Lumbar Puncture and CSF Analysis Quiz

Lumbar Puncture, CSF Analysis and Interpretation

• Learning Outcomes:
  • Recognize when lumbar puncture (LP) is necessary, including contraindications and risks to health.
  • Employ appropriate precautions to protect the patient and oneself during LP.
  • Describe the diagnostic pathway for processing CSF specimens from patients with CNS infections.
  • Interpret biochemical, cellular, and preliminary microbiological results of CSF analysis.

Clinical Case 1

• Patient: 63-year-old female with new-onset headache, photophobia, neck stiffness, and fever.
• Examination: Fever of 39°C, heart rate of 120/min, positive Kernig's sign, no localizing neurological signs or rash.
• Investigations: White blood cell count of 16 x 10^9/L (normal range 4-11).

Differential Diagnosis

• Likely Diagnosis: Bacterial meningitis, due to the patient's systemic illness (fever, tachycardia) and elevated white blood cell count.

Investigations for Bacterial Meningitis

• CSF Analysis: Gram stain, cell count, protein and glucose, culture, PCR (bacterial: N. meningitidis, Streptococcus pneumoniae, Listeria monocytogenes; viral).
• Blood Culture: Assess for bacteremia.
• Blood PCR: Additional testing when available.

CSF Transportation

• Transport CSF samples in leak-proof bags to the laboratory as soon as possible.
• Do not send via the chute system.

CSF Laboratory Analysis

• Appearance: Clear, cloudy, purulent, bloody.
• Microscopy: Cell count and differential (morphology of cells), Gram stain.
• Biochemistry: Protein, glucose, spectrophotometry.
• Culture and Susceptibility: Identifying pathogens and their responses to antibiotics.
• Additional Tests: PCR (bacterial, virus, fungi), antigen/antibody tests (e.g., cryptococcal, neuroborreliosis), cytology, biomarkers.

Normal CSF Findings in Adults

• Appearance: Clear and colorless.
• Cellular: Normally acellular; however, <5 white cells and <5 red cells are acceptable if obtained by LP.
• Protein: 15-45 mg/dL.
• CSF:Serum Glucose Ratio: > 0.6.

Raised Protein/Low Glucose CSF - Possible Causes

• Multiple sclerosis
• Bacterial meningitis
• Tuberculosis meningitis
• Subarachnoid hemorrhage
• CNS fungal infections

Management of Meningitis

• ABCs: Airway, Breathing, Circulation; IV fluids, possibly ventilation.
• Antibiotics: Administered promptly, ideally before/with other antibiotics.
• Steroids: Administered before or with antibiotics
• ICU Support: Especially for organ support related to bacteremia or sepsis.
• Seizure Management: If necessary.
• Correction of Coagulation Abnormalities: As needed.

Case 1: Empirical Therapy (Adults)

• 3rd-generation Cephalosporin (Cefotaxime/ceftriaxone): Because it crosses the blood-brain barrier.
• Vancomycin: For possible penicillin-resistant pneumococci.
• Amoxicillin: Addition, if Listeria suspected, patient is elderly, immunocompromised, or pregnant.
• Steroids: Prior to the first dose of antibiotics.

Case 1: CSF Results (Day 1)

• Cell count: 540 white blood cells/mm³ (abnormal).
• CSF protein: 80 mg/dL (abnormal).
• CSF glucose: 0.3 mmol/L (low).
• Blood glucose: 5.7 mmol/L.

Likely Pathogen

• Bacterial: Given the high white blood cell count, low CSF glucose, and presence of bacteria on the Gram stain.

Typical Bacterial Pathogens

• Neonates: Group B Streptococcus, E. coli, Listeria monocytogenes.
• Children/Adolescents: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae.
• Older Adults/Immunocompromised, Pregnant: Streptococcus pneumoniae, Neisseria meningitidis, Listeria monocytogenes, Staphylococcus aureus.

Case 1: CSF Gram Stain (Day 1)

• Gram-positive diplococci.

Case 1 Culture Results (Day 2)

• Streptococcus pneumoniae detected .

