Infections Of The Nervous System Flashcards
What microbes cause meningitis?
Neisseria meningitidis (meningococcus) Streptococcus pneumoniae
Viral - enteroviruses
What the traid symptoms of meningism?
stiff neck
photophobia
headache
What is the clinical presentation of meningitis?
Short history of progressive headache with fever and meningism (stiff neck, photophobia, nausea & vomiting)
Cerebral dysfunction (dementia, delirium, decreased conscious level)
Cranial nerve palsies
Seizures
Focal neurological symptoms/signs
Petechia rash
How would you investigate a rash suspected of meningitis and what would classify it as meningitis?
Petechial rash which doesnt blanch with tumbler test
What are the differential diagnoses of meningitis?
Bacterial, viral or fungal infection
Sarcoidosis
NSAIDS, IVIG
Metastatic, haematological i.e. leukaemia, lymphoma, myeloma
What investigations are carried out for suspected meningitis?
Blood cultures
Lumbar puncture
CT if contraindications for LP
What are the clinical features of encephalitis?
Flu like prodone 4-10 days Progressive headache with fever \+/- meningism Progressive cerebral dysfunction (confusion, abnormal behaviours, memory loss) Seizures Focal symptoms/signs
What is the difference in the clinical presentation of meningitis vs encephalitis?
Encephalitis will present with more neurological cerebral dysfunction but meningitis can present with this too
But meningitis will present with a petechial rash but encephalitis wont
Onset of encephalitis is also typically slower
What are the microbiological causes of encephalitis?
Viral;
- herpes simplex virus
- enteroviruses
- arboviruses
Autoimmune
What antibodies cause autoimmune encephalitis?
Anti - VGKC
Anti NMDA receptor
What is the difference in the presentation of bacterial encephalitis vs viral encephalitis?
Onset of viral encephalitis is generally slower and cerebral dysfunction is a more prominent feature
What are the features of meningism?
Neck stiffness
Photophobia
Nausea & Vomiting
Why can meningitis cause a CN palsy?
Because the cranial nerves run within the meninges so they can be affected
What viruses can cause meningitis?
Enteroviruses
What is the most common cause of encephalitis?
HSV (herpes simplex virus)
What antibody is responsible for causing encephalitis which can cause amnesia?
Anti-VGKC
What are the contraindications for a LP?
Focal symptoms or signs suggesting a brain mass
Reduced concious level suggesting raised ICP
Severe immunocompromised state
What are the cell counts like in meningitis and encephalitis?
Both are high
Meningitis = mainly neutrophils
Encephalitis = mainly lymphocytes
What is the glucose levels like in meningitis and encephalitis?
Meningitis = reduced Encephalitis = 60% is normal
In which infection (meningitis or encephalitis) is the protein high?
Meningitis
In encephalitis it is slightly increased
What si the treatment for bacterial meningitis?
At least 2 weeks of penicillin
What is the treatment for viral encephalitis caused by HSV?
Aciclovir
Where des the HSV virus remain latent after primary infection?
Trigeminal or sacral ganglion
How is viral encephalitis investigated?
PCR of CSF
What causes non paralytic meningitis?
Enteroviruses
I.e. poliovirus, coxsackie virus, echoviruses
How is arbovirus encephalitis transmitted?
Via a vector such as mosquito or tick
What is the difference between a brain abscess and subdural empyema?
Brain abscess is a localised area of pus within the brain
Subdural empyema is a thin layer of pus between the dura and arachnoid membrane over the brain surface
Why might you not get fever or neck stiffness with a brain abscess?
Because it is localised
What are the clinical features of a brain abscess / empyema?
Fever
Headache
Focal symptoms i.e. seizures, dysphasia, hemiparesis etc
Signs of raised ICP i.e. papiloedema, false localising signs, depressed conscious level
Meningism
Features of underlying source i.e. dental, sinus or ear infection
What are the causes of a brain abscess?
Penetrating head injury
Spread from adjacent infection i.e. dental, sinusitis, ottitis media
Blood borne infection i.e. bacterial endocarditis
Neurosurgical procedure
How do you diagose a brain abscess?
CT/ MRI
Blood cultures
Biopsy (by draining pus)
What is the management for a brain abscess?
Surgical drainage
Penicillin or ceftriaxone for streptococci
Metronidazole for anaerobes
What drug is given to treat a brain abscess caused by streptococci?
Penicillin or ceftriaxone
What drug is given to treat a brain abscess caused by anaerobes?
Metronidazole
What is the stage 1 presentation of Lyme disease?
Expanding rash at site of tick bite
Flu like symptoms i.e. fever, myalgia, arthralgia, headache, fever, chills, neck stiffness
What investigations would you carry out if you suspected Lyme disease?
Serological tests CSF lymphocytosis PCR of CSF MRI brain/spine Nerve conduction studies
What is the treatment for Lyme disease?
Prolonged antibiotics (3 weeks) IV ceftriaxone Oral doxycycline
What is the treatment for neurosyphillis?
High dose penicillin
What is the pre exposure prevention and post exposure treatment for rabies encephalitis?
Pre exposure active immunisation with killed vaccine
Post exposure treatment ;
- wash wound
- give active rabies immunisation
- give rabies immunoglobulin (passive immunisation)
What is the clinical presentation of botulism?
Descending symmetrical flaccid paralysis
Pure motor.
Respiratory failure
Autonomic dysfunction - pupil dilatation
What is the treatment for botulism?
Anti-toxin
Penicillin / metronidazole
Radical wound debriment
What is the difference in the presentation of Guilin barre syndrome and botulism?
GBS will have ascending paralysis with sensory involvement whereas botulism is descending paralysis with no sensory involvement
What bacteria is responsible for botulinum toxin and what type of bacteria is this?
Clostridium botulinum
Anaerobic, spore producing gram positive bacillus
How do you diagnose botulinum toxin?
Nerve conduction studies
Culture from debrieded wound
What are the modes of infection of botulism toxin?
Food borne
Infantile (intestinal colonization)
IV drug injections
What does rabies infection present with?
Ascending paralysis with encephalitis
