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year 2 neuro - Robbie > Infections of the Nervous System > Flashcards

Infections of the Nervous System Flashcards

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1
Q

What is the definition of meningitis?

A

inflammation/infection of the meninges

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2
Q

What is the definition of encephalitis?

A

inflammation/infection of brain substance

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3
Q

What is the definition of myelitis?

A

inflammation/infection of the spinal cord

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4
Q

What is the classic triad of features of meningitis?

A

fever, neck stiffness and altered mental status

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5
Q

What is the common histroy of meningitis like?

A

Present with a short history of progressive headache associated with:

  • Fever (>38º) and
  • Meningism (neck stiffness, photophobia, nausea and vomiting)

Neck stiffness is examined by passively bending the neck forward

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6
Q

What part of the brain may be dysfunctioning in 69% of >14?

A

Cerebral dysfunction (confusion, delirium, declining conscious level)

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7
Q

What other less common things may be a result of meningitis?

A

Cranial nerve palsy (30%)

seizures (30%)

focal neurological deficits (10-20%)

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8
Q

Look skin rash using a tmbler test in cases of meningitis, what is this a sign of?

A

hallmark of meningococcal meningitis, but can also occur in viral meningitis

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9
Q

What are some differential diagnosis of meningitis?

A

Infective: Bacterial, Viral, Fungal

Inflammatory: Sarcoidosis

Drug induced: NSAIDs, IVIG

Malignant: Metastatic and Haematological

e.g. Leukaemia, Lymphoma, Myeloma

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10
Q

What are some bacterial causes of meningitis?

A

Neisseria meningitidis (meningococcus)

Streptococcus pneumoniae (pneumococcus)

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11
Q

What is the commenest viral cause of meningitis?

A

enteroviruses

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12
Q

What are the clinical features of encephalitis?

A

Flu-like prodrome (4-10days)

Progressive Headache associated with fever:

  • +/- meningism
  • Progressive cerebral dysfunction - confusion, abnormal behaviour, memory disturbance, depressed conscious level
  • Seizures
  • Focal symptoms/signs
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13
Q

How is viral encephalitis different from bacterial meningitis?

A

Onset of a viral encephalitis is generally slower than for bacterial meningitis and cerebral dysfunction is a more prominent feature

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14
Q

What are some differential diagnosis of encephalitis?

A

Infective: Viral (most common is HSV)

Inflammatory: Limbic encephalitis (Anti VGKC, Anti NMDA receptor), ADEM

Metabolic: Hepatic, Uraemic, Hyperglycaemic

Malignant: Metastatic, Paraneoplastic

Migraine

Post ictal (after seizure)

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15
Q

Is auto-immune encephalitis as common as viral encephalitis?

A

May be as common as viral encephalitis

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16
Q

What are 2 important antibodies in auto-immune encephalitis?

A

Anti-VGKC (Voltage Gated Potassium Channel)

Anti-NMDA receptor

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17
Q

What Investigations of Meningitis?

A

Priority is to exclude (and treat) infection

Blood cultures (bacteraemia)

Lumbar puncture (CSF culture/microscopy)

No need for imaging if no contraindications to LP

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18
Q

What Investigations for Encephalitis?

A

Priority is to exclude (and treat) infection

Blood cultures

Imaging (CT scan +/- MRI)

Lumbar puncture

EEG

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19
Q

What do focal symptoms or signs suggest

What does reduced conscious level suggest

A

Focal symptoms or signs suggest a focal brain mass

Reduced conscious level suggests raised intracranial pressure

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20
Q

What are some contra-indicatiosn for a lumbar puncture?

A

focal neurological deficit, not including cranial nerve palsies

new-onset sezuires

papllioedema

abnormal level of consciousness, interfering with proper neurological examination

severe immunocomprimised state

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21
Q

Describe the CSF finding differences in bacterial meningitis and viral meningitis/encephalitis:

opening pressure

cell count

glucose

protein

A

Bacteria use glucose so lower in bacterial

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22
Q

Herpes simplex (HSV) encephalitis - is it rare or common?

A

Relatively rare, but commonest cause of encephalitis in Europe

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23
Q

What is the diagnosis of Herpes simplex (HSV) encephalitis?

A

Lab diagnosis by PCR of CSF for viral DNA

(opposed to growing bacteria as this is viral)

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24
Q

What is the treatment of herpes simplex (HSV) encephalitis?

