1(E): Encephalitis, Cerebral Abscess, Toxoplasmosis Flashcards
Define encephalitis
Inflammation brain parenchyma
What regions of the brain are more commonly affected by encephalitis
- Inferior Frontal
- Medial Temporal
What is the age distribution of encephalitis
<20 years-old and >50 years-old
What are the two types of encpehalitis
Viral
Autoimmune
What causes 90% of viral encephalitis in adults
HSV1
What can cause viral encephalitis in neonates
HSV2
What can cause viral encephalitis in immunocompromised
CMV
What are the two types of autoimmune encephalitis
NMDA encephalitis
Pareneoplastic encephalitis
What are the symptoms of encephalitis
- Strange behaviour: hyper-sexual, hypomanic
- Psychiatric
- Decrease GCS
- Fever, Vomitting, Headache
- Focal Neurological signs
- Seizures
What bloods should be taken in suspected encephalitis
PCR
Blood Culture
Toxoplasmosis IgM
What imaging is taken for encephalitis
CT
What will be seen on CT imaging
Petechial haemorrhages in middle-temporal and inferior-frontal lobe
What will be seen on LP in encephalitis
Lymphocytosis
Raised Protein
What will be seen on EEG in encephalitis
periodic 2Hz discharges
What is used to manage encephalitis
acyclovir
How quickly should acyclovir be started for suspected encephalitis
30-minutes
What is a cerebral abscess
Suppurative collection of pus within brain parecchyma
What typically causes cerebral abscess
Secondary to infections:
- Otogenic
- Oral
- Sinusitus
- Meningeal
What are rare causes of cerebral abscess
Skull Fracture
Septic Foci
Neurosurgery
What pathogen is most common cause of cerebral abscess
S. Viridian’s (50%)
Others:
- Staph. Aureus (15%)
What does strep viridian’s cause prior to cerebral abscess
Sinusitis
What can cause cerebral abscess if immunocompromised
Toxoplasmosis
What is the triad of signs/symptoms in cerebral abscess
- Raised WCC
- Fever
- Raised ICP
What headache is present in cerebral abscess
Dull persistent headache
What does rupture of cerebral abscess cause
If abscess ruptures, headache suddenly worsens and is associated with meningism
What are symptoms of raised ICP
- Vomitting
- Papilloedema
- Altered mental state
What are focal neurological deficits associated with cerebral abscess
CN3 palsy
CN6 palsy
= occur due to raised ICP
Apart from raised ICP, what other neurological feature may be present
Seizures
What is a systemic feature of cerebral abscess
Fever
Explain spread of pathogen in cerebral abscess
Pathogen can either spread via direct contamination (eg. skull fracture) or haematogenously
What happens 3-5 after pathogen infiltration
Early cerebritis - infiltration of neutrophils and oedema
What happens in late cerebritis (2-3W)
necrosis, liquefaction and macrophage infiltration. Then eventually a fibrotic capsule will form around the lesion
What are 3 blood tests for cerebral abscess
- FBC
- Blood Culture
- CRP
What will be seen on CT or MRI in cerebral abscess
Ring-enhancing lesions in peripheries
What is difference between cerebral abscess on CT/MRI and in toxoplasmosis gondii
Toxoplasmosis gondii = ring-enhancing lesions in basal ganglia. Cerebral abscess = ring-enhancing lesions in periphery
How is cerebral abscess managed
- Refer to neurosurgery for urgent drainage and biopsy
- IV Antibiotics
- Some recommend dexamethasone to reduce ICP (Controversial)
What causes cerebral toxoplasmosis
Toxoplasmosis Gondii
What is the most common neurological disorder associated with HIV
Cerebral toxoplasmosis
What causes cerebral toxoplasmosis
Infection toxoplasmosis Gondii
How is toxoplasmosis gondii usually transmitted
Cat faeces
Unpasteurised milk
Insufficiently cooked meat
What does CD4 count have to be in HIV to enable cerebral toxoplasmosis
<100
How does cerebral toxoplasmosis present clinically
Headache
Focal neurological deficit
Seizure
Change in mental status
What is first-line investigation for toxoplasmosis gondii
Sabin-Feldman Dye Test
Looks for amount IgG toxoplasmosis gondii that can bind to methylene blue
What other investigation is ordered in cerebral toxoplasmosis
CT/MRI
What does CT/MRI in toxoplasmosis gondii show
Ring-enhancing lesions in basal ganglia
Why type of organism is toxoplasmosis gondii
Protazoan
How is cerebral toxoplasmosis managed
Pyrimidine and Sulphadiazine for 6-Weeks
