Infections of the NS Flashcards
What is the aetiology of Meningitis?
- Infective: bacterial, viral, fungal
- Inflammatory: sarcoidosis
- Drug-induced: NSAIDs, IVIG
- Malignant: metastatic (haematological ie. leukaemia, lymphoma, myeloma)
What are the risk factors for Meningitis?
- Age: infants(<2), adolescence and early adulthood, older age (>65)
- Skipping vaccinations: hasn’t completed the recommended childhood or adult vaccination schedule
- Living in a community setting: ie. uni dorms, military barracks, boarding schools
- Pregnancy: (Listeriosis)
- Immunocompromised: HIV/AIDs, alcoholism, diabetes, immunosuppressant drugs
What are the clinical features of Meningitis?
-> Classic Triad:
1 - Fever (>38ºC)
2 - Neck stiffness (-> passively bend pt’s neck forwards)
3 - Altered mental status
- > Present w a short hx. of progressive headache associated with:
- Fever (>38ºC)
- Meningism (neck stiffness, photophobia, N+V)
- > Cerebral dysfunction
- confusion, delirium, declining conscious level
- GCS <14
- > Petechial skin rash
- Tumbler test = NON-BLANCHING)
- hallmark of meningococcal meningitis
- > Additional:
- CN palsy
- Seizures
- Focal Neurological deficits
What are the investigations for Meningitis?
- Priority = exclude (and treat) infection*
- Blood cultures: ?bacteraemia
- Lumbar puncture: CSF culture/microscopy
- No need for CT imaging if no contra-indications to LP
What is the acute treatment (and contacts) of Meningitis?
- IV Abx (cefotaxime)
- > change once blood cultures come back
- steroids
What is the aetiology of Encephalitis?
- Infective: viral (HSV)
- Limbic Encephalitis: auto-immune (anti-VGKC, anti-NMDA receptor, ADEM)
- Metabolic: hepatic, uraemic, hyperglycaemic
- Malignant: metastatic, paraneoplastic
What are the clinical features of Encephalitis?
- Flu-like prodrome (4-10 days)
- > slower onset than Meningitis
- Progressive headache, associated with fever (+/- meningism)
- Progressive cerebral dysfunction
- > confusion
- > abnormal behaviour
- > memory disturbance
- > depressed conscious level
- Seizures
- > think of viral encephalitis if someone is getting recurrent seizures w/o getting better from them
- Focal symptoms/signs
- > classically temporal lobe
What are the investigations of Encephalitis?
- priority = exclude (+ treat) infection*
- Blood cultures (unlikely to see anything)
- Imaging: contrast-enhanced CT
- Lumbar puncture: PCR of CSF for viral DNA (HSV)
- EEG
What is the treatment of Encephalitis?
- Aciclovir on clinical suspicion
most likely due to HSV
What is the aetiology of Cerebral Abscesses/Empyema?
- Penetrating head injury
- Spread from adjacent infection:
- > ie. dental, sinusitis, otitis media
- Blood-borne infection:
- > ie. Bacterial Endocarditis
- Neurosurgical procedure
What are the clinical features of Cerebral Abscesses/Empyema?
- Focal symptoms/signs
- > seizures, dysphasia, hemiparesis
- Fever, headache
- Signs of raised ICP
- > papilloedema, false localising signs, depressed conscious level
- Meningism (esp. w Empyema)
- Features of underlying source
- > ie. dental, sinus or ear infection
What are the investigations of Cerebral Abscesses/Empyema?
- often the diagnosis is made on CT imaging, rather than clinical presentation*
- Imaging: CT, MRI (to clarify) -> “ring-enhancing” lesion
- Investigate source
- Blood cultures
- Biopsy (CT-guided aspiration of pus)
What is the treatment of Cerebral Abscesses?
- Surgical drainage
- IV Ceftriaxone (or penicillin) to cover Streps
- IV Metronidazole for Anaerobes
- high doses required for penetration
- nb. culture and sensitivity tests on aspirate to guide treatment
What do the CSF Lumbar Puncture findings look like for Bacterial Meningitis?
- Increased opening pressure (manometer)
- High WCC: mainly neutrophils
- Reduced Glucose
- High Protein
What do the CSF Lumbar Puncture findings look like for Viral Meningitis + Encephalitis?
- Normal/Increased opening pressure (manometer)
- High WCC: mainly lymphocytes
- Normal Glucose: 60% of Blood glucose
- Slightly elevated Protein
What are the different types of immunisations available for preventing Neurological disease?
- Polio vaccine -> IPV (injected polio vaccine)
- Rabies -> (pre- + post-exposure prevention)
- > also passive immunisation of human rabies Ig (if high risk post-exposure)
- Tetanus -> toxoid (DTaP vaccine: combined w other antigens!)
