Neuroborreliosis Lyme Disease

Slide 1 · Neuroborreliosis

(Lyme disease)

Pathogenesis, neuropathology and clinicopathologic reasoning

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Recognize

Define neuroborreliosis and its clinical phenotypes.

Explain

Connect spirochetal persistence, immune activation and pathology.

Interpret

Distinguish CSF abnormalities from rare autopsy findings.

Integrate

Locate nervous-system disease within the phases of Lyme infection.

Slide 3 · What is neuroborreliosis?

Nervous-system involvement by Borrelia-associated Lyme disease.

Part of a multisystem arthropod-borne spirochetal infection.

Clinical expression ranges from meningeal to cranial-nerve, peripheral-nerve and encephalopathic syndromes.

INTERPRETATION

The label identifies the involved organ system, not one uniform neurological syndrome.

Slide 4 · Its place among chronic bacterial CNS infections

Shared context

Chronic infection may involve meninges and brain.

Chronic bacterial CNS infections include Borrelia, tuberculosis and syphilis.

Distinct Lyme emphasis

Aseptic meningitis with cranial-nerve involvement.

Facial palsy, other polyneuropathies, encephalopathy.

Slide 5 · The causal organism is a spirochete

Borrelia burgdorferi as the cause of Lyme disease in the United States.

Borrelia are spirochetal bacteria, not viruses or protozoa.

The neurological syndrome represents one possible manifestation of systemic infection.

INTERPRETATION

Etiology matters because pathogen-specific adaptive responses and immune escape shape the course.

Slide 6 · Borrelia species differ geographically

United States

B. Burgdorferi predominates account.

Europe and Asia

B. Afzelii and B. Garinii additionally cause Lyme disease.

Shared transmission

Ixodes ticks transmit these agents.

Interpretation

Species distribution depends on region; Do not equate every exposure with one species.

Slide 7 · Ixodes ticks transmit the infection

1

Infected animal reservoir

2

Ixodes tick vector

3

Human tick exposure

4

Borrelia introduced into skin

The vector links animal-host infection to human disease.

Slide 8 · Reservoir ecology is species dependent

Rodent-associated cycle

Rodents are relevant reservoirs for Lyme Borrelia.

Ixodes ticks carry organisms to humans.

Bird-associated cycle

The textbook also identifies birds as reservoirs for B. Garinii.

Tick transmission remains the common route.

Slide 9 · Endemic regions guide exposure assessment

Lyme disease occurs in the United States, Europe and Asia.

In the United States, the northeast and upper Midwest are emphasized.

Geographic context informs the plausibility of an Ixodes-associated illness.

INTERPRETATION

Exposure history is supporting context rather than a stand-alone proof of neuroborreliosis.

Slide 10 · A tick may carry more than Borrelia

Borrelia

Spirochete associated with Lyme disease.

Ehrlichia

Potential Ixodes-associated coinfection in endemic settings.

Babesia

Another organism that can be present in the same tick population.

Clinical principle

Do not attribute every symptom after a tick bite to a single pathogen.

Slide 11 · Lyme disease follows a staged framework

Early localized

Dermal proliferation; Erythema migrans

Early disseminated

Hematogenous spread; Neurologic and systemic involvement

Late disseminated

Arthritis; Less often neuropathy or encephalitis

Slide 12 · Early localized infection begins in the dermis

Spirochetes multiply at the site of inoculation after the tick bite.

Their local spread produces an expanding erythematous skin lesion.

Fever or regional lymphadenopathy can accompany the rash.

INTERPRETATION

A cutaneous beginning helps explain how an eventual neurological illness can belong to a systemic infection.

Slide 13 · Erythema migrans: The characteristic lesion

Distribution

An expanding area of erythema develops near inoculation.

Appearance

A pale center may be present; It is not required by the textbook description.

Course

The rash may resolve spontaneously over weeks.

Significance

Its presence connects a prior skin phase to later disseminated disease.

