Infections of the nervous system

Question 1

What is Encephalitis?

Answer 1

inflammation/infection of the brain substance

Question 2

What is myelitis?

Answer 2

inflammation/infection of the spinal cord

Question 3

What is the ‘classical triad’ of symptoms for Meningitis?

Answer 3

Fever
Neck stiffness
Altered mental status

Question 4

What are meningisms?

Answer 4

collective term for neck stiffness, photophobia, nausea and vomiting

Question 5

What sorts of cerebral dysfunction appear in Meningitis patients?

Answer 5

confusion
delirium
declining conscious level - GCS <14 in 69%

Question 6

What is the hallmark sign of meningococcal meningitis?

Answer 6

petechial skin rash - do tumbler test - if you can still see the rash through the glass then this is likely meningitis

Question 7

What 4 types of meningitis can you get?

Answer 7

Infective - bacterial, viral or fungal

Inflammatory - sarcoidosis

Drug induced - NSAIDs, IVIG

Malignant - metastatic, haematological (leukemia, lymphoma, myeloma)

Question 8

Name 2 common bacterium that cause bacterial meningitis

Answer 8

Neisseria meningitidis (meningococcus)

Streptococcus pneumoniae (pneumococcus)

Question 9

Cause of viral meningitis?

Answer 9

enteroviruses

viral meningitis is much milder than bacterial

Question 10

Clinical features of Encephalitis? (5)

Answer 10

Flu-like early symptoms (4-10days)

Progressive Headache associated with fever
+/- meningism

Progressive cerebral dysfunction

Seizures

Focal symptoms / signs

Question 11

How is viral encephalitis different to the bacterial form?

Answer 11

viral encephalitis has a generally slower onset and cerebral dysfunction is a more prominent feature

Question 12

Types of Encephalitis/ differential diagnosis? (6)

Answer 12

Infective - viral most common is HSV

Inflammatory - limbic encephalitis, ADEM

Metabolic - hepatic, uraemic, hyperglycaemic

Malignant - metastatic

Migraine

Post ictal (after repeated seizures - don’t fully recover)

Question 13

What are the 2 important antibodies associated with auto-immune Encephalitis?

Answer 13

Anti-VGKC - (Voltage Gated Potassium Channel) causes frequent seizures, amnesia and altered mental state

Anti-NMDA receptor - causes prominent psychiatric features, altered mental state and seizures progressing to a movement disorder and coma

Person with auto-immune Encephalitis mistakenly attacks healthy brain cells

Question 14

Investigations for Meningitis (3)

Answer 14

Blood cultures (bacteraemia)

Lumbar puncture (CSF culture/microscopy)

No need for imaging if no contraindications to LP

Question 15

Investigations for Encephalitis?

Answer 15

Blood cultures

Imaging (CT scan +/- MRI)

Lumbar puncture

EEG - electroencephalogram

Question 16

What are contraindications to Lumbar puncture? In these cases you should do a CT scan first.

Answer 16

If patient has:-

focal symptoms or signs suggest a focal brain mass

If they have reduced conscious level which suggests raised intracranial pressure

If you take CSF away from LP then you may cause focal mass to herniate if you alter the fluid balance

Question 17

What are the CSF findings for Bacterial Meningitis. Mention:- cell count
glucose level
protein level

Answer 17

Cell count - high, mainly neutrophils

Glucose - reduced (bacteria use it up)

Protein - high

Question 18

What are the CSF findings for Viral Meningitis and Encephalitis. Mention:- cell count
glucose level
protein level

Answer 18

Cell count - High, mainly lymphocytes

Glucose - Normal (60% of blood glucose - must compare CSF with blood sample)

Protein - slightly increased

Question 19

Herpes simplex (HSV) encephalitis

Answer 19

rare but commonest type of encephalitis in europe

Lab diagnosis by PCR of CSF for viral DNA

treat with aciclovir

over 70% mortality and high morbidity if untreated

Question 20

What do types 1 and 2 Herpes simplex cause?

