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Neuropsychiatric Disorders > Encephalitis > Flashcards

Encephalitis Flashcards

1
Q

What is encephalitis?

A

Inflammation of the brain

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2
Q

What are the main pathological signs of encephalitis?

A

▪️Oedema
▪️Destruction of tissue when infection persists
▪️Parenchymal haemorrhages and intravascular thrombosis

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3
Q

What is the main diagnostic criteria for encephalitis?

A

▪️Altered mental state
▪️Lasting 24 hours or longer
▪️No alternative identified cause

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4
Q

What is considered in the minor diagnostic criteria for encephalitis?

A

▪️Fever
▪️Generalised or partial seizures
▪️New onset focal neurological findings
▪️Increased CSF WBC count
▪️Abnormality of brain parenchyma on neuroimaging
▪️Abnormality on EEG

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5
Q

What are the three main types of encephalitis?

A

▪️Infectious (42%)
▪️Immune-mediated (21% although increasing)
▪️Unknown (37%)

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6
Q

What is the most common category of infectious encephalitis?

A

Viral encephalitis

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7
Q

What is the most common cause of infectious encephalitis in the west?

A

Herpes simplex virus

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8
Q

Non-viral causes of infectious encephalitis are much more _____________

A

Region specific

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9
Q

How does viral encephalitis differ from viral meningitis?

A

▪️Life-threatening (not benign)
▪️Not self-limiting so needs intervention
▪️Frequently causes neurological damage
▪️Host inflammatory response is significant and can cause damage on its own

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10
Q

What are ubiquitous pathogens?

A

Microorganisms found almost everywhere

(E.g. Herpes simplex virus type 1, VZV, HIV, enteroviruses)

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11
Q

What is the most common cause of infectious encephalitis in the world?

A

Japanese encephalitis virus

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12
Q

What is a zoonotic virus?

A

A virus transmitted from animals to humans, e.g. through ticks

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13
Q

What is the most common region specific pathogen in Europe?

A

Tick-borne encephalitis virus

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14
Q

Where is West Nile virus typically localised to?

A

▪️North Africa
▪️America

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15
Q

Where are chikungunya and zika virus typically localised to?

A

▪️Sub-Saharan Africa
▪️South America

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16
Q

What are the main factors to consider when diagnosing infectious encephalitis?

A

▪️Travelling history
▪️History of bites
▪️Exposure to disease animals and humans
▪️Age
▪️Health status (vaccinations, immune status)
▪️Occupation

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17
Q

Who is most at risk from less common pathogens?

A

▪️Younger people
▪️Older adults
▪️Immunocompromised patients

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18
Q

What symptoms are common across infectious encephalitis types?

A

▪️Fever
▪️Altered consciousness
▪️Headache

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19
Q

What symptoms are specific to rhabdoviruses (rabies)?

A

▪️Hypersalivation and dysphagia
▪️Hydrophobia
▪️Aerophobia
▪️Multiple organ failure (almost always fatal)

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20
Q

What symptoms are more specific to retroviruses (e.g. HIV)?

A

▪️Mental concentragion and severe cognitive change
▪️Personality change
▪️Apathy
▪️Social withdrawal

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21
Q

What symptoms are typically seen with herpesviruses?

A

▪️Seizure
▪️Focal neurological deficits
▪️General encephalopathy

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22
Q

What more specific symptoms might be seen with arboviruses?

A

▪️Muscle aches
▪️Lack of muscle coordination
▪️Disorientation
▪️Convulsions
▪️Coma

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23
Q

What are the most common types of arbovirus?

A

▪️West Nile virus
▪️Japanese encephalitis virus
▪️Zika virus
▪️Tick-borne encephalitis virus

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24
Q

What specific symptoms might be seen with influenza virus?

A

▪️Febrile seizures
▪️Convulsions
▪️Ataxia
▪️Status epilepticus

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25
Q

What symptoms have been seen with coronavirus 2 (covid) encpehalitis?