Slide 14 · Skin pathology reflects inflammation

The Lyme-associated skin lesion shows edema.

A lymphocytic–plasma cell infiltrate characterizes the reaction.

These observations are inflammatory findings, not unique histologic proof of Borrelia.

INTERPRETATION

The local immune response provides tissue-level context for later inflammatory organ injury.

Slide 15 · Systemic dissemination changes the phenotype

1

Local skin infection

2

Hematogenous spread

3

Additional organ sites

4

Neurologic or other manifestations

Dissemination explains why rash, cardiac signs, joint symptoms and neurologic disease may coexist.

Slide 16 · Early disseminated Lyme disease is multisystem

Skin / lymph nodes

Secondary skin lesions and lymphadenopathy.

Musculoskeletal

Migratory joint and muscle pain.

Cardiac

Arrhythmias can occur.

Nervous system

Meningitis, often with cranial-nerve involvement.

Slide 17 · Four neurological phenotypes

Meningeal

Aseptic meningitis.

Cranial nerve

Facial nerve palsy and other cranial involvement.

Peripheral nerve

Other polyneuropathies.

Encephalic

Encephalopathy; Less commonly encephalitis.

Slide 18 · Aseptic meningitis is a core presentation

Meningeal inflammation is explicitly included in the neuroborreliosis spectrum.

Robbins locates meningitis among early disseminated manifestations.

Cranial-nerve involvement may accompany the meningeal syndrome.

INTERPRETATION

A meningitis syndrome and cranial neuropathy can be two manifestations of the same infection.

Slide 19 · Meningitis and cranial neuropathy can coexist

1

Disseminated Borrelia infection

2

Meningeal inflammatory response

3

Cranial-nerve involvement

4

Combined neurological presentation

The source associates these features; The schematic does not assert a specific microscopic route.

Slide 20 · Facial nerve palsy is a characteristic clue

Facial nerve palsy is specifically named in the neurological syndrome description.

It is one neurological phenotype, not a mandatory sign.

Its interpretation is strengthened by relevant Lyme exposure or other staged manifestations.

INTERPRETATION

A normal facial nerve examination cannot exclude other forms of neuroborreliosis.

Slide 21 · The syndrome extends beyond the facial nerve

“other polyneuropathies” in the neurologic spectrum.

Late disseminated disease can less often involve polyneuropathy.

Peripheral nerve complaints therefore belong in the same differential framework as CNS features.

INTERPRETATION

Separate central and peripheral neurological involvement when describing the phenotype.

Slide 22 · Encephalopathy is part of the spectrum

Encephalopathy is a recognized neurological manifestation.

Encephalitis is described in some late disseminated cases.

The two terms are not interchangeable: Avoid assuming all cognitive symptoms prove parenchymal infection.

INTERPRETATION

Use the clinical term supported by the evidence rather than equating all altered cognition with encephalitis.

Slide 23 · Late neurological disease is less common

Late disseminated Lyme disease may occur months after inoculation.

Chronic large-joint arthritis is a dominant late manifestation.

Polyneuropathy or encephalitis occurs less often account.

INTERPRETATION

Neurological timing should be interpreted alongside the full course of illness.

Slide 24 · Clinical staging: Timing and phenotype

Stage

Characteristic involvement

Neurologic relevance

Early localized

Local skin / erythema migrans

Provides evidence of preceding infection

Early disseminated

Bloodborne multisystem spread

Meningitis and cranial nerves

Late disseminated

Arthritis and selected late effects

Less often neuropathy / encephalitis

Slide 25 · A skin-to-nervous-system causal map

1

Inoculation through skin

2

Dermal multiplication

3

Systemic dissemination

4

Neural involvement + host response

Conceptual sequence derived from the staged Lyme disease model.

