Lumbar Puncture

Preparation
- - Indications
  - Contraindications including blood thinners
  - Investigations: CT-H & coagulation studies
  - Consent- capacity & risks
  - Prepare Equipment
Procedure
- - Positioning- patient & proceduralist
  - Palpate and mark spot
  - Aseptic Technique
  - Needle insertion
  - CSF Collection
Post Procedure
- - Immediate
  - CSF Intepretation

Preparation

Indications

CNS infection- Meningitis & Encephalitis
Subarachnoid Haemorrhage
Papilledema/ raised ICP signs- IIH (Idiopathic Intracranial Hypertension)
Neurological disorders- e.g. Multiple Sclerosis (MS) , Guillain-Barré Syndrome, CNS vasculitis
Normal Pressure Hydrocephalus
CNS Lymphoma
Access to give intrathecal medication- haematological cancers, anaesthesia (spinal/ epidural)

Contraindications

Absolute

Capacity and lack of consent
Local lumbar cellulitis around area of needle insertion
Signs of raised ICP

Relative

Platelets > 50, INR < 1.5,
Recent anticoagulation/ antiplatelet
Agitation
Given invasiveness- Frailty & End of Life Care

Medication timescales

DOAC: 48hrs
Clopidogrel: 7 days
Aspirin: nil
Warfarin- INR < 1.5

Prior Investigations

CT-Head
Coagulation screen

A CT-H is usually required prior to a lumbar puncture to rule out a space occupying lesion compressing the CSF circulation and its associated risk of coning. A CT-H can be a low yield investigation and delay treatment in bacterial meningitis or viral encephalitis. You can go straight to lumbar puncture if there are:

No risk factors for an evolving space occupying lesion
- Immunocompromise is cited here
Symptoms or signs of raised intracranial pressure
- New focal neurology including seizures or posturing
- Abnormal pupillay reactions
- GCS < 10
- Progressive and sustained fall in consciousness

Equipment Checklist

Varies per hospital

Preparation

Consent form
Sterile gloves - useful to have a spare and set for assistant
Chlorhexidine sterility applicators (chloraprep) x2
Catheter pack for drapes
Trolley

Local Anaesthetic

Lidocaine 1% 10mls vial x1
Syringe- 10mls
Needles- drawing up (blue), superficial (blue), deep (green)

Procedure

Lumbar puncture needles- worth having spare and longer length depending upon BMI
Introducer- not all trusts use these
CSF Mamometer
Containers (double check for your hospital!) - x4 white top (lable 1-4) + grey blood tube
Specimen blood forms + bags + Xanthochromia envelope
Plaster

Consent

In order to give informed consent an individual with capacity must be told the risks and benefits of all treatment options, including doing nothing. Capacity is the ability to understand, retain, weight up and communicate risks and is presumed over the age of 16 years.

Risks of lumbar puncture

Treatment failure
Low pressure headache
Damage to local structures
Bleeding- spinal haematoma
Pain
Infection- spinal abscess
Local anaesthetic reaction

This is in my experience the most common risk and can be tedious having to repeat the procedure. Increased BMI is the commonest reason for failure and eventually this can be escalated to anaesthetics.

A persistent CSF drip can be associated with a spinal headache.

Local anaesthetic is used to alleviate this. Usually only minimal oral pain is given to ensure the patient is alert and able to warn for damage to local structures.

Aseptic technique is used. Small risk of spinal abscess- monitor for ongoing pain.

Damage to local structures is minimized by using an introducer with an atraumatic needle. If feeling pain down one leg, is not a sign of damage but can help localise the needle.

Bleeding is similarly reduced by using an introducer with an atraumatic needle.

An allergic reaction is a risk associated with all medications and this is unlikely if you've had local anaesthetic before.

Benefits

Diagnosis- particularly in Meningitis & Encephalitis; IIH and Subarachnoid Haemorrhage
Therapeutic- IIH (Idiopathic Intracranial Hypertension),
Giving medications: chemotherapy, anaesthesia

Alternative treatment options

Do nothing- watch and wait
Alternative investigations
- Neuroimaging- e.g. an MRI head can be done if onset of headache is > 72hrs in subarachnoid haemorrhage
Give therapy without lumbar puncture- e.g. CNS infection, could be advised in e.g. severe frailty

If approaching out of hours, can inform biochemistry/ microbiology to come in to process samples.

Procedure

Positioning

Patient

Ensure patient is lying with spine parallel to end of the bed
Knees tucked to chin, neck flexed but comfortable
Pillow under neck & between legs

Proceduralist

Patient's spine level with eye line (raise bed)
Chair

Palpate spot

Usually go L3/4 then L4/5
L4 is level with ASIS- can be useful to palpate & mark prior to positioning
Feel spinal processes
Press syringe plastic to indent skin to create mark
Double check equipment/ procedure

Aseptic Technique

Open catheter pack and open items onto pack with non touch technique- if doing solo, remember to open local anaesthetic
Wash hands & don sterile gloves
Clean area with chlorhexidine
Apply drapes
Re-palpate mark

Local Anaesthetic

Assistant open anaesthetic and draw up using drawing needle
Draw up anaesthetic into syringe
Apply superficially to mark
Apply deep to mark

Needle Insertion

Insert Lumbar Puncture needle:
- Inbetween spinus processes
- At an angle pointing towards umbilicus
- At a horizontal plane
Aim to feel pop of spinal muscle before CSF
Adjust in horizontal access if hitting bone
Remove needle if very painful
If CSF pressure not required, can be attempted sitting up

CSF Flowing

Attach CSF Mamometer to attain opening pressure
Then collect 10 drops per white bottle and 20 drops for culture in order of labelled number, 10 drops for grey bottle and contain number 4 in an envelope for Xanthochromia
Remove needle & apply plaster

Post Procedure

Immediate

Patient Advice

Lie flat on bed for one hour (nil evidence for caffeine)
Drink plenty water and can have simple analgesia- paracetamol/ ibuprofen

Documentation

Noting number and spinal level of attempts
Volume of local anaesthetic given

Samples

Send to lab via porters
Inform biochemistry & microbiology +- handover results to chase
Fingerprick glucose to pair with CSF glucose.

CSF Interpretation

Opening Pressure

Normal is 12-20
IIH ideally > 30
Other causes include infection, malignacy and GBS

Glucose

Reduced in bacterial and TB meningitis: bacteria 'eat the glucose'
Preserved in viral meningitis
Can be reduced in fungal CNS infections

Protein

Most cells contain protein, so usually raised if organisms in CNS
Bacteria and TB significantly raises protein
Viruses can cause normal or mild protein eleveation

Microscopy

A normal WCC is reassuring against infection
RCC can be a sign of a traumatic tap rather than blood in the brain; trauma RCC decrease with each sample 1-4
Viruses cause lymphocytosis and bacteria cause raised neutrophils

Culture & sensitivities, and PCR

CNS is usually sterile so any organism would be abnormal

Xanthochromia

This degrades with UV light and should be in an envelope
Some hospitals do not run this overnight

Discussion

Is a CT-Head required?

Greig et al found [4] in their department in the last 6 months, 64 patients were indicated for a lumbar puncture and all received a CT-Head. 6 of these CT-Heads showed a Subarachnoid Haemorrhage and therefore the lumbar puncture was not required. In all of these cases it was considered a probable diagnosis. Therefore Greig et al suggest a CT-H may only change management if it is to rule out a subarachnoid haemorrhage.

NICE guidance [5]