A

▪️Delirium/altered mental status
▪️Aphasia
▪️Dysarthria
▪️Seizures

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26
Q

How does covid related encephalitis show on MRI?

A

▪️Florid manifestations (severe)
▪️ADEM-like = demyelination often post infection

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27
Q

What is the germ theory of disease?

A

Microorganism/pathogens cause disease when they invade the body

(as oppose to “bad air” in the miasma theory)

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28
Q

What is the hallmark of Immune-mediated disease?

A

Expression of autoantibodies

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29
Q

What are the two types of autoantibodies that might be seen with immune-mediated encephalitis?

A

▪️Directly pathogenic autoantibodies
▪️Non-pathogenic autoantibodies as part of an immune inflammatory process

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30
Q

What are examples of immune-mediated encephalitis where the autoantibodies are NOT pathogenic?

A

▪️Connective tissue diseases and vasculitis (e.g. Lupus)
▪️Hashimoto encephalitis
▪️Basal ganglia encephalitis (encephalitis lethargica)
▪️ADEM (acute disseminated encephalomyelitis)

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31
Q

What are the two major types of antigen associated with antibody-associated encephalitis?

A

▪️Intracellular antigens
▪️Neuronal surface antigens

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32
Q

What are immunoglobulins (Ig) ?

A

Antibodies

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33
Q

What is the main class of immunoglobulin that causes anti-body associated encephalitis?

A

IgG

Y-shaped with binding arms (bind to antigen) and body

34
Q

What is an epitope?

A

The part of the antigen that the immune system recognises, illiciting an immune response to the pathogen

35
Q

What is a paratope?

A

The antigen-binding site on the antibody

36
Q

What is limbic encephalitis?

A

An inflammatory disease of the hippocampus, amygdala, insula, and frontobasal regions which presents as a distinct clinical syndrome

37
Q

What are the main clinical manifestations of limbic encephalitis?

A

▪️Cognitive change (anterograde memory or confusion)
▪️Seizures (temporal lobe or generalised)
▪️Psychiatric manifestations (mood change, psychosis, hallucinations, delusions)
▪️”Extra-limbic” symptoms (language, movement disorder)

38
Q

When does limbic encephalitis usually present?

A

▪️ Predominantly elderly
▪️ In less than 3 months
▪️ Often paraneoplastic - driven by tumour elsewhere

39
Q

What might you see with investigations of limbic encephalitis?

A

▪️ T2 FLAIR areas of hyperintensity in one or both medial temporal lobes (bright, inflammation)
▪️ Focal slowing in temporal lobes on EEG
▪️ Epileptic discharges in 45%
▪️ Lymphocytic pleocytosis and OCBs in CSF

40
Q

What is classic paraneoplastic encephalitis?

A

▪️ Target is intracellular (e.g., Hu, Ma, GAD) - not exposed to circulating antibody
▪️ Other factor disrupts the membrane
▪️ Antibody is secondary to another cause of disease (e.g., tumour)

41
Q

What is novel antibody-mediated encephalitis?

A

▪️ Target is extracellular (e.g., NMDAR, CASPR2, LGI1) - easily accessible to circulating antibody
▪️ Usually non-paraneoplastic
▪️ Antibody is primary cause for the disease

42
Q

Why is it important to distinguish between paraneoplastic (intracellular) and non-paraneoplastic (extracellular) causes of encephalitis?

A

Intracellular targets usually do not respond so well to immunotherapy and steroids - need to treat the primary cause (e.g., remove tumour)

43
Q

What determine whether an antibody is pathogenic?

A

▪️ Present during clinical manifestations (detectable in blood or tissue)
▪️ Interacts with protein expressed on cell membrane
▪️ Transfer replicates disease in an animal model
▪️ Active immunisation produces model of disease
▪️ Improvement occurs with immunosuppression

44
Q

What are the main pathogenic mechanisms of autoantibodies?

A

▪️ Direct disruption of the epitope (e.g., agonist or antagonist on receptor)
▪️ Internalisation - receptor enters cell and gets broken down
▪️ Complement activation

45
Q

How can we detect pathogenic antibodies if we know the target?

