Infections of The Nervous System Flashcards Preview

Systems Nervous System > Infections of The Nervous System > Flashcards

Flashcards in Infections of The Nervous System Deck (23)
Loading flashcards...
1
Q

What is the definition of meningitis, encephalitis and myelitis?

A
  • Meningitis = inflammation / infection of meninges
  • Encephalitis = inflammation / infection of brain substance
  • Myelitis = inflammation / infection of spinal cord

In reality the distinction is artificial and patients often have a

mixture

2
Q

What are the clinical features of meningitis?

A

•Clinical Features

–“classical triad” – fever, neck stiffness and altered mental status

–Present with a short history of progressive headache associated with

  • Fever (>38º) and
  • Meningism (neck stiffness, photophobia, nausea and vomiting)

Neck stiffness is examined by passively bending the neck forward

–Cerebral dysfunction (confusion, delirium, declining conscious level) is common and GCS is <14 in 69%

–Cranial nerve palsy (30%), seizures (30%), focal neurological deficits (10-20%) may also occur

–Look for a petechial skin rash (Tumbler test)

•hallmark of meningococcal meningitis, but can also occur in viral meningitis

3
Q

What are the differentials for meningitis?

A

Infective: bacterial, viral, fungal

Inflammatory: Sarcoidosis

Drug induced: NSAIDs, IVIG

Malignant: Metastatic, haemotological

4
Q

What are the bacterial causes of meningitis?

A

Neisseria meningitidis (meningiococcus)

Streptococcus pneumoniae

5
Q

What are the viral causes of meningitis?

A

Include enteroviruses

6
Q

What are the clinical features of encephalitis?

A

–Flu-like prodrome (4-10days)

–Progressive Headache associated with fever

  • +/- meningism
  • Progressive cerebral dysfunction

–Confusion

–Abnormal behaviour

–Memory disturbance

–Depressed conscious level

  • Seizures
  • Focal symptoms / signs
7
Q

How does viral encephalitis compare with bacterial meningitis?

A

Viral encephalitis is generally slower than bacterial meningitis and cerebral dysfunction is a more prominent feature

Cerebral dysfunction = Confusion, abnormal behaviour, memory disturbance, depressed conscious level

8
Q

What are the differentials for encephalitis?

A

–Infective: Viral (most common is HSV)

–Inflammatory: Limbic encephalitis (Anti VGKC Anti NMDA receptor)

ADEM

–Metabolic: Hepatic, Uraemic, Hyperglycaemic

–Malignant: Metastatic, Paraneoplastic

–Migraine

  • Post ictal - The postictal state is the altered state of consciousness after an epileptic seizure. It usually lasts between 5 and 30 minutes, but sometimes longer in the case of larger or more severe seizures, and is characterized by drowsiness, confusion, nausea, hypertension, headache or migraine, and other disorienting symptoms
9
Q

What are the antibodies associated with autoimmune encephalitis?

A

Anti VGKC (voltage gated potassium channel)

Anti - NMDA

10
Q

What are the feautres of Anti - VGKC?

A

Frequent seizures

Amnesia (not able to retain new memories)

Altered mental state

11
Q

What are the features of NMDA receptor autoimmune encehpalitis?

A

Flue like prodrome

Prominent psychiatric features

Altered mental state and seizures (as seen in anti VGKC)

Progressing to a movement disorder and coma

12
Q

What are the investigations for meingitis?

A

Blood cultures (searching for bacteraemia)

Lumbar punture (CSF culture/microscopy)

No need for imaging if there is no contraindications for LP

13
Q

What are the investigations for encephalitis?

A

Blood cultures

Imaging (CT scan and MRI)

Lumbar puncture

EEG

14
Q

What are contraindications to lumbar punture?

A

Indications for CT before a lumbar puncture:

  • Focal neurological deficit, not including cranial nerve palsies (focal signs suggest a focal brain mass)
  • New onset seizures
  • Papiloedema - swelling of the optic disk caused by increase in intracranial pressure (very rarely unilateral)
  • Abnormal level of consciousness, interfering with proper neurological examination (glasgow coma scale less than 10) - reduced conscious level suggests raised intracranial pressure

Severe immunocomprimised state

15
Q

What are the CSF findings in meningitis for bacterial meningitis and viral meningitis and encephalitis?

A
16
Q

What is the commonest cause of encephalitis in europe?

A

Herpes simples virus

17
Q

How is lab diagnosis of herpes simplex virus achieved?

A

PCR of CSF for viral DNA

18
Q

What is treatment of herpes simplex virus encephalitis?

A

Aciclovir on clinical suspicion

19
Q

What does type 1 and type 2 HSV viruses cause?

A

–cold sores (type 1 >> 2)

–genital herpes (type 1 & 2)

20
Q

Where does the virus simplex virus remain latent?

A

In the trigeminal or sacral ganglion

21
Q

Which type of herpes simplex virus is likely to cause encaphalitis?

A

•Encephalitis is a rare complication of HSV

– other than neonates, nearly all caused by type 1

22
Q

How do enteroviruses spread?

A

Faecal oral route

23
Q

Give examples of enteroviruses

A

•Include polioviruses, coxsackieviruses and echoviruses

They do not cause gastroenteriris

They may cause non-paralytic meningitis

Decks in Systems Nervous System Class (48):