Lumbar Puncture

Question 1

What are the indications for a lumbar puncture?

Answer 1

1. ) administration of spinal or epidural anesthesia
2. ) collection of CSF in order to diagnose infectious conditions such as meningitis, encephalitis, myelitis
3. ) inflammatory conditions such as multiple-sclerosis, Guillan-Barre,
4. ) oncologic disease such as leukemia, or
5. ) metabolic diseases.
6. ) LP also allows for intrathecal administration of antibiotics or chemotherapeutic agents.

Question 2

What are the contraindications for lumbar puncture?

Answer 2

Cardiorespiratory compromise
Signs of cerebral herniation
Focal neurologic signs
Bleeding diathesis or use of anticoagulants
Previous lumbar surgery (should be referred to an interventional radiologist)

Question 3

What two advantages does the lateral recumbent position have?

Answer 3

Prevention of post-puncture headache

Allows you to obtain an opening cerebrospinal pressure

Question 4

Where is the needle inserted?

Answer 4

Between L3 and L4, or between L4 and L5, because is this is below the end of the spinal cord.

Question 5

What is the conus medullaris?

Answer 5

The cone-shaped end of the spinal cord, found at approximately the level of L1

Question 6

Direct the needle at approximately an angle of __ degrees, aiming it toward the patient’s _________.

Answer 6

15 degrees

Umbilicus

Question 7

What is the cauda equina?

Answer 7

The bundle of spinal nerves which continue from the end of the spinal cord.

Question 8

What is the filum terminale?

Answer 8

The thin filament anchor from the conus medullaris to the coccyx.

Question 9

Either use a pencil-tipped needle, or ensure that the bevel of the needle is in the ________ _____.

Answer 9

sagittal plane

Question 10

How much CSF is typically collected?

Answer 10

3 - 4 ml

Question 11

List 7 possible complications of a lumbar puncture.

Answer 11

Herniation
Pain, local or referred
Headache
Bleeding
Infection
Subarachnoid epidermal cyst
CSF leakage
Cardiorespiratory compromise

Question 12

List the layers the needle must go through in order to obtain CSF.

Answer 12

Skin and subcutaneous tissue
Supraspinous ligament
Interspinous ligament (between the spinous processes)
Ligamentum flavum
Posterior epidural space (including the internal vertebral venous plexus, dura mater, and arachnoid mater)
Into the subarachnoid space, and between the nerve roots of the cauda equina

Question 13

Why does the patient need to arch their back during the procedure?

Answer 13

This widens the gap between the spinous processes.

Question 14

What equipment is required for a lumbar puncture?

Answer 14

Sterile gloves
Spinal needle with a stylet (3.5 in. for adults), preferably 22-gauge 
Chloroprep
Sterile drapes 
Collection tubes for CSF
Manometer (if indicated) 
Skin-marking pen
Anesthetic agents

Question 15

After inserting the needle into the subarachnoid space, if the flow of CSF is poor, you should…

Answer 15

…rotate the needle 90 degrees, since a nerve root may be obstructing the opening.

Question 16

Why should CSF never be aspirated with the syringe?

Answer 16

Even a small amount of negative pressure can precipitate a hemorrhage.

Question 17

Despite the widely held belief, bed rest after a lumbar puncture does not…

Answer 17

…decrease the incidence of headaches after lumbar puncture.

Question 18

What conditions may warrant consultation with an interventional radiologist to do the procedure?

Answer 18

Ankylosing spondylitis
Degenerative disk disease
Kyphoscoliosis
Morbid obesity
Osteoarthritis
Previous lumbar surgery

Question 19

Headache is the most common complication of lumbar puncture. What’s the incidence of it within 48 hrs post-procedure?

Answer 19

36.5%

Question 20

Subarachnoid epidermal cysts can be avoided by…

Answer 20

…using a needle with a stylet.