• Clinical presentation:
o Rapid onset headache, fever, neck stiffness, photophobia, vomiting.
o Possible petechial rash (meningococcal).
o Kernig’s & Brudzinski’s signs.
• Aetiology:
o Bacterial (common):
Adults: Neisseria meningitidis, Streptococcus pneumoniae.
Elderly/alcoholics: Listeria monocytogenes.
Post-neurosurgery/trauma: Staph aureus, Gram-negatives.
o Viral (aseptic): enteroviruses (most common), HSV-2, VZV.
• CSF findings (bacterial):
o ↓ Glucose (<50% of serum).
o ↑ Protein.
o ↑ Neutrophils.
o ↑ Opening pressure.
• Initial management:
o Empirical Abx: IV ceftriaxone ± ampicillin (for Listeria cover in elderly or immunocompromised).
o Dexamethasone if pneumococcal suspected (reduces hearing loss, mortality).
• Contraindications to immediate LP:
o GCS <12, focal neurology, papilloedema, recent seizures → do urgent CT first.
• Clinical features:
o Altered mental status, confusion, behavioural changes, seizures.
o ± fever, focal signs.
• Common causes:
o HSV-1: most common sporadic encephalitis in adults; temporal lobe involvement.
o VZV, EBV, CMV (immunocompromised).
• Diagnosis:
o CSF: lymphocytic pleocytosis, normal/↑ protein, normal glucose.
o PCR: HSV DNA.
• MRI:
o Temporal lobe hyperintensities.
• Management:
o IV aciclovir ASAP (do not delay for PCR results).
• Features:
o Early disseminated phase: facial nerve palsy (often bilateral), radiculopathy, lymphocytic meningitis.
• Diagnosis:
o Serum ELISA → confirm with Western blot.
• Treatment:
o IV ceftriaxone (for neuro involvement).
• Features:
o Rapidly progressive dementia, myoclonus, ataxia.
o Startle-induced myoclonus characteristic.
• Investigations:
o MRI: pulvinar sign ("hockey stick sign") in variant CJD.
o EEG: periodic sharp wave complexes (sporadic CJD).
o CSF: 14-3-3 protein (supportive, not definitive).
• Prognosis:
o Rapidly fatal; no effective treatment.
• Cause:
o JC virus reactivation in severe immunosuppression (CD4 <100).
• Features:
o Subacute neurological deficits (weakness, speech, vision).
o No mass effect or enhancement.
• MRI:
o Multifocal white matter lesions, no contrast enhancement.
• Features:
o Headache, confusion, focal deficits, fever.
o Common with CD4 <100, especially if not on prophylaxis.
• Imaging:
o Multiple ring-enhancing lesions (basal ganglia, corticomedullary junction).
• Treatment:
o Pyrimethamine, sulfadiazine, leucovorin.
o Empirical treatment often started if imaging suggests.
Extra Revision Pearls
• Rash with meningitis → think meningococcal septicaemia (urgent Abx even before LP).
• Empirical meningitis Abx always include Listeria cover (>60, immunocompromised, pregnancy).
• HSV encephalitis clue → temporal lobe (olfactory/gustatory hallucinations, personality change).
• Bilateral CN VII palsy → classic clue for Lyme neuroborreliosis.
• HIV CNS lesions → toxoplasmosis (multiple rings) vs lymphoma (usually solitary).
• Avoid LP in suspected raised ICP → risk of herniation.
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Author & Educational Disclaimer
Author:
Dr Phillip Cockrell BM FRCP DipClinEd
Dr Phillip Cockrell is a UK Consultant Physician in Internal Medicine, currently working at Queen Alexandra Hospital, Portsmouth University Hospitals NHS Trust. He has previously worked as a registrar across Intensive Care Medicine, Gastroenterology, Cardiology, Stroke Medicine, Acute Medicine, and Respiratory Medicine.
He has held senior leadership roles including Associate Clinical Director of the Acute Medical Unit, Clinical Director of Internal Medicine, and Chief of Medicine. Dr Cockrell has over 15 years’ experience in postgraduate medical education, having lectured extensively across the MRCP syllabus and contributed to MRCP revision teaching and course development.
Dr Cockrell holds a Bachelor of Medicine (BM), Fellowship of the Royal College of Physicians (FRCP), and a Diploma in Clinical Education (DipClinEd). His teaching approach is based on structured consolidation of complex medical topics to support efficient and effective revision for postgraduate examinations.
Purpose of this content:
The material on this page is intended solely for educational purposes to support revision for the MRCP (UK) Part 1 examination. It reflects examination-relevant principles of internal medicine and is designed to aid learning and pattern recognition.
Medical disclaimer:
This content is designed for postgraduate medical examination revision and does not constitute medical advice, diagnosis, or treatment guidance and must not be used as a substitute for professional clinical judgement, local guidelines, or specialist consultation. Clinical decisions should always be made in the context of individual patient circumstances and current national guidance.
