Lecture 23Infections of the Nervous System Flashcards
1
Q
Define Meningitis
A
inflammation / infection of meninges
2
Q
Define Encephalitis
A
inflammation / infection of brain substance
3
Q
Define Myelitis
A
inflammation / infection of spinal cord
4
Q
What are the clinical features of Meningitis
A
Fever Neck stiffness Altered mental status Fever Photophobia Nausea Vomiting Cerebral dysfunction Cranial nerve palsy Seizures Petechial skin rash
5
Q
Differential diagnosis of Meningitis
A
Bacterial, Viral, Fungal Sarcoidosis NSAIDs Metastatic Leukaemia Lymphoma Myeloma
6
Q
Bacterial causes of meningitis
A
o Neisseria meningitidis (meningococcus)
o Streptococcus pneumoniae (pneumococcus)
7
Q
Viral causes of meningitis
A
Enteroviruses
8
Q
Clinical features of Encephalitis
A
Flue like Progressive headache with fever • Progressive cerebral dysfunction – Confusion – Abnormal behaviour – Memory disturbance – Depressed conscious level • Seizures • Focal symptoms / signs
9
Q
Onset of which type of encephalitis is slower bacterial or viral
A
Viral
10
Q
Differential diagnosis for encephalitis
A
HSV Limbic encephalitis Hepatic Uraemic Hyperglycaemic Metastatic Paraneiplastic Post ictal (after seizure)
11
Q
What are the 2 main types of auto-immune Encephalitis
A
Anti-VGKC
Anti-NMDA
12
Q
What is Anti-VGKC
A
(Voltage Gated Potassium Channel)
– Frequent seizures
– amnesia (not able to retain new memories)
– Altered mental state
13
Q
What is Anti-NMDA receptor
A
– Flue like prodrome
– Prominent psychiatric features
– Altered mental state and seizures
– Progressing to a movement disorder and coma
14
Q
What investigations are carried out for Meningitis and Encephalitis
A
Exclude and treat infection • Meningitis – Blood cultures (bacteraemia) – Lumbar puncture (CSF culture/microscopy) – No need for imaging if no contraindications to LP • Encephalitis – Blood cultures – Imaging (CT scan +/- MRI) – Lumbar puncture – EEG
15
Q
Name contraindications for a lumbar puncture
A
- Focal symptoms or signs to suggest a focal brain mass
* Reduced conscious level suggests raised intracranial pressure
16
Q
Name indications for CT brain scanning before lumbar puncture
A
Focal neurological deficit, not including cranial nerve palsies New onset seizures Papilloedema Abnormal level of consciousness GCS<10 Severe immunocompromised state
17
Q
Describe the opening pressure, cell count, glucose and protein that would be seen in Bacterial meningitis
A
Increased opening pressure
High cell count (neutrophils)
Reduced glucose
High protein
18
Q
Describe the opening pressure, cell count, glucose and protein that would be seen in Viral meningitis
A
Normal/increased opening pressure
High cell count (lymphocyte)
Normal glucose (60% of blood glucose)
Protein slightly increased
19
Q
66 Female Headache, photophobia, neck stiffness, vomiting, agitated. Treated empirically with IV Ceftriaxone • CSF protein 3256 mg/L (150-700) CSF Glucose 0.0 mmol/L • CSF: Appearance cloudy • Microscopy: • RBC 0 cells per cubic mm • WBC 8856 cells per cubic mm • Polymorphs 80% • Mononuclear cells 15% • Unidentified white cells 5% What would you find in the gram stain and what would be the diagnosis
A
- Blood culture Gram stain: Gram positive cocci in chains - looks like streptococci
- Culture streptococcus pneumoniae sensitive to penicillin
- Bacterial meningitis
20
Q
Name the commonest cause of encephalitis in Europe
A
HSV
21
Q
How is HSV Encephalitis diagnosed
A
PCR of CSF for viral DNA
22
Q
How is HSV Encephalitis treated
A
Aciclovir
23
Q
What HSV causes col sores
A
Type 1> 2
24
Q
What HS causes herpes
A
Type 1 and 2
25
After primary infection of HSV what happens
The virus lays latent in the trigeminal or sacral ganglion
26
How are enteroviruses spread
Faecal-oral route
27
What are the consequences of enteroviruses
```
non-paralytic meningitis
CN infections (neurotropic)
```
28
Name examples of Enteroviruses (RNA viruses)
polioviruses, coxsackieviruses and echoviruses
29
Other causes of Encephalitis
```
Arbovirus encephalitides
Brain abscess and Empyema
HIV
Spirochaetes
Lyme disease
Neurosyphillis
```
30
How is Arbovirus encephalitides transmitted
Main vector mosquito or tick
31
What is a brain abscess
Localised area of pus within the brain
32
What is a subdural empyema
thin layer of pus between the dura and arachnoid membranes over the surface of the brain
33
Clinical features of brain abscess
```
• 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
```
34
What underlying issues can cause a brain abscess
Dental, sinus or ear infection, tumour, subdural haematoma, bacterial endocarditis, penetrating head injury, neurosurgical procedure
35
What investigations are conducted for a suspected brain abscess and Empyema
CT/MRI
Blood culture
Biopsy (drainage of pus)
36
What organisms are responsible for brain abscesses
Streptococci
| Anaerobes (Bacteroides, Prevotella)
37
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
38
Differential diagnosis for HIV indicator illnesses (brain)
* Cerebral toxoplasmosis - parasitic
* Aseptic meningitis /encephalitis
* Primary cerebral lymphoma
* Cerebral abscess
* Cryptococcal meningitis
* Space occupying lesion of unknown cause
* Dementia
