Meningitis/encephalitis Flashcards
meningitis
general
Inflammation of the pia mater, arachnoid, and CSF-filled subarachnoid space
Characterized by CSF pleocytosis (increased cell count)
Bacterial
Neisseria meningitidis
Strep pneumoniae
Haemophilus influenzae
Group B Strep
Listeria monocytogenes
Aseptic
viruses
fungi
protozoa
drugs
systemic disorders
Meningitis
patho
Invasion of bloodstream (bacteremia, viremia, fungemia, parasitemia) and subsequent hematogenous seeding of CNS
Most common mode of spread, characteristic of meningococcal, cryptococcal, syphilitic, and pneumococcal meningitis.
Direct contiguous spread (sinusitis, otitis media, trauma, direct inoculation during intracranial manipulation)
Local extension from contiguous extracerebral infection (otitis media, mastoiditis, sinusitis) is common cause.
Retrograde neuronal pathway (olfactory and peripheral nerves)
Meningitis
newborns and infection
Meningitis in newborn may be transmitted vertically, involving pathogens that have colonized the maternal GI or genital tract, or horizontally, from caregivers.
bacetrial meningitis
Most common bacteria and second most
Strep pneumoniae
Most common: >50% of US bact meningitis cases (2000/year)
Leading cause of bact meningitis in children < 5 y.o.
Neisseria meningitidis
Second most common
Close contact outbreaks, adolescents (dorms/barracks)
15% death rate; 20% of survivors have disabilities (limb loss, deafness, neuro problems)
bacterial meningitis
clin man
Triad
Triad
Fever
HA (in over 80%)
Nuchal Rigidity
Fourth symptom can be AMS (Altered Mental Status; confused, lethargic)
95+% of patients at least two of these four
May be photophobia, N/V
Short time from onset to presentation: less than 24 hours in 25%
Bacterial Meningitis
Physical Exam Findings
Fever
Meningismus
+ Kernig and Brudzinski
Nuchal Rigidity
Chin to chest
Seizures: 30-50%
Focal Neuro Deficits - CN deficits ~25% (CN VI, then III, IV VIII)
Papilledema: rare
Skin Rashes: Meningococcal
Petechial esp with meningococcal septicemia
Meningitis signs
Kernig and brudszinski
Papilledema
meningitis
Meningococcal Meningitis
Clin man
- Fever, headache, vomiting, delirium, convulsions.
- Petechial rash on skin and mucous membranes in many.
- Neck and back stiffness and positive Kernig and Brudzinski signs are characteristic.
- Purulent spinal fluid with gram-negative intracellular and extracellular diplococci.
- Culture of cerebrospinal fluid, blood, or petechial aspiration confirms the diagnosis.
meningitis
Head CT before LP
Immunocompromised state (HIV infection, immunosuppressive therapy, transplantation)
History of CNS disease (mass lesion, stroke, focal infection)
New onset seizure (within one week of presentation)
Papilledema
Abnormal level of consciousness
Focal neurologic deficit
Bacterial Meningitis
LP results
glucose will be low
opeining pressure will be elevated
Protein will be very high
few RBCs
Viral meningitis
LP results
opening pressure - slightly elevated
< 200/mm WBC
Glucose will be normal
protein will be normal
no RBC
Bacterial vs. Viral Meningitis
Bacterial meningitis highly probable when any one of the following CSF parameters present:
Glucose <34 mg/dL
Protein concentration >220 mg/dL
WBC count >2,000 microL
Neutrophil count >1180 microL
But many exceptions: empiric antibiotics warranted when bacterial meningitis is suspected clinically even if CSF abnormalities are not diagnostic
bacterial meningitis
Dx
CBC
CMP
Glucose for comparison with CSF
Liver and kidney function to adjust dosing
PT/PTT?; Lactic Acid?; HIV testing? Syphilis testing?
Blood Cultures X 2
Positive in majority of bacterial meningitis patients
Guide therapy if CSF not available
Urine (UA & CX)
Imaging
CXRay
Most critical issue in a patient with suspected bacterial meningitis
is initiation of antibiotics
Avoid Delay
ABX before LP if strong suspicion
Minimal effect on chemistry
Limited effect on CSF culture
Prompt tx = rapid recovery of neurologic function
Bacterial Meningitis
Treatment
Empiric treatment: high dose third generation cephalosporin with vancomycin.
