Infections Of The Nervous System Flashcards
What is meningitis
Inflammation/infection of meninges
What is encephalitis
Inflammation/infection of brain substance
What is myelitis
Inflammation/infection of spinal cord
What is the clinical presentation of encephalitis (6)
- Flu-like prodrome (4-10days) (prodrome = symptom indicating onset of disease or illness)
- progressive headache associated with fever
- +/- meningism
- Progressive cerebral dysfunction (confusion, abnormal behaviour, memory disturbance, depressed conscious level)
- seizures
- focal symptoms/signs
What are meningism symptoms (3)
Neck stiffness
Photophobia
Nausea + vomitting
What are focal symptoms/signs
Movement changes
Paralysis
Weakness
Loss of muscle control
Increased/loss of muscle tone
Involuntary movements (e.g. tremors)
What is difference in the onset of viral encephalitis and bacterial meningitis
Onset of viral encephalitis is slower and cerebral dysfunction is a more prominent feature
What is the priority when investigating encephalitis? What are the investigations
Priority is to exclude (and treat) infection
Blood cultures
imaging (CT and MRI)
Lumbar puncture
EEG
What is the most common cause of encephalitis in Europe
Herpes simplex
What is a brain abscess
Localised area of puss within the Brian
What is a Subdural empyema
Thin layer of pus between the dura and arachnoid membranes over the surface of the brain
What is the clinical presentation of cerebral abscesses (7)
Fever
Headache
Focal symptoms/signs
Seizures
Signs of raised ICP
Meningism may be present (especially with empyema)
Features of underlying source (e.g. dental, sinus, ear infection)
What are the common causes of brain abscesses and empyema
Penetrating head injury
Spread from adjacent infection (dental, sinusitis, otitis media)
Blood borne infection
Neurosurgical procedure
Which organism causes most brain abscesses
Streptococci (70%)
How are cerebral abscesses diagnosed (4)
Imagine (CT or MRI)
Investigate source
Blood cultures
Biopsy (drainage of pus)
How are brain abscesses managed
Surgical drainage if possible
Abx - high dose for penetration (penicillin or ceftiaxone to cover streps - Metronidazole for anaerobes)
(Culture and sensitivity test on aspirate provide a useful guide)
High mortality without appropriate treatment
What is the clinical presentation of meningitis
Classic triad of: fever, stiff neck, altered mental status
History of progressive headache associated with fever and meningism
Cerebral dysfunction is common
LOOK FOR A PETECHIAL SKIN RASH (pinpoint round spots that appear on skin as result of bleeding - see photo)
Which bacteria often cause meningitis
Neisseria meningitidis (meningococcus)
Streptococcus pneumoniae (pneumococcus)
Which viruses often cause meningitis
Enteroviruses
What is the investigation for meningitis (what is the priority)
Priority to exclude (and treat) infection
Blood cultures
Lumbar puncture (CSF culture/microscopy)
No need for imaging if no contraindications to lumbar puncture)
What is the bacteria responsible for Lyme disease
Borrelia burgdorferi
What is stage 1 of Lyme disease
Early localised infection (1-30days)
Characteristic expanding rash at the site of the tick bite (erythema migrans)
50% will have flu like symptoms in the first week
What is stage 2 of Lyme disease
Early disseminated infection (weeks-months)
One or more organ systems become involved
- haematological or lymphatic spread
Muskuloskeletal and neurological involvement (PNS > CNS)
What is stage 3 of Lyme disease
Chronic infection (months - years, occurring after latent period)
Neurological and muskuloskeletal involvement
IMPORTANT - LYME DOES NOT CAUSE CHRONIC FATIGUE SYNDROME
What are the investigations for Lyme (4)
Serological tests
CSF lymphocytosis
MRI brai/spine (if CNS involved)
EMG (if PNS involved)
What is the treatment for Lyme
Prolonged abx treatment
(IV ceftriaxone + oral doxycycline)
What is a common prion disease
Creutzfeldt-Jakob disease (CJD)
What is a prion
Transmissible proteinaceous particle (prion)
What are the clinical features of sporadic CJD (6)
usually >60
Early behavioural abnormalities
Rapidly progressive dementia
Motor abnormalities
Cortical blindness
Seizures
What motor abnormalities present in CJD
Cerebellar ataxia
Extrapyramidal (tremor, rigidity, bradykinesis, dystonia)
Pyramidal (weakness, spasticity, hyper-reflexia)
What is the prognosis of CJD
Rapid progression
Death within 6mths
