Infections of the Nervous System Flashcards
Clinical features of encephalitis
Flu-like symptoms for 4-10 days Fever and progressive headache Progressive cerebral dysfunction - confusion, abnormal behaviour, memory disturbance, depressed conscious level Seizures Focal signs
Differential diagnoses for encephalitis
Infective e.g. viral Inflammatory e.g. limbic encephalitis Metabolic e.g. uraemic Malignancy e.g. metastases Migraine Post-ictal
Antibodies present in autoimmune encephalitis
Anti-VGKC and anti-NMDA receptor antibodies
Features of Anti-VGKC autoimmune encephalitis
Frequent seizures
Amnesia
Altered mental state
Features of Anti-NMDA receptor autoimmune encephalitis
Flu-like prodrome Prominent psychiatric features Altered mental state Seizures Progression to movement disorder and coma
How is encephalitis caused by HSV (herpes simplex virus) diagnosed?
Lab diagnosis by PCR of CSF for viral DNA
Treatment of encephalitis caused by HSV
Acyclovir on strong clinical suspicion
Morbidity/mortality rate of encephalitis caused by HSV
over 70% mortality and high morbidity if untreated
Where does the HSV lie latent after primary infection and what does this mean there is a risk of?
Lies latent in trigeminal or sacral ganglion after primary infection, risk of reactivation
Investigation of encephalitis
Blood cultures
Imaging - CT, MRI
LP
EEG
Encephalitis treatment
Acyclovir
What is a brain abscess?
Localised area of pus within the brain which causes high-pressure symptoms
When would a fever be present in brain abscess?
If there was systemic infection
Clinical features of brain abscess
Fever Headache Seizures Dysphasia Hemiparesis Papilloedema False localising signs Depressed conscious level Meningism Features of underlying source of infection e.g. poor dentition
Differential diagnoses for brain abscess
Any focal lesion, most commonly a tumour
Subdural haematoma
Causes of brain abscess
Penetrating head injury
Spread from adjacent infection e.g. dental, sinusitis
Blood borne infection e.g. bacterial endocarditis
Neurosurgical procedure
Brain abscess investigation
MRI, CT
Investigate source
Blood cultures
Biopsy
What is the risk of a biopsy of a brain abscess?
Drainage of pus and removal of needle puts patient at risk of spread of infection
Infective organisms in brain abscess
Streptococci - 70%, especially streptococcus Milleri group
Anaerobes
Treatment of brain abscess
Surgical drainage if possible
Penicillin or ceftriaxone to cover strep infection
Metrondiazole for anaerobe infection
What is meningitis?
Inflammation/infection of the meninges
Clinical features of meningitis
Fever, neck stiffness, altered mental status Short history of progressive headache May be associated with fever and meningism Cerebral dysfunction Cranial nerve palsy Seizures Focal neurological deficits Petechial skin rash
Differential diagnoses of meningitis
Infective - bacterial, viral or fungal
Inflammatory - sarcoidosis
Drug induces - NSAIDs, IVIG
Malignant - metastatic, haematological
Causes of meningitis
Bacterial
Viral (enteroviruses)
Bacterial organisms that cause meningitis
Neisseria meningitidis
Streptococcus pneumoniae
Investigation of meningitis
Blood cultures
Lumbar puncture
Opening pressure in LP of bacterial meningitis
Increased
Opening pressure in LP of viral meningitis and encephalitis
Normal or increased
Cell count in LP of bacterial menignitis
High, mainly neutrophils
Cell count in LP of viral meningitis
High, mainly lymphocytes