Infections of the nervous system Flashcards
What 3 symptoms does meningism refer to
Neck stiffness
Photophobia
Headache
Class triad of meningitis symptoms
Neck stiffness
Fever
Altered mental status
Symptoms (4) /signs (5) of meningitis
Symptoms: NECK STIFFNESS Progressive headache Nausea vomiting
Signs:
FEVER
ALTERED MENTAL STATUS
Photophobia
Meningism = neck stiffness, photophobia + headache +/- nausea/ vomiting
Petechial skin rash (in meningococcal meningitis)
Meningococcal meningitis can present with what skin feature
Petechial skin rash
Bacterial/viral causes of meningitis
Bacterial - neisseria meningitidis (meningococcus), streptococcus pneumoniae (pneumococcus)
Viral - enteroviruses
Meningitis investigations (3)
Blood culture + gram stain
Lumbar puncture + CSF culture
-CSF BACTERIAL CULTURE IS GOLD STANDARD FOR BACTERIAL MENINGITIS
CT/MRI - don’t need this if LP not contra-indicated
When not to do an LP + why
When there are signs and symptoms to suggest an intracranial mass lesion or if there’s a known brain lesion as it may cause herniation syndrome
Microbiological features of CSF in BACTERIAL meningitis (4)
Increased opening pressure >25cm H2O
High cell count (neutrophils)
Low CSF glucose (<40% of serum glucose)
High CSF protein (–> cloudy CSF)
Microbiological features of CSF in VIRAL meningitis (4)
Opening pressure – normal/increased
Cell count – high (LYMPHOCYTES)
CSF glucose – normal (60% of blood glucose)
CSF protein – slightly increased
Commonest enterovirus that causes viral meningitis
Coxsackievirus
Definition of encephalitis
Inflammation of brain substance
Symptoms (2) /signs (4) of encephalitis
Symptoms:
Preceding FLU-LIKE symptoms (cough, sore throat, runny nose etc)
Progressive headache
Signs: Fever Cerebral dysfunction - CONFUSION, abnormal behaviour, memory disturbance, decreased consciousness SEIZURES Focal symptoms/signs
Causes of encephalitis (3)
Viral - herpes simplex virus, arbovirus
Autoimmune
Investigations of encephalitis (6)
Blood culture CT +/-MRI Lumbar puncture + CSF culture EEG CSF PCR
For all suspected viral encephalitis, what is the empirical treatment
Aciclovir
Pathophysiology of autoimmune encephalitis
-2 autoantibodies
2 antibodies attacking receptors in brain:
- Anti-VGKC (voltage gated potassium channel) antibodies
- Anti-NMDA antibodies,
Encephalitis typically presents with what features (5)
Presents with acute onset of a: febrile illness (Fever) altered mental status headache, seizures, focal neurological signs
Microbiological features of CSF in VIRAL encephalitis (4)
Opening pressure – normal/increased
Cell count – high (LYMPHOCYTES)
CSF glucose – normal (60% of blood glucose)
CSF protein – slightly increased
Viral encephalitis most commonly is caused by what virus
HSV
Encephalitis is a rare complication of which type of HSV
Type 1 HSV
Name 3 examples of HSVs
varicella zoster virus (VZV),
epstein barr virus (EBV),
cytomegalovirus (CMV)
Main diagnostic investigation of viral encephalitis
CSF PCR for viral DNA
Treatment of bacterial meningitis (4)
- empirical antibiotics (2)
- other medical
Empirical antibiotics for >1 months if <50yrs:
IV ceftriaxone + IV vancomycin
IV dexamethasone
Supportive care
Treatment of encephalitis (2)
Aciclovir + supportive care (treat symptoms - fever etc)
What is a brain abscess
Localised area of pus in brain
What is a subdural empyema
Layer of pus between dura and arachnoid
Brain abscesses can cause what type of meningitis - but rarely bacterial meningitis
Reactive meningitis
Abscess vs empyema
Abscess is a collection of pus anywhere in the body, usually inside an organ or under the skin
Empyema is a collection of pus in body cavities, e.g. pleural cavity or between layer of meninges
Symptoms (1) /signs (5) of brain abscess/empyema
Symptoms:
Headache
Signs: Fever Focal symptoms/signs (focal neurological deficit) Cranial nerve palsy Signs of raised ICP -Papilloedema -Decreased conscious level Meningism
Causative microbes of brain abscess (3) + name 2 bacteria that commonly cause brain abscesses
Bacterial - often a mix of strep milleri & anaerobes
Fungal
Parasitic
5 risk factors for brain abscess
Sinusitis Dental infection Otitis media Meningitis Recent neurosurgery
Bacterial brain abscess treatment (5) + specify which of the empirical antibiotics is targeted towards anaerobes
Empirical antibiotics:
IV:
Vancomycin +
Metronidazole - for anaerobes +
Ceftriaxone
Anticonvulsant
If doesn’t respond to antibiotics then:
surgical drainage
Brain abscess investigations
- imaging (2)
- bloods (4)
CT/MRI
Blood culture
FBC - elevated WBCs
ESR - elevated
CRP - elevated
Biopsy of abscess