Case 1: Day 3 Therapy Changes

• Stop vancomycin and amoxicillin.
• Consider if oral antibiotics can be started if the patient is stable.
• Minimum 14 days of intravenous antibiotics for uncomplicated pneumococcal meningitis.

Potential Complications of Lumbar Puncture

• Back pain
• Bleeding
• Cerebral herniation
• Infection
• Post-LP headache

Clinical Case 2

• Patient: 53-year-old male with headache, neck stiffness, fever, and reported episode of shaking/unresponsiveness.
• Examination: Fever of 39.5°C, HR 130/min, BP 90/60 mm Hg, positive Kernig's sign.
• Investigations: White blood cell count 20 x 10^9/l, CRP 150 mg/L.

Contraindications to Lumbar Puncture

• Relative: Platelet count 20-40 x 10^9/L, thienopyridine therapy.
• Absolute: Non-communicating obstructive hydrocephalus, uncorrected bleeding diathesis, anticoagulant therapy, platelet count <20 x 10^9/L, spinal stenosis or spinal cord compression above the puncture level, local skin infections, spinal or cranial developmental abnormalities.

Clinical Case 3

• Patient: 45-year-old female with acute onset confusion, increasing drowsiness, and pyrexia. Headache for the previous 2 days.
• Examination: Temperature 38°C, BP 100/70, HR 90, not oriented. No rashes or other skin lesions. No sick contacts or recent travel history.

Case 3: Likely Pathogens (HPSC data 2019)

• Potential pathogens include varicella/herpes zoster virus, enteroviruses, herpes simplex virus, parechovirus, human herpes virus type 6, and tick-borne encephalitis virus. 

Case 3: Microbiological Investigations

• CSF for Gram stain, cell count, protein & glucose, culture, PCR (viral & bacterial).
• Blood culture.

Case 3: Radiological Investigations

• MRI brain is a useful tool in diagnosis.

Case 3: HSV Encephalitis MRI Findings

• Asymmetrical changes in the medial temporal lobes.

Case 3 CSF Results

• CSF Appearance: cloudy
• Erythrocyte count: 3 cells/mm³
• Leucocyte count: 60 cells/mm³
• Polymorphs: 2%
• Lymphocytes: 98%
• Other cells: 0%
• CSF Total Protein: 60 mg /dL
• CSF glucose: 65 mg/dL
• Blood glucose: 75 mg/dL
• Gram stain: negative

Case 3 Empirical Therapy

• Acyclovir 10 mg/kg t.d.s. IV

Case 3: HSV-DNA detected by PCR

• Continue acyclovir.
• Anti-infective therapy for 21 days, administer intravenously.
• No antibiotic prophylaxis for contacts.
• Notify public health.

Clinical Case 4

• Patient: 36-year-old male with acute onset headache, photophobia, and pyrexia, receiving chemotherapy for lymphoma.
• Examination: Temperature 38°C, BP 90/70, HR 100, positive Kernig's sign. No other significant findings.
• Investigations: WBC 6 x 10^9/L, platelets 3 x 10^9/L, CRP 250 mg/L.

Clinical Case 5

• Patient: 38-year-old female with chronic headache, low-grade pyrexia, weight loss, and increasing confusion with a history originally from India.
• Examination: Temperature 37.8°C, BP 110/80, HR 90, positive Kernig's sign. No other significant findings.
• Investigations: WBC 12 x 10^9/L, CRP 60 mg/L (normal ranges).

Case 5 CSF Results

• CSF Appearance: cloudy
• Erythrocyte count: 5 cells/mm³
• Leucocyte count: 2000 cells/mm³
• Polymorphs: 4%
• Lymphocytes: 96%
• Other cells: 0%
• CSF Total Protein: 60 mg /dL
• CSF glucose: 20 mg/dL
• Blood glucose: 65 mg/dL

Additional tests in case 5

• CSF Ziehl-Neelsen or auramine stain
• CSF TB PCR
• CSF TB culture
• Chest X-ray (CXR)
• sputum for TB culture if productive

Test your knowledge on the indications and procedures of lumbar puncture, including patient safety and CSF analysis. This quiz also covers the interpretation of results in cases of central nervous system infections, especially bacterial meningitis. Enhance your understanding of clinical diagnostics with real case scenarios.