CNS infections Flashcards
8 opportunistic CNS infections
1) HIV encephalopathy
2) CMV encephalitis
3) Aspergillosis
4) Primary CNS lymphoma/PTLD - post transplant lymphoproliferative disease
5) Aspergillosis
6) Cerebral toxoplasmosis
7) Progressive multifocal leukoencephalopathy = JC virus
8) Nocardia
8 other CNS infections
1) TB meningitis
2) Cerebral malaria
3) Neurosyphilis
4) Rabies
5) Acute poliomyelitis
6) Tetanus
7) GBS - group b strep
8) ADEM - acute disseminated encephalomyelitis - inflammatory flare up of CNS white matter causing demyelination - like MS but one flare up as opposed to multiple and can occur in children and lead to coma/death
3 routes of entry for CNS infection
Blood-borne (BBB or Blood-CSF barrier)
Neural - replication at peripheral site and then transportation up the axons
Direct invasion
What position and where do you do lumbar puncture?
Left lateral decubitus position with knees drawn up and neck flexed
In between L3 and L4 (level of iliac crest) because termination of spinal cord
What is meningitis?
Inflammation of the meninges - abnormal number of WBC’s in the CSF
Hallmarks of meningitis
Meningism
- Headache, N and V, neck and back stiffness and photophobia
If fever too and acute symptoms presentation then query infectious meningitis
Features of bacterial meningitis
Life threatening, poor prognosis, fever, altered consciousness, very unwell
Common bacteria in bacterial meningitis x4
Neisseria meningitidis (meningococcus)
Haemophilus influenzae
Strep pneumoniae (pneumococcus)
Listeria monocytogenes
Common bacteria in baby meningitis x 3
Group B strep (strep agalactiae),
E.coli
Listeria monocytogenes (typically affects children, elderly, pregnant women and immunocompromised adults)
Immunosuppressed meningitis infective agents x2
Listeria monocytogenes
Cryptococcus neoformans
CSF in bacterial meningitis x4
Raised protein (>1g - 0.4g = normal)
Raised CSF pressure
Clear colourless
White cell count v.raised - predominantly neutrophils
Meningococcal meningitis features
Young children and susceptible adolescents
Abrupt onset
Often accompanied by haemorrhagic, non-blanching skin rash of meningococcal septicaemia
Treatment of bacterial meningitis
Cefotaxime + ampicillin if >55 years
Viral meningitis features
Less severe, typically benign and self-limiting
Headache, photophobia and vomiting
But no LOC and patient appears generally well
Mild pleocytosis
Eg of infective viruses in viral meningitis x4
Enteroviruses (polio)
Mumps virus (50% no parotid swelling, can present before, during or after swelling)
HSV
HIV seroconversion illness
Focal neurological signs with meningitis
Indicates TB or abscess
What is encephalitis?
Inflammation of brain parenchyma - usually viral
Symptoms of encephalitis x5
Fever and meningism can occur
Behaviour and personality change is a common early manifestation
Progresses to reduced level of consciousness and coma
Seizures and focal neurological deficits are common
Many cause a mild self-limiting disease with headache and drowsiness
Causes of viral encephalitis in UK x5
HSV (commonest cause), VZV, other Herpes virus, Mumps, Adenovirus
Causes of viral encephalitis outside of UK x4
Japanese Encephalitis, West Nile Virus, Tick-borne encephalitis, Rabies
Which lobe often affected in HSV encephalitis?
Temporal Lobe - will show up on EEG and MRI
Treatment of viral encephalitis
Urgent aciclovir
CSF in encephalitis
White cells and protein raised
Clear and colourless
CSF pressure normal or slightly raised
Mortality of HSV encephalitis and morbidity
80% without treatment and 30% with
Memory loss, personality change and epilepsy following infection
Post-infectious encephalomyelitis - what is it?
