PBL: Spinal Fluid Flashcards
List the anatomy of the skull starting w/ outer → inner
- Skull
- Dura mater
- Arachnoid
- Subarachnoid space
- Pia mater
- CSF
CSF is produced by the ____ ____ in the 4 ventricles of the brain
Choroid plexus
CSF flows from the two ____ ventricles to the ____ ventricle and enters the ____ ventricle via the ____ ____ ____
Lateral; third;fourth; aqueduct of Sylvius
CSF is absorbed primarily by the ____ ____ through tight junctions of the endothelium
Arachnoid villi
What are the 3 types of CSF specimens an MD can collect?
- Lumbar region (spinal tap)
- Subdural (for abscesses in the brain)
- Ventricular aspiration
Infectious disease characterized by the inflammation of the meninges (dura, arachnoid, pia mater)
Meningitis
A condition characterized by a lymphocyte pleocytosis in the CSF and lack of an identifiable causative agent after routine stains and culture of the CSF
Aspetic meningitis
The most common mycobacterial infection of the CNS caused by Mycobacterium tuberculosis
Tuberculosis meningitis
Inflammation of the brain
Encephalitis
Presence of meningococci (N. meningitidis) in the bloodstream
Meningoencephalitis (meningitis + encephalitis)
Meningeal inflammation that persists for more than 4 weeks; common in immunocompromised patients
Chronic meningitis
Inflammation in the meninges that persists for hours to days
Acute meningitis
____ is caused by inflammation and collection of infected material coming from local infectious source (e.g., ear infection and infection of paranasal sinuses)
Brain abscess
Increase in CSF cell count
Pleocytosis
Normal value for WBCs in CSF
ZERO
CSF is obtained by inserting a sterile hollow needle into the spinal subarachnoid space (b/w L3 and L4) in th elower back
Lumbar puncture
Used for treatment of chronic subdural hematomas, usually caused by severe head injuries
- Performed under local anesthesia, followed by partial shaving and disinfection
Subdural tap
Method used to treat conditions such as hydrocephalus which are due to excessie fluid accumulation in the ventricles
- Blood and CSF are drained to reduce intracranial hypertension
Ventricular aspiration
What is the preferred site of entry for a ventricular aspiration?
Right frontal cerebral hemisphere
Why is the right frontal cerebral hemisphere the preferred site of entry for a ventricular aspiration?
Due to its non-dominance for language function for 90% of patients
List the general signs and symptoms of meningitis
- Sudden onset of fever
- Headache
- Stiff neck
- Nausea
- Photophobia (↑ sensitivity to light)
- Altered mental status
- Vomiting
List the more severe symptoms, due to the progression of meningitis
- Seizures
- Coma
- Death
Signs and symptoms of meningitis in newborns
- Fevere, headache, and stiff neck may be absent or difficult to see
- Newborn appears to be slow or inactive
Signs and symptoms of meningitis in babies
- Bulging fontanelles (soft spot on head) due to ↑ CSF
- Abdominal reflex (restlessness)
- Poor feeding
- Irritability
2 methods to diagnose meningitis
- Kernig sign
- Brudzinski sign
Back pain occurs when physician flexes patient’s hip and knee while extending the leg at the knee
Kernig sign
In this method, involuntary flexion of the patient’s hip and knee when the physician lifts the patient’s head flexing it towards his chest
Brudzinski sign
What complications may occur in patients w/ meningitis?
- Brain damage
- Hearing loss
- Seizures (epilepsy)
- Hydrocephalus (buildup of fluid inside the skull)
- Buildup of fluid b/w skull and the brain
- Issues w/ memory
- Partial vision loss
What is the function of CSF?
