDS can be confused neuropsychologically because both exhibit similar levels of psychomotor slowing. However, problems on memory-related tasks, though mild, are more pronounced in PTLDS. PTLDS patients with poorer memory also exhibit poorer language fluency, and less deficit in processing speed and attention compared to MDD.

Cognitive Decline in Post-treatment Lyme Disease Syndrome

OBJECTIVE

Patient-reported cognitive complaints are common in those with post-treatment Lyme disease syndrome (PTLDS). Objective evidence of cognitive impairment in this population is variable in part due to methodological variability in existing studies. In this study, we sought to use a systematic approach to characterizing PTLDS based on the most current consensus diagnosis. We further examined PTLDS-related cognitive decline, operationalized as a significant decline in cognitive test performance relative to premorbid cognitive ability.

METHOD

We enrolled a case series of 124 patients with confirmed PTLDS defined by Infectious Diseases Society of America-proposed case definition. Cognitive functioning was evaluated using standardized neuropsychological measures.

RESULTS

The majority (92%) of participants endorsed some level of cognitive difficulty, yet 50% of the sample showed no statistically or clinically significant cognitive decline, 26% of the sample evidenced significant cognitive decline on measures of memory and variably on measures of processing speed, and 24% of the sample were excluded from analyses due to suboptimal test engagement.

CONCLUSIONS

The current findings are consistent with the literature showing that the most robust neurocognitive deficit associated with PTLDS is in verbal memory and with variable decline in processing speed. Compared to population normative comparison standards, PTLDS-related cognitive decline remains mild. Thus, further research is needed to better understand factors related to the magnitude of subjective cognitive complaints as well as objective evidence of mild cognitive decline.

Imaging in Lyme neuroborreliosis

Abstract

Lyme neuroborreliosis (LNB) is a tick-borne spirochetal infection with a broad spectrum of imaging pathology. For individuals who live in or have travelled to areas where ticks reside, LNB should be considered among differential diagnoses when clinical manifestations from the nervous system occur. Radiculitis, meningitis and facial palsy are commonly encountered, while peripheral neuropathy, myelitis, meningoencephalitis and cerebral vasculitis are rarer manifestations of LNB. Cerebrospinal fluid (CSF) analysis and serology are key investigations in patient workup. The primary role of imaging is to rule out other reasons for the neurological symptoms. It is therefore important to know the diversity of possible imaging findings from the infection itself. There may be no imaging abnormality, or findings suggestive of neuritis, meningitis, myelitis, encephalitis or vasculitis. White matter lesions are not a prominent feature of LNB. Insight into LNB clinical presentation, laboratory test methods and spectrum of imaging pathology will aid in the multidisciplinary interaction that often is imperative to achieve an efficient patient workup and arrive at a correct diagnosis. This article can educate those engaged in imaging of the nervous system and serve as a comprehensive tool in clinical cases.

Key Points

• Diagnostic criteria for LNB emphasise exclusion of an alternative cause to the clinical symptoms.

• MRI makes a crucial contribution in the diagnosis and follow-up of LNB.

• MRI may have normal findings, or show neuritis, meningitis, myelitis, encephalitis or vasculitis.

• White matter lesions are not a prominent feature of LNB.

Autoimmunity against a glycolytic enzyme as a possible cause for persistent symptoms in Lyme disease

Some patients with a history of Borrelia burgdorferi infection develop a chronic symptomatology characterized by cognitive deficits, fatigue, and pain, despite antibiotic treatment. The pathogenic mechanism that underlines this condition, referred to as post-treatment Lyme disease syndrome (PTLDS), is currently unknown. A debate exists about whether PTLDS is due to persistent infection or to post-infectious damages in the immune system and the nervous system. We present the case of a patient with evidence of exposure to Borrelia burgdorferi sl and a long history of debilitating fatigue, cognitive abnormalities and autonomic nervous system issues. The patient had a positive Western blot for anti-basal ganglia antibodies, and the autoantigen has been identified as γ enolase, the neuron-specific isoenzyme of the glycolytic enzyme enolase. Assuming Borrelia own surface exposed enolase as the source of this autoantibody, through a mechanism of molecular mimicry, and given the absence of sera reactivity to α enolase, a bioinformatical analysis was carried out to identify a possible cross-reactive conformational B cell epitope, shared by Borrelia enolase and γ enolase, but not by α enolase. Taken that evidence, we hypothesize that this autoantibody interferes with glycolysis in neuronal cells, as the physiological basis for chronic symptoms in at least some cases of PTLDS. Studies investigating on the anti-γ enolase and anti-Borrelia enolase antibodies in PTLDS are needed to confirm our hypotheses.