Answer 20

cold sores - 1>2

Genital herpes - both

Question 21

How does the Herpes virus act in the body?

Answer 21

Virus remains latent in the trigeminal or sacral dorsal root ganglion after primary infection

can become reactivated due to stress

(as with all herpes viruses, once infected, always infected)

Question 22

Enteroviruses

Answer 22

Tendency to cause CNS infections (neurotropic) Human infections, no animal reservoir

Spread by the faecal-oral route
Many can cause non-paralytic meningitis

They do not cause gastroenteritis

Question 23

Arbovirus encephalitis

Answer 23

Variety of virus groups

Geographical distribution. Vector – not present all over the world - need to take travel history.

transmitted to man by vector (mosquito or tick)

Called Arbo as ARthropod BOrne

Question 24

What is a brain abscess

Answer 24

localised area of pus within the brain

Fever if abscess bursts and get meningitis

Question 25

What is Empyema of the brain?

Answer 25

A collection of fluid around the brain – sub dural or extra dural

Question 26

Clinical features of brain abscess or empyema?

Answer 26

Fever, Headache Focal symptoms / signs - Seizures, dysphasia, hemiparesis, etc Signs of raised intracranial pressure - papilloedema (optic disc swelling), depressed conscious level Meningism may be present, particularly with empyema Features of underlying source e.g dental, sinus or ear infection or endocarditis

Question 27

Causes of brain abscess and empyema?

Answer 27

Any focal lesion, but most commonly tumour Subdural haematoma Penetrating head injury Spread from adjacent infection - sinusitis, dental, otitis media Blood borne infection e.g. Bacterial endocarditis Neurosurgical procedure

Question 28

How do you diagnose a brain abscess or empyema? What tests/imaging are done? (4)

Answer 28

Imaging: CT or MRI investigate source blood cultures Biopsy (drainage of pus) – sample of abscess itself - this depends on where the problem is - if in brainstem then may not be able to take sample

Question 29

Causative organisms for brain abscess?

Answer 29

Often mixtures of organisms present due to closed space (polymicrobial) - depends on predisposing condition Streptococci in 70% of cases Anaerobes in 40 - 100% of cases

Question 30

Management of brain abscess? (4)

Answer 30

Surgical drainage if possible Penicillin or ceftriaxone to cover streps, Metronidazole for anaerobes High doses required for penetration Culture and sensitivity tests on aspirate provide useful guide

Question 31

What does a low CD4 count mean?

Answer 31

Patient's HIV is not well managed

Question 32

Diagnostic tests for HIV?

Answer 32

Cryptococcal antigen Toxoplasmosis serology CMV PCR - cytomegalovirus HIV PCR

Question 33

Spirochates: cause which diseases affecting the CNS (3)

Answer 33

Lyme Disease Syphilis Leptospirosis

Question 34

Describe Lyme disease: including the 3 stages

Answer 34

spirochaete - Borrelia burgdorferi multi-system - skin, rheumatological, neurological, cardiac and ophthalmological involvement stage 1 - target rash, 505 flu like symptoms stage 2 - one or more organ systems become involved (blood or lymphatic spread) stage 3 - chronic infection, can take months to years

Question 35

Which 2 systems are most commonly involved first in Lyme's disease ?

Answer 35

Musculoskeletal | neurological

Question 36

Neurological involvement in Lyme disease: examples

Answer 36

Subacute encephalopathy Encephalomyelitis Mononeuropathy - one nerve Mononeuritis multiplex - multiple nerves Painful radiculoneuropathy Cranial neuropathy Myelitis Meningo-encephalitis

Question 37

Investigations for Lyme disease (4)

Answer 37

Complex range of serological tests CSF lymphocytosis - bacteria produce a more viral picture so lymphocytes are raised which you wouldn't expect MRI brain / spine (if CNS involvement) Nerve conduction studies / EMG (if PNS involvement)