Acute disseminated encephalomyelitis often follows many infections
Rarely 1-2 weeks after immunisation
Monophasic illness
Caused by immune mediated host response to infection
Epidemiology of post-infectious encephalomyelitis
Typically young children and adults
Treatment of post-infectious encephalomyelitis
Steroids and anticonvulsants
Autoimmune encephalitis presentation
Limbic encephalitis, psychiatric disturbances and seizures
3 egs of autoimmune encephalitis
1) Paraneoplastic limbic encephalitis
- typically with small cell lung cancer and testicular tumours
- antibodies in 60% of cases
- preceeds cancer diagnosis
2) Voltage-gated potassium channel limbic encephalitis
- older patients >50
- get faciobrachial dystonic seizures and neuromyotonia
3) Anti-NMDA
- younger women
- often ovarian teratomas
Treatment of autoimmune encephalitis
IV immunoglobulin or plasma exchange
Followed by steroids
What is a brain abscess?
Focal encapsulated area of infection
Stages of a brain abscess?
Passes through them over about 2 weeks
Localised suppurative cerebritis (brain infection with suppuration)
To complete encapsulation
What causes brain abscesses to develop?
Conditions that cause tissue necrosis with simultaneous infection by an appropriate organism - leads infection to reach brain by local spread or bloodstream
Disease states which predispose to abscess
Chronic Lung Infection
Congenital Heart Disease (esp R-L shunts)
Bacterial Endocarditis
Infections in immunocompromised
Bacterial usually causative of abscess
Streptococcus
Bacteriodes
Enterobacteria
Staph A
What infective agents are more common in causing abscesses in immunosuppressed?
Fungi and protozoa
eg. toxoplasma, candida, listeria
Presentation of abscess x 5
1) Short 1 month history and progressive
2) Signs of SOL and raised ICP
- Headache
- Vomiting
- Deteriorating consciousness
- Papilloedema
3) Focal features
- Seizures
- Hemiparesis
- Dysphasia
- Visual field defects
4) Signs of systemic infection
- Fever
- Malaise
OR
5) Signs of focal infection
- Ear ache
- Cough
Signs on investigation with an abscess
CT or MRI - ring of enhancement - usually spherical - surrounding area of oedema
May be ventricular compression and midline shift (lumbar puncture contraindicated)
Look for primary cause of infection
Treatment of abscess
1) Antibiotics
2) Surgical drainage or excision
3) Treat raised ICP and seizures
4) Treat source of infection
Prognosis of abscess
Mortality has fallen (5-15%)
Can have neurological deficits, seizures, hemiparesis, speech and language disorders (all less than 50%)
What is neurosyphilis caused by?
Spirochaete - Treponema pallidum
When does neurological involvement occur in syphilis?
3rd stage of disease - typically many years later - in less than 10% of untreated cases
Often treated without knowing by penicillin for other infections
Treatment of neurosyphilis
Parenteral benzylpenicillin for 2-3weeks
Neurological disease can be arrested but not reversed
Adverse effect associated with neurosyphilis treatment
Allergic reaction - Jarisch-Herxheimer - by endotoxin produced by spirochaete when treated with antibiotics
Therefore penicillin often given with steroids
The different presentations of neurosyphilis x 3
1) Meningovascular syphilis
- subacute meningitis with a gumma and paraparesis
2) Tabes Dorsalis
- demyelination in dorsal roots
- lightening pains usually in lower limb, chest or abdomen
- visceral crises
- sensory ataxia
- Neuropathic joints
- Argyll robertson pupils
- Ptosis and optic atrophy
3) General paralysis of insane
- psychiatric abnormality and weakness
- dementia, paralysis
What are neuropathic joints?
Charcots joints
Painless joint damage
What are argyll robertson pupils?
Small, irregularly shaped pupils
Do not react to light
But do accommodate
Occur in neurosyphilis but can also occur in diabetic retinopathy
Occurrence of neurological symptoms in HIV patients - 3 features
80% of patients get them
Either directly or via opportunistic infections
Can be CNS or PNS or both
3 types of Primary HIV infection neurological abnormalities
HIV encephalopathy (AIDS dementia)
HIV myelopathy
Acute atypical meningitis - self-limiting and occurs at seroconversion
Opportunistic infections causing neurological deficits in HIV
CNS toxoplasmosis
Cryptococcal meningitis
JC virus
CMV, HSV2, VZV, Candida, Aspergillus
3 other neurological deficits in HIV
Neoplasia - CNS lymphoma
Peripheral neuropathy
Myopathy
Tetanus, Rabies, Malaria, TB
Can all cause neurological deficits - more details in notes
