Infections of the Nervous System

Question 1

What is inflammation of the meninges known as?

Answer 1

Meningitis

Question 2

What is inflammation of the brain substance known as?

Answer 2

Encephalitis

Question 3

What is inflammation of the spinal cord known as?

Answer 3

Myelitis

Question 4

What is the classic triad of symptoms of meningitis?

Answer 4

Fever
Neck stiffness
Altered mental status

Question 5

What are the characteristics of meningitis?

Answer 5

Patients present with a short history of progressive headache associated with fever and meningism (neck stiffness, photophobia, N&V)
Cerebral dysfunction (confusion, delirium, declining consciousness level)
Cranial nerve palsy
Seizures
Focal neurological deficits
Petechial skin rash (Tumbler test)

Question 6

What are the bacterial and viral causes of meningitis?

Answer 6

Bacterial- Nesseria meningitidis
Streptococcus pneumoniae
Viral- enteroviruses

Question 7

What are the clinical features of encephalitis?

Answer 7

Flu-like prodrome
Progressive headache associated with fever
Potential meningism
Progressive cerebral dysfunction (confusion, abnormal behaviour, memory disturbance, depressed conscious level)
Seizures
Focal symptoms/signs

Question 8

What are the causes of meningitis?

Answer 8

Infective- viral, bacterial, fungal
Inflammatory- sarcoidosis
Drug induced- NSAIDs, IVIG
Malignant- metastatic haematological

Question 9

What are the causes of encephalitis?

Answer 9

Infective- viral (most commonly HSV)
Inflammatory- limbic encephalitis
Metabolic- Hepatic, uraemic, hyperglycaemic
Malignant- Metastatic, paraneoplastic

Question 10

What two antibodies cause auto-immune encephalitis?

Answer 10

Anti-VGKC (voltage gated potassium channel)

Anti-NMDA receptor

Question 11

What are the characteristics of auto-immune encephalitis that is mediated by anti-VGKC antibodies?

Answer 11

Frequent seizures
Amnesia
Altered mental state

Question 12

What are the characteristics of auto-immune encephalitis that is mediated by anti-NMDA receptor antibodies?

Answer 12

Flu like prodrome
Prominent psychiatric features
Altered mental state and seizures
Progresses to movement disorder and coma

Question 13

What tests can be used when investigating meningitis?

Answer 13

Blood cultures (bacteraemia)
Lumbar puncture (CSF culture/microscopy)

Question 14

What tests can be used when investigating encephalitis?

Answer 14

Blood cultures
Imaging- CT scan with additional MRI if necessary
Lumbar puncture
EEG

Question 15

What features would indicate the need for a CT scan before a lumbar puncture?

Answer 15

Focal neurological deficit- not including cranial nerve palsies
New onset seizures
Papilloedema
GCS <10
Severe immunocompromised state

Question 16

What are the difference in findings in CSF in bacterial and viral meningitis?

Answer 16

Bacterial:
-Increased opening pressure
-High cell count, mainly neutrophils
-Reduced glucose
-High protein
Viral:
-Normal/increased opening pressure
-High cell count, mainly lymphocytes
-Normal glucose
--Slightly increased protein

Question 17

How is herpes simplex encephalitis diagnosed?

Answer 17

Lab diagnosis by PCR of CSF for viral DNA

Question 18

How is herpes simplex encephalitis treated?

Answer 18

Treat with aciclovir on clinical suspicion

Question 19

What feature of a history is relevant to arbovirus encephalitides?

Answer 19

Travel abroad

Question 20

What is a brain abscess?

Answer 20

A localised area of pus within the brain

Question 21

What is subdural empyema?

Answer 21

A thin layer of pus between the dura and arachnoid mater

Question 22

What are the clinical features of brain abscess/empyema?

Answer 22

Fever
Headache
Focal symptoms- seizures, dysphagia etc
Signs of raised intracranial pressure- papilloedema, false localising signs, depressed conscious level
Mengism may be present, particularly for empyema
Signs of underlying source eg sinus, dental or ear infection

Question 23

What are the causes of brain abscess/empyema?

Answer 23

Penetrating head injury
Spread from adjacent infection
Blood borne infection
Neurosurgical procedure

Question 24

What investigations can be used in brain abscess/empyema?

Answer 24

CT or MRI
Investigate source
Blood cultures
Biopsy- drainage of pus

Question 25

How is a brain abscess managed?

Answer 25

Surgical drainage if possible Penicillin or ceftriaxone to cover streps Metronidazole for anaerobes

Question 26

What infections are common in HIV patients with low CD4?

Answer 26

``` Cryptococcus neoformans Toxoplasma gondii Progressive multifocal leukoencephalopathy Cytomegalovirus HIV-encephalopathy ```

Question 27

What tests can be done in cases of suspected HIV related brain infection?

Answer 27

Cryptococcal antigen Toxoplasmosis serology CMV PCR HIV PCR

Question 28

What is the causative organism of Lyme disease?

Answer 28

Borrelia burgdorferi

Question 29

What is the causative organism of leptospirosis?

Answer 29

Leptospira interrogans

Question 30

What is the causative organism of syphilis?

Answer 30

Treponema pallidum

Question 31

What are the characteristics of the first stage of Lyme disease infection?

Answer 31

Early localised infection Expanding rash at site of tick bite 50% flu-like symptoms

Question 32

What are the characteristics of the second stage of Lyme disease?

Answer 32

Early disseminated infection One or more organ systems may become involved through haematologic or lymphatic spread Musculoskeletal and neurologic involvement common

Question 33

What are the characteristics of the third stage of Lyme disease?

Answer 33

Chronic infection | Musculoskeletal and neurologic involvement common

Question 34

How is Lyme disease investigated?

Answer 34

Complex range of serological tests CSF lymphocytosis MRI brain/spine Nerve conduction studies/EMG

Question 35

How is Lyme disease treated?

Answer 35

Prolonged antibiotic treatment

Question 36

How is rabies encephalitis diagnosed?

Answer 36

PCR and serology

Question 37

What is the causative organism of tetanus?

Answer 37

Clostridium tetani

Question 38

What is the clinical presentation of botulism?

Answer 38

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

Question 39

How is botulism diagnosed?

Answer 39

Nerve conduction studies Mouse neutralisation bioassay for toxin in blood Culture from debrided wound

Question 40

How is botulism treated?

Answer 40

Anti-toxin Penicillin/ metronidazole Radical wound debridement

Question 41

What is the causative organism of botulism?

Answer 41

Clostridium botulinum

Question 42

What are the clinical features of sporadic Creutzfeldt-Jakob disease?

Answer 42

``` Insidious onset (usually 60+) Early behavioural abnormalities Rapidly progressive dementia Myoclonus Progressing to global neurological decline Motor abnormalities Cortical blindness Seizures may occur ```

Question 43

How is Creutzfeldt-Jakob disease investigated?

Answer 43

MRI-Pulvinar sign in new variant CJD, no changes in sporadic EEG- Generalised periodic complexes common, often normal in early stages CSF- Normal or raised protein, immunoassay 14-3-3 brain protein