Question 38

Treatment for Lyme disease

Answer 38

Prolonged antibiotic treatment – 3-4 weeks at least intravenous ceftriaxone oral doxycycline

Question 39

Neurosyphilis

Answer 39

Syphilis (Treponema pallidum) has a similar 3 stage presentation - primary, secondary, latent Test CSF for antibodies:- Treponema specific and non-treponemal specific antibody tests Expect to see CSF lymphocytes raised treat with high dose penicillin

Question 40

Poliomyelitis

Answer 40

99% of infections are asymptomatic caused by poliovirus types 1, 2 or 3 Asymmetric, flaccid paralysis, esp legs No sensory features

Question 41

Rabies

Answer 41

Acute infectious disease of CNS affecting almost all mammals Transmitted to human by bite or salivary contamination of open lesion Neurotropic - virus enters peripheral nerves and migrates to CNS Ascending paralysis and encephalitis

Question 42

Rabies encephalitis

Answer 42

No useful diagnostic tests before clinical disease apparent - Once this disease is in place, it is very difficult to treat Diagnosis: PCR and Serology Important sources of human infection: Dogs in Africa/Asia Bats in the developed world.

Question 43

Who is the rabies vaccine given to in UK

Answer 43

bat handlers regular handlers of imported animals selected travelers to enzootic areas

Question 44

Post-exposure treatment for rabies?

Answer 44

Wash wound Give active rabies immunisation Give human rabies immunoglobulin (passive immunisation) if high risk If you just give the active vaccine then the body takes weeks to develop an antibody. Need to give active and passive for rabies immunoglobulin

Question 45

Tetanus

Answer 45

Infection with c tetani anaerobic Gram positive bacillus, spore forming toxin acts at neuro-muscular junction blocks inhibition of motor neurones rigidity and spasm (risus sardonicus) – makes you very stiff

Question 46

Prevention of tetanus?

Answer 46

Immunisation (toxoid) given combined with other antigens (DTaP) Penicillin and immunoglobulin for high risk wounds/patients

Question 47

Botulism (clostridium botulinum) 3 modes of infection

Answer 47

Infantile (intestinal colonization) – Immature gut Food-borne (outbreaks) – canned food Wound: Almost exclusively injecting or “popping” drug users

Question 48

Presentation of botulsim

Answer 48

Incubation period 4-14 days Descending symmetrical flaccid paralysis Pure motor Respiratory failure Autonomic dysfunction Usually pupil dilation

Question 49

Diagnosis of botulism

Answer 49

Nerve conduction studies Mouse neutralisation bioassay for toxin in blood – ethical? Need to be sure of diagnosis before testing on mouse Culture from debrided wound

Question 50

Treatment for botulism

Answer 50

Anti-toxin (A,B,E) Penicillin / Metronidazole (prolonged treatment) Radical wound debridement

Question 51

Creutzfeldt-Jakob Disease (CJD)

Answer 51

a rare and fatal condition caused by an abnormal infectious protein in the brain called a prion. It can be sporadic, new variant, familial or acquired (blood transfusion etc) No treatment

Question 52

When should you consider sporadic CJD as the diagnosis?

Answer 52

Consider in any rapidly progressive dementia ``` Clinical features:- Insidious onset (usually older than 60) ``` Early behavioural abnormalities Rapidly progressive dementia Myoclonus - quick, involuntary muscle jerk

Question 53

What diagnoses are you thinking for sporadic CJD? (4)

Answer 53

Alzheimer’s disease with myoclonus Subacute sclerosing panencephalitis (SSPE) Very rare, chronic infection with defective measles virus CNS vasculitis Inflammatory encephalopathies

Question 54

Prognosis of sporadic CJD

Answer 54

death often within 6 months

Question 55

New variant CJD

Answer 55

Younger onset <40 Linked to Bovine Spongiform Encephalopathy in Cattle ie eating infected material