Encephalitis Flashcards
Define Encephalitis
Inflammation of the brain parenchyma associated with neurological dysfunction
Aetiology of Encephalitis
Infection:
Viral: Herpes/HSV (UK), Arbovirus (worldwide)
Bacterial: Neisseria meningitides, TB< syphillis
Fungal: cryptococcus, histoplasma
Parasitic: toxoplasma gondii, amoebic
Para-infectious: acute disseminated encephalomyelitis
Prion disease: Creutzfeldt Jakob disease
Paraneoplastic: Anti-NMDR, Anti-GABA
Risk factors for Encephalitis
Age <1 or >65 Immunodeficiency Viral infection Blood/bodily fluid exposure Organ transplant Animal/insect bite Recent travel Season Swimming in freshwater
Symptoms of Encephalitis
Often self-limiting
Confusion
Altered mental state
Fever
Seizure
Symptoms of underlying disease e.g. parotitis (mumps) | lymphadenopathy (bartonella) | Optic neuritis (ADEM) | Jaundice (leptospirosis) | Arthritis (SLE) | Seizure (HSV) | Cough (URTI, LRTI)
Signs of Encephalitis
Fever
Rash (vesicular | maculopapular | malar | petechial | erythema migricans | erythema nodosum | erythema multiforme)
Altered mental state/fluctuating GCS (cognitive dysfunction | memory disturbance | behavioural changes | apathy | personality change | psychotic behaviour | hallucination)
Focal neurological deficit (Aphasia | hemianopia | hemiparesis | ataxia | brisk reflexes | Babinski’s sign | CN deficits
Investigations for Encephalitis
CT brain: often hypodensity, depends on cause - used as screening tool and ordered in all patients with altered mental status
MRI: depends on aetiology
LP: depends on aetiology
Throat swab: detect viruses
Nasopharyngeal aspirate + PCR: detect respiratory viruses
Sputum, urine and stool cultures
FBC: elevated WBC (infectious cause), lymphocytosis (viral), eosinophilia (parasitic) Blood smear: exclude malaria LFTs: elevated CMV, EBM, coxiella Blood cultures: +ve for cause Serology
CXR: non-infectious or infectious causes - TB, sarcoid
EEG: background slowing
CT/PET: bg cancer
Brain biopsy: diagnosis, not used often
