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Flashcards in Infections in the CNS Deck (85):
1

define meningitis

infection/inflammation of the meninges

2

define encephalitis

infection/inflammation of the brain substance

3

define myelitis

inflammation/infection of the spinal cord

4

what is the classical triad of meningitis?

> fever
> neck stiffness
> altered mental status

5

what are the clinical features of meningitis?

> short history of progressive headache
> petechial skin rash (non-blanching)
> cranial nerve palsy
> seizures
> focal neurological deficit

6

what is the differential diagnosis for meningitis?

> infective: bacterial, viral and fungal
> inflammatory: sarcoidosis
> drug induced: NSAIDs, IVIG
> malignant: metastatic, haematological

7

what are the bacterial causes of meningitis?

> Neisseria meningitidis : meningococcus
> streptococcus pneumonia : pneumococcus

8

what are the viral causes of meningitis?

enteroviruses

9

what are the clinical features of encephalitis?

> flu like prodrome
> progressive headache with associated fever
> progressive cerebral dysfunction
> seizures
> focal symptoms/signs

10

what is the difference between viral encephalitis and bacterial meningitis?

viral encephalitis is generally slower and cerebral dysfunction is a more prominent feature

11

what is the differential diagnosis for encephalitis?

> infective: viral
> inflammatory: limbic encephalitis
> metabolic: hepatic, uraemic, hyperglycaemic
> malignant: metastatic, paraneoplastic
> migraine
> post ictal

12

what are the two antibodies involved in autoimmune encephalitis?

> anti-VGKC (voltage gated potassium channel)
> anti-NMDA receptor

13

describe the clinical features of Anti-VGKC encephalitis

> frequent seizures
> amnesia (not able to retain new memories)
> altered mental state

14

describe the clinical features of anti-NMDA receptor

> flue like prodrome
> prominent psychiatric features
> altered mental state and seizures
> progressing to a movement disorder and coma

15

what investigations would you carry out for meningitis?

> blood cultures
> lumbar puncture
> there is no need to image if there are no contraindications to lumbar puncture

16

what investigations would you carry out for encephalitis?

> blood cultures
> CT (+/- MRI)
> lumbar puncture
> EEG

17

what are the contraindications for a lumbar puncture?

> focal symptoms or signs suggesting a focal brain mass
> reduced conscious level suggesting raised intracranial pressure
> in the immunocompromised you should image first as some features can be lost

18

what CSF findings would you find in bacterial meningitis?

> increased opening pressure
> high neutrophillic cell count
>reduced glucose (as bacteria consume glucose)
> high protein

19

describe the CSF findings in viral meningitis and encephalitis

> normal/increased opening pressure
> high mainly lymphocytic cell count
> normal glucose
> slightly increased protein

20

what is the commonest cause on encephalitis in Europe?

herpes simplex encephalitis

21

what is the lab diagnosis for herpes simplex encephalitis?

PCR of CSF for viral DNA

22

how do you treat herpes simplex encephalitis?

aciclovir in clinical suspicion

23

where does the herpes simplex virus remain latent?

in the trigeminal ganglion or sacral ganglion

24

how are enterovirses spread?

by the faecal-oral route

25

what can cause non-paralytic meningitis?

enteroviruses

26

do enteroviruses causes gastroenteritis?

no

27

how are arbovirus encephalitides transmitted?

by vector (mosquito or tick) from non-human host

28

give some examples of arbovirus encephalitides?

> west nile virus
> st louis encephalitis
> western equine encephalitis
> Japanese b encephalitis

29

define a brain abscess

localised area of pus within the brain

30

what is a subdural empyema?

thin layer of pus between the dura and arachnoid membrane over the surface of the brain

31

what are the clinical features of brain abscesses and empyema?

> fever
> headache
> focal symptoms and signs (depressed conscious level)
> meningism (particularly in empyema)
> features of the underlying source

32

name some causes of brain abscesses and empyema

> penetrating head injury
> spread form adjacent infection (dental, sinusitis, otitis media)
> blood borne infection
> neurosurgical procedure

33

how would you diagnose a brain abscess and empyema?

> imaging: CT or MRI
> investigate source
> blood cultures
> biopsy (drainage of pus)

34

what streptococci group are often present in brain abscesses?

penicillin sensitive strep-milleri group (strep. anginosus, strep intermedius, strep constellatus)

35

in a brain abscess is there more likely to be one organism present of a mixture of organisms present?

a mixture of organisms

36

how would you manage a brain abscess?

> surgical drainage if possible
> high dose antibiotics (culture and sensitivity tests on aspirate provide useful guide)

37

what antibiotics could you give to cover strep infection in a brain abscess?

> penicillin
> ceftriaxone

38

what treatment would you give for an anaerobic brain abscess?

metronidazole

39

name HIV indicator illnesses

> cerebral toxoplasmosis
> aseptic meningitis/encephalitis
> primary cerebral lymphoma
> cerebral abscess
> cryptococcal meningitis
> space occupying lesion of unknown cause
> dementia
> leucoencephalopathy

40

what brain infections could you see in HIV patients with low CD4 counts?

> Cryptococcus neoformans
> toxoplasma gondii
> progressive multifocal leukoencephalopathy
> crytomegalovirus
> HIV encephalopathy

41

what tests could you carry out to differentiate the causative organisms in HIV low CD4 count brain infections?

