Encephalitis Flashcards
1
Q
Define encephalitis
A
inflammation of the brain perenchyma
2
Q
What are the causes/risk factors of encephalitis
A
Viruses • Herpes simplex virus (most common cause) • Herpes zoster • Mumps • Coxsackie • Echovirus • Adenovirus • Enterovirus • Measles • Rabies • Arboviruses (transmitted by mosquitoes) e.g. Japanese B encephalitis
Bacteria
• Syphilis
• Staphylococcus aureus
Risk Factors • Immunocompromised -> CMV, EBV, toxoplasmosis • Recent travel • Animal/insect bites
3
Q
What are the symptoms of encephalitis?
A
• Fever • Meningism – headache, neck stiffness, photophobia • Vomiting • Behavioural changes (*) • Confusion (*) • Drowsiness • Focal neurological deficit e.g. hemianopia, hemiplegia, hemiparesis, cranial nerve palsies, dysphasia
4
Q
What are the signs of encephalitis?
A
• Reduced level of consciousness (deteriorating GCS) (*) • Seizures (*) • Pyrexia • Rash Meningism • Neck stiffness • Photophobia • Kernig’s sign • Brudzinski’s sign Raised ICP • Cushing reflex – hypertension, bradycardia, irregular breathing • Papilloedema
5
Q
What investigations are carried out for encephalitis?
A
- FBC - lymphocytosis
- U&Es - may reveal signs of SIADH –hyponatraemia, as encephalitis is a cause of SIADH.
- Blood Glucose - to compare with CSF Glucose
- Viral Serology - may be positive for the causative pathogen.
- Viral PCR - first Line for diagnosing encephalitis; shows the causative organism.
- MRI/CT - excludes mass lesion. HSV produces characteristic oedema of the temporal lobe on MRI.
- LP - findings depend on aetiology; may have elevated white cell count (WCC), normal/elevated protein, normal/low glucose, normal/elevated RBC
- EEG - may show epileptiform activity, e.g. spiking activity in temporal lobes. Confirms encephalitis diagnosis but doesn’t indicate the causative organism