* Leucoencephalopathy- brain white matter disease
39
Name brain infections in HIV patients with low CD4 counts
* Cryptococcus neoformans
* Toxoplasma gondii
* Progressive multifocal leukoencephalopathy (PML)
* Cytomegalovirus (CMV)
* HIV-encephalopathy
40
Investigations for HIV indicator illnesses
* Cryptococcal antigen
* Toxoplasmosis serology
* CMV PCR
* HIV PCR
41
What disease involve Spirochaetes in the CNS
* Lyme Disease (Borrelia burgdorferi)
* Syphilis (Trepomena pallidum)
* Leptospirosis (Leptospira interrogans)
42
How is Lyme disease spread
Vector borne- tick (wooded area)
43
How many stages are there in a Lyme disease infection
3
44
Describe stage 1 of Lyme disease
• Early localized infection (1-30d)
• erythema migrans
• 50% flu like symptoms (days – 1 week)
– Fatigue, myalgia, arthralgia, headache, fever, chills, neck stiffness
45
Describe stage 2 of 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
46
Describe stage 3 of Lyme disease
```
• Chronic infection
– months to years
– occuring after a period of latency
– Musculoskeletal and neurologic involvement most common
• Neurologic involvement
– As described for stage 2
– Subacute encephalopathy
– Encephalomyelitis
• Does NOT cause a chronic fatigue syndrome
```
47
What are the investigations for Lyme disease
– Complex range of serological tests
– CSF lymphocytosis
– MRI brain / spine (if CNS involvement)
– Nerve conduction studies / EMG (if PNS involvement)
48
Treatment for Lyme disease
• Prolonged antibiotic treatment
– intravenous ceftriaxone
– oral doxycycline
49
What organism causes Neurosyphillis
Treponema pallidum
50
How many stages are involved in Neurosyphyllis
3
51
How is Neurosyphillis diagnosed
CSF lymphocyte increased
| Intrathecal antibody prduction
52
How is Neurosyphillis treated
High dose penicillin
53
What causes Poliomyelitis
Poliovirus 1,2 and 3
54
Describe the effects of Infection with polio irus
– infects anterior horn cells of lower motor neurones
• Asymmetric, flaccid paralysis, esp legs
• No sensory features
99% asymptomatic
55
Name important vaccines
Polio
Rabies
Tetanus
56
How is tetanus transmitted
Transmitted from bit or salivary contamination of open lesion
57
What are the consequences of a rabies infection
* Neurotropic - virus enters peripheral nerves and migrates to CNS
* Paraesthesiae at site of original lesion
* Ascending paralysis and encephalitis
58
How is Rabies Encephalitis diagnosed
PCR and Serology
59
In the UK Rabies pre-exposure is given to who
– bat handlers
– regular handlers of imported animals
– selected travellers to enzootic areas
60
Dsribe rabies post-exposure treatment
* Wash wound
* Give active rabies immunisation
* Give human rabies immunoglobulin (passive immunisation) if high risk
61
What organism causes Tetanus
* infection with Clostridium tetani
| * anaerobic Gram positive bacillus, spore forming
62
What is the effects of a tetanus infection
* toxin acts at neuro-muscular junction
* blocks inhibition of motor neurones
* rigidity and spasm (risus sardonicus)
63
How is Tetanus prevented
* Immunisation (toxoid)
* given combined with other antigens (DTaP)
* Penicillin and immunoglobulin for high risk wounds/patients
64
What is Botulism
Illness caused by Clostridium botulinum
– Anaerobic spore producing gram positive bacillus
– Neurotoxin
• Binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions
• Toxin binding blocks acetylcholine release
65
What are the modes of infection for Botulism
– Infantile (intestinal colonization)
– Food-borne (outbreaks)
– Wound: Almost exclusively injecting or “popping” drug users
Present in soil, dust and aquatic environments
66
Describe the clinical presentation of Botulism
```
– Incubation period 4-14 days
– Descending symmetrical flaccid paralysis
– Pure motor
– Respiratory failure
– Autonomic dysfunction
• Usually pupil dilation
```
67
How is Botulism diagnosed
– Nerve conduction studies
– Mouse neutralisation bioassay for toxin in blood
– Culture from debrided wound
68
How is Botulism treated
– Anti-toxin (A,B,E)
– Penicillin / Metronidazole (prolonged treatment)
– Radical wound debridement
69
What is post infective inflammatory syndromes
– Latent interval between the precipitating infection and onset of neurological symptoms
– Autoimmune
– Central nervous system
70
Name an example of post infective inflammatory syndromes
Acute disseminated encephalomyelitis (ADEM)
| Guillain Barre Syndrome (GBS)
71
How is Creutzfeldt-Jakob Disease (CJD) caused
• Transmissible Proteinaceous particle – Prion
72
What are the aetiology of CJD
```
– Sporadic CJD
– New variant CJD
– Familial CJD (10-15%)
– Acquired CJD (<5%)
• Cadeveric Growth Hormone
• Dura matter grafts
• Blood transfusion
```
73
Differential diagnosis for sporadic CJD
Alzheimer's disease
Subacute sclerosing panencephalitis (SSPE)
CNS vasculitis
Inflammatory encephalopathies
74
Prognosis of sporadic CJD
– Rapid progression
| – Death often within 6 months
75
New variant CJD cause
```
• Younger onset <40
• Linked to Bovine Spongiform Encephalopathy in Cattle
– Eating infected material
– Less cases than predicted
– No new cases last few years
– May be a genetic susceptibility
```
76
Investigations for CJD
MRI- Pulvinar sign
EEG
CSF