> india ink, cryptococcal antigen
> toxoplasmosis serology
> JC virus PCR
> CMV PCR
> HIV PCR

42

what do cryptococcal antigens loos like in an indian ink stain?

as a capsule organism in double circles

43

what spirochaetes infections involve the CNS?

> lyme disease
> syphilis
> leptospirosis

44

how is lyme disease transmitted?

vector borne, tick

45

describe stage one in lyme disease?

> early localised infection
> erythema migrans: characteristic expanding rash at site of tick bite
> 50% flue like symptoms

46

describe stage 2 lyme disease

> early disseminated infection (weeks-months)
> one or more organ system involvement
> musculoskeletal and neurological involvement

47

what neurological involvement is there in stage 2 lyme disease if the patient is untreated?

> mononeuropathy
> mononeuritis multiplex
> painful radiculoneuropathy
> cranial neuropathy
> myelitis
> meningo-encephalitis

48

describe stage 3 lyme disease

> chronic infection occurring after a period of latency
> musculoskeletal and neurological involvement is the most common

49

what are the investigations for lyme disease?

> serological tests
> CSF lymphocytosis
> PCR of CSF
> MRI brain/spine
> nerve condition studies

50

what is the treatment for lyme disease?

> intravenous ceftriaxone
> oral doxycycline

51

when does tertiary syphilis (neurosyphilis)occur?

years/decades after primary disease

52

what tests are carried out for neurosyphilis?

> treponema specific antibody test
> non-treponemal specific antibody test
> CSF PCR

53

how does the CSF change in neurosyphilis?

> CSF lymphocytes increase
> there is evidence of intrathecal antibody production

54

what is the treatment for neurosyphilis?

high dose penicillin

55

what causes poliomyelitis?

poliovirus type 1,2 or 3 (enterovirus)

56

what part of the central nervous system does paralytic poliomyelitis affect?

the anterior horns of the lower motor neurons

57

describe the paralysis seen in poliomyelitis

> asymmetric
> flaccid paralysis
> no sensory features

58

in the uk what polio types does the vaccine contain?

all three types

59

rabies is described as neurotropic. what does this mean?

the virus enters the peripheral nerves and migrates to CNS

60

what is there at the site of the initial lesion in rabies?

paraesthesiae

61

what is the affect of rabies infection?

> ascending paralysis
> encephalitis

62

how would you diagnose rabies encephalitis?

> culture (detection or serology)

63

who is given the rabies pre-exposure prevention?

> bat handlers
> regular handlers of imported animals
> selected travellers to enzootic areas

64

what is the rabies post exposure treatment?

> wash wound
> active rabies immunisation
> human rabies immunoglobulin (passive immunisation) if high risk

65

what is the bacteria involved in tetanus infection?

clostridium tetani:
anaerobic gram positive bacillus
spore forming

66

describe the pathology of tetanus

toxin acts on the neuro-muscular junction blocking inhibition of motor neurons causing rigidity or spasm

67

describe the prevention of tetanus

> immunisation (toxoid) combined with other antigens
> penicillin and immunoglobulin for high risk wounds/patients

68

describe the bacteria involved in botulism

clostridium botulinum
> anaerobic spore producing gram positive bacillus

69

describe the effect of the neurotoxin in botulism

> binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions
> toxin binding blocks acetylcholine release

70

what is the recovery form botulism neurotoxin?

sprouting new axons

71

where is clostridium botulism naturally present?

> soil
> dust
> aquatic environments

72

what are the three modes of infection of botulism?

> infantile (intestinal colonisation)
> food-borne
> wound (drug abuse)

73

what is the clinical presentation of botulism?

> incubation period (4-14 days)
> descending symmetrical flaccid paralysis
> pure motor
> respiratory failure
> autonomic dysfunction

74

how do you diagnose botulism?

> nerve conducting studies
> mouse neutralisation bioassay for toxin in blood
> culture from debrided wound

75

what is the treatment for botulism?

> anti-toxin
> penicillin/metronidazole
> radical would debridement

76

name a post infective inflammatory syndrome affecting the central nervous system

acute disseminated encephalomyelitis

77

name a post infective inflammatory syndrome affecting the peripheral nervous system

guillain barre syndrome

78

what is the aetiology of Creutzfeldt-Jakob disease?

> sporadic
> new variant
> familial
> acquired (cadaveric growth hormone, dura matter grafts, blood transfusion)

79

what should you consider in any rapidly progressing dementia?

sporadic CJD

80

what are the clinical features of sporadic CJD?

> insidious onset
> early behavioural abnormalities
> rapidly progressing dementia
> myoclonus
> progressing global neurological decline
> motor abnormalities
> cortical blindness
> seizures (sometimes)

81

what is the differential diagnosis for sporadic CJD?

> Alzheimer's disease my myoclonus
> subacute sclerosing panencephalitis
> CNS vasculitis
> inflammatory encephalopathies

82

what is the prognosis of sporadic CJD?

> rapid progression
> death within 6 months

83

what is new variant CJD linked to?

bovine spongiform encephalopathy in cattle

84

what is the difference in the clinical features of new variant CJD compared to sporadic CJD?

> early behavioural changes are more important
> longer course (average 13 months)

85

what is the investigation for Creutzfeldt-Jakob disease?

> MRI (pulvinar signs in variant)
> EEG (generalised periodic complexes typical though often normal)
> CSF (normal or raised protein. immunoassay 14-3-3-brain protein)