CNS infection Flashcards
Describe the clinical features of meningitis?
Meningisms aka photophobia, neck stiffness, headache.
Patient may also have pyrexia, malaise, vomiting and rigors.
Describe the some of the complications of meningitis and the signs of them?
Progressive drowsiness, lateralising signs, cranial nerve lesions and seizures are suggestive of complications such as:
- venous sinus thrombosis
- cerebral oedema
- hydrocephalus
- abscess
- encephalitis.
Petechial rash: meningococcal septacaemia, complications of this include gangrene and death.
What are the long term complications of meningitis?
Deafness
Cranial nerve dysfunction
Seizures
Intellectual deficits
Cortical blindness
What are the common bacterial and viral organisms which cause meningitis in adults?
Bacterial:
- N. meningitidis
- Strep pneumoniae
- HIB
- Gram-negative bacilli
- Staph and Strep
- Legionella
- TB
Viral:
- Echovirus and Coxsackievirus (not severe clinically)
- Mumps/measles (in unvaccinated)
- HSV (severe)
Describe how you would investigate a patient with suspected meningitis?
Routine bloods:
FBC/LFTs/UE’s/CRP/Blood culture
Lumbar puncture if no signs of raised ICP*
Samples of CSF are usually sent for:
- Gram stain
- Ziehl-Neelsen stain (TB)
- Cytology/glucose/protein
- Culture
- Rapid antigen screen or PCR
*Focal neurology, seizures, reduced consciousness, very severe headache
What is an appropriate antibiotic regimen in bacterial meningitis in an adult?
Empirical IV ceftriaxone should be used in all people aged greater than 3 months until the organism has been identified. A 7 day course is the minimum used.
If younger than 3 months give ceftriaxone and amoxicillin
What are the risk factors which predispose patients to Tb or fungal meningitis?
Main risk factor is immunosupression.
Other risk factors for Tb meningitis is living in endemic areas.
Likely organism in fungal meningitis is cryptococcus.
Describe the typical appearance of CSF in bacterial meningitis
Bacterial:
Appearance: Cloudy
Cells: V.high mostly neutrophils
Protein: V high
Glucose: low
Typical appearance of CSF in Viral Meningitis
Viral:
Clear
Cells: High Lymphocytes (earlier will be neutrophils)
Protein: Low
Glucose: N
Typical appearance of CSF in fungal meningitis
Fungal:
Cloudy
Cells: High IgG levels
Protein: Normal or slightly raised
Glucose: Normal or slightly low
Typical appearance of CSF in TB meningitis
TB:
Cloudy
Cells: High Lymphocytes
Protein: Low or N
Glucose: V low
What is granulomatous meningitis?
A granulomatous inflammation of the meninges associated with Tb, syphyllis and fungal infections.
What are the main clinical features of encephalitis?
Triad of main symptoms:
- Fever
- Headache
- Altered mental state
Other symptoms may include:
- Meningisms
- Vomiting
- Focal neurology
- Seizures
- Psychiatric disturbances
Describe the common causes of encephalitis?
Viral illness
It is usually caused by HSV infection. Can also be caused by:
- CMV
- Adenovirus
- Influenza
Or as an opportunistic infection in immunosuppressed patients:
-Toxoplasmotic meningoencephalitis
Describe how you would investigate a patient with suspecyed encephalitis?
Routine bloods:
FBC/UE’s/LFTs/CRP/Blood culture
Lumbar puncture: Send CSF for viral PCR for HSV, VZV and enteroviruses
CT scan: Used to help rule out raised ICP before a lumbar puncture. Rules out SOL.
