Infections of the CNS Flashcards
Encephalitis
Etiology
Encephalitis: infection of the brain and its meningies with assocaited inflammation response of the CSF
Etiology
- these pt are super sick
- symptoms arise after a primary infection: HA and N/V
- usually a viral pathogen (like HSV) & spread via neuronal transport throughout the brain
- most frequently a viral infection : West Nile Virus (most common in US) and HSV-1 or HSV-2, or enterovirus
Encephalitis
Pt. Presentation of symptoms and signs
Presentation
always get the best history you can about travel, illnesses, insect/animal/work expsoures
Early Signs/Symptoms
- Fever
- Headache
- Meningeal Irritation
Later Findings = cortical dysfunction
- AMS
- Weakness
- Seizures
- CN palsies
- Brainstem findings
- psychosis
- cerebellar findings
Encephalitis
Diagnosis
Diagnosis
- in order ot dx. encephalitis you NEEEEED CSF, PCR and Serology
CSF
- gram stain/culture
- cell count with diff. (see neutrophils inc., then lymphcytes, and RBCs if its HSV)
- protein
- glucose
- PCR testing: for HSV on all patients
Culture any other sites you may want, blood, skin etc.
MRI is the perferred imaging
Brain biposy is rarely done but possible
Encephalitis
Treatment
Treatment
empericially treat all pts. with encephalitis for HSV with acyclovir until it has been ruled out: HSV encep. is fatal if left untreated
- if sus for tick borne; give doxycycline
- broad abx. for immunocomp. pts.
- also treat via supportive measures (fluids, neuro exams, ICP monitor, anticonv. meds if needed)
West Nile Virus Encephalitis
- specific clincal features
- specific diagnositic studies
- specific treatment
West Nile: MCC of encephalitis in US
- common in summer via mosquitos, in those who are immunocomp.
Clinical features (not really specific to west nile)
- fever, HA and stiff neck like usual encephalitis
- parkinsonism and myoclonus
- flaccid paralysis
Diagnosis
- for WNV, you NEEED to get a serum IgM: its more sensitive thatn PCR testing for detecting WNV
- get IgM via CSF, and can get PCR and serology and cultures still
- Imaging: MRI scan will show hyperintense lesions in the middle deeper structures: substantia nigra, basal ganaglia, and thalamus
Treament
- for WNV, supportive measures is only treatment
- once confirmed that its WMV from IgM, can take them off the prophlyatic acyclovir
HSV Encephalitis
- specific features
- specific diagnosis
- specific treatment
HSV Encephalitis
- will be 100% fatal if left untreated
- the HSV travels through trigem nerve to the brain and retroactively gets in there, or direct innoculation through open wound
Specific Clinical Features
- the typical HA, fever and neck stiffness
- Behavioral abnormalities : hypomania, blindness, lost fear response and increase sexuality = Kluver Bucy
Specific Diagnosis
- the CSF PCR culture and cell count and antibodies will show HSV 1 or 2
- MRI: specific pattern of inferior temoral lobe edema or bilateral temporal lobe is a slam dunk dx. on FLAIR T2 weighted imaging since think about the trigem. nerve traveling into brain this way
Treatmetn
- the acyclovir for a long time
Acute Disseminated Encephalomyelitis (ADEM)
etiology
features
diagnosis
treatment
Etiology
- a post-infection encephalomylesis
- an autoimmune demyleinating disease that results after infection or immunization (viral or flu)
Symptoms (demyleinated disroder: simiarl presentation to MS)
- HA, meningismus, fever
- N/V
- AMS
- could have apraxia, aphasaia, seizures increased ICP
Diagnosis
- MRI: multiple lesions in white matter: indicating demyleination
- CSF: nonspecific findings, but WBC will be LESS THAN 100 so you know its not a bacterial infection
Treatment
- high dose glucocorticoids = first line
- plasma exchange or IvIG or cyclophos. if steroids dont work
Meningitis
Etiology
Meningitis = inflammation of the meningies: any of them from the dura to the pia
Two categories of Meningitis
1. Bacterial Meningitis: meningoccocal meningitis or meningococcemia
2. Aseptic Meningitis: viral, mycobacterial, funcal, spirochetes, drugs or neoplastic processes
Meningitis
Clinical Presentation
Presentation
- fever
- altered level of consciousness
- nuchal rigidity
- (if they above three are all present: this is most commonly a presenation of a pneumococcal disease (like streph pneumococcal))
- HA
- menigeal signs
- photophobia
- N/V
- seizures
- CN abnormalities
- rashes: maculopapular = penumococcal meningitis
- rashes: macular/papular/maculopapular = meningococcal disease
Physical Exam Findings of Meningitis
- Kernig’s Sign = if leg/knee cannot be fuly flexed due to pain = +
- Brudzinksi’s Sign = when the neck is passively flexed, the knee and hip also flexes
- Nuchal Rigidity = cant flex neck to reach chin
- Jolt Sign = HA when rotating head side to side fast
Meningitis
Diagnosis
who gets Ct before LP
Diangnosis
An LP is critical to the diagnosis of meningitis
- get LP in LLD postion: measure opening pressure (normal = 5-25 cm of water) & should be clear: if cloudy/purulent = a sign
- want to get LP before starint abx. if possible but sometimes you cant
dont get LP without a CT first if you’re concerned about increased ICP : herniation risk
who gets CT before LP?