To act as a cushion protecting the brain and spine from injury
Normal values of CSF
- Pressure
- Appearance
- Total protein
- Glucose
- WBC count
- RBC count
- Differential
- Pressure: 70-180 mm H2O
- Appearance: clear, colorless
- Total protein: 15-60mg/100mL
- Glucose: 50-80mg/100mL
- WBC count: 0-5 (adults/children)
- RBC count: 0
- Differential: 60-70% lymphs, up to 30% monocytes/macrophages, other cells ≤ 2%
Bacterial meningitis
- WBCs
- Glucose
- Protein
- WBCs: > 500 cells (neutrophils predominate)
- Glucose: very low (< 40% of serum glucose concentration)
- Protein: significantly ↑
Fungal meningitis
- WBCs
- Glucose
- Protein
- WBCs: Normal; 500 lymphs
- Glucose: < 40 mg/dL
- Protein: 25-500 mg/dL
Tubercular meningitis
- WBCs
- Glucose
- Protein
- WBCs: 50-500 (lymphs predominate)
- Glucose: ↓
- Protein: 150 mg/dL
Viral meningitis
- WBCs
- Glucose
- Protein
- WBCs: Normal; 200 lymphs predominate
- Glucose: normal
- Protein: normal
Parasitic meningitis
- WBCs
- Glucose
- Protein
- WBCs: Normal; 200 lymphs and/or eosinophils predominate
- Glucose: Normal to ↓
- Protein: ↑
How do we route CSF tubes in the lab?
#1 → Chemistry #2 → Microbiology #3 → Hematology
Why does hematology get tube #3?
Possibility of being a bloody tap which could be clear by tube #3
If you recieve > 2 mL of CSF, what should you do?
Centrifuge for 20 minutes @ 1500-3000 Xg
If you receive < 1 mL of CSF, what should you do?
Vortex before processing
- Remove supernatant and vortex the sediment for 30 seconds to resuspend pellet before plating
What primary media is set up for CSF?
BAP, CHOC, THIO broth, 2 gram stains
What does THIO grow?
Grows anaerobes and detects small amounts of organisms
WHat do you incubate CSF plates at?
CO2 at 37°C
When do you plate CSF on an anaerobe plate?
If it’s a brain abscess
How many slides do you set up for a CSF?
2! Gram stain them one at a time and have someone else look at the other one to confirm
What do you do if the gram stain is positive?
Read 2nd gram stain and then stain w/ acridine orange. If bacteria are present, CALL MD!
If you only have 1 drop of CSF what do you do?
Put it on a CHOC plate
If GPC in clusters are seen on a positive direct smear, what is set up?
Tube coagulase and ANA BAP
If GPC in chains are seen on a positive direct smear, what is set up?
Bile esculin, NaCl, ANA BAP
If GNRs are seen on a positive direct smear, what is set up?
MAC and ANA BAP
If yeast are seen on a positive direct smear, what is set up?
BAP
If GNCB are seen on a positive direct smear, what is set up?
ML and ANA BAP
What do you incubate MAC and SAB at?
CO2 for 2 days
What do you incubate ML plates at?
CO2 for 3 days
What do you incubate ANA BAPs at?
Anaerobic for 48 hours
What are common pathogens in neonate?
- S. agalacticae (Group B Strep) (GPC)
- Listeria (small GPR)
- E. coli (GNR)
What are common pathogens in infants?
- Haemophilus (GNR/GNCB)
- S. pneumoniae (GPC)
- E. coli (GNR)
- N. meningitidis (GN diplococci)
- S. agalacticae (Group B Strep)
What are common pathogens in older children and young adults?
- N. meningitidis (most common) (GN diplococci)
- S. pneumoniae (GPC)
If ANY infection w/ N. meningitidis is left untreated, it can result in ____ ____
Waterhouse-Friderichsen syndrome
What occurs in individuals w/ Waterhouse-Friderichsen syndrome?
- Hemorrhaging into adrenal glands
- Rapidly fatal (12-24 hours)
What are the common pathogens in older adults?
- S. pneumoniae (most common) (GPC)
- N. meningitidis (GN diplococci)
- L. monocytogenes (GPR)
WHat are the common pathogens in immunocompromised patients?
Anything listed previously plus fungi and Nocardia
What are the common pathogens in brain abscesses?
- S. intermedius (most common isolate) (GPC)
- Anaerobes (Prevotella spp, Bacteroides spp)
- Enteric GNRs (E. coli, Proteus spp, Enterobacter spp, etc.)
- Nocardia spp (immunocompromised patients)
How is CSF stored?
Always keep at RT (22-25°C), NEVER refrigerate!
Common causes of meningitis
Bacteria
Common causes of aseptic meningitis
Viruses (no growth on cultures)
Common causes of chronic meningitis
Fungi
