CNS infection Flashcards
Discuss aetiology of bacterial meningitis
- N. Meningitidis - most common organism in adults under the age of 45
- Strep pneumo - most common
- listeria - especially in adults over 50
- H.influenzae
- klebsiela
Associate with dural leak secodnary to neurosurg or trauma
- Staph
- pseudomonas
- coliforms
Other
-TB
-crytocococcus neoformans (immunocompromised)
aseptic
List host factors predisposing to meningitis
1)Age younger than 5 or older than 60
2)reduced immunity
-splenectomy - encapsulated organisms
-alcoholism
-diabetes
-HIV IVDU
3) incresed exposure
-low socioeconomic status
-crowding
-Household contact with meningitis patient
4)Haematology risk
Thalassemia major
-sickle cell
5) infection risk
-surgery
-Bacterial IE
-VP shunt
Malignancy
Discuss complications of bacterial meningitis
Immediate
- coma
- loss of airway refexes
- seizures
- vasomotor collapse
- DIC
- respiratory arrest
- dehydration
- pericardial effusion
- death
- others
Delayed - more common in paeds
1) sensorineural hearing loss
2) learning difficulties
3) motor problesm
4) speech delay
5) hyperactivity
6) blindeness
7) obstrucive hydrocephalus
8) recurrent seizures
- bialteral adrenal haemorrhage (Waterhouse friderichsen syndrome)
- death
- CVT
Discuss clinical features of bacterial meningitis
Fever, headache photophobia, nuchal rigidity (only important in the sagital plane or fowards and backwards) , lethargy, malaise altered sensorium seizures vomiting and chills.
Exam
- Kernigs (inability to straighten leg to a postion of full knee extenrsion when aptient is lying supine wiht hip flexed to a right angle)
- Brudzinski (attempts to flex the neck passively are accompanied by flexion of the hips)m
- Othalmoplegia
- Altered GCS
Discuss investigation of bacterial meningitis
Procalcitonin is emerging as a promising serum marker of serious bacterail infections
2-3 bloods cultures
FBC, U&E, LFTs,
Imaging
CT - for anyone with the possibility of intracranial abcess, ICH or mass lesion - should not delay LP
Indications for CT prior to LP
- seizures,
- immunocompromised,
- GCS <10,
- focal neurological signs
- papilloedema
CSF
At least 3 but idealy 4 tubes each containing 1-1.5ml fo CSF are obtained and numbered in sequence
Send for cell count and differential, glucose, protein, gram stain and culture, antigen (cryptococcal), turbidity
-1) opening pressure
-the normal CSF pressure in adult varies from 5-20cm h2o
-this value onyl applies to patients in the left lateral recumbent position
2) cell count
-normal CSF has <5WBC and <1PMN – any more is indiciative of infection
-Bacterial meningitis classically has a glucose concentration <2.2mmol/L, protein >200mg/dl, and WBC >1000 with PMN >80%
-If bloody can have 1 WBC for every 500 red
-Subtract 1mg/dl of protein for every 1000 RBCS
3) Antigen detection
-Nucleic acid amplification test such as PCR have reported sensitivities of 92% for HIB 100% for s pneumo and 88% for N Meningitidis
-Particular utility in HSV encephalitis
Contraindications for LP
- Deep coma GCS <8 CT does not exclude risk of uncal herniation in these patients
- focal neuro signs – CT first
- infection over the site
- signifiacnt surgery to Lspine
Discuss management of Bacterial meningitis
For adults and children >2months of age incoluding those with nonsever penicllin allergies
-Ceftriaxone 2G (50mg/kg) BD
or
-Cefotaxime 2g(50mg/kg) IV q6hourly
plus
Dexamethasone 10mg (0.15mg/kg) preferebraly starting before or with the first dose of antibiotic than 6hourly for 4 days – should only be continued if Strep pneumo menigitis (used to reduce hearing loss and other neuroogical sequalae)
Listeria monocytogenes is intrinsically resistant to cephalosporins and for patient who are
