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Flashcards in Meningitis- Week 2 Deck (43)
1

what is meningitis

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

2

the meninges consist of 3 parts

the pia, arachnoid and dura maters

3

bacterial meningitis- when?

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

4

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

streptococcus pneumoniae neisseria meningitides

5

bacterial meningitis- where?

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

6

 normal rate of CSF production, where does it circulate?

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

7

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

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

8

old major cause before vaccination?

haemophilus influenzae

9

classic triad

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

10

important caveat

clinical picture is often "unimpressive" when patient is first seen

11

HINT

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

12

pneumococcal meningitis- s. pneumoniae

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

13

meningococcal meningitis- neisseria meningitis

characteristic skin changes, petechiae and palpable purpura

14

listeriosis

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

15

to determine what kind

perform and interpret CSF examinations

16

normal findings of CSF

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

17

CSF abnormalities

>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

18

pleocytosis

an elevated CSF WBC

19

xanthochromia

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

20

indications for lumbar puncture

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

21

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

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

22

contraindications for LPs

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)

23

Glasgow Coma Scale

3 is the worst

15 is the best

eye opening, motor response, verbal response

24

bottom line for CSF

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)

25

CSF analysis- color

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**

26

CSF analysis- pressure

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

27

CSF analysis- cell count

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)

28

CSF analysis- final considerations

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

29

CSF- more final considerations

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

30

2 major tests performed in chemistry lab on CSF are

determination of protein and glucose concentrations

31

meningococcal disease: warning signs

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

 

 

32

with symptoms of menigitis, always assume the worst

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

33

rash with meningitis

petechiae and purpura

34

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

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

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

stat lumbar puncture

36

CSF WBC indicating meningitis

>1,000

37

CSF PMN indicating meningitis

>100

38

ratio of CSF to serum glucose in meningitis

<0.4

39

CSF serum glucose in meningitis

<40

40

CSF gram stain in meningitis

positive

41

kernig

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

42

brudzinkski

flex the neck causes flexion of the hips and knees

43

CSF protein indicating meningitis

100-500