Infection of the nervous system Flashcards

1
Q

What is encephalitis?

A

Encephalitis means acute inflammation of brain parenchyma, usually viral

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2
Q

What is the most common cause of encephalitis?

A

Viral

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3
Q

What are viral causes of encephalitis?

A
  • HSV 1 + 2
  • Arbovirus (japanese encephalitis)
  • CMV, EBV, VZV, HIV
  • Measles
  • Mumps
  • Rabies
  • West nile virus
  • Tick-borne encephalitis
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4
Q

What are non-viral causes of encephalitis?

A
  • Any bacterial meningitis
  • TB
  • Malaria
  • Listeria
  • Lyme disease
  • Legionella
  • Leptospirosis
  • Aspergillosis
  • Crytococcus
  • Schistosomiasis
  • Typhus
  • Taoxoplasmosis gondii (AIDS)
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5
Q

What would be your differential diagnosis for someone with features of encephalitis?

A

If no infectious prodrome, think encephalopathy

  • Hypoglycaemia
  • Hepatic encephalopathy
  • Diabetic ketoacidosis
  • Drugs
  • Hypoxic brain injury
  • Uraemia
  • SLE
  • Wernicke’s encephalopathy
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6
Q

What are autoimmune causes of encephalitis?

A

Limbic encephalites

  • Paraneoplastic limbic encephalitis
  • Voltage gated potassium channel limbic encephalitis
  • Anti-NMDA receptor antiobody panencephalitis
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7
Q

What are signs and symptoms of encephalitis?

A
  • (Infectious prodome - fever, rash, lymphadenopathy, cold osres, conjunctivitis, meningeal signs)
  • Bizarre encephalopathic behaviour or confusion
  • Decreased GCS/Coma
  • Fever
  • Headache
  • Focal neurological signs
  • Seizures
  • Meningitsm - fever, headache, drowsiness
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8
Q

When should you suspect encephalitis?

A

Whenever someone presents with odd behaviour, decreased consciousness focal neurology or seizure which was preceded by an infectious prodrome

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9
Q

What kind of infectious prodromes would you want to find out about in someone presenting with features of encephalitis?

A
  • Pyrexia
  • Rash
  • Lymphadenopathy
  • Cold sores
  • Conjunctivitis
  • Meningeal signs
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10
Q

What might cold sore indicate about the cause of a presentation of encephalitis?

A

Caused by Herpes Simplex virus

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11
Q

What might parotid gland swelling indicate as to the cause of encephalitis?

A

Caused by mumps

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12
Q

How can rabies present?

A

Features of encephalitis, hydrophobia (water provoked muscle spasms), delusions, hallucinations and anxiety

Acending paralysis of the limbs

Parasthesia at site of lesion

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13
Q

Rabies pre-exposure prevntion

+

Rabies post-exposure treatment

A

Active immunisation

Wash wound, active rabies immunisation, human rabies immunoglobulin (passive immunisation)

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14
Q

What investigations would you consider doing in someone with features of encephalitis?

A
  • Bloods
    • FBC - reduced WBC (immunopcompromsised)
    • U+Es
    • Clotting screen
    • Septic screen + Blood cultures
    • Blood cultures, Viral PCR, Malaria film, Toxoplasma IgM titre, HIV test, Mantoux test
  • CXR - TB?
  • Contrast enhanced CT brain
    • ​Focal bilateral temporal lobe involvement is suggesive of HSV encephalitis (areas of oedema)
  • LP
    • ​Obvs CT first
    • Send CSF for PCR for HSV (PCR is 95% specific for HSV1)
  • EEG
    • Non specific slow wave activity
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15
Q

In someone with features of encephalitis, what would focal bilateral temproal lobe involvement on Contrast-enhanced CT indicate ?

A

HSV encephalitis

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16
Q

What would meningeal enhancement on contrast-enhanced CT suggest in someone with features of encephalitis?

A

Meningeal involvemnent

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17
Q

What should you do before doing an LP?

A

CT scan to rule out coning

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18
Q

What are features seen on LP in someone with encephalitis?

A
  • Increased CSF protein
  • Increased lymphocytes
  • Decreased glucose
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19
Q

What is important to remember when interpreting LP CSF results for someone with suspected encephalitis?

A

Normal CSF does not exclude ecnephalitis

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20
Q

How would you manage someone with encephalitis?

A
  • Start aciclovir within 30 mins arrival
  • Supportive therapy in HDU
    • Oxygen, IV fluids, steroids, phenytoin (for seizures)
  • Anticonvulsants for seizures
  • Dexamethaose - if raised ICP
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21
Q

What is mortality rate in untreated encephalitis?

A

70%

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22
Q

What is the mortality rate in treated encephalitis?

A

10-30%

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23
Q

Whats the difference between a brain abscess and brain empyema?

A

Abscess - localised area of pus in brain

Brain empyema - thin layer of pus between dura and arachnoid membrains

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24
Q

What are causes of a cerebral abscess?

