CP Central Nervous systems Flashcards
Define = Meningitis
Inflammation of meninges
Define = Encephalitis
inflammation of brain
Define = Meningo-encephalitis
inflammation of brain and meninges
Aseptic Meningitis
- provide clinical picture
- what is most common cause
- other causes x7
White cell count >5x106/L (5/mm3) in cerebrospinal fluid (CSF) Negative bacterial culture of the CSF Viruses are the commonest cause, others include: Partially treated bacterial meningitis Listeria TB Syphilis Malignancy, Autoimmune conditions, Drugs
What is the basic infectious particle of a virus
viron
what do viral proteins form
capsid, membrane projections
what do viral enzymes do
used for replicating genetic material, influencing transcription and protein modification
Epidemiology of viral meningitis
COMMON - children neonates
5-15 cases per 100,000
Aetiology of viral meningitis
Enterovirus - commonest cause Echoviruses Coxsackie viruses Parecho viruses Enteroviruses 70 and 71 Poliovirus Herpes viruses Herpes Simplex Virus 2 (HSV 2) >> HSV 1 Varicella Zoster Virus (VZV) Cytomegalovirus (CMV), Epstein Barr Virus (EBV) HHV6, HHV7 Arboviruses (e.g. Japanese Encephalitis virus) Mumps Virus HIV Adenovirus Measles Influenza Parainfluenza type 3 Lymphocytic choriomeningitis virus (LCMV)
What must you always check if you think the patient has viral meningitis
travel history, sexual history, and
IMMUNOCOMPROMISED
Pathogenesis of viral meningitis
colonization of mucosal surfaces
invades epithelial surface
replicated in cells
desseminates and invades CNS - via cerebral micro vascular endothelial cells, choroid plexus epithelium, olfactory nerve
How does the enterovirus enter the CNS
blood stream (haematogenous spread)
How does HSV or VZV enter CNS in viral meningitis
traveling up peripheral nerves (neurotropically)
clinical presentation of viral meningitis
Fever,
Meningism (headache, stiffneck, photophobia)
Children = bulging anterior fontanelle
What is Kernig’s Sign
With hip and knee flexed to 90o, the knee cannot be extended due to pain/stiffness in the hamstrings
What is Brudzinski’s sign
Flexing the neck causes the hips and knees to flex
What is nuchal rigidity
Resistance to flexion of the neck
What investigations for viral meningitis
Bloods - FBC, U&E, clotting, culture
CT head (do 1st)
Lumbar puncture - ASAP
Viral PCR - gold standard
CSF findings viral meningitis
White cell count
Pleocytosis = white cells in CSF
Lymphocytic, usually
CSF findings Bacterial meningitis
High opening pressure WBC - 100-20,000 v high high protien high glucose gram stain 60-90% +ve
Treatment
IV antibiotics cefotaxime if bacterial HSV and VZV = aciclovir supportive therapy NOTIFY PUBLIC HEATH
Enteroviral Meningitis
COMMONEST UK
fever, vom, anorexia, rash, URT symptoms,
No specific treatment
Full recovery
HSV - Herpes Simplex Virus 1
causes/
Cold Sores and viral encephalitis
HSV2 - Herpes simplex virus 2 causes
genital herpes, meningitis
2nd common cause
Mollarets meningitis - recurrent aseptic meningitis
VZV - varicella zoster virus
causes
Chickenpox, shingles
Meningitis RARE but possible
Aciclovir may be useful
normal recovery expected
Mumps meningitis
10-30% mumps cases
CNS symptoms 5 days post parotisis
No specific treatment
preventable with vaccination
HIV and meningitis
can occur as part of primary infection
fever, lymphadenopathy, pharyngitis, rash
IMPORTANT TO DIAGNOSE
Viral Encephalitis
Main causes
others
90% Herpes Simplex Virus1 Other viruses causes: VZV, EBV, CMV Adenovirus Measles Mumps Enteroviruses (including polio) Arboviruses (e.g. West Nile, Japanese B, St Louis, Eastern and Western Equine Encephalitis) Influenza Rubella HIV Rabies Other causes: Bacteria (e.g. Strep pneumoniae, Neisseria meningitidis, TB) Malignancy (paraneoplastic) Autoimmune Acute disseminated encephalomyopathy (ADEM) Other immune-mediated