A

Treat with aciclovir on clinical suspicion

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25
What is the prognosis of herpes simplex (HSV) encephalitis if left untreated?
Over 70% mortality and high morbidity if untreated
26
Herpes simplex is one of what groups?
One of the herpes group of viruses
27
What are the different types of HSV and what do they cause
HSV types 1 & 2 cause: cold sores (type 1 \>\> 2) genital herpes (type 1 & 2 (more so in type 2))
28
How does HSV present?
Virus remains latent in the trigeminal or sacral ganglion after primary infection (as with all herpesviruses, once infected, always infected) Virus never leaves the body – causes acute infection then the virus disappears in the ganglia and lies dormant and if the patient goes under any stress, physical or emotional and then the virus gets reactivated and another re-infection happens and the symptoms come
29
How does HSV cause encephalitis?
Encephalitis is a rare complication of HSV other than neonates, nearly all caused by type 1
30
What do enteroviruses (large family of RNA viruses) cause?
viral meningitis
31
What do enteroviruses have a tendency to cause?
CNS infection
32
Who do enteroviruses effect?
humans only no animal reservoir
33
How are enteroviruses spread?
faecal oral route
34
Enterovirus are _____ virus which is different form herpes which is _____ virus
Enterovirus are RNA virus which is different form herpes which is DNA virus
35
What is an arbovirus and can it cause encephalitis
yes it causes arbovirus encephalitides Inflammation of the brain (encephalitis) caused by infection with an arbovirus, a virus transmitted by a mosquito, tick or another arthropod
36
How is arbovirus encephalitides transmitted?
Transmitted to man by vector (mosquito or tick) from non-human host
37
WHat is important to do when someone present that may have a arbovirus encephalitides
Relevant to travel so a travel history important and some preventable by immunisation
38
What is a brain abscess?
localized area of pus within the brain
39
What is subdural empyema?
thin layer of pus between the dura and arachnoid membranes over the surface of the brain
40
What are the clinical features of a brain abscess and empyema?
Fever, Headache Focal symptoms/signs - seizures, dysphasia, hemiparesis, etc Signs of raised intracranial pressure - Papilloedema, false localizing signs, depressed conscious level Meningism may be present, particularly with empyema Features of underlying source - e.g dental, sinus or ear infection
41
What are some causes of Brain Abscess and Empyema?
Penetrating head injury Spread from adjacent infection - Dental, Sinusitis, Otitis media Blood borne infection - e.g. Bacterial endocarditis Neurosurgical procedure
42
What is the diagnosis of brain abscess and empyema
Imaging: CT or MRI investigate source blood cultures Biopsy (drainage of pus)
43
What organisms tend to be present in a brain abscess?
Often mixtures of organisms present (polymicrobial) - depend on predisposing condition Streptococci in 70% of cases - Strep anginosus, Strep intermedius, Strep constellatus Anaerobes (any organism that does not require oxygen for growth) in 40 - 100% of cases
44
What is the management of a brain abscess?
* Surgical drainage if possible * Penicillin or ceftriaxone to cover streps * Metronidazole for anaerobes * High doses required for penetration * Culture and sensitivity tests on aspirate provide useful guide * High mortality without appropriate treatment
45
WHat conditions seen in patients would make you suspect HIV
* Cerebral toxoplasmosis * Aseptic meningitis/encephalitis * Primary cerebral lymphoma * Cerebral abscess * Cryptococcal meningitis * Space occupying lesion of unknown cause * Dementia * Leucoencephalopathy
46
Spirochaetes in the CNS may cause what diseases?
* Lyme Disease (Borrelia burgdorferi) * Syphilis (Trepomena pallidum) * Leptospirosis (Leptospira interrogans)
47
How is lyme disease transmitted?
Vector borne: Tick (wooded areas) Spirochaete: Borrelia burgdorferi
48
How many stages of lyme disease is there?
3
49
Where does lyme disease affect in the body?
it is multi-system Skin, rheumatological, neurological/neuropsychiatric, cardiac and ophthalmological involvement Untreated 80% will develop multi-system disseminated disease
50
What symptoms is there in stage 1 lyme disease?
* Early localized infection (1-30d) * Characteristic expanding rash at the site of the tick bite: erythema migrans * 50% flu like symptoms (days – 1 week) Fatigue, myalgia, arthralgia, headache, fever, chills, neck stiffness
51
What is seen in stage 2 lyme disease?
**Early disseminated infection** (weeks – months) One or more organ systems become involved - Haematologic or lymphatic spread Musculoskeletal and neurologic involvement most common Neurologic involvement (10-15%) untreated patients PNS \> CNS
52
What is seen in stage 3 lyme disease?