Slide 26 · Neurologic disease can accompany extra-CNS signs

Neurological observations

Aseptic meningitis

Facial palsy or other neuropathy

Encephalopathy

Concurrent systemic clues

Prior expanding rash

Migratory joint or muscle pain

Lymphadenopathy or cardiac manifestations

Slide 27 · Borrelia injury is not toxin driven

B. Burgdorferi does not produce the endotoxin or exotoxins invoked for many other bacterial injuries.

Much pathology is attributed to the host immune response.

Inflammatory tissue injury can persist despite attempts to clear infection.

INTERPRETATION

The host reaction is central to the pathogenesis model.

Slide 28 · Innate immune recognition begins at TLR1/TLR2

1

Borrelial lipoproteins

2

TLR1 and TLR2 on macrophages

3

Macrophage activation

4

Inflammatory mediator generation

Native recognition of bacterial lipoproteins initiates the innate immune response.

Slide 29 · Macrophages release inflammatory cytokines

IL-6

One of the named proinflammatory mediators.

TNF

Another inflammatory cytokine released after receptor activation.

Reactive nitrogen

Bactericidal intermediates are generated.

Net effect

Microbial control and host inflammation occur together.

Slide 30 · Microbicidal mechanisms are incomplete

Reactive nitrogen intermediates reduce the organism burden.

, this first response usually does not fully eliminate the infection.

A persisting organism can maintain antigenic stimulation and inflammatory responses.

INTERPRETATION

Partial clearance helps explain the transition from an acute encounter to prolonged disease.

Slide 31 · T cells and cytokines sustain lesions

1

Microbial stimulation

2

T-cell / cytokine response

3

Inflammatory cell recruitment

4

Tissue lesion

This is the proposed inflammation-centered mechanism; Not a claim of a unique CNS histologic sequence.

Slide 32 · Humoral immunity develops after infection

Initial infection

Innate sensing begins

Approximately 2–4 weeks

Borrelia-specific antibodies develop

Thereafter

Antibodies aid killing; Escape variants may persist

Slide 33 · Antibodies promote microbial clearance

1

Borrelia-specific IgG response

2

Complement involvement

3

Phagocytosis

4

Spirochetal killing

Anti-Borrelia antibodies with complement-mediated microbial clearance.

Slide 34 · Antibody emergence does not ensure eradication

Protective response

Antibodies recognize Borrelia.

Complement and phagocytosis kill organisms.

Evasion response

Bacterial surface proteins can change.

Variants escape established antibody recognition.

Slide 35 · Outer surface protein C changes over time

Outer surface protein C (OspC) is needed during establishment of infection.

It is not required for persistence in the model presented.

Downregulation of OspC contributes to evasion of an evolving antibody response.

INTERPRETATION

Expression change can be as important as acquisition of new antigens.

Slide 36 · VlsE antigenic variation supports persistence

A plasmid encoding a variable antigenic surface protein, VlsE.

Alternative coding segments can be expressed next to a common promoter.

Antibodies against one expressed form select for organisms displaying another form.

INTERPRETATION

The mechanism creates moving targets for the host humoral immune response.

Slide 37 · The VlsE immune-escape cycle

1

One VlsE variant expressed

2

Host produces matching antibodies

3

Alternate VlsE form emerges

4

Reduced recognition permits persistence

This is a simplified conceptual model of antigenic variation, not a measured evolutionary timeline.

Slide 38 · An integrated pathogenesis model

1

Spirochetal infection

2

Innate + adaptive immunity

3

Antigenic escape / persistence

4

Inflammatory tissue responses

Host defense and immune escape help account for prolonged or recurrent disease manifestations.

Slide 39 · Meningitic CSF shows cellular inflammation

Lyme meningitis produces a hypercellular cerebrospinal fluid compartment.

This to a marked lymphoplasmacytic infiltrate.

The CSF finding reflects a host inflammatory response in the meningeal space.

INTERPRETATION

The key textbook CSF morphological feature is a lymphoplasmacytic response.