Posttreatment Lyme disease syndrome

The prognosis following appropriate antibiotic treatment of early or late Lyme disease is favorable but can be complicated by persistent symptoms of unknown cause termed posttreatment Lyme disease syndrome (PTLDS), characterized by fatigue, musculoskeletal pain, and cognitive complaints that persist for 6 months or longer after completion of antibiotic therapy. Risk factors include delayed diagnosis, increased severity of symptoms, and presence of neurologic symptoms at time of initial treatment. Two-tier serologic testing is neither sensitive nor specific for diagnosis of PTLDS because of variability in convalescent serologic responses after treatment of early Lyme disease. Optimal treatment of PTLDS awaits more precise understanding of the pathophysiologic mechanisms involved in this illness and future treatment trials.

Cerebral small vessel disease: Capillary pathways to stroke and cognitive decline

Cerebral small vessel disease (SVD) gives rise to one in five strokes worldwide and constitutes a major source of cognitive decline in the elderly. SVD is known to occur in relation to hypertension, diabetes, smoking, radiation therapy and in a range of inherited and genetic disorders, autoimmune disorders, connective tissue disorders, and infections. Until recently, changes in capillary patency and blood viscosity have received little attention in the aetiopathogenesis of SVD and the high risk of subsequent stroke and cognitive decline. Capillary flow patterns were, however, recently shown to limit the extraction efficacy of oxygen in tissue and capillary dysfunction therefore proposed as a source of stroke-like symptoms and neurodegeneration, even in the absence of physical flow-limiting vascular pathology. In this review, we examine whether capillary flow disturbances may be a shared feature of conditions that represent risk factors for SVD. We then discuss aspects of capillary dysfunction that could be prevented or alleviated and therefore might be of general benefit to patients at risk of SVD, stroke or cognitive decline.

Clinical determinants of Lyme borreliosis, babesiosis, bartonellosis, anaplasmosis, and ehrlichiosis in an Australian cohort

Background

Borrelia burgdorferi is the causative agent of Lyme borreliosis. This spirochete, along with Babesia, Bartonella, Anaplasma, Ehrlichia, and the Rickettsia spp. are recognized tick-borne pathogens. In this study, the clinical manifestation of these zoonoses in Australia is described.

Methods

The clinical presentation of 500 patients over the course of 5 years was examined. Evidence of multisystem disease and cranial nerve neuropathy was sought. Supportive laboratory evidence of infection was examined.

Results

Patients from every state of Australia presented with a wide range of symptoms of disease covering multiple systems and a large range of time intervals from onset. Among these patients, 296 (59%) were considered to have a clinical diagnosis of Lyme borreliosis and 273 (54% of the 500) tested positive for the disease, the latter not being a subset of the former. In total, 450 (90%) had either clinical evidence for or laboratory proof of borrelial infection, and the great majority of cases featured neurological symptoms involving the cranial nerves, thus mimicking features of the disease found in Europe and Asia, as distinct from North America (where extracutaneous disease is principally an oligoarticular arthritis). Only 83 patients (17%; number [n]=492) reported never leaving Australia. Of the 500 patients, 317 (63%) had clinical or laboratory-supported evidence of coinfection with Babesia or Bartonella spp. Infection with A. phagocytophilum was detected in three individuals, and Ehrlichia chaffeensis was detected in one individual who had never traveled outside Australia. In the cohort, 30 (11%; n=279) had positive rickettsial serology.

