Meningitis & other IC infections Flashcards
What are 7 symptoms of meningitis?
- fever (high grade)
- myalgia
- headache
- photophobia
- neck stiffness
- rash (non-blanching)
- N&V
NB: meningism = photophobia, neck stiffness, headache
What are the 3 main organisms causing meningitis?
- N.meningitidis
- strep pneumonia
- haemophilus influenzae
what else can n.meningitidis cause apart from meningitis (BBB)?
can cause meningitis across the BBB or septicaemia
Which age group is haemophilus influenzae likely to effect & cause meningitis?
children <5yrs
What 3 cultures should be taken in suspected meningitis?
- blood culture + EDTA for PCR
- CSF culture + gram stain + PCR
- Throat swab culture
Is neisseria meningitidis G-ve or positive?
gram -ve
they do not retain the violet colour they remain pink
is strep pneumoniae g+ve or negative?
g +ve
retains the violet dye after use
g+ve retaian due to the THICK pepdigoglycan cell wall - they lack the outer membrane and have thick cell walls
What is the pathophysiology of meningitis?
can get infection of the meningies POST HEAD INJURY –> infection spreads
e.g. pneumococcus (strep p) via nose and staph aureus via compound fracture
a ?infection post-head injury is the ONLY indication for LP on a patient w/a head injury (e.g. otherwise coning risk)
Apart from bacteria what other organsims should you consider for meningitis?
- worry about HSV encephalitis
- Tuberculosis
Which is the most common cause of meningitis out of meningococcus or pneumococcus (s.pneumonie causing acute pneumonia)?
pneumococcus! - 25%
while meningococcus = 10%
at 0-3 months the common causative agents for meningitis are different to the usual n.meningitidis, s.pneumonia and Hib.
What organisms are the commest for meningitis causing 0-3m?
Group B strep - MOST COMMON CAUSE IN NEONATES
E.coli
listeria monocytogenes
listeria monocytogenes is a cause of meningitis for neonates, what other groups does it become one of the top causative agents for?
if >60 years
and
immunosupressed
if Hib is most common in children <5y/o which bacteria are most causative for meningitis between 6 yrs - 60 yrs?
- Neisseria meningitidis
- Streptococcus pneumoniae
What are the most common bacteria causing meningitis over 60yrs?
- Streptococcus pneumoniae
- Neisseria meningitidis
- Listeria monocytogenes
What is the most common causative agents for bacterial meningitis from 3m-6y/o
- Neisseria meningitidis
- Streptococcus pneumoniae
- Haemophilus influenzae
What does a non-blanching rash indicate?
actually indicates meningococcal septicaemia
- from DIC, bacteria release toxin –> cytokine storm –> CLOT then BLEED
What are 2 signs O/E for meningitis?
Kernigs sign = pain and resistance on attempting to extend the leg at the knee with thigh flexed @ hip
Brudzinski sign = neck flexion causes knee flexion
overall: stretching meninges = pain produced
How can you tell chronic meningitis?
whether the chronic meningitis is malignant, TB or fungal –>
tends to pick off the lower CNs one by one e.g. the larynx/pharynx contol ones e.g. CN9, 10,11,12
What complications can you get of meningitis?
include infective, pressure & other neurological?
deafness (most common)
- other neurological: epilepsy, paralysis
- infective: sepsis, intracerebral abscess
- pressure: brain herniation, hydrocephalus
how do:
- malaria,
- encephalitis,
- septicaemia,
- subarachnoid,
- dengue,
- tetanus
all relate to meningitis?
they are differentials for they syx of meningitis
TB can cause meningitis. What Ix should you do to rule out TB in meningitis cases?
CXR
mantoux
gastric washings (sputum)
What cultures/swabs both bacterial and viral should be done in meningitis/infections?
blood
rash scrapings
throat
stool/rectal
What bloods should be done for ?meningitis?
- FBC,
- U&Es,
- LFT,
- glucose,
- clotting,
- viral serology (EBV, HIV)
What imaging should be done for ?meningitis?
- CTH,
- CXR
What tests can be done on lumbar puncture to indicate that there is infection?
