Infections of the Nervous System Flashcards
(123 cards)
1
Q
Definition of meningitis
A
Inflammation/infection of meninges
2
Q
Definition of encephalitis
A
Inflammation/infection of brain substance
3
Q
Definition of myelitis
A
Inflammation/infection of spinal cord
4
Q
Presentation of meningitis
A
Fever (>38C) Neck stiffness Altered mental status Short progressive headache Photophobia Nausea and vomiting Cranial nerve palsy (30%) Seizures (30%) Focal neurological deficits (10-20%) Petechial skin rash
5
Q
What is the classic triad of meningitis?
A
Fever
Neck stiffness
Altered mental status
6
Q
What is the petechial skin rash a hallmark of?
A
Meningococcal meningitis
But can also occur in viral
7
Q
Differential diagnosis of meningitis
A
Infective; bacterial, viral, fungal
Inflammatory; sarcoidosis
Drug induced; NSAIDs, IVIG
Malignant; metastatic, haematological e.g. leukaemia, lymphoma, myeloma
8
Q
Bacterial causes of meningitis
A
Neisseria meningitidis (meningococcus) Stretococcus pneumoniae (pnuemococcus)
9
Q
Viral causes of meningitis
A
Enteroviruses
10
Q
Presentation of encephalitis
A
Flu like prodrome (4 - 10 days) Progressive headache Fever \+/- meningism Progressive cerebral dysfunction (confusion, abnormal behaviour, memory disturbance, depressed conscious level) Seziures Focal symptoms/signs
11
Q
Main differences of viral encephalitis vs bacterial meningitis
A
VE = Slower onset and cerebral dysfunction more prominent feature
12
Q
Differential diagnosis of encephalitis
A
Infective; Viral (most common HSV)
Inflammatory; limbic encephlaitis (Anti VGKC Anti NMDA receptor). ADEM
Metabolic; hepatic, uraemic, hyperglycaemic
Malignant; metastatic, paraneoplastic
Migraine
Post ictal
13
Q
What does post ictal mean?
A
Post seizure
14
Q
What are the two important antibodies recognized in autoimmune encephalitis?
A
Anti-VGKC
Anti-NMDA receptor
15
Q
What does anti-VGKC stand for?
A
Voltage gated potassium channels
16
Q
Presentation of Anti-VGKC Autoimmune encephalitits
A
Frequent seizures
Amnesia
Altered mental state
17
Q
What is amnesia?
A
Not able to retain new memories
18
Q
Presentation of anti-NMDA receptor autoimmune encephalitis
A
Flu like prodrome
Prominent psychiatric features
Altered mental state and seziures
Progressive to movement disorder and coma
19
Q
Investigations for meningitis
A
Blood cultures (bacteraemia) LP (CSF culture/microscopy)
20
Q
Investigations for encephalitis
A
Blood cultures
Imaging (CT scan +/- MRI)
LP
EEG
21
Q
Contraindications to LP
A
Focal neurological deficit, not including cranial nerve palsies
New onset seizures
Papilloedema
Abnormal level of consciousness, interfering with proper neurological examination (GCS < 10)
Severe immunocompromised state
22
Q
What do focal symptoms and signs suggest?
A
A focal brain mass
23
Q
What does reduced consciousness level suggest?
A
Raised intracranial pressure
24
Q
CSF findings in bacterial meningitis
A
Opening pressure increased
Cell count high, mainly neutrophils
Glucose reduced
Protein high
25
CSF findings in viral meningitis and also encephalitis
Opening pressure normal or increased
Cell count high, mainly lymphocytes
Glucose normal (60% of BG)
Protein slightly increased
26
How do you assess the level of glucose in the CSF?
Compare it to the level of glucose in the blood
27
Which bacterial cause of bacterial meningitis is sensitive to penicillin?
Culture streptococcus pneumoniae
28
If not pyrexial, does the patient need a blood culture?
No
29
How common is HSV Encephalitis?