- immunocomp. pt.s
- those with known CNS disease
- new seizure in past 1 week
- papilledeam
- abnormal LOC
- neruo deficts focally
if need to CT: obtain blood culutres then start emperic abx. before getting CT
LP of CSF and send for Gram-Staining
Meningitis
LP gram stain results and culture results
LP for CSF Gram Stain
Gram Stain Results
- Gram + diplococci = strep. pneumo
- Gram - diplococci = nisseria meningitidis
- Gram - rods/coccobacilli = H. flu
CSF Analysis
Bacterial: > 1,000 WBC with lots of PMN & low glucose
Viral: < 100 WBC with lymphocyte predom.
Tubular or Fungal: lymphocytes high in CSF
Meningitis
Meningococcal Disease Specifics
Lab Specifics
Specifics - Etiology
- theres a vaccine for pneumococcal or menigiococcal and H. flu!!!
- dorm students at increase risk
- called meningiococcal = meaning streptococcus pneumonia or neisseria meningitdis or H. flu i guess too
- if it gets to blood stream = meningococcal septicemia/coccemia and goes to destory organs and tissue
- spreads to meningies via nasopharynx, choroid plexus, or a local infection to bacteremia or direct entry
Findings on Labs
- remeber bacterial: CSF will have > 1,000 WBC with PMN predom.
- get blood culutres, they will be postive usually and can help if the LP was delayed for CT
- PCR can be used to rapidly identify pathogen
Meningitis: Bacterial Treatment
- sus for meningococcal meningitis/meningococcemia = what do you give
- emperic treatment for age groups
Treatment
if you are sus for bacterial meningitis & blood infection (coccemia) = treat IMMEDIATELY and emperically
- outpt. = give ceftriaxone or PCN-G and send them to the ER
- inpt. = get blood culutres, treat immediately (dont wait for LP to come back or for CT)
Guideline
- treat emperically via age/hx. —> get gram stain back? –> adjust —> get culture? —> adjust —> treat those who were in contact too
Emperic Treatment
- 18-50 years old = ceftriaxone + vancomycin (assuming is pneumococcal or n. meningiditis)
- 50+ = ceftriaxone + vancomycin + ampucillin (covers lisera)
- immunocomp. = vancomycin + cefipime + ampucillin (cover listera and pseudomonas)
- post-op = vancomycin + cefipime (cover gram -)
Meningitis: Bacterial Treament
- if beta lactam allergy?
- role of steroids?
Beta Lactam allergy:
- okay with cephalosporins = meropenem
- not ok = moxifloxicin + vancyo
Steroids?
- can reduce complications if given and pt. has pneumococcal
- dextamethasone right after the LP or blood culutre
- continue dextamethasone until stain or cluture shows its not pneumo.
- may need to add rifampin if only moderate susceptibilty to beta lactam on report
Meningitis: Bacterial Treatment
after Gram Stain Reslults
Gram + Diplococci = strep. pneumococcal
- ceftiaxone
- vancomycin
- dextamethasone
Gram - Diplococci = N. meningitidis
- cefotaxime/cefapime
- ceftriaxone
Gram + bacilli or diplococci = liseria
- ampucillin
Gram - bacilli = H. flu or pseudomonas
- Ceftazidime or cefepime
- Gentamicin
