Lumbar puncture Flashcards
Doherty, Diagnostic Lumbar Pncture (2014) Wright, Cerebrospinal fluid and lumbar puncture: a practical review (2012) UpToDate
Lumbar puncture indicaions
A) To investigate or exclude meningitis
Bacterial Viral Tuberculous Cryptococcal Chemical Carcinomatous
B) To investigate neurological disorders
Multiple Sclerosis Sarcoidosis Guillian Barre, Chronic Inflammatory Demyelinating Polyneuropathy Mitochondrial Disorders Leukencephalopathies Paraneoplastic Syndromes
C) To demonstrate and manage disorders of Intracranial Pressure
Idiopathic Intracranial Hypertension
Spontaneous Intracranial Hypotension
D) To administer therapeutic or diagnostic agents*
Spinal anaesthesia Intrathecal chemotherapy Intrathecal antibiotics Intrathecal baclofen Contrast media in myelography or cisternography
Lumbar pncture anatomy: which tissues does the needle pierce?
The Lumbar Puncture needle pierces in order: skin subcutaneous tissue supraspinous ligament interspinous ligament ligamentum flavum epidural space containing the internal vertebral venous plexus dura arachnoid the subarachnoid space
Tests frequently performed on CSF
- Microbiology
Cell count, culture and sensitivity - Biochemistry
Protein and glucose - Xanthochromia
Spetrophotometry - Oligoclonal bands
Investigation of CNS inflammation - Cytology
Investigation of malignant meningitis - Cytospin
Investigation of CNS lympoma - Viral PCR
PCR for viral DNA - ACE
Investigation of neurosarcoidosis - Lactate
Investigation of neurodegenerative disorders
Post lumbar puncture headache: Incidence, risk factors, symptoms, management
Incidence: 32%
Risk Factors:
younger age, female gender, and headache before or at the time of the procedure
Symptoms:
The symptoms of PLPH usually develop within 24 hours of Lumbar Puncture, and the natural history is for symptoms to resolve by about 10 days. The pain is usually diffuse, global or bitemporal headache, which can be accompanied by nausea, altered hearing, tinnitus, photophobia or neck stiffness. Low pressure may produce diplopia due to traction on the fourth or sixth cranial nerve
Management:
Maintaining a supine posture
Oral or intravenous fluids
Symptomatic management with analgesia and antiemetics
There is some evidence for the use of intravenous caffeine or intravenous theophylline
The definitive treatment if conservative management fails is epidural blood patching
Lumbar puncture: complications
Local discomfort and radicular pain Spinal hematoma Meningitis Post lumbar puncture headache Epidermoid tumor Abducens palsy
Lumbar puncture: Red flags
Platelet count <40
International normalized ratio (INR) >1.5
Local skin infection
Local developmental abnormality, e.g., myelomeningocele
Raised intracranial pressure (with a pressure gradient across the CNS compartments)
When is a head CT before LP recommended?
Suspicion of raised intracranial pressure Age >60 years Immunocompromised patient Previous CNS disease Recent seizure Reduced consciousness Papilloedema Abnormal neurological examination
Anticoagulant managemet prior to LP
- There is no clear evidence that low-dose aspirin given
alone increases hemorrhagic risk following LP - It is recommended that thienopyridine derivatives, e.g., clopidogrel and ticlopidine, should be discontinued for 7 and 14 days respectively
- Discontinuing platelet glycoprotein IIb/IIIa inhibitors for 8 h prior to LP, e.g., tirofiban, has also been suggested.
- Unfractionated heparin is routinely discontinued for 2–4 h prior to LP
Post LP, unfractionated heparin should be delayed by at least 1 h to minimize hematoma risk - Low-molecular-weight heparin at prophylactic dose is discontinued for 12 h and at therapeutic dose for 24 h to allow normalization of coagulation
**No evidence to guide how long after thrombolysis a LP could be conducted
Lumbar puncture: Risk of CNS herniation pathophysiology
CNS herniation occurs if there is a change in the pressure gradient within the CNS compartment sufficient to cause movement of CNS tissue out of its normal position.
This can involve brain, spinal cord, and nerve root tissue, often with devastating and fatal consequences. In these cases, an abnormal pressure gradient already exists, and it is the further transient lowering of pressure, as a result of CSF withdrawal from an LP, which allows the raised pressure compartment above the LP to move along the pressure gradient and consequently move CNS tissue.
This is in contrast to states of uniformly raised intracranial pressure within the whole CNS compartment, e.g., idiopathic intracranial hypertension (IIH), where no internal pressure gradient has developed so is it is safe to perform an LP
Normal Intracranial Pressure in adults
10-20 cm
Differential diagnosis
of neurological disease
according to intracranial
pressure: Hypotension
A) Primary
- CSF leak
Atraumatic/ spontaneous
B) Secondary - CSF leak Post LP Post surgical Trauma
- Post-coital
- Drugs Acetazolamide Bendroflumethiazide Furosemide Indometacin Topiramate
Differential diagnosis
of neurological disease
according to intracranial
pressure: Normotension
- Normal pressure hydrocephalus
- CNS demyelination
- Bechet’s syndrome
- CNS vasculitis
- Neuropathy
- Encephalitis
Differential diagnosis
of neurological disease
according to intracranial
pressure: Hypertension
- Idiopathic intracranial hypertension
- Intracranial hypertension without papilloedema (IWOP)
- Intracranial space-occupying lesiona
- Choroid plexus papilloma
- Arachnoid granulation agenesis
- Hydrocephalus (communicating and noncommunicating)
- Infective meningitis Acute bacterial Cryptococcal Tuberculosis Viral Fungal
- Cerebral venous sinus thrombosis
- Acute hemorrhagic leucoencephalitis
- Neurosarcoidosis
- Guillian-Barre´ syndrome
- Malignant meningitis
Which parameter indicates subdural hematoma and how to interpret it correctly
Subdural hematoma is indicated by xanthochromia
Xanthochromia is correctly assesed if
• Normal serum bilirubin levels.
• Delaying CSF sampling until the red cells have broken
down to bilirubin (12-h post-event is recommended).
• Using the least blood-stained CSF sample, usually the
last CSF sample collected.
• Transporting the CSF sample in the dark with minimal
agitation.
• Analyzing the sample with spectrophotometry rather
than visual inspection.
Normal CSF Findings
Appearance:
Clear
White cells:
0-5
Protein:
<0,5 g/L (23-38 mg d/L)
Glucose
>60-75% of serum glucose
