Infections of the CNS Flashcards
A patient presents with acute headache and fever. What are your differential diagnoses?
- Meningitis
- Encephalitis
- Brain abscess
- URTI
- Tropical disease
- Vascular (SAH/venous sinus thrombosis)
- Autoimmune
What is the major difference in presentation between meningitis and encephalitis?
Encephalitis presents with cognitive changes, such as confusion and behavioural changes. Meningitis does not.
What are the signs and symptoms of meningitis?
- Stiff neck (kernig’s and brudinski’s)
- Photophobia
- Headache
- Fever
- Non-blanching rash
What is the significance of a non-blanching rash in meningitis?
It is a sign that the infection has spread to the blood (meningococcal septicaemia) and is a sign of SEPSIS
What are the causes of meningitis?
- Bacterial
- Viral
- Fungal (cryptococcus, pneuomcystus)
- Tuberculous
- Autoimmune
- Parasitic
- Malignant
What are the causes of encephalitis?
- VIRAL (eg HSV)
- Bacterial
- Parasitic (eg toxoplasmosis)
- Autoimmune (post infection such as measles, paraneoplastic)
What are the main bacterial pathogens for meningitis/encephalitis?
N.meningitidis (children, adolescents)
H.influenzae (children)
S.pneumonia (older adults)
Listeria monocytogenes (extremes of age/immunocompromised)
What are the signs and symptoms of encephalitis?
- Headache
- Drowsiness
- Confusion
- Focal neurology
- Previous cold sores/conjuncitivitis
What should bacterial meningitis be treated with and why?
Cephalosporins e.g. cefotaxime - they penetrate the BBB well
Amoxicillin (if risk of listeria)
IV steroids (unless severe sepsis)
ABC - oxygen, fluids etc
Why shouldn’t pregnant women eat soft cheese?
It contains Listeria, which is a bacterial pathogen that can cause encephalitis in the immunosuppressed
What investigations should be done for suspected meningoencephalitis?
Routine bloods Blood cultures Malaria film (if travel) HIV test Serum antigens/antibodies CT/MRI head Lumbar puncture Throat swab? ABG?
What are the symptoms of raised ICP?
- Headache when leaning forwards
- Drowsiness
- Vomiting
- Seizures
- Change in respiration
- Focal neurology or pupil changes
- Papillodema
SEND FOR URGENT CT
What does raised ICP look like on a CT scan?
- Increased ventricular space
- Disfiguration of sulci and gyri
Why dont we use Tazocin in CNS infections?
It, like many other penicillins, does not penetrate the BBB
What is neurocysticercosis?
Tapeworm invasion of the brain