ADD:
Ampicillin added when suspicion of listeriosis
Acyclovir when suspicion of HSV
Doxycycline when suspicion of Rocky Mountain Spotted Fever
4 drug anti-TB treatment when suspicion of TB
IV dexamethasone starting shortly before or at same time as antibiotics when bacterial meningitis suspected:
Steroids reduce overall mortality and neurological sequelae
Bacterial Meningitis
Treatment
β-lactamase-producing N meningitidis
determine susceptibility to penicillin before using penicillin/ampicillin.
bacterial meningitis
nasopharyngeal carriage Tx
Ceftriaxone clears nasopharyngeal carriage effectively after 1 dose.
Aseptic Meningitis
general
Clinical and lab evidence for meningeal inflammation with mononuclear (lymphocytic) pleocytosis with negative gram stain, negative bacterial cultures.
HA, fever; mental status changes less common
Often self limited course: 5-7 days
Aseptic Meningitis
causes
Viral: enterovirus, HSV, HIV, VZV, West Nile HSV, HIV, West Nile virus, Varicella-Zoster virus, mumps, CMV
Mycobacteria, fungi, spirochetes
Medications
Malignancy
Autoimmune hypersensitivity diseases
Viral Meningitis
General
And LP resulted
Many viruses causing meningitis also cause encephalitis
Enteroviruses (Coxsackie, echovirus) most common
rash, sore throat, diarrhea, joint ache, HA
late summer/early fall
CSF: increased WBCs but <250; modest increase in protein; normal glucose; PMNs predominate early but repeat LP shows evolution to lymphocytic predominance. CSF PCR+ for enterovirus
Viral Meningitis
HSV-1&2
LP findings
high CSF RBC count
~85% with HSV-2 meningitis have genital lesions which precede onset of CNS sx.
HA, photophobia, stiff neck
Neurologic complications in about 1/3: paresthesias in perineum or sacral area, urinary retention, constipation, motor weakness in LE
Most HSV-1 CNS infection is manifest as encephalitis rather than aseptic meningitis
High mortality rate: Treat with IV acyclovir; transition to oral on discharge; total 10-14 day treatment
Viral Meningitis
HIV infection
Primary infection mono-like syndrome (fever, malaise, lymphadenopathy, rash pharyngitis)
Subset will develop meningitis or meningoencephalitis: HA, photophobia, N/V, stiff neck, confusion, seizures or CN palsies
May resolve without treatment after a few weeks
Look at risk factors; have high degree of suspicion
Aseptic Meningitis
Fungal, TB, Syph
Fungal: cryptococcus – especially in HIV+; coccidioidal infections in SW US and Central and S America
TB: usually presents sub-acutely, more common in older, debilitated or HIV+
Spirochetes:
Treponema pallidum: may disseminate to CNS during early infection: may also present in secondary syphilis with HA, malaise, disseminated rash
Borrelia burgdorferi (Lyme disease)
Tick exposure, erythema migrans, may be CN VII palsy
meninigitis
Cryptococcosis Essentials of Dx [Cryptococcus neoformans]
Most common cause of fungal meningitis.
Headache, abnormal mental status; meningismus seen occasionally, though rarely in patients with AIDS.
Demonstration of capsular polysaccharide antigen or positive culture in CSF is diagnostic.
80+% of Cryptococcus infections are opportunistic infection in pts with AIDS
Cryptococcus neoformans meningitis
Predisposing factors:
chemotherapy for hematologic malignancies, Hodgkin lymphoma, corticosteroid therapy, structural lung diseases, transplant recipients, TNF-alpha inhibitor therapy, and AIDS.
Noninfectious Causes of Aseptic Meningitis
Malignancy:
hematologic malignancies often seed CNS, esp large cell lymphomas & acute leukemia
Solid tumors: breast, lung, melanoma, GI
Dx: cytology shows malignant cells in CSF
Systemic processes: SLE, other collagen-vascular disease
Inflammatory processes primarily involving CNS
Drug hypersensitivity
Drug induced Meningitis
Unusual adverse reaction; usually dx of exclusion:
NSAIDS
Antibiotics (TMP-SMX/Bactrim)
IV immune globulin
Chemotherapeutic drugs
Antiepileptic drugs
Probably due to delayed hypersensitivity reaction or direct meningeal irritation
Symptoms usually resolve a few days after drug DC
May be more common in patients with autoimmune disease
Aseptic meningitis
Physical exam -
HA, fever, often photophobia
Clues to specific etiology:
Diffuse maculopapular exanthem in mildly ill patient: think enteroviral infection, primary HIV, syphilis
Parotitis: think mumps in unvaccinated patient
Severe vesicular and ulcerative genital lesions: think HSV-2 infection
Oropharyngeal thrush and cervical lymphadenopathy: think HIV
Asymmetric flaccid paralysis: think West Nile
Aseptic Meningitis
Dx & Management
CSF
>50% CSF lymphocytes, protein <80-100, normal glucose, negative gram stain
virus detection assay or virus culture and bacterial culture
PCR if suspect HSV or VZV
VDRL, HIV testing, Lyme serology, serologic testing for mumps
Elderly, immunocompromised – treat for presumed bacterial meningitis
Empiric antibiotics until culture results available (24-48 hrs). If sxs improve and culture negative, can DC antibiotics
Consider repeating LP
AN 18 year old with 1 week history of fever, HA, increasing confusion and lethargy presents to ED.
