Infection of the CNS Flashcards
What is meningitis and the potential causes?
- Inflammation of the meninges (if inflammation of the cerebrum too then its meningo-encephalitis)
- Bacterial causes: Meningococcus, pneumococcus, Listeria, TB, Lyme, syphilis
- Viral causes: HSV, VZV, enterovirus, HIV or mumps
What are the signs and symptoms of meningitis?
- Headache, neck stiffness, reduced GCS or fever.
- Confusion which indicates encephalitis as well as meningitis.
- Rash which can be purpuric +/- petechial, this indicates meingococcal
What are the risk factors for pneumococcal and listeria
Pneumococcal - Middle ear disease, head injury, neurosurgery, alcohol and immunosupression.
Listeria - Immunosupression and pregnancy
What are a specific features associated with pneumococcal meningitis?
- Focal signs, seziures and VIII palsy.
- May have signs of pneumococcal infection elsewhere such as endocarditis
- Pneumococcal meningitis has a higher mortality than meningococcal
What are the investigations for suspected meningitis?
- History and examination (examine throat and examine LNs)
- Blood cultures including PCR.
- Throat culture and viral gargle,
- FBC, UEs, LFTs and CRP
- Lumbar puncture including cell count, gram stain, culture and PCR, protein and glucose and viral PCR
When should you do a CT scan before an LP and what must you give pre-CT
Must give antibiotics otherwise the delay in antibiotics is bad.
CT patients before an P if they have:
- GCS < 12,
- CNS signs,
- Papilloedema,
- Immunocompromised,
- Seziures
When is a LP contraindicated?
- Brain shift,
- Rapid GCS reduction,
- Resp/cardiac compromise,
- Rapidly evolving rash,
- Infection at LP sight,
- Coagulopathy
What are the differences in a LP in a bacterial and viral infection
Bacterial - Raised proteins, reduced glucose and neutrophils.
Viral - Raised protein, normal glucose and lymphocytes
What is the treatment for suspected bacterial meningitis?
- Do not delay starting IV antibiotics,
- Start IV ceftriaxone 2g 12 hourly,
- If you suspect listeria then give amoxicillin 2g 4 hourly WITH the ceftriaxone
- If you suspect pneumococcal then add steroids
- If in primary care then give IM benzylpenicillin
What is the definitive antibiotic therapy for the different bacterial meningitis?
Meningococcal - IV ceftriaxone/benzyl penicillin for 5 days.
Pneumococcal - IV ceftriaxone/benzyl penicillin for 10-14 days.
Listeria - IV amocixillin for 21 days
What are the primary and secondary preventions for bacterial meningitis
- Immunisation for haemophilus influenza B and pneumococcus and meningococcal.
- Patients who are asplenia, complement deficient require men and pneumo boosters
- Patients which cochlear implants require pneumo boosters
- Chemoprophylaxis for close contacts (ciprofloxacin)
What is the management of viral meningitis
- Done by exclusion of BM
- Commonly caused by enterovirus, HSV, VZV, HIV seroconversion.
- Mainly supportive care and only consider aciclovir in immunocompromised patients/
What are the features of encephalitis, the investigations and treatment?
- Presents with confusion, fever +/- seizures. Most common is HSV encephalitis
- Investigations are LP which shows lymphocytic CSF, temporal lobe changes on EEG and MRI scanning can be done.
- Treat with IV aciclovir for 2-3 weeks
Describe features of intra-cerebral TB
- Can occur once started TB treatment.
- Commonly presents with cranial nerve lesions.
- Treat with rifampicin, isoniazid, pyrazinamide and ethambutol
Explain the presentation of HIV brain disease
Occurs due to untreated infections and marked immunideficiency. It can present with:
- Encephalitis, dementia, neuro-syphilis and opportunistic infections such as TB, Cryptococcus, toxoplasmosis or JCV