->50 years of age
-immunocompromised
-pregnant
-debilitates
Add: benpen 2.4G (60mg/kg) Q4 hourly - if allergic to penicillin can use Bactrim 5+25mg/kg (480/2400) TDS
Add vancomycin if Gram +ve cocci, pneumococcal antigen assay of CSF is positive or if the patient has known or suspected OM or sinusitis or has recently been treated with B lactam Abs
Vanc 25-30mg/kg IV
List viral aetiologies of meningits
Enteroviruses
-polio, coxsackie, echovirus
Herpes
- HSV 1 and 2
- VZV
- CMV
- EBV
Resp
-Adeno
Rhino
Flu A and B
Arbovirus
Mumps
HIV
Describe viral meningitis and encephalitis
With rare exceptions the overall prognosis for complete recovery from viral meningitis is excellent
The outcome in viral encephaltitis are dependant on the infecting agent. The mortality from HSV is approximately 30% with treatment and 60-70% without Sequalae of encephalitits include - Seizure -motor deficits -changes in mentation
They may have all the symptoms of meningeal irritation + an lateration in consciouness or delirium is almost universal.
Fever headache, personalitiy changes, confusion and disorientation are also usually present
Discuss management of viral enecphalitis
IV acyclovir should be administered in dose of 10mg/kg (500mg/m2) TDS for 2-3 weeks
Discuss fungal menigitis aetiology, clinical features and treatment
Present similarly to other menigitic pictures in an immunocompromised person
Aetiology -Cryptococcus neoformans histoplasma capsulatum coccidioides demartitids candida
Treatment
- amphotericin B 3-4mg/kg
- flucytosine
Discuss CNS abcess
Can occur at any age and any time of year.
They are asscoiated with local contiguous and remote systemic infection, IVDU, neurological surgery and cranial trauma.
Brain abcess secondary to ottits media most often occurs in paediatric or older atulde populations.
Most commonly seen in the immunocompromised poplaution specificall HIV
CT with con is diagnositc for brain abcess
Can be treated medically, aspiration or with surgery
COvered with ceftriaxone and vanc as above wiht added metronidazole for anareobic coverage
Discuss Noninfectious causes of menigitis
Post infectious(PIE)/ post vaccinal -rubella -varicella -rabies -pertusis 0flu -measles
Drugs
- NSAIDS
- BACTRIM
- Isoniazid
- IVIG
- Carbamazapine
Systemic disease
-Collagen vascular disorders (SLE, Wegeners granulomatosis, CNS vasculitis, RA, Kawasaki’s disease)
-Sarcoidosis
_leptomeningeal cancer
Neoplastic
-leukemia
Inglammation of neighboring structurs
- brain abscess
- epidural abcesses
Discuss meningococcal disease prophylaxis
Indications
- Should be offered in cases of N meningitidis or HIB who are
1) Household or household like contacts (those who live in the same house (or dormitry) or were havin an equivalent degree of contact with the case in the 7 days prior to the onset of the cases symptoms until completion of 24 hours of appropriate antibiotics)
2) Passenger immediatley adjacent to the index case on a trip of 8 hours or longer
3) any person who has potentially shared saliva ( such as eating utensils or drink botle) or had intimate contact with the index case
4) health workers who ahve given mouth to moth or had unprotected close exposure to large particle resp droplets during airway management
Rifampin 600mg BD for 48 hours (5mg/kg in nenoates <1 month, 20mg/kg in children) preferred for kids
Cipro 500mg PO single dose (250mg for kids over 5 and 30mg/kg up to 125 for kids under) - preferred for adults kids and females on the OPC
Ceftriaxone 250mg IM single dose –> pregnant ladies
Rifampin preferred in neonates but excluded in pregnancy and severe liver disease
Ceftriaxone preferred in women