similar to stage 2 but further down the line Chronic infection - months to years occuring after a period of latency Musculoskeletal and neurologic involvement most common Neurologic involvement Does NOT cause a chronic fatigue syndrome
53
What is the investigtion of lyme disease?
Complex range of serological tests CSF lymphocytosis - higher-than-normal amount of lymphocytes MRI brain/spine (if CNS involvement) Nerve conduction studies/EMG (if PNS involvement)
54
What is the treatment of lyme disease?
• Prolonged antibiotic treatment intravenous ceftriaxone oral doxycycline
55
How does neurosyphilis present?
syphilis has a similar 3 stage presentation primary - secondary - latent tertiary disease (neurosyphilis) years/decades after primary disease - not common
56
How do you investiage syphilis?
antibody tests CSF lymphocytes increased
57
What is the trestment of neurosyphilis?
high dose penicillin
58
moving onto important vaccines
59
What causes Poliomyelitis?
Caused by poliovirus types 1, 2 or 3 all enteroviruses
60
What does polimyelitis cause?
* 99% of infections are asymptomatic * Paralytic disease in ~1% infects anterior horn cells of lower motor neurones Asymmetric, flaccid paralysis, esp legs No sensory features
61
What is the polio immunisation?
In UK, both contain all three poliovirus types UK 2004 changed from oral to injected vaccine
62
What is rabies?
Acute infectious disease of CNS affecting almost all mammals
63
How is rabies transmitted?
Transmitted to human by bite or salivary contamination of open lesion
64
Rabies is neurotropic, what does this mean?
virus enters peripheral nerves and migrates to CNS
65
WHat are the symptoms of rabies?
* Paraesthesiae (an abnormal sensation, typically tingling or pricking (‘pins and needles’)) at site of original lesion * Ascending paralysis and encephalitis
66
What is the diagnosis of rabies encephalitis?
No useful diagnostic tests before clinical disease apparent Diagnosis: PCR and Serology
67
WHat is the pre-exposure prevention of rabies?
active immunisation with killed vaccine
68
What is the post-exposure treatment of rabies?
Wash wound Give active rabies immunisation Give human rabies immunoglobulin (passive immunisation) if high risk
69
What is tetanus an infection of?
infection with Clostridium tetani anaerobic Gram positive bacillus, spore forming
70
How does tetanus cause infection?
wound may not be apparent toxin acts at neuro-muscular junction blocks inhibition of motor neurones
71
What does tetanus cause?
rigidity and spasm (risus sardonicus)
72
How is tetanus prevented?
Immunisation (toxoid) given combined with other antigens (DTaP) Penicillin and immunoglobulin for high risk wounds/patients
73
What is botulism?
a serious illness caused by the botulinum toxin. The toxin causes paralysis Anaerobic spore producing gram positive bacillus Binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions Toxin binding blocks acetylcholine release Recovery is by sprouting new axons Naturally present in soil, dust and aquatic environments
74
What are the modes of botulism infection?
Infantile (intestinal colonization) Food-borne (outbreaks) Wound: Almost exclusively injecting or “popping” drug users
75
What is the clinical presentation of botulism?
Incubation period 4-14 days Descending symmetrical flaccid paralysis Pure motor Respiratory failure Autonomic dysfunction - Usually pupil dilation
76
What is the diagnosis of botulism?
Nerve conduction studies Mouse neutralisation bioassay for toxin in blood Culture from debrided wound
77
What is the treatment of botulism?
Anti-toxin (A,B,E) Penicillin/Metronidazole (prolonged treatment) Radical wound debridement
78
Creutzfeldt-Jakob Disease (CJD) is what type of disease?
Prion prion is a type of protein that can trigger normal proteins in the brain to fold abnormally
79
What is the aetiology of CJD?
Sporadic CJD New variant CJD Familial CJD (10-15%) Acquired CJD (\<5%) • Cadeveric Growth Hormone • Dura matter grafts • Blood transfusion
80
How common is CJD?
Very rare: sporadic 1 per million per year (incidence)
81
When would you consider sporadic CJD in a patient?
Consider in any rapidly progressive dementia
82
What are the clinical features of sporadic CJD?
Insidious onset (usually older than 60) Early behavioural abnormalities Rapidly progressive dementia Myoclonus Progressing to global neurological decline Motor abnormalities • Cerebellar ataxia • Extrapyramidal: tremor, rigidity, bradykinesis, dystonia • Pyramidal: weakness, spacticity, hyper-refexia Cortical blindness Seizures may occur
83
What is the prognosis of sporadic CJD?
rapid progession death often within 6 months
84
What age does new varient CJD present at?
Younger onset \<40
85
What is more prominent in new varient CJD?
Early behavioural changes more prominent
86
What investigations can be used for CJD?
MRI - Often no specific changes in sporadic CJD EEG CSF - Normal or raised protein

year 2 neuro - Robbie (48 decks)

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