A

Direct spread =75%

Haematogenous spread =25%

  • Ear/Sinus/dental/peridontal infection
  • Skull fracture
  • Congenital heart disease
  • Endocarditis (blood borne)
  • Bronchiectasis
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25
Q

What are the typical causative bacteria implicated in brain abscesses?

A
  • Strep anginosss (sinus/teeth)
  • Bacteriodes (sinus/teeth)
  • Staphylococci (penetrating trauma)
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26
Q

What are symptoms of a brain abscess?

A
  • Headache - worse on bending over/lying down
  • Fever
  • Generally unwell
  • Seizures
  • Signs of raised ICP
  • Features of underlying source - dental, sinus, infection
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27
Q

What are signs seen in someone with a cerebral abscess?

A
  • Decreased GCS/Coma
  • Signs of sepsis elsewhere
  • Fever
  • Focal neruology
  • Signs of increased ICP
  • Meningism may be present
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28
Q

What investigations might you consider doing in someone with a cerebral abscess?

A
  • CT/MRI
    LP NOT PERFORMED DUE TO DANGER OF CONING
  • Bloods - FBC, ESR
  • Biopsy (aspiration)
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29
Q

What might you see on FBC in someone with a cerebral abscess?

A

Increased WCC

30
Q

What might you see on investigation of ESR in someone with a cerebral abscess?

A

Raised ESR

31
Q

How would you manage someone with a cerebral abscess?

A

Urgent neurosurgical referral

  • Treat ICP
  • High dose ABx
    • ​Penicillin or cefriaxone (cover strep)
    • Metronidazole (for anaerobes)
  • Surgical resection/decompression
32
Q

What dose of aciclovir would you start someone on if they presented with encephalitis?

A

IV acicolvir 10mg/kg 8 hrly for 14-21 days

33
Q

What antibiotics would you use to treat a cerebral abscess?

A
  • Penicillin/ceftraixone - cover streps
  • Metranidazole - anaerobes
34
Q

What is the morality rate in those with a cerebral abscess?

A

Treated - 25%

35
Q

What cerebral problems can occur in those with HIV infection?

A
  • Cerebral toxoplasmosis
  • Aseptic meningitis/encephalitis
  • Primary cerebral lymphoma
  • Cerebral abscess
  • Cryptococcal meningitis
  • SOL of unkown cause
  • Dementia
  • Leucoencephalopathy
36
Q

What infectious organisms can infect the CNS in those with chronic HIV infection?

A
  • Cryptococcus neoformans
  • Toxoplasma gondii
  • Cytomegalovirus
37
Q

What is acute disseminated encephalomyelitis?

A

A rare autoimmune disease marked by a sudden, widespread attack of inflammation in the brain and spinal cord that often follows many types of infection (measles, mycoplasma, mumps, rubella). As well as causing the brain and spinal cord to become inflamed, ADEM also attacks the nerves of the central nervous system and damages their myelin insulation, which, as a result, destroys the white matter.

38
Q

What organism causes neurosyphillis

A

Treponema Pallidum

39
Q

Describe presentation of primary neurosyphillus

A

PRIMARY:

  • Macule at site of secual contact
  • Ulcerates and becomes a painless firm chancre
  • Any urogenitcal ulcer or sole is syphillus until proven otherwise
40
Q

Describe presentation of secondary neurosyphillus

A

SECONDARY

  • After 6 weeks (6 weeks-6 months) post infection appearance of lesion
  • Constitutional symptoms (eg fever, sore throat and arthralgia), generalised lymphadenopathy, rash (exceept face), ulcers on mouth and on genetalia (nsal-track ulcers) and condylomata lata (warty perennial lesions) man sites affected (hepatitis, arthritis, menignitis)
41
Q

Describe presentation of teritary neurosyphillus

A

TERTIARY

  • Latent period of 2 years or more
  • Characteristic lesion is Gumma, occuring in skin, bones, liver and testes
42
Q

What are the main forms of neurosyphillis?

A
  • Asymptomatic neurosyphillis
  • Meningovascular syphillis
  • Tabes dorsalis
  • General paralysis of the insane
43
Q

What is Meningovascular Neurosyphillis?

A

Syphillitic infection which causes:

  • Subacute meningitis with cranial nerve palsies and papilloedema
  • A gumma – a chronic expanding intracranial mass, causes raised ICP and FNS
  • Paraparesis – caused by a spinal meningovasculitis

Occurs 3-4 years postinfection

44
Q

What is asymptomatic neurosyphillis?

A

Neurosyphillis with positive CSF but no neurological signs

45
Q

What is tabes dorslis?

A

Can occur 10-35 years post syphillis

Demyelination in dorsal roots causes a complex deafferentation syndrome. The elements of tabes:

  • Lightning pains
  • Ataxia, stamping gait, reflex/sensory loss, wasting
  • Neuropathic (Charcot) joints
  • Argyll Robertson pupils - accomodate but dont react
  • Ptosis and optic atrophy
46
Q

What is general paralysis of the insane?