what percentage of viral encephalitis are unknown aetiology
37%
clinical presentation of viral encephalitis
Altered mental state confusion --> coma fever, headache, meningism Focal neurology seizures weakness, dysphasia, cranial nerve palsy, ataxia
What should patient be started ON for viral encephalitis
IV aciclovir
if ANY change in mental state even if not 100% sure encephalitis
Viral encephalitis investigations
Bloods - FBC, U&E, CRP, clotting, serology
CT
LP - microscopy, culture and sensitivity, protien and glucose, viral PCR
MRI - looking for HSV
EEG - 75% in HSV encephalitis have abnormal temporal lobe activity
Treatment for Viral encephalitis
HIGH dose IV aciclovir
14-21 days
HSE epidemiology
rare
high risk 50 yo
HSE pathogenesis
Direct transmission of virus via neural or olfactory pathway OR Reactivation in trigeminal ganglia acute focal necrotising encephalitis inflammation of brain
outcome HSE
untreated - 70% dead
survivors - paralysis, speech lose, personality change
BEST - aciclovir within 4 days of symptoms
Acute disseminated encephalomyelopathy (ADEM
immune mediated CNS demyelination,
clinical findings = encephalitis
CSF findings - Viral meningitis
Treatment - steriods
What are the different types of primary bacterial infections of the CNS
Meningitis Encephalitis Ventriculitis Brain Abscess Ventriculoperitoneal shunt and external ventricular drain infection subdural empyema eye infections
What is a brain abscess
focal suppurative process within the brain parenchyma (pus in the substance of the brain
What causes brain abscesses
often polymicrobial 60-70% Streptococci "milleri" 10-15% Staph aureus common post trauma Anaerobes Gram -ve enteric bacteria fungi, TB, toxoplasma gondii, nocardia, actinomyces
4 clinical settings of brain abscess pathogenesis
- Direct Spread from contiguous suppurative focus
- haematogenous spread from distant focus
- trauma
- cryptogenic - no focus
Clinical presentation of brain abscess
headache - COMMON
focal neurological deficit 30-50%
confusion
fever
Management of brain abscess
Drainage = gold standard
why should brain abscesses be drained
1 - reduce intercranial pressure 2 confirm diagnosis 3 obtain pus for microbiological investigation 4 enhance efficacy of antibiotics 5 avoid infection spread to ventricles
Antibiotics treatment for brain abscess?
ampicillin penicillin cefuroxime cefotaxina ceftazidime metronidazole Challenge penetration of drugs into CSF blood barrier and blood brain barrier
What empirical treatment for a
ODONTOGENIC abscess
IV cefotaxime 2g 6hourly
IV metronidazole 500mg 8hourly
Empirical treatment plan for OTOGENIC abscess
IV benzyl penicillin 2.4g 6 hourly
IV ceftazidime 2g 8hourly
IV metronidazole 500g 8hourly
possible complications for brain abscess
rained intracranial pressure
mass effect
cloning
rupture into ventricles causing ventriculitis
Subdural empyema
- define
- causes
- pathogenesis
1) Infection between dura and arachnoid mata
2) causes often polymicrobial
anaerobes, streptococci, gram -ve, strep pneumoniae, haemophilus influenzae, staph aureus
3) spread infection from sinuses 50-80%, middle ear and mastoid 10-20%, distant site 5%, can be post trauma or surgery
Subdural empyema
- presentation
- management
1) headache, fever, focal neurological deficit, confusion, seizure, coma
2) urgent drainage of pus, antimicrobial agents
Ventriculoperitoneal VP shunt External ventricular drain EVD infection - what - how - diagnosis - treatment
1) device to monitor inter cranial pressure or drain excess CSF
2) colonised by organisms that cause ventriculitis
3) CSF microscopy and culture (usually coagluase -ve staph)
4) device removal, intraventricular antibiotics
What is Neisseria Meningitidis
- gram -ve diplococci
- require blood for growth
