Pathology Project

Pathology Project

Rahul Varshney

Roll no. 66

Definition

In medicine, a lumbar puncture (colloquially known as a spinal tap) is a diagnostic and at times therapeutic procedure that is performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis, or occasionally as a treatment ("therapeutic lumbar puncture") to relieve increased intracranial pressure.

HistoryThe technique for lumbar puncture was first described by the

German physician Heinrich Quincke; he first reported his experiences at an internal medicine conference in Wiesbaden in 1891. He subsequently published a book on the subject.

The lumbar puncture procedure was brought to the United States by Arthur H. Wentworth M.D., an assistant professor at the Harvard Medical School, based at Childrens Hospital. In 1893, he published a long paper on diagnosing cerebro-spinal meningitis by examining spinal fluid. His career took a nosedive, however, when the antivivisectionists prosecuted him for having obtained spinal fluid from children. He was acquitted, but he was disinvited to the then forming Johns Hopkins Medical School where he would have been the first professor of pediatrics.

Indications • Lumbar puncture, or spinal tap, is used to diagnose some

malignancies, such as certain types of brain cancer and leukemia, as well as other medical conditions that affect the central nervous system. It is sometimes used to assess patients with certain psychiatric symptoms and conditions.

• It is also used for injecting chemotherapy directly into the CSF. This type of treatment is called intrathecal therapy.

Other medical conditions diagnosed with lumbar puncture include:

• viral and bacterial meningitis

• syphilis, a sexually transmitted disease

• bleeding (hemorrhaging) around the brain and spinal cord

• multiple sclerosis, a disease that affects the myelin coating of the nerve fibers of the brain and spinal cord

• Guillain-Barré syndrome, an inflammation of the nerves

Risks

Significant risks include (but are not limited to) the following:

• Post–spinal tap headache

• Nerve root trauma (eg, previous surgery in the area, scar tissue)

• CNS infection (eg, immunocompromised patients)

• Cranial, cervical, and lumbar subdural (more common) hematomas (eg, patients on anticoagulation therapy)

• Also possible but very rare are discitis, system/portal venous gas (following a traumatic tap), clinical deterioration in the presence of dural arteriovenous fistula, symptomatic pneumocephalus in a patient with normal pressure hydrocephalus, cranial nerve palsies (4th and 6th)

Contraindications

• 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.

Steps in performing a lumbar puncture

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 10-

30% 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 equipment)

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.

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 nail).

The diagrams on the following slides provide illustrations

Site for Lumbar Puncture in a Child

Note: Having the patient curl around a pillow can help ensure proper position.

posterior iliac crest

Site for Lumbar puncture in an Adult

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.

A patient undergoes a lumbar puncture at the hands of a neurologist. The reddish-brown swirls on the patient's back are tincture of iodine (a disinfectant)

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 2-3mm, 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 check:

— 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.

Measuring opening pressure

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— Chemistry

— Microbiology

— Antibody testing (in particular Japanese Encephalitis IgM)

• Collect extra tube of CSF to hold in lab for possible later testing.

Collecting CSF into sterile tubes

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

• Anti-JEV IgM ELISA

• JEV RT-PCR (If available)

  Normal Bacterial Viral TB

Cells 0-5 WBC/mm3 >1000/mm3 <1000/mm3 25-500/mm3

Polymorphs 0 predominate early +/- increased

Lymphocytes 5 late predominate increased

Glucose 40-80 mg/dl decreased normal decreased

66% < 40% Normal < 30%

Protein 5-40 mg/dl increased +/-increased increased

Culture negative positive negative +TB

Gram stain negative positive negative positive

CSF plasma : glucose ratio

Summary of typical CSF findings

Diagnostics • Increased CSF pressure can indicate congestive heart failure,

cerebral edema, subarachnoid hemorrhage, hypo-osmolality resulting from hemodialysis, meningeal inflammation, purulent meningitis or tuberculous meningitis, hydrocephalus, or pseudotumor cerebri.

