Lumbar Puncture Flashcards
A lumbar puncture is needed to obtain CSF for the diagnosis of what 7 things
Meningitis
Meningoencephalitis
Subarachnoid haemorrhage
Malignancy – diagnosis and treatment
Idiopathic Intracranial Hypertension
Other neurologic syndromes
Infusion of Drugs or contrast
When must a lumbar puncture not take place
Unstable patient with cardiovascular or respiratory instability
Localized skin/soft tissue infection over puncture site
Evidence of unstable bleeding disorder
Increased intracranial pressure
Chiari malformation - be cautious
When can neurological deterioration occur in a lumbar puncture
If LP is done below the level of complete spinal subarachnoid block
What must be performed before a lumbar puncture if there is suspected increased intracranial pressure
Head CT
What are the three position approaches for lumbar puncture
Lateral decubitus approach
sitting position
Paramedia approach
Where should a lumbar puncture take place
L3 - L4
L4 - L5
so is below where the spinal cord ends at L1-L2
What is the positioning of lateral decuticus approach
maximally flex spine without compromising airways
keep alignment of feet, knees and hips
Position head to left if right handed etc
What is the step procedure of a lumbar puncture
Aseptic technique – clean skin with betadine Local anaesthetic Spinal needle, angled towards umbilicus Aim for interlaminar space through ligamentum flavum Feel for ‘a give’ after lig. flavum Check for CSF Measure pressure Obtain samples Withdraw needle Dressing to cover entry site
Why does manometry occur in LP
To obtain opening and potential closing pressure
What position can pressure only be accurately measured with manometry in a lumbar puncture
Lateral debuticus postion
What is the CSF for in each of the three vials
- culture and fram stain
- glucose and protein
- cell count and differential
When is the sitting position lumbar puncture carried out
In infants
When is paramedic lateral approach lumbar puncture carried out
Patients who have calcification from repeated LP
Patients with anatomical abnormalities
What is the benefit of paramedical approach,
spinal headache is less because the holes through the dura and arachnoid tissue do not overlap
What is additional indications for lumbar punctures
Measurement of pressure
CSF drainage for raised pressure
diagnostic test for normal pressure hydrocephalus
What needs to be check before a lumbar puncture takes place
Awake & conscious patient
No focal neurological deficit (6th nerve palsy)
CT/MRI: rule out intracranial mass lesion
Ensure patient not on anticoagulants
What is the main risks of lumbar puncture
Bleeding
Infection
Nerve root injury
Retroperitoneal /
intra-abdominal injury
Brainstem herniation
What is the complication of lumbar puncutre
Headache
Backpain
Subarachnoid epidermal cysts
What is the procedure if brainstem herniation occurs in lumbar puncture
Remove needle
Raise bed to improve venous return from the brain
What is performed if suspected subdural heamatoma
CT
What is performed is suspected epidural haemtoma
MRI spine
What is the signs of meningitis in the CSF
Cloudy, turbid
WBC - lots!! – mostly polymorphs
Protein >1g/l
Glucose - low
If the CSF is bloody what does this indicate
Traumatic tap
Following SAH
What does it indicate if CSF is yellow - Xanthochromic
Yellow due to blood breakdown products
Most commonly seen in SAH
What helps a bilateral spinal headache
Supine postion
Hydration
caffeine
Epidural blood pattch
What is the best prevention of a spinal headache
passing needle beval parallel to longitudinal fibres of dura
replacing sytlet before removing needle
using small diameter needles or atraumatic needles
bed rest
If fail to complete procedure
ask someone else
radiographic guided procedure
bedside ultrasound
Why is indication for CT scanning before lumbar puncture
Focal neurological deficit - not including cranial nerve palsies
New onset seizures
Papilloedema
Abnormal level of consciousness
severe immunocompromised state
What is contradiction for a lumbar puncture
Focal symptoms suggesting a focal brain mass
Reduced conscious level suggesting intracranial pressure
Cranial nerve palsy
Why do you no perform a lumbar puncture when there are signs and symptoms to suggest an intracranial mass lesion
You might cause meningitis
You might cause a herniation syndrome and the patient could die
You might cause an air embolism
You might make the patient’s headache worse