Conclusion

The study suggests that there is a considerable presence of borreliosis in Australia, and a highly significant burden of coinfections accompanying borreliosis transmission. The concept sometimes advanced of a “Lyme-like illness” on the continent needs to be re-examined as the clinical interplay between all these infections. Evidence is presented for the first report of endemic anaplasmosis and ehrlichiosis on the continent.

Updating the mild encephalitis hypothesis of schizophrenia

Schizophrenia seems to be a heterogeneous disorder. Emerging evidence indicates that low level neuroinflammation (LLNI) may not occur infrequently. Many infectious agents with low overall pathogenicity are risk factors for psychoses including schizophrenia and for autoimmune disorders. According to the mild encephalitis (ME) hypothesis, LLNI represents the core pathogenetic mechanism in a schizophrenia subgroup that has syndromal overlap with other psychiatric disorders. ME may be triggered by infections, autoimmunity, toxicity, or trauma. A 'late hit' and gene-environment interaction are required to explain major findings about schizophrenia, and both aspects would be consistent with the ME hypothesis. Schizophrenia risk genes stay rather constant within populations despite a resulting low number of progeny; this may result from advantages associated with risk genes, e.g., an improved immune response, which may act protectively within changing environments, although they are associated with the disadvantage of increased susceptibility to psychotic disorders. Specific schizophrenic symptoms may arise with instances of LLNI when certain brain functional systems are involved, in addition to being shaped by pre-existing liability factors. Prodrome phase and the transition to a diseased status may be related to LLNI processes emerging and varying over time. The variability in the course of schizophrenia resembles the varying courses of autoimmune disorders, which result from three required factors: genes, the environment, and the immune system. Preliminary criteria for subgrouping neurodevelopmental, genetic, ME, and other types of schizophrenias are provided. A rare example of ME schizophrenia may be observed in Borna disease virus infection. Neurodevelopmental schizophrenia due to early infections has been estimated by others to explain approximately 30% of cases, but the underlying pathomechanisms of transition to disease remain in question. LLNI (e.g. from reactivation related to persistent infection) may be involved and other pathomechanisms including dysfunction of the blood-brain barrier or the blood-CSF barrier, CNS-endogenous immunity and the volume transmission mode balancing wiring transmission (the latter represented mainly by synaptic transmission, which is often described as being disturbed in schizophrenia). Volume transmission is linked to CSF signaling; and together could represent a common pathogenetic link for the distributed brain dysfunction, dysconnectivity, and brain structural abnormalities observed in schizophrenia. In addition, CSF signaling may extend into peripheral tissues via the CSF outflow pathway along brain nerves and peripheral nerves, and it may explain the peripheral topology of neuronal dysfunctions found, like in olfactory dysfunction, dysautonomia, and even in peripheral tissues, i.e., the muscle lesions that were found in 50% of cases. Modulating factors in schizophrenia, such as stress, hormones, and diet, are also modulating factors in the immune response. Considering recent investigations of CSF, the ME schizophrenia subgroup may constitute approximately 40% of cases.

Risk factors for a non-favorable outcome after treated European neuroborreliosis

AIM

To identify possible risk factors for reduced health-related quality of life (HRQoL) and fatigue after treated Lyme neuroborreliosis (LNB).

METHODS

We included 50 patients with LNB and analyzed associations between their demographic, clinical, and laboratory characteristics at baseline and outcome at 30 months assessed by the self-report questionnaires Short Form-36 (SF-36) and Fatigue Severity Scale (FSS).

RESULTS

Lower scores in the SF-36 domain Physical Component Summary were associated with pretreatment symptom duration >6 weeks (B = -11.0, P = 0.001) and non-complete recovery at 4 months (B = -5.5, P = 0.037) (R(2) = 0.35). Lower scores in the SF-36 domain Mental Component Summary were associated with non-complete recovery at 4 months (B = -8.9, P = 0.01 (R(2) = 0.14). Higher FSS scores were associated with pretreatment symptom duration >6 weeks (B = 1.4, P = 0.006), high scores on the composite clinical score pretreatment (B = 0.1, P = 0.003), and non-complete recovery at 4 months (B = 1.6, P = 0.005) (R(2) = 0.46). No laboratory test results were associated with these predefined outcomes.