Vitals: BP 110/68, HR 98; T 100.8
PE normal, no focal neurologic signs
Head CT negative
LP: WBC 250 with 78% lymphocytes, RBCs 500 in tube 1, 630 in tube 2. No organisms on gram stain
A. IV ceftriaxone and vancomycin
B. IV fluconazole
C. IV ceftriaxone, acyclovir and vancomycin
D. Ampicillin and aminoglycoside
C IV ceftriaxone, acyclovir and vancomycin
62 year old man with history of colon cancer currently receiving chemotherapy presents with fever and HA of 3 days duration.
LP shows gram + rods, culture pending
Based on Gram stain, wotf is the most likely diagnosis?
A. GBS
B. H influenza
C. Listeria
D. Meningococcus
E. Strep pneumonia
C. Listeria
18 year old male is brought to the ED by his roommates. He is confused and cannot give a history.
Vitals: BP 90/60; HR 110; T 104.0
Head cannot be moved because of nuchal rigidity; multiple petechiae on legs and buttocks
Patient admitted for antibiotics, LP and careful monitoring in ICU
What do you do with his roommates?
Preventive chemoprophylaxis with rifampin or ceftriaxone
Eliminate nasopharyngeal carriage
Check resistance patterns before considering ciprofloxacin
Azithromycin if no other viable option
Meningitis Prevention
Vaccinations (H influenzae type B and some strains of S pneumoniae)
Meningiococcal vaccine forall between 11 and 18 , and for those between 2-10 and 19-55 who are at increased risk for invasive meningococcal disease
Post exposure/close household contacts of index case of meningococcemia or meningococcal meningitis:
Rifampin 600 mg BID x 2 days
Single dose ciprofloxacin 500 mg
Cipro if resistance low
Meningitis vs Encephalitis
Two disorders, sometimes challenging to distinguish
Patients may have both meningeal and parenchymal processes with clinical features of both: meningioencephalitis
Meningitis: may be uncomfortable, lethargic, distracted by HA, but cerebral function remains essentially normal
Encephalitis: abnormalities in brain function - altered mental status, motor or sensory deficits, altered behavior/personality changes, speech or movement disorders
Encephalitis
Presentation
Viral prodrome: fever, malaise, myalgia, HA, nonspecific symptoms
N/V/D, cough, sore throat, rash can precede neurologic symptoms
Signs of causative agent: vesicles from HSV, parotitis from mumps, lymphadenopathy/hepatosplenomegaly from EBV, rash from measles/VZV, etc.
Altered mental status from subtle deficits to complete unresponsiveness - depends on area of brain involved and specific pathogen
Seizures common
Papilledema rare
Focal neurologic abnormalities: hemiparesis, aphasia, CN palsies
Encephalitis
Diagnosis: Imaging
MRI sensitive for demyelination, edema, necrosis and inflammation
Head CT with/without contrast if suspicion of space occupying lesions, brain abscess
Temporal lobe involvement strongly suggests HSV encephalitis
Encephalitis
Diagnosis using LP
Opening pressure normal to slightly increased
Increased WBC but not as high as bacterial meningitis
Differential predominance: lymphocytes/monocytes (bacterial meningitis usu PMNs)
Elevated protein but may but not be as high as bacterial meningitis
Usually normal glucose
RBCs in atraumatic LP suggest HSV-1 encephalitis
PCR of CSF:
HSV-1 and 2; enteroviruses; VZV, CMV; others depending on clincal situation
Virus may also be detectable in serum
Consider HIV testing
IgM antibody in CSF and serum for West Nile virus
Encephalitis
Tx
Causative agent rarely identified
Important to R/O HSV since high fatality rate if untreated. If suspect HSV, start acyclovir while awaiting confirmation
If organism identified, treat accordingly: Foscarnet (antiviral) for CMV, Ceftriaxone for Borrelia burgdorferi, PCN for syphilis
Corticosteroids
No specific therapies for most viral encephalitis. Supportive care in ICU - may include intubation, sedation and mechanical ventilation if significant mental status changes.
encephalitis
Most frequent sequelae:
difficulties in concentration, behavioral and speech disorders, memory loss.