- measure opening pressure - will be raised
- (normal = 7-18)
- do MC&S
- (Ziehl-neelsen stain - mainly mycobacteria)
- PCR
What would the appearance, glucose, proteins & WCC in CSF of bacterial infection be?
cloudy
low glucose (<0.5 of plasma)(eaten)
high protein >1g/l
WCC 10-5,000 polymorphs or neurtophils (has the most WCC out of viral or TB as they cap at around 1,000 neut)
What would the appearance, glucose, proteins & WCC in CSF of viral infection be?
clear/cloudy
60-80% of plasma glucose
normal or raised protein
max 1,000 lymphocytes or from 15-1,000
NB: low glucose maybe seen in herpes encephalitis & MUMPS
What would the appearance, glucose, proteins & WCC in CSF of TB infection be?
unlike other bacteria CSF you may see a slightly cloudy fibrin web
again, glucose would be low - <50% plasme conc (eaten) & high protein e.g. >1g/L
but lymphocytes would be 10-1,000 max (other bacterial can go up to 5,000.
What are the contraindications for lumbar puncture?
NB: spinal cord ends @ level of vertebrae L1-L2 (–>s2)
while limbar punctures are usually perfored between L3 & L5 e.g. cauda eqina level to avoid damage to spinal cord.
- Raised ICP/risk incipient herniation
- shock/CVS compromise
- respiratory insufficiency (e.g. in a baby you have to curl them up into a ball for LP- TF making it even harder for them to breathe)
- extensive or spreading purpura or local superficial infection at LP site
- bleeding disorders, low platelets
- dont do LP if it will DELAY abx starting
What are the INDICATIONS for LP?
- fever without focus <3months old, or if older
- meningitis/encephalitis suspicion
- suspected SAH or CT normal
- diagnostic workup of certain malignancies, seizures, metabolic disorders, neurological conditions (e.g. MS, GBS)
What are the complications of LP?
- post dural puncture headache (common)
- local back pain
- infection
- spinal haematoma
- subarachnoid epidermal cyst
- apnoea
Neck stiffness, photophobia and headahce are signs of meningitis/encephalitis. What signs in addition to these would you see in neonates w/meningitis/encephalitis?
- poor feeding
- irritability
- hypotonia
- altered cry
- opisthotonus
- bulging fontanelle
What GCS signs indicated raised ICP/incipient herniation risk?
- GCS <9 or
- GCS that fluctuates by 3 or more points
*
What is cushings triad?
raised systolic BP, dc pulse and dc respiration
There is CNS ischaemia –> increase sympathetic e.g. raises BP but the baroreceptor senses the raised BP (trying to overcome the high pressure in brain/cranial vault) so slows HR to bradycardia
irregular respirations are from reduced perfusion of the brainstem from swelling/possible brainstem herniation
(the opposite of shock e.g. low bp & high pulse and resp)
What does “abnormal dolls eye movements” show?
e.g. where the eyes should move in the direction opposite to that of head movement the eyes now move in the direction of head movement
- shows brainstem abnormality
(as part of raised ICP/risk incipient herniation)
(negative dolls eye reflex signifies severe brain damage or brain death)
Raised ICP/risk incipient herniation is a contraindication for LP
what else besides fluccutating/reduced <9 GCS, cushings reflex & abnormal dolls eye shows signs of raised ICP?
- Focal neurological signs
- abnormal posture or posturing
- papilloedema
- unequal, dilated or poorly responsive movements
- seizures - within 30m or prolonged >30mins siezures
What is the managment of meningitis without septicaemia?
- ABCDE
- DEXAMATHASONE 4-10mg/6h IV
- Abx =
- Benzyl penicillin 1.2g IM/IV in 1o care
- broad spec: IV cefotaxime 2g/6h slow IV
- then refer to local guidelines once MC&S back
- Fluids
- cerebral monitoring - neuro obs
- notify public health and contact prophylaxis
What should you give if you suspect viral encephalitis?
worry about HSV encephalitis
so
aciclovir!
for someone with meningitis we need to notify public health and give prophylaxis to contacts.
What do we give?
give rifampicin or ciprofloxacin
to household contacts in droplet range or those who have kissed the pts mouth
What are the features of encepalitis e.g. herpes simplex (HSV) encephalitis?
- fever
- headache
- psychiatric symptoms
- seizures
- vomiting
- focal features of HSV = aphasia e.g. the virus characteristically affects temporal lobes
- NOT peripheral lesions e.g. cold sored have no relation to HSV encephalitis
Which HSV causes encephalitis in adults & where does it impact?