Relatively rare
| Commonest cause of encephalitis in Europe
30
Investigations of HSV Encephalitis
```
CSF
- PCR for Viral DNA
- Lymphocytosis
- elevated protein
CT
- medial temporal and inferior frontal lobe changes (e.g. petechial changes)
MRI (better)
EEG
```
31
Treatment of HSV Encephalitis
Aciclovir on clinical suspicision
32
Types of HSV
Type 1
| Type 2
33
What do both types of HSV cause?
```
Cold sores (type 1 > 2)
Genital herpes (both types)
```
34
Where does the HSV virus lie in the body?
Remains latent in the trigeminal or sacral ganglion after primary infection
35
What type of HSV usually causes HSV encephalitis?
Type 1 (other than neonates)
36
What type of viruses are enteroviruses?
RNA viruses
37
Spread of entero-viruses
Faecal oral route
38
What do enteroviruses have the tendency to cause?
CNS infections (neurotrophic)
39
Do enteroviruses also cause gastroenteritis?
NO
40
Examples of enteroviruses
Polioviruses
Coxsackieviruses
Echoviruses
41
Causes of encephalitis
HSV
Enteroviruses
Arbovirus
42
Where is arbovirus encephalitis common?
Certain areas of the world where there is certain types of ticks/mosquitos - therefore have to have travel history
43
Types of arbovirus encephalitis
West nile virus
St Louis encephalitis
Tick borne encephalitis
Japanese B encephalitis
44
Definition of brain abscess
Localized area of pus within the brain
45
Definition of subdural empyema
Thin layer of pus between the dura and arachnoid membranes over the surface of the brain
46
Presentation of brain abscess/empyema
```
Fever
Headache
Focal symptoms
- seizures
- dysphagia
- hemiparesis
Signs of raised ICP
- papilloedema
- false localising signs
- depressing conscious level
Meningism may be present, particularly with empyema
Features of an underlying source
- dental, sinus or ear infection
```
47
Differential diagnosis of brain abscess/empyema
Any focal lesion but most commonly tumour
| Subdural haematoma
48
Causes of brain abscess/empyema
```
Penetrating head injury
Spread from adjacent infection
- dental
- sinusitis
- otitis media
Blood borne infection e.g. bacterial endocarditis
Neurosurgical procedure
```
49
Investigations for brain abscess and empyema
Imaging; CT or MRI
Investigate source
Blood cultures
Biopsy (drainage of pus)
50
Causative organisms of a brain abscess
```
Often a mixture present - depends on predisposing condition
Streptococci (70% of cases)
- Strep anginousus
- Strep intermediuss
- Strep constellatus
Anaerobes in 40-100% of cases
- bacteriodes
- prevotella
```
51
Treatment of brain abscess
Surgical drainage if possible
Penicillin or ceftrixazone to cover streps
Metronidazole for anaerobes
HIGH DOSES REQUIRED FOR PENETRATION
52
HIV indicator illnesses of the brain
```
Cerebral toxoplasmosis
Aseptic meningitis/encephalitis
Primary cerebral lymphoma
Cerebral abscess
Cryptococcal meningitis
Space occupying lesion of unknown cause
Dementia
Leucoencephalopathy
```
53
Brain infections in HIV patients with low CD4 counts
Cryptococcus neoformans
Toxoplasma gondii
Progressive multifocal leykoencephalopathy (PML)
CMV
HIV encephalopathy (HIV-associated dementia)
54
Investigations of brain infections in HIV patients with low CD4 counts
```
India ink, cyptococcal antigen
Toxoplasmosis serology (IgG)
JC virus PCR
CMV PCR
HIV PCR
```
55
Causative organisms of cryptococcal infections
Cryptococcus neoformans
56
Exposure of cryptococcus organisms is due to what?
Inhalation of airborne organisms into the lungs
57
Most clinical cases of cryptococcal infections present with what?
Meningoencephalitis
58
What do most patients with cryptococcal infections also have?