• Decreased CSF pressure can indicate complete subarachnoid blockage, leakage of spinal fluid, severe dehydration, hyperosmolality, or . Significant changes in pressure during the procedure can indicate tumors or spinal blockage resulting in a large pool of CSF, or hydrocephalus associated with large volumes of CSF. Lumbar puncture for the purpose of reducing pressure is performed in some patients with idiopathic intracranial hypertension (also called pseudotumor cerebri.)

• The presence of white blood cells in cerebrospinal fluid is called pleocytosis. A small number of monocytes can be normal; the presence of granulocytes is always an abnormal finding. A large number of granulocytes often heralds bacterial meningitis. White cells can also indicate reaction to repeated lumbar punctures, reactions to prior injections of medicines or dyes, central nervous system hemorrhage, leukemia, recent epileptic seizure, or a metastatic tumor. When peripheral blood contaminates the withdrawn CSF, a common procedural complication, white blood cells will be present along with erythrocytes, and their ratio will be the same as that in the peripheral blood.

Diagnostics….•Measurement of chloride levels may aid in detecting the presence of tuberculous meningitis. •Glucose is usually present in the CSF; the level is usually about 60% that in the peripheral circulation. A fingerstick or venipuncture at the time of lumbar puncture may therefore be performed to assess peripheral glucose levels in order to determine a predicted CSF glucose value. Decreased glucose levels can indicate fungal, tuburculous or pyogenic infections; lymphomas; leukemia spreading to the meninges; meningoencephalitic mumps; or hypoglycemia. A glucose level of less than one third of blood glucose levels in association with low CSF lactate levels is typical in hereditary CSF glucose transporter deficiency. •Increased glucose levels in the fluid can indicate diabetes, although the 60% rule still applies. •Increased levels of glutamine are often involved with hepatic encephalopathies, Reye's syndrome, hepatic coma, cirrhosis and hypercapnia. •Increased levels of lactate can occur the presence of cancer of the CNS, multiple sclerosis, heritable mitochondrial disease, low blood pressure, low serum phosphorus, respiratory alkalosis, idiopathic seizures, traumatic brain injury, cerebral ischemia, brain abscess, hydrocephalus, hypocapnia or bacterial meningitis. •The enzyme lactate dehydrogenase can be measured to help distinguish meningitides of bacterial origin, which are often associated with high levels of the enzyme, from those of viral origin in which the enzyme is low or absent

Diagnostics….•Changes in total protein content of cerebrospinal fluid can result from pathologically increased permeability of the blood-cerebrospinal fluid barrier, obstructions of CSF circulation, meningitis, neurosyphilis, brain abscesses, subarachnoid hemorrhage, polio, collagen disease or Guillain-Barré syndrome, leakage of CSF, increases in intracranial pressure or hyperthyroidism. Very high levels of protein may indicate tuberculous meningitis or spinal block. •IgG synthetic rate is calculated from measured IgG and total protein levels; it is elevated in immune disorders such as multiple sclerosis, transverse myelitis, and neuromyelitis optica of Devic. •Numerous antibody-mediated tests for CSF are available in some countries: these include rapid tests for antigens of common bacterial pathogens, treponemal titers for the diagnosis of neurosyphilis and Lyme disease, Coccidioides antibody, and others. •The India ink test is still used for detection of meningitis caused by Cryptococcus neoformans, but the cryptococcal antigen (CrAg) test has a higher sensitivity. •CSF can be sent to the microbiology lab for various types of smears and cultures to diagnose infections. •Polymerase chain reaction (PCR) has been a great advance in the diagnosis of some types of meningitis. It has high sensitivity and specificity for many infections of the CNS, is fast, and can be done with small volumes of CSF. Even though testing is expensive, it saves cost of hospitalization.

Spinal Needles

Acknowledgements

• www.JEproject.org

• eMedicine: Lumbar puncture

• Medstudents: Procedures: Lumbar puncture

• Wikipedia