HSV-1 is responsible for 95% of cases in adults
HSV typically affects TEMPORAL and INFERIOR-FRONTAL lobes
Rx: with IV aciclovir
NB: if treatment is started promptly the mortality is 10-20%; if untreated the mortality approaches 80%
What CSF signs are there of encephalitis?
lymphocytosis and elevated protein in CSF
apart from CSF what Ix do you do for encephalitis?
- PCR for HSV
- Bloods:
- cultures,
- PCR,
- toxoplasma IgM titre
- (causes encephalitis in adutlts- eating cat/dog parasite egs in soild/water/food; IgM indicates its recent infection),
- malaria film
- CTH contrast enhanced - for medial temoral and inferior frontal changed e/g. petichial haemorrhages (normal in 1/3 patients) –>
- MRI is better
- EEG
What does this EEG pattern mean?
lateralised periodic discharges at 2 Hz
encephalitis
A patient presents with toxaemia, fever, meningism, leucocytosis, riased ICP, localising signs and also a penetrating wound to the head. What condition does this indicate?
due to it being those symptoms which could be meningitis/encephaltis + local signs + underlying cause including penetrating wound or could be direct spread e.g. from middle ear or mastoid or blood borne spread
–> intracranial abscess.
How do you Ix an intracranial abscess?
- X-ray (to see if frontal sinus/ethmoid sinus infection or mastoid has spread)
- CXR ( to look for septic embolus from lung or systemic circulation in R->L cardiac shunt & for MCA territory)
- CT/MRI
How do you Rx an intracranial abscess?
- aspirate
- abx into abscess cavity
- high dose systemic antibiotics,
- anticonvulsant therapy –> 1/3rd patients develop epilepsy
What follow up should be given for intracranial abscess?
- serial CT scan follow ups
- aspiration may need to be repeated
- abscess capsule may need to be excised if it fails to respond to aspiration
A patient presents with seizures and this CTH what is this?
neurocysticerosis
a form of cysticercosis e.g. the most common worm infection of CNS (developing countries)
can form giant cysts in brain
Px: seizures (meningism & fever are not typical)
Meningitis does not usually require imaging - normally is clinical and CSF diagnosis
You should only image is it is a non-straight forward course, worried about ddx
or worried about complications… such as what?
what are the complications of meningitis?
- ↑ICP/hydrocephalus - inflamed meninges are adhesive –> block CSF flow
- Spread of infection causing cerebritis (brain parenchyma due to bacterial whereas encephalitis = inflam due to virus/PNP/AI)
- Collection causing subdural empyema/ cerebral abscess
- Ischaemia due to infection coating vessels
- CN due to inflammation spread
What are the most common things causing encephalitis?
cerebritis is normally infection due to bacteria/non viral pathogens/2ndry to another cause
HSV & Varicella
they can be non-infective e.g. limbic encephalitis - autoimmune, paraneoplastic
A patient presents confused and comatose with low GCS. What could this indicate?
encephalitis
can lead to LT complications e.g. memory loss, seizures
What is imaging used for in encephalitis?
imaging is only supportive - it cannot differentiate between infective & non-infective causes
otherwise Dx is done on clinical diagnosis
What does initial imaging of encephalitis show vs 4 months later?
initial imagins = enhancement and swelling (px: confused, comatose/low GCS)
4 months later = scarring, volume loss, dilation of ventricles (fits with the LT comps. memory loss & seizures)
Where is the characteistic location of enceptalitis ?HSV?
medial temporal lobe
insula
cingulate gyrus
What do these images show and how do you know?
- irregular mass
- surrounded by cerebral oedema
- doesnt affect grey/white equally like a vascular event would
- diffusion characteristics allow distinguishment from tumour - as diffusion not restricted in a tumour –> its restricted in Pus
TF…
this is a cerebral abscess!
What is an extra axial infected collection called?
extra axial means external to brain parenchyma
–> subdural empyema
NB: abscesses are usually parenchymal
other infected collections = sinus filling, epidural abscess.
Who can JC virus reactivation happen in and what does it cause?
causes multiple lesions in immunocompromised/HIV
HIV pt presenting with 4wk history of:
Dysarthria (DBM, non-dominant hemisphere)
Somnolence/sleepiness (thalamic, brainstem)
Right arm weakness (L hemisphere)
what could this be?
JC virus reactivation –> it causes multiple lesions
this happens from Prior infection in HIV/imimunocompromised
Usually older patients
Signal abnormality in the cortex and basal ganglia
–> Characteristic hockey stick appearance in the pulvinar of the thalami
= viral CJD
Creutzfeldt-Jakob disease