A

Cell-based assay
▪️grow (incubate) receptors
▪️add patients CSF/blood
▪️look for binding to receptor with fluorescence, indicating antibody is present

46
Q

How can we detect pathogenic antibodies if we don’t know the target?

A

▪️ Live rodent primary neuronal cultures
▪️ Look for patterns of staining on rodent tissue sections

47
Q

What are the main triggers of autoimmune encephalitis?

A

▪️ Tumours (5-60%)
▪️ Previous infection (e.g., HSV and NMDAR encephalitis)
▪️ Drugs (isolated cases)
▪️ Majority unknown

48
Q

What is the most common form of autoimmune encephalitis and what antibodies is it associated with?

A

▪️ NMDAR encephalitis
▪️ NMDAR antibodies

49
Q

What antibodies are associated with limbic encephalitis?

A

▪️ LGI1 antibodies (also faciobrachial dystonic seizures)
▪️ Paraneoplastic antibodies

50
Q

What antibodies are associated with Morvan’s syndrome?

A

CASPR2 antibodies

51
Q

What antibodies are associated with progressive encephalomyelitis with rigidity and myoclonus (PERM)?

A

Glycine receptor antibodies

(also stiff-person syndrome, cerebella ataxia)

52
Q

What is the most common antigen target in limbic encephalitis?

A

Leucine-rich glioma inactivated protein 1 (LGI1)

▪️ Highly expressed in hippocampus
▪️ Secreted protein that targets voltage-gated potassium channels to stabilise them

53
Q

What are the main components of the VGKC-complex?

A

▪️ Voltage-gated potassium channel (VGKC)
▪️ LGI1
▪️ CASPR2
▪️ Contactin2

54
Q

What are the main signs of limbic encephalitis associated with LGI1 antibodies?

A

▪️ Subacute onset of memory loss, seizures, and personality change
▪️FBDS
▪️ Predominantly men in their 50s-60s
▪️ Tumours in less than 10%
▪️ Low plasma sodium

55
Q

What is the prognosis of LGI1 limbic encephalitis?

A

▪️ Most respond well to immunotherapies and return to work
▪️ Can be long-term cognitive deficits

56
Q

What is typically seen on MRI scans of individuals following LGI1 limbic encephalitis?

A

▪️ Marked hippocampal atrophy explaining anterograde and retrograde episodic defects
▪️ Particularly hippocampus CA3 volume - predicts episodic defects?
▪️Increased medial temporal lobe signal (bright)

57
Q

What antibody is associated with faciobrachial dystonic seizures?

A

LGI1 antibodies

58
Q

How do you treat faciobrachial dystonic seizures?

A

▪️ Poor response to AEDs
▪️ Very good response to immunosuppressive treatment
▪️ Timely treatment can prevent cognitive impairment

59
Q

Where is CASPR2 protein expressed?

A

▪️ Park of the VGKC-complex in CNS at the synapses
▪️ At juxtaparanodes of Ranvier in PNS

60
Q

What neurological condition may be caused by CNS CASPR2 antibodies and where would the antibodies be detectable?

A

Limbic encephalitis

Detectable in serum and CSF

61
Q

What neurological syndrome may be caused by both CNS and PNS CASPR2 antibodies and where would these antibodies be detectable?

A

Morvan syndrome

Detectable in serum only

62
Q

What neurological condition may be caused by peripheral CASPR2 antibodies and where would these be detectable?

A

Neuromyotonia (myasthenia)

Detectable in serum only

63
Q

What type of tumour is most associated with Morvan syndrome and neuromyotonia?

A

Thymoma

64
Q

What are the main symptoms of neuromyotonia?

A

▪️ Spontaneous muscular activity of peripheral nerve origin
▪️ Muscle cramps
▪️ Stiffness
▪️ Myokymia (eyelid twitch)
▪️ Sweating
▪️ Pain

65
Q

How do you treat acquired neuromyotonia and Morvan’s syndrome?