What are the 2 different types of autoimmune Encephalitis?
- anti-VGKC (“limbic” encephalitis)
- > associated with the Temporal lobe - amnesia (unable to retain new memories)
- > frequent seizures
- > altered mental state
- anti-NMDA receptor
- > similar to viral encephalitis (flu-like prodrome)
- > progression to a movement disorder and coma
What are the 2 different types of autoimmune Encephalitis?
- anti-VGKC (“limbic” encephalitis)
- > associated with the Temporal lobe - amnesia (unable to retain new memories)
- > frequent seizures
- > altered mental state
- anti-NMDA receptor
- > similar to viral encephalitis (flu-like prodrome)
- > progression to a movement disorder and coma
Why is it important to take a travel history when a pt. presents with suspected Encephalitis?
- due to the possibility of a diagnosis of Arbovirus Encephalitides which is related to travel
- transmitted to man by vector (mosquito or tick) from non human host
- immunisation is important!!
- ie. West Nile virus, St Louis Encephalitis, Japanese B Encephalitis, etc
(nb. generally related to where first described, NOT to current geographical distribution!)
What is the differential diagnosis of a Cerebral Abscess?
- Any focal lesion, most commonly tumour
- Subdural haematoma
What is the differential diagnosis of a Cerebral Abscess?
- Any focal lesion, most commonly tumour
- Subdural haematoma
What is the microbiology of a Cerebral Abscess?
- Often mixture of organisms present (polymicrobial)
- Streptococci = most common!!
- > Strep Milleri group (!!)
- anaerobes in 40-100% of cases
- > bacteroides, prevotella
What is the microbiology of a Cerebral Abscess?
- Often mixture of organisms present (polymicrobial)
- Streptococci = most common!!
- > Strep Milleri group (!!)
- anaerobes in 40-100% of cases
- > bacteroides, prevotella
Which brain infections can you get as a complication in HIV with low CD4+ counts?
- Cryptococcus Neoformans
- Toxoplasma Gondii
- Progressive Multifocal Leukoencephalopathy (PML)
- Cytomegalovirus (CMV)
- HIV-Encephalopathy (HIV-associated Dementia)
Which investigations would you do for brain infections in HIV with low CD4+ counts?
- Cryptococcal Antigen
- Toxoplasmosis serology
- CMV PCR
- HIV PCR -> high viral load = high risk for complications
Which investigations would you do for brain infections in HIV with low CD4+ counts?
- Cryptococcal Antigen
- Toxoplasmosis serology
- CMV PCR
- HIV PCR -> high viral load = high risk for complications
What are the indications for CT prior to a Lumbar puncture?
- Focal neurological deficit, not including CN palsies
- New-onset seizures
- Papilloedema
- Abnormal level of consciousness, interfering with proper neurological examination (GCS <10)
- Severe immunocompromised state
- Focal symptoms/signs: suggests a focal brain mass*
- Reduced conscious level: suggests raised ICP*
What are the indications for CT prior to a Lumbar puncture?
- Focal neurological deficit, not including CN palsies
- New-onset seizures
- Papilloedema
- Abnormal level of consciousness, interfering with proper neurological examination (GCS <10)
- Severe immunocompromised state ie. HIV
- Focal symptoms/signs: suggests a focal brain mass*
- Reduced conscious level: suggests raised ICP*
What are the different microbes which can cause neurological diseases?
+ their treatments?
- Borrelia Burgdoferi: Lyme Disease
- > IV ceftriazone, oral doxycycline
- Treponema Pallidum: Neurosyphilis
- > high-dose Penicillin
- Poliovirus: Poliomyelitis
- > Immunisation: IPV (injected vaccine)
- Rabies virus: Rabies
- > pre-exposure: immunisation
- > post-exposure: wash wound, give active rabies immunisation, give human rabies Ig (passive immunisation) if high risk
- Clostridium Tetani: Tetanus
- > immunisation: DTaP vaccine (w other antigens)
- Clostridium Botulinum: Botulism
- > ant
What are the different microbes which can cause neurological diseases?
+ their treatments?
- Borrelia Burgdoferi: Lyme Disease
- > IV ceftriazone, oral doxycycline
- Treponema Pallidum: Neurosyphilis
- > high-dose Penicillin
- Poliovirus: Poliomyelitis
- > Immunisation: IPV (injected vaccine)
- Rabies virus: Rabies
- > pre-exposure: immunisation
- > post-exposure: wash wound, give active rabies immunisation, give human rabies Ig (passive immunisation) if high risk
- Clostridium Tetani: Tetanus
- > immunisation: DTaP vaccine (w other antigens)
- Clostridium Botulinum: Botulism
- > anti-toxin (A, B, E)
- > penicillin/metronidazole (if due to wound)
- > radical wound debridement
