Meningitis OSCE — Recognition, Lumbar Puncture, and Emergency Treatment

Why Meningitis Is a Core OSCE Station

Bacterial meningitis has a mortality of 10-15% and neurological morbidity in 30% of survivors. It is a time-critical emergency — outcome is directly related to the time to antibiotic administration. OSCEs examine it in acute management stations, data interpretation (CSF results — which type of meningitis?), and communication stations (explaining meningitis to a patient's family). Examiners mark speed of antibiotic initiation and correct interpretation.

Clinical Features — The Classic Triad and Beyond

Classic triad (present in only 44% of adult cases):

• Headache
• Fever
• Neck stiffness (nuchal rigidity)

Additional features:

• Photophobia and phonophobia
• Nausea and vomiting
• Altered consciousness (GCS impairment)
• Seizures
• Cranial nerve palsies (III, VI, VII)
• Non-blanching petechial or purpuric rash — Neisseria meningitidis

Clinical Examination Signs

Kernig's Sign

• Patient supine, hip and knee flexed to 90 degrees
• Attempt to passively extend the knee
• Positive: resistance or pain in the hamstrings and back — indicates meningeal irritation

Brudzinski's Sign

• Patient supine
• Passive flexion of the neck by examiner
• Positive: involuntary flexion of the hips and knees — indicates meningeal irritation

Sensitivity of both signs is low (under 50%) — a negative test does not exclude meningitis.

The Non-Blanching Rash

Differential for non-blanching rash:

• Meningococcal septicaemia (most dangerous)
• Henoch-Schönlein Purpura (HSP)
• Immune thrombocytopaenic purpura (ITP)
• Vasculitis
• Fat embolism

Contraindications to Immediate LP

Do not perform LP if any of the following are present — give antibiotics first and arrange CT head:

• Papilloedema
• Focal neurological deficit
• GCS below 13
• Seizure within 1 hour
• Severely immunocompromised
• Active coagulopathy or platelets below 50

CSF Interpretation

Immediate Management

Step 1: Antibiotics — Do Not Delay

Adults (age 16-50):

• IV ceftriaxone 2 g BD — covers the commonest organisms (Neisseria meningitidis, Streptococcus pneumoniae)
• Duration: 10-14 days for bacterial meningitis

Add IV amoxicillin/ampicillin if:

• Age above 50 or below 3 months
• Immunocompromised
• Known alcohol excess
• Reason: covers Listeria monocytogenes (cephalosporins do not cover Listeria)

Add IV aciclovir 10 mg/kg TDS — if herpes simplex encephalitis cannot be excluded (altered consciousness, focal neurology, temporal lobe changes on MRI).

Step 2: Dexamethasone

• IV dexamethasone 0.15 mg/kg QDS for 4 days
• Give with or just before the first dose of antibiotics
• Reduces neurological complications (hearing loss, vasculitis, cerebral oedema)
• Especially important for pneumococcal meningitis
• Stop if bacterial meningitis not confirmed on culture

Step 3: Supportive Care

• IV fluids (avoid hypotension which worsens cerebral perfusion)
• Seizure management if needed
• Raised ICP management (head of bed 30 degrees, mannitol 0.5-1 g/kg if deteriorating, ITU for ventilation)
• Isolation (droplet precautions) until 24 hours of antibiotics given

Contact Tracing and Chemoprophylaxis

Indication: all close contacts (household members, intimate contacts) of confirmed meningococcal meningitis.

Regimen:

• Ciprofloxacin 500 mg single dose (first-line in UK — single dose, convenient)
• Rifampicin 600 mg BD for 2 days (alternative — more side effects, drug interactions)
• Ceftriaxone 250 mg IM single dose (in pregnancy)

Frequently Asked Questions

"What is the difference between meningitis and encephalitis?"

Meningitis is inflammation of the meninges (pia mater, arachnoid, dura) and typically presents with meningism (neck stiffness, photophobia, Kernig's and Brudzinski's signs) and fever, but with preserved consciousness. Encephalitis is inflammation of the brain parenchyma itself — it presents with altered consciousness, personality change, focal neurological deficits, and seizures, often with less prominent meningism. Herpes simplex encephalitis characteristically affects the temporal lobes. Both can coexist (meningoencephalitis).

"Why does bacterial meningitis cause low CSF glucose?"

Bacteria in the CSF consume glucose as an energy source, directly depleting CSF glucose. In addition, bacterial meningitis triggers inflammatory changes that impair the blood-brain barrier transport of glucose into the CSF. The key threshold is a CSF:serum glucose ratio below 0.4 (normally above 0.6). Always check blood glucose at the time of LP to calculate this ratio accurately.

"What organisms cause bacterial meningitis and why does it vary by age?"

Neonates (under 3 months): Group B Streptococcus, Escherichia coli, Listeria monocytogenes. Children/young adults: Neisseria meningitidis (especially serogroup B and C). Adults: Streptococcus pneumoniae (most common in adults over 30). Elderly and immunocompromised: Listeria monocytogenes (cover with amoxicillin), Streptococcus pneumoniae. The vaccines (MenB, MenC, MenACWY, PCV13) have dramatically reduced the incidence of the covered serogroups.

"How do you differentiate meningism from a stiff neck due to other causes?"

Meningism causes pain and restriction on passive flexion of the neck (forward flexion), with Kernig's and Brudzinski's positive. Lateral and rotational movement is relatively preserved. Cervical spondylosis causes restriction of all cervical movements equally. Neck muscle spasm (e.g., from tension headache or trauma) usually resolves with analgesia. Torticollis causes predominantly rotational restriction. In meningism, the resistance to neck flexion is due to dural irritation, not bony or muscular pathology.

"What is the role of PCR in meningitis diagnosis?"

CSF and blood PCR for meningococcal DNA and pneumococcal DNA can detect bacterial infection even after antibiotics have been started (when culture may be negative). Blood PCR for Neisseria meningitidis remains positive for up to 24 hours after antibiotics. PCR for HSV, VZV, Enterovirus, and other viruses guides viral meningitis and encephalitis management. PCR is the most sensitive test in partially treated meningitis and should always be sent even when culture is likely negative.

Related Posts

• Glasgow Coma Scale OSCE — assessing and monitoring consciousness in the meningitis patient
• Blood Results Interpretation OSCE — interpreting inflammatory markers and metabolic changes in meningitis
• Basic Life Support OSCE — managing the patient with meningococcal septicaemia and cardiovascular collapse