A

Occurs 10-15 years

Dementia and weakness associated with neurosyphillis, in addition to:

  • Seizures
  • Brisk reflexes
  • Extensor plantar reflexes
  • Tremor
  • Argyll-Robertson pupils
47
Q

Investigations neurosyphillus

A

Blood tests:

  • Dark groun microscopy fluid, serological test
  • VDLR (Venereal Disease Research Laboratory)
    • Non-treponema specific (cardiolipin antibody)
    • Detectable in primary disease but not in late syphillus
    • Indicates active disease and becomes negative if treated
  • TPHA (Treponema Pallidum haemogglutination Assay)
    • Presents in syphillus and remain positive depite treamtent
    • Treponema specific
    • Doesnt distinguish between syphillus and other treponemas eg yaws
  • PCR
48
Q

How would you manage someone with neurosyphillis?

A

Benzylpenicillin

49
Q

What is Creutzfeld-Jakob Disease

A

Progressive dementia

Characterised pathologically by spongiform changes in the brain

Caused by prions (proteinaceous infectios particles)

50
Q

Types of CJD

A

Sporadic CJD

Variant CJD

Familail CJD

Acquired CJD

Iatrogenic CJD - contaminated material such as corneal grafts

51
Q

What are features of Sporadic CJD?

A
  • Rapidly progressive dementia with early behavioural abnormalities
  • Myoclonus
  • Cerebellar ataxia
  • Extrapyamidal: tremor, rigidity, bradykinesia, dystonia
  • Pyramidal signs: wakenss, spasticity, hyper-reflexia
  • Extrapyramidal and pyramidal signs
  • Eye signs - supranuclear palsies, complex visual disturbance, hallucinations, cortical blindness
  • Seizures
52
Q

Invetigations CJD

A

Tonsillar biopsy
CSF Gel elecrophoresis

53
Q

What are characteristic fatures of CJD?

A

Younger onset<40,

Early behavioural symptoms

Ataxia

Dementia

54
Q

What is variant CJD linked to?

A

Bovine spungiform encephalopathy

55
Q

How can varient CJD be acquired?

A

Transmitted via meat contaminated by CNS tissue affected by bovine spongiform encephalopathy

56
Q

What organism most commonly causes spinal epiderual abscess

A

Staph aureus

Back pain and gever followed by paraparesis and local root lesions

57
Q

What are argyll-robertson pupil

A

Argyll Robertson pupils (AR pupils or, colloquially, “prostitute’s pupils”) are bilateral small pupils that reduce in size on a near object (i.e., they accommodate), but do not constrict when exposed to bright light (i.e., they do not react to light). They are a highly specific sign of neurosyphilis; however, Argyll Robertson pupils may also be a sign of diabetic neuropathy

58
Q

What are neurological manifestations of lyme disease?

A
  • Mononeuropathy
  • Mononeuritis multiplex
  • Painful radiculopathy
  • Cranial neuropathy
  • Myelitis
  • Meningoencephalitis
  • Encephalomyelitis
59
Q

What bug causes lyme disease

A

Borrelia Burgdorferi

60
Q

Describe the three stages of lyme disease

A
  1. STAGE 1
    Early localised infection (1-30 days)
    Erythema migrans rasg
    50% have flu-like symptoms (fatigue, myalgia arthralgia, fever, chills, headache, neck stiffness)
  2. STAGE 2
    Early disseminated infection (weeks-months)
    One or more organ systems included
    MSK -arthritis
    CArdiac - myocarditis
    neorlogical - meingoencephalitis, cranial or polyneuropathies
  3. STAGE 3
    Chronic infection (months- years
    May continue to experience fatigue and MSK pain for months - years
61
Q

Investigations of lymes

A

Serological - IgM and IgG

Imaging - MRI, CSF lymphocytosis

62
Q

Management Lyme disease

A

Oral doxycycline (or amoxicillin)

IV benzyl penicillin or ceftriazone in later stages

63
Q

What bug causes tetanus?

A

Clostridium tetani (anaerobic gram positive bacillus, spore forming)

64
Q

Pathology of tetanus

A

Toxin acts on MNJ blokcing inhibtion of motor neurones

65
Q

Presentation of tetanus

A

Prodrome illness

Trismus )jaw lock)

Risus sardonicus (grin-like posture of hyperteonic facial msucles)

Spasms

66
Q

What bug causes botulism?

A

Clostridium Botulinum

67
Q

How is botulism transmitted

A

Naturally present in soil, dust, aquaritc and environments.

Modes of infection: food borne, would (ALMOST EXCLUSIVELY IVDU)

68
Q

Pathology botulism

A

Toxin binds to presynaptic membranes of peripheral NMJ

69
Q

Presentation botulism

A

Incubation of 4-14- days

Descening symmetrical flaccid paralysis

Pure motor

Resp failure

70
Q

Diagnosis botulism

A

Culture from debried wound, mouse neutralisation bioassay for toxin in blood, nerve conduction studies.

71
Q

Mangement botulism

A

Wound debridement

Anti-toxin

Benzylpenicillin and metrinodazole