Slide 40 · Antispirochete IgG can occur in CSF

The source describes antispirochete IgGs in Lyme meningitis CSF.

This supports the biological link between nervous-system inflammation and Borrelia-directed immunity.

The excerpt does not specify a validated CSF antibody-index threshold or sensitivity.

INTERPRETATION

Do not convert a qualitative textbook finding into a numerical diagnostic criterion.

Slide 41 · CSF and brain parenchyma are different compartments

CSF in meningitis

Marked lymphoplasmacytic cellularity

Antispirochete IgGs

Rare autopsy brain findings

Focal microglial proliferation

Scattered extracellular organisms

Slide 42 · Focal microglial proliferation at autopsy

Rare autopsied cases have shown focal microglial-cell proliferation in brain tissue.

Microglia are the resident immune-effector cell population in the CNS.

Robbins does not describe this finding as a pathognomonic lesion.

INTERPRETATION

Interpret the observed response as evidence of CNS inflammatory activation, not a specific diagnostic hallmark.

Slide 43 · Scattered extracellular organisms at autopsy

Scattered extracellular organisms have been observed in rare autopsy material.

Their presence supplies direct morphologic evidence in those exceptional cases.

The source does not justify assuming that organisms will be visible in routine tissue sections.

INTERPRETATION

A documented rare observation must not be presented as a routinely demonstrable diagnostic sign.

Slide 44 · Neuropathologic evidence has major limitations

Sampling

Only rare cases have undergone autopsy in the account.

Distribution

Microglial reaction is described as focal.

Detection

Organisms are scattered, not abundant.

Inference

Neither distribution nor sensitivity can be quantified from this excerpt.

Slide 45 · Morphology across affected compartments

Compartment

Textbook morphological feature

Interpretation

Dermis

Edema; lymphocytes and plasma cells

Inflammatory local lesion

CSF / meninges

Hypercellularity; lymphoplasmacytic infiltrate

Meningeal immune response

Brain at autopsy

Focal microglial proliferation

Parenchymal response in rare cases

Brain at autopsy

Scattered extracellular organisms

Occasional direct tissue evidence

Slide 46 · Diagnosis is a clinicopathologic synthesis

1

Recognize compatible neurological syndrome

2

Assess exposure + Lyme disease stage

3

Seek Borrelia-directed laboratory evidence

4

Integrate rather than isolate findings

The source provides principles rather than a complete modern neuroborreliosis case definition.

Slide 47 · Serology is the principal Lyme diagnostic method

Serology as the main method of Lyme disease diagnosis.

The interpretation must relate a positive antibody response to the clinical syndrome.

The supplied excerpts do not supply a specific modern testing algorithm or assay thresholds.

INTERPRETATION

Do not confuse evidence of exposure or immune response with proof of the current site of disease.

Slide 48 · PCR is discussed for infected tissues

PCR can be applied to infected tissue in Lyme disease.

Synovial fluid is a specific application in Lyme arthritis.

Neither excerpt provides a validated CSF PCR rule-out strategy for neuroborreliosis.

INTERPRETATION

Specimen choice and diagnostic performance must not be extrapolated without supporting data.

Slide 49 · Diagnostic timing must respect seroconversion

Early symptoms

Clinical stage may precede mature antibodies

Weeks after infection

Specific antibody response develops

Later disease

Combine serologic findings with phenotype

The source gives a 2–4-week antibody-development interval, not a complete testing schedule.

Slide 50 · Meningitis differentials require syndromic care

Disease

Textbook emphasis

Important distinction

Neuroborreliosis

Aseptic meningitis; facial palsy

Borrelia-linked multisystem course

CNS tuberculosis

Chronic meningitis; basal complications

Different pathogen and pathologic pattern

Neurosyphilis

Meningovascular / paretic / tabetic disease

Different spirochete and syndrome spectrum

Slide 51 · CNS versus peripheral nerve involvement

Central / meningeal

Aseptic meningitis

Encephalopathy

Encephalitis in some later cases

Cranial / peripheral

Facial-nerve palsy

Other cranial involvement

Polyneuropathies

Slide 52 · Case 1: Cranial neuropathy after skin disease

Teaching scenario: A patient from an endemic area recalls an expanding erythematous lesion and later develops facial weakness.