Defects in immune function
59
Major risk factor for cryptococcal infections
AIDs
60
Risk factors for cryptococcal infections
AIDs
Immunosuppressive medications
- particularly in the setting of solid organ transplantation
61
What spirochaeates can be found in the CNS?
Borrelia Burgorferi
Trepomena pallidum
Leptospira interrogans
62
What does borrelia burgorgeri cause?
Lymes disease
63
What does trepomena pallidum cause?
Syphillis
64
What does leptospira interrogans cause?
Leptospirosis
65
How do you get lyme disease?
Vector borne; tick (wooded areas)
66
3 stages of lymes disease
Stage 1 , 2, 3
67
Presentation of stage 1 lymes disease
Early localised infection (1 - 30 days)
Characteristic expanding rash at the site of the tick bites - erythema migrans
50% flu like symptoms (days - 1 week)
- fatigue, myalgia, arthralgia, headache, fever, chills, neck stiffness
68
Presentation of stage 2 lymes disease
Early disseminated infections (weeks - months)
One or more organ systems involved - hematological or lymphatic spread
MSK and neurological involvement most common
Neurological involvement in 10 - 15% of untreated patients
- mononeuropathy
- mononeurtis multiplex
- painful radiculoneuropathy
- cranial neuropathy
- myeltiis
- meningo-encephalitis
PNS > CNS
69
When does stage 3 lymes disease occur?
Chronic infection - months to years
| Occurring after a period of latency
70
Presentation of stage 3 lymes disease
MSK and neurological involvement most common
Neurological involvement as per stage 2 plus
- subacute encephalopathy
- encephalomyeltiis
71
Does stage 3 lymes disease cause chronic fatigue syndrome?
NO
72
Investigations for lymes disease
```
Serological testing
CSF Lymphocytosis
PCR of CSF
MRI brain spine if CNS involvement
Nerve conduction studies/EMG if PNS involvement
```
73
Treatment of lymes disease
IV ceftrixazone
| Oral doxycycline
74
Stages of syphillis
Primary
Secondary
Latent
75
What stage of syphillis can affect the CNS? When does this occur?
```
Tertiary disease (neurosyphillis)
Years / decades after primary disease
```
76
Investigations of syphillis
Treponema specific and non teponema specific (VDRL) antibody tests
CSF lymphocytes increased
Evidence of intrathecal antibody production
PCR
77
Treatment of syphillis
High dose penicillin
78
What is poliomyelitis caused by?
Poliovirus types 1, 2 or 3
79
What % of poliomyelitis infections are asymptomatic? What happens to the symptomatic group?
99%
| 1% symptomatic - paralytic disease as infects anterior horn cells of LMNs
80
Presentation of symptomatic poliomyelritis
Asymmetric, flaccid paralysis, especially on the legs
| No sensory features
81
In the UK, what is done to prevent poliomyelitis?
Polio immunization against all 3 poliovirus types
82
What is rabies?
Acute infectious diseases of the CNS affecting almost all mammals
83
How are rabies transmitted from animal to human?
Bite
| Salivary contamination of an open lesion
84
Features of the rabies virus
Neurotropic
| Virus enters peripheral nerves and migrates to the CNS
85
Presentation of rabies
Paraesthesia at site of original lesion
Ascending Paralysis
Encephalitis
86
Investigations of rabies encephalitis
**No useful diagnostic tests before clinical disease apparent**
Culture
Detection or serology
87
What animals often carry rabies?
Dogs in Asia/Africa
| Bats in developed world
88
What can be done for rabies pre-exposure prevention?
Active immunization with killed vaccine
89
Who is the rabies vaccine given to in the UK?
Bat handlers
Regular handlers of imported animals
Selected travelers to enzoonotic areas
90
Rabies post exposure treatment
Wash wound
Give active rabies immunisation
Give human rabies immunoglobulin (passive immunisation) if high risk
91
What is the causative organism of tetanus?
