CNS & Meningitis Flashcards
What are the causative agents for meningitis?
NM Strep pneumo H influenzae TB Various viruses Cryptococcus neoformans
What are the causative agents of encephalitis?
Rabies virus Arbovirus Trypanosoma species Prions Amoeba
What are the causative agents of myelitis?
Poliovirus
What are the causative agents of neurotoxin?
Clostridium tetani
Clostridium botulinum
What is meningitis?
Inflammatory process of meninges and CSF
What is meningoencephalitis?
Inflammation of meninges and brain parenchyma
What is the neurological sequlae of meningitis?
Direct bacterial toxicity (endotoxins from gram neg, E. coli, NM, pos produce exotoxinss in ecellular space, s aureus
Indirect inflammatory process and cytokines release and oedema
Shock, seizures, and cerebral hypoperfusion
What is the mortality rate of meningitis?
10%, 5% survivors have neurological sequlae, sensineural deafness
What is the classification of meningitis?
Acute- bacterial
Chronic- TB, spirochetes (syphilus), Cryptococcus
Aseptic- acute viral
What are the causes of acute meningitis?
NM
Strep pneumo
H influenzae type B
What are the less common causes of acute meningitis?
Listeria - alcoholics with diabetes, soft cheese
Group B strep neonates, vaginal colonisation
E. coli neonates
What about NM?
Infectious cause of childhood death in all countries
Person to person, symptomatic carriers
Pathogenic strains found in 1% of carriers
Nasopharyngeal mucosa in susceptible individual
Infections in less than 10 days
What ins the dermatological presentation of meningococcal meningitis?
Nonblanching purpuric rash 80%
Maculopapular rash 13%
No rash 7%
Vaccines re: NM?
Present- type C
Absent- A, Y, W135, and B which is common in UK (antigenic shift)
What are the clinical outcomes of NM?
Meningitis- 50%
Septicaemia- 7-10%
Both- 40%
Tx is different for hypotension and raised ICP
What happens if you give steroids in septicaemia?
You suppress their immunogenicity which is keeping them alive
If meningitis- oedema, vasodilation is harmful, steroids help.
What CT signs can be seen with chronic meningitis?
Enhancement in the basal cistern and meninges with dilation of ventricles
What about TB chronic meningitis?
Incidence 544 per 100000
Immunosuppressed
Meninges, basal cisterns.
Granulomas, absecces, cerebritis
How do you manage chronic meningitis?
DO NOT manage chronic meningitis- refer to specialist
Supportive neurosurgeons
Radiologists
Pharmacists
What about aseptic meningitis?
Most common infection of CNS
Non specific rash can accompany symptoms
Coxsackie group B and echovirus 80-90 % cases in which a causative organism is identified
What are the viral causes of CNS infections in children, infants, young adults?
Mumps Measles Varicella zoster Epstein Barr, cytomegalovirus Other- myxovirus, paramyxovirus, adenovirus
What are the viral causes of CNS infections in adults?
Enterovirus- coxsackie, echo, polio. All ages.
Herpes simplex 1-2 high dose IV acyclovir won’t alter course. Crystallises renal tract.
Summer autumn.
What is the presentation of encephalitis?
Headache, neck stiffness, confusion
What is the transmission for encephalitis?
Person to person, or vectors Mosquitoes Lice Ticks Various viridae from Togavirus, Flavivirus, Bunyavirus
What should you do for herpes simplex encephalitis?
High dose IV acyclovir
Which virus is becoming leading cause of viral encephalitis?
West Nile virus
Birds migrate to New York and bring mosquitoes
Italy
What are the other infectious causes of encephalitis?
Bacterial- listeria
Amoebic- naegleria fowleri, habitat warm water
acanthamoeba species, balamuthia mandrillaris- brain abcess, aseptic or chronic meningitis. South west England, Bath.
What is a non bacterial, non viral cause of encephalitis?
Toxoplasmosis, obligate intracellular protozoal parasite
Oral, transplacental, organ transplantation
Immunocompromised
Grey and white matter of brain, retina, alveolar, heart, skeletal muscle
Brain abcess pathophysiology?
Otitis media,mastoiditis, parasinuses, endocarditis, haematology
What is the microbiology of brain abcess?
Streptococci, staph, gram neg, TB, fungi, parasite, actinomycetes, nocardia species
What is the common form of vertebral infection?
(Htlv1- transverse myelitis, polio)
Pyogenic vertebral osteomyelitis, IVDU
Direct open spinal trauma, infections in adjacent structure, haematogenous spread
Left untreated, neurological deficits, spinal deformity, death.
What are the risk factors for spinal infections?
Advanced age IVDU Long term systemic steroids DM Organ transplantation Malnutrition Cancer
What imaging is the best?
Contrast MRI - detecting parenchymal abnormalities such as abcess and infections
CSF sample, brain tissue.
What other samples can you get for meningitis case?
Blood culture
Blood for PCR
Throat swab
What is the microscopy for purulent meningitis?
Turbid, 100-200 polymorphs, high protein, low glucose
What is the microscopy for aseptic meningitis?
Slightly turbid, lymphocytes, high protein, normal glucose
Partially treated bacterial meningitis
What is the microscopy for TB meningitis?
Slightly turbid, lymphocytes, high protein, low glucose
What is the link with HIV and cryptococcus meningitis?
Immunocompromised, opportunitistic infection
Indian ink stain
What are the limitations of diagnostics?
MRI oedema pattern cannot be differentiated from tumour/stroke/vasculitis Early infection and serological tests Amount of CSF PCR techniques Methods to detect amoebic infections Availability of good lab technique
What is the management approach?
Hx, empirical abx, LP
CSF analysis
CSF culture
What is the therapy for meningitis?
Ceftriaxone 2g IV bd
If >50 years or immunocompromised add amoxicillin 2g IV 4 hourly
What is the therapy for meningitis- encephalitis?
Aciclovir 10mg/kg IV tds
Ceftriaxone 2g IV bd
If more than 50 years or immunocompromised add amoxicillin 2g IV 4 hourly, covers listeria
What are the 4 routes of entry?
Haematogenous spread
Direct implantation via instrumentation
Local extension secondary to established infections
PNS to CNS- viruses