CONCLUSIONS

Delayed treatment start, more symptoms and findings before treatment, and non-complete recovery at 4 months after treatment are possible predictors of a poorer HRQoL and more fatigue 30 months after treated LNB. We did not find age, gender, educational level, involvement of the central nervous system, coexisting diseases, or cerebrospinal fluid findings to be associated with reduced HRQoL or fatigue. Our findings should be replicated in future studies before any conclusions can be drawn.

European neuroborreliosis: neuropsychological findings 30 months post-treatment

BACKGROUND

The aim of this study was to compare neuropsychological (NP) functioning in patients with Lyme neuroborreliosis (LNB) 30months after treatment to matched controls.

METHODS

We tested 50 patients with LNB and 50 controls with the trail-making test (TMT), Stroop test, digit symbol test, and California Verbal Learning test (CVLT). A global NP sumscore was calculated to express the number of low scores on 23 NP subtasks.

RESULTS

Mean scores were lower amongst LNB-treated patients than amongst controls on tasks assessing attention/executive functions: (Stroop test 4: 77.6 vs. 67.0, P=0.015), response/processing speed (TMT 5: 23.4 vs. 19.2, P=0.004), visual memory (digit symbol recall: 6.6 vs. 7.2, P=0.038), and verbal memory (CVLT list B: 4.68 vs. 5.50, P=0.003). The proportion of patients and controls with NP sumscores within one SD from the mean in the control group (defined as normal) and between one and two SD (defined as deficit) were similar, but more LNB-treated patients than controls had a sumscore more than two SD from the mean (defined as impairment) (8 vs. 1, P=0.014).

CONCLUSIONS

As a group, LNB-treated patients scored lower on four NP subtasks assessing processing speed, visual and verbal memory, and executive/attention functions, as compared to matched controls. The distribution of NP dysfunctions indicates that most LNB-treated patients perform comparable to controls, whilst a small subgroup have a debilitating long-term course with cognitive problems.

The use of hydrogel microparticles to sequester and concentrate bacterial antigens in a urine test for Lyme disease

Hydrogel biomarker capturing microparticles were evaluated as a biomaterial to amplify the sensitivity of urine testing for infectious disease proteins. Lyme disease is a bacterial infection transmitted by ticks. Early diagnosis and prompt treatment of Lyme disease reduces complications including arthritis and cardiac involvement. While a urine test is highly desirable for Lyme disease screening, this has been difficult to accomplish because the antigen is present at extremely low concentrations, below the detection limit of clinical immunoassays. N-isopropylacrylamide (NIPAm)-acrylic acid (AAc) microparticles were covalently functionalized with amine containing dyes via amidation of carboxylic groups present in the microparticles. The dyes act as affinity baits towards protein analytes in solution. NIPAm/AAc microparticles functionalized with acid black 48 (AB48) mixed with human urine, achieved close to one hundred percent capture and 100 percent extraction yield of the target antigen. In urine, microparticles sequestered and concentrated Lyme disease antigens 100 fold, compared to the absence of microparticles, achieving an immunoassay detection sensitivity of 700 pg/mL in 10 mL urine. Antigen present in a single infected tick could be readily detected following microparticle sequestration. Hydrogel microparticles functionalized with high affinity baits can dramatically increase the sensitivity of urinary antigen tests for infectious diseases such as Lyme disease. These findings justify controlled clinical studies evaluating the sensitivity and precision of Lyme antigen testing in urine.

Inflammation and central nervous system Lyme disease

Lyme disease, caused by the bacterium Borrelia burgdorferi, can cause multi-systemic signs and symptoms, including peripheral and central nervous system disease. This review examines the evidence for and mechanisms of inflammation in neurologic Lyme disease, with a specific focus on the central nervous system, drawing upon human studies and controlled research with experimentally infected rhesus monkeys. Directions for future human research are suggested that may help to clarify the role of inflammation as a mediator of the chronic persistent symptoms experienced by some patients despite antibiotic treatment for neurologic Lyme disease.