- 13 capsular types: A,B,C W135 -and Y are most common
- Can be detected by PCR
- natural Habitat = NASOPHARYNX
- 5-20% people are carriers
- crosses blood brain barrier and multiplies in subarachnoid space
What can be causes be Neisseria Meningitidis
1 ) Fulminant septicaemia
2) septicaemia with purpuric rash
3) Septicaemia with meningitis
4) Pyogenic (purulent) meningitis with no rash
5) Chronic meningococcal bacteraemia with arthralgia
6) Focal sepsis
7) Conjunctivitis, endophthalmitis
Treatment for Neisseria Meningitidis
- Ceftriaxone, cefotaxime
- Penicillin
- Intensive Care
- Chemo prophylaxis of contacts = Rifampicin, ciprofloxacin
- Vaccination - group A,C, W135
What is Haemophilius Influenzae
- must be grown in blood
- small pleopmorphic Gram -ve cocci-bacilli
- six antigenic types a-f
- type b causes most invasive disease
Carriage of Haemophilus influenzae
- normal carriage
- passage to blood stream
- virulence factors
Normal
- restricted to humans
- 25-80% carry non-capsulated strain
- 5-10% carry capsulated stains
Throat - invade submucosa - blood
Virulence factors
- type b capsule
- Fimbrae, IgA proteases, outer membrane proteins, liposaccahrides
Treatment for Haemophilus influenzae
Treatment
Ceftriaxone, cefotaxime
Ampicillin
β-lactamase producing strains common
Chemoprohylaxis of contacts of invasive disease
Rifampicin
H.influenzae Type b conjugate vaccines
Dramatic reduction in the incidence of invasive disease
What is Streptococcus Pneumoniae
- gram +ve cocci - cells grow in pairs
- needs blood or serum from growth
- polysaccahride capsule: 95 capsular types
- normal habitat - human respiratory tract
- transmission - droplet spread
Treatment Streptococcus pneumoniae
Ceftriaxone, cefotaxime
- Penicillin resistant common in some parts of the world
- No Chemoprohylaxis of contacts of invasive disease
- Conjugate vaccine available against common serotypes
- reduction in the incidence of invasive disease in children introduced US
When should steroids be used in meningitis in adults
- given shortly before 1st dose of antibiotics
- S. pneumoniae = give steroids
- no benefit - meningococcal meningitis
Neonatal meningitis?
Group B beta-haemolytic Streptococci
Escherichia coli
Listeria monocytogenes
Neonatal
Neonatal infection. Variable onset
Early ( 5 days). Usually meningitis.
Cefotaxime
Ampicillin and gentamicin
Complications for meningitis
Death
overwhelming sepsis, raised intracranial pressure
Deafness, delayed development, seizures, stroke, hydrocephalus
Lymphocytic meningitis
Viral meningitis
Most common form of meningitis
Enteroviruses
Herpes simplex
Benign outcome
Symptomatic treatment
Spirochete
Treponemal
Borrelia
Note Polio virus can cause meningitis that may lead to paralysis
Prevented by vaccination
Tb meningitis
- insidious onset
- diagnosis - hard - AFB not seen on microsopy
- 12 months standard Tb treatment
- steroids beneficial
Cryptococcal Meningitis
cryptococcus = yeast common problem patients with late stage HIV lymphocytic meningits prolonged course of treatment - amphotericin, flucytosine, fluconazole
Clostridium tetani
- Gram +ve spore forming bacillus
- terminal round spore
- strict anaerobe
Spread of clostridium tetani
organism widespread in soil
organism - non invasive but produces tetanospasmin
- toxin genes plasmid encoded
- toxin spreads via blood stream and retrograde transport
- binds to ganglioside receptors, blocks release of inhibitory interneurones
- convulsive contractions of voluntary muscles
What does clostridium tetani
Tetanus (lockjaw)
Tonic muscle spasms
Trismus
Opisthotonus
Respiratory difficulties
Cardiovascular instability
(sympathetic nervous system)
Treatment of Clostridium tetani
Treatment
Antitoxin (horse or human)
Penicillin or metronidazole
Drugs for spasms
Muscle relaxants
Respiratory support
Prevention
Toxoid
