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
