Meningitis- Week 2

Question 1

what is meningitis

Answer 1

inflammatory disease of the leptomeninges, the tissues surrounding the brain and spinal cord, defined by an abnormal number of WBC’s in the CSF

Question 2

the meninges consist of 3 parts

Answer 2

the pia, arachnoid and dura maters

Question 3

bacterial meningitis- when?

Answer 3

can be community acquired or healthcare associated- associated with a variety of invasive procedures or head trauma, and in patients with internal or external ventricular drains or following trauma - characteristic features of common causes of bacterial meningitis depends in part upon the route of acquisition and underlying host factors

Question 4

major causes of community- acquired bacterial meningitis in adults in developed countries are

Answer 4

streptococcus pneumoniae neisseria meningitides

Question 5

bacterial meningitis- where?

Answer 5

produced by the choroid plexus in the lateral, third and fourth ventricles–> by both filtration and active transport normal adults- CSF volume is 125 to 150ml 20% of CSF contained in ventricles 80% is contained in the subarachnoid space in the cranium and spinal cord

Question 6

normal rate of CSF production, where does it circulate?

Answer 6

approximately 20ml/ hour circulates through the subarachnoid space between the arachnoid mater and the pia mater. Circulates from the lateral ventricles into the 3rd ventricle and then the 4th ventricle via the cerebral aqueduct *CSF secretion and reabsorption remain in balance in most healthy individuals to maintain a CSF pressure of less than 150mmH20

Question 7

the major causes of healthcare- associated bacterial meningitis are different but usally

Answer 7

staphylococci and aerobic gram- negative bacilli, often after neurosurgery especially if patient was not put on antimicrobial prophylaxis to prevent surgical site infection

Question 8

old major cause before vaccination?

Answer 8

haemophilus influenzae

Question 9

classic triad

Answer 9

change in mental status fever nuchal rigidity but be aware: one or more of the classic findings on history or physical are absent in many patients

Question 10

important caveat

Answer 10

clinical picture is often “unimpressive” when patient is first seen

Question 11

HINT

Answer 11

URI interrupted by one of the “meningeal symptoms”: vomiting, headache, lethargy, confusion, stiff neck

Question 12

pneumococcal meningitis- s. pneumoniae

Answer 12

gram + diplococci most common cause in adults- especially in older adults- 60% of cases in adults up to age 60 and almost 70% in older patients. - watch for neuro changes- hearing loss, seizures, papilledema, cerebral infarction - most common in kids 1 month- 4 years. Mortality 30% in kids, 80% in elderly - prevented by vaccine- PCV7

Question 13

meningococcal meningitis- neisseria meningitis

Answer 13

characteristic skin changes, petechiae and palpable purpura

Question 14

listeriosis

Answer 14

listeria monocytogenes- gram negative aerobic rod, usually foodborne; it can be transmitted to fetus - reproduce in phagocyttes often with the classic triad

Question 15

to determine what kind

Answer 15

perform and interpret CSF examinations

Question 16

normal findings of CSF

Answer 16

CSF is normally acellular. However, up to 5 WBC’s and 5 RBC’s are considered normal in adults when the CSF is sampled by lumbar puncture

Question 17

CSF abnormalities

Answer 17

>3 polymorphonuclear leukocytes (PMNs)/ microL are abnormal in adults The CSF cell count determination should be performed promptly since the count may be falsely low if measured more than 60 minutes after the LP is performed

Question 18

pleocytosis

Answer 18

an elevated CSF WBC

Question 19

xanthochromia

Answer 19

normal CSF is clear and colorless - but yellow or pink discoloration of the CSF, represents most often the presence of hemoglobin degradation products and indicates that blood has been in the CSF for at least hours (eg, subarachnoid hemorrhage) - both infectious and noninfectious processes can alter the appearance of CSF - as few as 200 WBCs/ microL or 400 RBCs/ microL will cause CSF to appear turbid - CSF will appear grossly bloody > or eqal to 6000 RBCs/ microL are present

Question 20

indications for lumbar puncture

Answer 20

suspicion of meningitis suspicion of subarachnoid hemorrhage suspicion of CNS diseases such as Guillain- Barre and carcinomatous meningitis therapeutic relief of pseudomotor cerebri injection of drugs and anesthetics

Question 21

indications for CT prior to LP (in suspicion of meningitis)

Answer 21

patients older than 60 years patients immunocompromised patients with known CNS lesions patients who have had a seizure within 1 week of presentation patients with an abnormal level of consciousness patients with focal findings on neurologic exam patients with papilledema seen on physical exam, with clinical suspicion of elevated ICP

Question 22

contraindications for LPs

Answer 22

increased ICP of an unidentified origin- can cause cerebral herniation (exception- therapeutic use of LP ro reduce ICP) infections- skin infections at puncture site may cause sepsis abnormal respiratory pattern- HTN with bradycardia and deteriorating consciousness, vertebral deformitites (scoliosis or kyphosis) in hands of an inexperienced clinician bleeding diathesis- coagulopathy, decreased platelet count (<50 x 10/L)