Clostridium tetani
92
Pathology of tetanus
Toxin acts at the NMJ
| Blocks the inhibition of motor neurones
93
Presentation of tetanus
Rigidity and spam (risus sarconicus)
94
Prevention of tetanus
Immunisation (toxoid)
Given combined with other antigens (DTaP)
Penicillin and immunoglobulin for high risk wounds/patients
95
What is the causative organism for botulism?
Clostridium Botulinium
96
Pathology of botulism
Neurotoxin binds irreversibly to the presynaptic membranes of peripheral neuromuscular autonomic nerve junctions
Toxin binding blocks acetylcholine release
Recovery is by sprouting new axons
97
Where is clostridium botulinium naturally present?
Soil
Dust
Aquatic environments
98
Three modes of infection of clostridium botulinium
Infantile (intestinal colonisation)
Food-borne (outbreaks)
Wound; almost exclusively injecting or "popping" drug users
99
Presentation of botulism
Incubation period 4-14 days
Descending symmetrical flaccid paralysis
Pure motor
Resp failure
Autonomic dysfunction - usually pupil dilation
100
Investigations of botulism
Nerve conduction studies
Mouse neutralisation bioassay for toxin in the blood
Culture from debrided woud
101
Treatment of botulism
Anti-toxin (A,B,E)
Penicillin/Metronidazole (prolonged treatment)
Radical wound debridement
102
Example of a CNS post infective inflammatory syndrome
Acute disseminated encephalomyeltitis (ADEM)
103
Example of a PNS post infective inflammatory syndrome
Guillian Barre Syndrome (GBS)
104
What does CJD stand for?
Cretuzfeldt-Jakob Disease
105
Types of CJD
Sporadic
New variant
Familial
Acquired
106
How do patients get acquired CJD?
Cadaveric growth hormone
Dura mater grafts
Blood transfusion
107
Who should sporadic CJD be considered in?
Rapidly progressive dementia
108
Presentation of sporadic CJD
```
Insidious onset (usually older than 60)
Early behavioral abnormalities
Myoclonus
Rapidly progressive dementia
Motor abnormalities
- cerebellar ataxia
- extrapyramidal
- pyramidal
Cortical blindness
Seizures may occur
```
109
Features of extrapyramidal motor abnormalities
Tremor
Rigidity
Bradykinesis
Dystonia
110
Features of pyramidal motor abnormalities
Weakness
Spasticity
Hyper-reflexia
111
Differential diagnosis of sporadic CJD
Alzheimer's disease with myoclonus - usually more prolonged
Subacute sclerosing panencephalitis (SSPE)
CNS vasculitis
Inflammatory encephalopathies
112
Prognosis of sproadic CJD
Rapid progression
| Death often within 6 months
113
What age do people get new variant?
< 40 y/o (usually < 25 y/o)
114
How do people get new variant CJD?
Linked to Bovine Spongiform Encephalopathy in cattle
| - eating infected material
115
Investigations of CJD
```
MRI
- pulvinar sign in variant CJD
- no specific changes in sporadic CJD
EEG
- generalised periodic complexes typical
CSF
- normal or raised protein
- immunoassay 14-3-3 brain protein (non specific but helpful in a clinical context)
```
116
What lobes does HSV encephalitis tend to affect?
Temporal lobes
| Inferior frontal lobe
117
Presentation of HSV encephalitis
```
Fever
Headache
Psychiatric symptoms
Seizures
Vomiting
Focal features e.g. aphasia
```
118
What is CJD caused by?
Prion proteins
119
Features of CJD
Rapidly progressive dementia
| Myoclonus
120
Investigations of CJD
CSF = normal
EEG
MRI
121
Presentation of new variant CJD
```
Younger patients
Psychological symptoms
- anxiety
- withdrawal
- dysphonia
```
122
Median survival for new variant CJD
13 months
123
What is the most common complication of meningitis?
Sensorineural hearing loss