A

Plasma exchange (circulate blood to remove antibodies) and immunosuppression

66
Q

What are the main symptoms of Morvan’s syndrome?

A

▪️ Neuromyotonia
▪️ Insomnia
▪️ Confusion
▪️ Hallucinations

Also memory loss, excessive REM, excessive salivation, cardiac arrhythmia, constipation?

67
Q

What are the core signs of CASPR2 antibody-mediated encephalitis?

A

▪️ Cerebral symptoms (cognition, epilepsy)
▪️ Cerebellar symptoms
▪️ Peripheral nerve hyperexcitability
▪️ Autonomic dysfunction
▪️ Insomnia
▪️ Neuropathic pain
▪️ Weight loss

68
Q

What conditions are previously seen in up to 30% of patients with CASPR2-associated encephalitis?

A

Thymoma and myasthenia gravis

69
Q

What rarer targets may be considered in limbic encephalitis?

A

▪️ AMPA receptor (rare)
▪️ GABA a & b receptors (more common)
▪️ DPPX (potassium channel associated protein) (rare)

70
Q

What symptoms and signs might be seen with LE associated with AMPAR antibodies?

A

▪️ Amnesia
▪️ Sometimes psychosis
▪️ Seizures
▪️ Refractory status epilepticus
▪️ Often paraneoplastic (e.g., thymoma, lung, breast)

71
Q

What symptoms and signs might be seen with LE associated with GABA a and b receptor antibodies

A

▪️ Predominantly seizures
▪️ Cerebellar ataxia
▪️ B has strong association with small cell lung cancer (SCLC)

72
Q

What symptoms and signs might be seen with LE associated with DPPX antibodies?

A

▪️ Diarrhoea
▪️ Weight loess
▪️ Myoclonus
▪️ Tremors
▪️ Excessive startle (hyperplexia)

73
Q

Who is most commonly affected by NMDAR encephalitis?

A

▪️ Young people
▪️ Females
▪️ People with ovarian teratomas
▪️ Can affect children

74
Q

What is the most common presentation of NMDAR encephalitis?

A

Psychiatric

75
Q

What are the main symptoms of NMDAR encephalitis?

A

▪️ Florid psychotic features
▪️ Seizures
▪️ Amnesia
▪️ Facial grimacing and chewing
▪️ Mutism
▪️ Choreoathetoid limb movements/catatonia
▪️ Autonomic failure (often end up in ITU)
▪️ Reduced level of consciousness

76
Q

How should you treat someone who presents with autoimmune encephalitis/relapsed response following previous infection?

A

With immunosuppressants

NOT more anti-virals

77
Q

What are the main conditions on the spectrum of NMDAR antibody diseases that may be seen in adults and children?

A

▪️ Classic NMDAR-Ab encephalitis
▪️ Partial phenotypes with predominant psychosis, seizures, or cognitive impairment
▪️ Relapse following HSV encephalitis

78
Q

What are the main challenges associated with antibody-mediated diseases?

A

▪️ Diagnosis cannot rely on antibody testing results - sometimes need to start treatment before results
▪️ Other diagnostic tests can appear normal, particularly when testing serum
▪️ Response to treatment can be partial and take many months
▪️ Early immunotherapy is key
▪️ MRI doesn’t always show anything
▪️ Healthy individuals may test positive

79
Q

What are the three diagnostic criteria for possible autoimmune encephalitis?

A
  1. Subacute onset of WM deficits, altered mental status, or psychiatric symptoms
  2. At least one of: focal CNS findings, seizure, CSF pleocytosis, MRI features
  3. Reasonable exclusion of other causes
80
Q

What is the first line treatment for autoimmune encephalitis?

A

Immunotherapy:
▪️ Steroids with plasma exchange
▪️ Immunoglobulins (e.g. rituximab)
▪️ Stronger immunosuppressants if not responding

81
Q

What treatment is needed for someone with infectious encephalitis?

A

Anti-virals

DO NOT USE IMMUNOSUPPRESSION

Neuropsychiatric Disorders (30 decks)

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