Infections of the nervous system

Question 1

what is meningitis

Answer 1

inflammation/ infection of the meninges

Question 2

what is encephalitis

Answer 2

inflammation/infection of the brain substance

Question 3

what is myelitis

Answer 3

inflammation/infection of the spinal cord

Question 4

what is the classic triad presentation for meningitis

Answer 4

classic triad

- fever, neck stiffness, altered mental state

Question 5

what are other signs and symptoms of meningitis

Answer 5

short history of progressive headache

fever

meningism - neck stiffness, photophobia, vomiting, nausea

cerebral dysfunction

GCS <114

cranial nerve palsy, seizures

rash - petechial

Question 6

what can cause meningitis

Answer 6

infective - bacrerial, viral, fungal

inflammatory - sarcoidosis

drug induced - NSAIDS, IVIG

malignant - metastatic, haematological

Question 7

what bacteria can cause meningitis

Answer 7

neisseria meningitidis

streptococcus pneumoniae

Question 8

what are viral causes of meningitis

Answer 8

enteroviruses

Question 9

what are the clinical features of encephalitis

Answer 9

flu-like prodrome (4-10 days)

progressive headache with fever

+/- meningism

progressive cerebral dysfunction

seizures

focal symptoms/signs

Question 10

what is the difference between onset of viral encephalitis and bacterial meningitis

Answer 10

viral encephalitis slower than bacterial meningitis

cerebral dysfunction more prominent in viral encephalitis

Question 11

what can cause encephalitis

Answer 11

infective - viral - HSV

inflammatory - limbic encephalitis (anti VGKC, anti NMDA receptor)

metabolic - hepatic, uraemic, hyperglycaemic

malignant - metastatic, paraneoplastic

can occur in migraine

can occur after seizure

Question 12

what are the two antibodies involved in auto-immune encephalitis and how do they present

Answer 12

Anti-VGKC

• frequent seizure
• amnesia
• altered mental state

Anti-NMDA

• flu like prodrome
• psychiatric features
• altered mental state
• seizures
• progresses to a movement disorder and coma

Question 13

what investigations can be done for meningitis

Answer 13

blood cultures (bacteraemia)

lumbar puncture (CSF culture/microscopy)

no need for imaging if no contraindications to LP

Question 14

what investigations can be done for encephalitis

Answer 14

blood cultures

imaging (CT scan +/- MRI)

LP

EEG

Question 15

what are contraindications for LP and why

Answer 15

Focal symptoms or signs - suggest a focal brain mass

Reduced conscious level - suggests raised intracranial pressure

papilloedema

severe immunocompromised state

Question 16

what can be found in the CSF in meningitis

Answer 16

high cell count - neutrophils, lymphocytes

reduced glucose

high protein

Question 17

what is the best treatment for bacterial meningitis from S pneumoniae

Answer 17

penicillin

Question 18

how would you diagnose and treat HSV encephalitis

Answer 18

lab diagnosis = PCR of CSF for viral DNA

treat with acyclovir on clinical suspicion

Question 19

what group of viruses commonly cause CNS infections

Answer 19

enteroviruses

spread by faecal oral route

include - polioviruses, coxsackieviruses, echoviruses

Question 20

what is another cause of viral encephalitis

Answer 20

arbovirus encephalitis

transmitted to man by vector (e.g. mosquito or tick) from non-human host

travel history relevant here

Question 21

what is a brain abscess

Answer 21

localised area of pus in the brain

Question 22

what is a subdural empyema

Answer 22

thin layer of pus between the dura and arachnoid membranes over the surface of the brain

Question 23

what are the clinical features of brain abscess and empyema

Answer 23

fever
headaches
focal signs (seizure, hemiparesis)
signs of raised ICP - papilloedema, depressed consciousness
meningism
features of underlying source - dental, sinus, ear infection

Question 24

what can cause brain abscess and empyema

Answer 24

Penetrating head injury

Spread from adjacent infection

Dental, Sinusitis, Otitis media

Blood borne infection
e.g. Bacterial endocarditis

Neurosurgical procedure

Question 25

what are the differential diagnosis for abscess and empyema

Answer 25

focal lesion - most commonly tumour | subdural haematoma

Question 26

how are brain abscess and empyema diagnosed

Answer 26

imaging - CT, MRI investigate source blood cultures biopsy - drainage of pus

Question 27

what bacteria most commonly cause brain abscess

Answer 27

often polymicrobial streptococci - eps penicillin resistant gorup - strep anginosus, intermedius, constellatus anaerobes - bacteroides, prevotella

Question 28

what s the management of brain abscess

Answer 28

Surgical drainage if possible Penicillin or ceftriaxone to cover streps Metronidazole for anaerobes High doses required for penetration

Question 29

what brain infections are common in patients with HIV (low CD 4 counts)

Answer 29

Cryptococcus neoformans Toxoplasma gondii Progressive multifocal leukoencephalopathy (PML) Cytomegalovirus (CMV) HIV-encephalopathy (HIV-associated dementia)

Question 30

how can HIV associated infections be diagnosed

Answer 30

Cryptococcal antigen Toxoplasmosis serology CMV PCR HIV PCR

Question 31

what diseases can spirochetes in the CNS cause

Answer 31

lyme disease syphilis leptospirosis

Question 32

what is the first stage of lyme disease

Answer 32

early localised infection - expanding rash at the site of the tick bite - erythema migrans - flu like symptoms days - 1 week

Question 33

what is the second stage of lyme disease

Answer 33

early disseminated infection - one or more organ systems become involved - haematological or lymphatic spread - musculoskeletal and neurologic involvement most common - neurologic involvement PNS>CNS

Question 34

what is the third stage of lyme disease

Answer 34

chronic infection - months to years after a period of latency - musculoskeletal and neurologic involvement most common

Question 35

what is included in the neurologic involvement of stages 2 and 3 of lyme disease

Answer 35

``` 2/3 Mononeuropathy Mononeuritis multiplex Painful radiculoneuropathy Cranial neuropathy Myelitis Meningo-encephalitis ``` 3 Subacute encephalopathy Encephalomyelitis

Question 36

what are the investigations for lyme disease

Answer 36

Serological tests CSF lymphocytosis PCR of CSF MRI brain / spine (if CNS involvement) Nerve conduction studies / EMG (if PNS involvement)

Question 37

what is the treatment of lyme disease

Answer 37

prolonged antibiotics - IV ceftriaxone - oral doxycycline

Question 38

how does neurosyphilis present

Answer 38

similar 3 state presentation primary - secondary - latent tertiary disease years/decades later not common

Question 39

what are the investigations for neurosyphilis

Answer 39

treponema specific and non-treponema specific antibody tests LP - CSF lymphocytes increased - evidence of intrathecal antibody production

Question 40

what is the treatment of neurosyphilis

Answer 40

high dose penicillin