Which Lyme stage and neurological phenotype best fit the sequence?

Early dissemination with cranial-nerve involvement is consistent with Robbins. The vignette is illustrative, not a patient record.

Slide 53 · Case 2: Meningeal inflammation with IgG

Teaching scenario: A patient has an aseptic meningeal syndrome; CSF examination reveals lymphoplasmacytic cellularity and Borrelia-directed IgG.

What is the most defensible pathology interpretation?

These findings support a Borrelia-associated meningeal immune response. The excerpt alone does not establish a numerical definitive criterion.

Slide 54 · Case 3: Delayed multisystem presentation

Teaching scenario: Months after a suspected tick exposure, a patient develops chronic large-joint inflammation and neuropathic symptoms.

What stage and cross-system connection should be considered?

A late disseminated pattern is plausible. Arthritis is prominent in this stage; Neuropathy is described less often.

Slide 55 · Lyme arthritis illustrates systemic persistence

Large joints, particularly knees, are emphasized in Lyme arthritis.

Untreated late disease can produce prolonged joint attacks and erosion of cartilage.

This extraneural manifestation contextualizes neuroborreliosis within one systemic infection.

INTERPRETATION

Joint disease is relevant for staging and systemic integration, not evidence of CNS infection by itself.

Slide 56 · Synovial pathology parallels immune activation

Synoviocyte hyperplasia and fibrin deposition occur.

Mononuclear inflammatory cells, including T cells, infiltrate the synovium.

Arteriolar onion-skin–like thickening and obliterative endarteritis may occur.

INTERPRETATION

The characteristic inflammatory joint response differs in tissue distribution from meningeal or cerebral findings.

Slide 57 · Treatment context from the Robbins excerpt

Antibiotics active against Borrelia are effective for Lyme disease in the described clinical context.

Most Lyme arthritis cases are described as responding to antibiotic therapy.

The excerpts do not specify neuroborreliosis antibiotic selection, dose or treatment duration.

INTERPRETATION

A pathology lecture should not infer a therapeutic regimen from source text that does not provide one.

Slide 58 · Frequent interpretive errors

Overgeneralization

Not every neuroborreliosis case has facial palsy.

Compartment error

CSF lymphoplasmacytosis is not identical to a brain biopsy pattern.

Diagnostic inflation

Qualitative CSF IgG is not a published threshold in these excerpts.

Morphology inflation

Rare autopsy observations are not routine diagnostic criteria.

Slide 59 · Synthesis: Organism, host and neurological injury

1

Ixodes-transmitted Borrelia

2

Early skin / systemic dissemination

3

Immune response + evasion

4

Variable CNS / peripheral syndromes

Interpret neuroborreliosis as the neurological face of a host–pathogen interaction across disease stages.

Slide 60 · The five defensible teaching conclusions

Organism

An Ixodes-borne Borrelia spirochete causes Lyme disease.

Neurology

Meningitis, cranial palsy, neuropathy and encephalopathy define the spectrum.

Mechanism

Innate inflammation, antibodies and antigenic variation shape persistence.

Pathology

CSF lymphoplasmacytosis contrasts with rare focal microglial brain findings.

Context

Stage, exposure and systemic features anchor interpretation.

Caution

Avoid unverified numerical diagnostic or therapeutic rules.

Slide 61 · Source references

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th ed. (2026).

The Central Nervous System — Neuroborreliosis (Lyme Disease).

Same textbook.

Infectious Diseases — Lyme Disease.

Same textbook.

Bones, Joints, and Soft Tissue Tumors — Lyme Arthritis.