Diagnosis of Encephalitis: Review of Neurological Exam and

Instructions for users
• This slide presentation provides an overview
of performing a lumbar puncture.
• Below many of the slides, there are notes to
explain the information in the slide.
• You should adapt the presentation for your
own use.
Diagnosing Encephalitis:
Review of Lumbar Puncture (LP)
Learning Objectives
Participants will:
• Know how to prepare a patient for LP.
• Revise the steps for safely performing an LP.
• Know what tests can be performed on CSF
that is collected.
Relative contraindications to
lumbar puncture
• Evidence of a space-occupying lesion such as
tumor or brain abscess.
• Signs of increased intracranial pressure.
Unequal pupils, elevated blood pressure, slow heart
rate, irregular breathing, posturing
• Cardiopulmonary instability.
• Soft tissue infection at puncture site.
• Significant, uncontrolled bleeding disorder.
*See note
Steps in performing a lumbar
1. Obtain informed consent.
2. Gather materials.
3. Position patient.
4. Administer local anesthetic.
5. Insert needle with sterile technique.
6. Measure opening pressure.
7. Collect cerebrospinal fluid (CSF).
Informing the patient
• Reason for the lumbar puncture:
Collection and testing of spinal fluid are standard management
for encephalitis patients to direct treatment (e.g., if CSF profile
suggests bacterial infection).
• Potential complications:
The most common side effect is a headache which occurs in 1030% of adult patients. It is managed with bed rest and analgesics
and usually disappears in a few days.
Soreness of the lower back may also occur.
Other risks, including infection, bleeding, leakage of spinal fluid or
damage to the spinal cord, are extremely rare.
• Children tolerate lumbar punctures really well.
Materials to prepare
• Materials for sterile technique (gloves, mask)
• Spinal needle
• Manometer (typically used in patients > 2 years of age)
• Three-way stop-cock
• Sterile drapes
• Anesthetic
• Solutions for skin sterilization
• Adhesive dressing
• Sponges
• Get assistant (to help position patient and handle
1. Place the patient in the left
lateral position
• The lower back should be as close to the edge of the
bed as possible.
• Ask the patient to curl up and hug his knees as close
to the chest as possible (“fetal position”).
• The neck should be flexed forward.
• If physician is left-handed, the right lateral position
should be used.
• The patient may also be positioned sitting upright.
However, the lateral position is preferred for accurate
measurement of opening pressure.
Note: The most important part of performing a successful lumbar puncture is
good position! Be sure you give feedback to your assistant to ensure
the patient is in proper fetal position.
2. Locate the site
• Find and palpate the posterior iliac crest.
• Move your finger down and palpate the L4
spinous process.
• Mark the puncture site at L4-5 or L3-4 (e.g.
put a slight indent in the skin with your finger
The diagrams on the following slides provide illustrations
Site for
in a Child
posterior iliac crest
Note: Having the patient curl
around a pillow can help
ensure proper position.
Source: Harriett lane - 16th edition
Site for Lumbar puncture in an Adult
Source: http://www.postgradmed.com
Indicating site of
posterior iliac
crest and
puncture site
Source: http://www.emedicinehealth.com
3. Prepare sterile area
• Use iodine to swab in a circle from the L4-5
area outwards.
• Cover an area of 20cm diameter.
• Once dried, remove the iodine with alcohol
(to avoid introduction of iodine into the
subarachnoid space).
• Put on sterile gloves.
• Drape the patient.
4. Anesthetize the area
• Anesthetize the skin.
• Anesthetize between the spinous processes.
Insert the needle.
Draw back to ensure it has not reached the
subarachnoid space.
Gradually withdraw the syringe while slowly
injecting anesthetic into the interspace.
Note: For infants local anesthetic is not needed. Instead,
may give sugar water solution orally to help soothe.
5. Insert the lumbar puncture needle
• Insert the LP needle, with stylet, in the midline.
• Direct the point of the needle to the umbilicus.
• Keep the needle parallel to the ground.
• Continue to insert until a slight pop is felt.
• Withdraw the stylet slightly to be sure the needle is in
the subarachnoid space.
• If there is no CSF return, advance the needle about 23mm, and withdraw the stylet again.
• When CSF begins to flow, attach a three-way stop-cock.
Note: Only remove the spinal needle when the stylet is inserted.
Notes on LP needle insertion
• If the needle strikes bone, withdraw it to just below the
skin, then reinsert.
• If blood slowly drips from the needle when the stylet is
removed, discard the needle and start again.
• Never aspirate CSF with a syringe, as a nerve root may
be trapped against the needle and injured.
• If you are unsuccessful in reaching subarachnoid space
Is the needle aimed towards the umbilicus?
Is the needle in the midline?
Is the needle parallel to the ground?
6. Measure the pressure
• Attach a manometer to the hub of the needle
(via three-way stop-cock).
• Have your assistant gently extend the patient’s
leg and return his neck to a neutral position.
• Ensure the patient is relaxed and watch for
good respiratory variation of the fluid level as
the patient breathes normally.
• Check the CSF pressure.
• Remove the manometer.
Note: Typically used in patients older than 2 years of age.
Source: http://www.emedicinehealth.com
7. Collect cerebrospinal fluid (CSF)
• Allow CSF to flow into sterile tubes.
• Rubbing the fontanel of an infant may help
increase flow of CSF.
• CSF can be collected for
Antibody testing (in particular Japanese Encephalitis
• Collect extra tube of CSF to hold in lab for
possible later testing.
CSF into
Source: http://www.emedicinehealth.com
8. Final steps
• Replace stylet and withdraw the needle.
• Massage the puncture point with a
sterile sponge.
• Cover with a Band-Aid.
• Advise adult patients to lie flat in bed for
3 hours and limit activity for 24 hours to
minimize headache.
Note: Children may resume their usual activity.
9. Recording
• Label tubes with patient information and
date of collection.
• Record immediate results.
Appearance of CSF
– ?clear ?turbid
Pressure of CSF
Note: pressures over 200mm H2O are probably abnormal
Laboratory tests on CSF
• Cell count, differential
• Glucose
• Protein
• Gram stain
• India ink preparation
• Stain for acid-fast bacilli
• Viral, bacterial, and fungal cultures
• JEV RT-PCR (If available)
Summary of typical CSF findings
0-5 WBC/mm3
+/- increased
40-80 mg/dl
CSF plasma :
glucose ratio
< 40%
< 30%
5-40 mg/dl
Gram stain
Please include the following acknowledgement
if you use this slide set:
This slide set was adapted from a slide set
prepared by PATH’s Japanese Encephalitis
For information: www.JEproject.org

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