Question 23

Glasgow Coma Scale

Answer 23

3 is the worst

15 is the best

eye opening, motor response, verbal response

Question 24

bottom line for CSF

Answer 24

it should be examined in every patient inwhom the clincal finsings are consistent with even the possibility of meningitis, no matter how minimal the manifestations are

Examine the CSF for: pressure, appearance (clear or turbid), wet mount, gram stain (for bacteria), Geimsa stain (for presence of neutrophils or lymphocytes or RBC’s)

Question 25

CSF analysis- color

Answer 25

crystal clear- normal finding, viral meningitis

turbid- indicates presence of >200 WBCs or >400 RBCs, bacterial meningitis

xantochromia- yellow, orange or pink discoloration (in more than 90% subarachnoid hemorrhages), physiologic in newborns

pink- RBC’s breakdown, high carotenoid intake

green- hyperalbuminemia, purulent CSF (bacterial meningitis)

brown- meningeal melanomatosis

the 2 major tests performed in chemistry lab on CSF are determination of protein and glucose concentrations**

Question 26

CSF analysis- pressure

Answer 26

measured with a column manometer (fetal position is optimal)

increased pressure: CHF, cerebral edema, subarachnoid hemmorrhage, hypo- osmolality, resulting from HD, purulent or tuberculous meingitis, hydrocephalus or pseudotumor cerebri

decreased pressure: complete subarachnoid blockage, leakage of spinal fluid, severe dehydration, hyperosmolality or *circulatory collapse*

normal CSF pressure= 60- 200mm h20; obese patients may have pressures up to 250

Question 27

CSF analysis- cell count

Answer 27

normal= <5 WBC’s/ mm in adults and <20 WBCs/mm in newborns (70% lymphocytes and 30% monocytes)

99% of patients with bacterial meningitis have >100 WBCs/mm (less than that is common with viral meningitis)

viral memnigitis: predominately T lymphocytes

bacterial meningitis: predominately PMNs

fungal and teburcular meningitis: predominance of lymphocytes and high content of proteins, glucose

RBC’s: abnormal finding (be careful with traumatic taps- 3 samples are needed)

Question 28

CSF analysis- final considerations

Answer 28

normal CSF pressure measured with a manometer in patient lying flat in the lateral decubitus position with the legs extended, normal range is between 60 and 250 (although some experts consider normal upper limit 200)

infection, bleeding or tumor can alter the balance between CSF secretion and reabsorption, resulting in intracranial hypertension

the term “blood brain barrier” is used to describe the barrier systems that separate the brain and the CSF from the blood to prevent entry by simple diffusion of fluids, electrolytes, and other substances from blood into CSF or brain

Question 29

CSF- more final considerations

Answer 29

the mechanism by which bacteria or other microbes traverse the blood brain barrier and enter the CNS remains poorly understood

the CSF is normally acellular, although up to 5 WBCs and 5 RBCs are considered notmal in adults when the CSF is sampled by LP

an elevated CSF WBC concentration DOES NOT diagnose an infection, since increases in CSF WBC concentration can occur in a variety of both infectious and noninfectious inflammatory states

Question 30

2 major tests performed in chemistry lab on CSF are

Answer 30

determination of protein and glucose concentrations

Question 31

meningococcal disease: warning signs

Answer 31

classic signs: severe headache, dislike of bright lights, fever/ vomiting, stiff neck, rapid breathing, drowsy and less responsive, stomach/ joint/ muscle pain, rash- at later stages of disease

early signs: skin very pale, blue or dusky around the lips, severe leg pain, cold hands or feet with high temp

Question 32

with symptoms of menigitis, always assume the worst

Answer 32

if you wait for culture resutls and they show meningococcal menigitis or other bacterial meningitis, its too late

Question 33

rash with meningitis

Answer 33

petechiae and purpura

Question 34

treatment protocol for patients with suspect mass lesion, immunocompromised, comatose or cannot give history OR if CSF cloudy or high probability of meningitis

Answer 34

1) decadron q6 2) ceftriaxone q12 3) vanco q12 4) ampicillin q4

Question 35

first step of protocol for patients with OUT suspect mass lesion, immunocompromised, comatose or cannot give history who have AMS, nuchal rigidity, headache and fever

Answer 35

stat lumbar puncture

Question 36

CSF WBC indicating meningitis

Answer 36

>1,000

Question 37

CSF PMN indicating meningitis

Answer 37

>100

Question 38

ratio of CSF to serum glucose in meningitis

Answer 38

<0.4

Question 39

CSF serum glucose in meningitis

Answer 39

<40

Question 40

CSF gram stain in meningitis

Answer 40

positive

Question 41

kernig

Answer 41

flex the hip 90 degrees and extend the knee will cause pain

Question 42

brudzinkski

Answer 42

flex the neck causes flexion of the hips and knees

Question 43

CSF protein indicating meningitis

Answer 43

100-500