Viral meningitis/encephalitis

Question 1

What are the causes of aseptic meningitis?

Answer 1

• Most common=viruses
• Listeria
• TB
• Syphilis
• Malignancy
• Autoimmune conditions
• Drugs

Question 2

What is the aetiology of viral meningitis?

Answer 2

-Leading cause= enteroviruses (echovirus, coxsackie, poliovirus, enterovirus, parecho virus)
-Herpes virus (varicella zoster, cytomegalovirus, epstein-barr, herpes simplex)
-Arbovirus (japanese encephalitis virus)
-Mumps virus
_HIV
-Adenovirus
-Measels
-Influenza
-Parainfluenza type 3
-Lymphocytic choriomeningitis

Question 3

What is the pathogenesis of viral meningitis?

Answer 3

• Colonisation of mucosal surfaces
• Invasion of epithelial surface
• Replication in cells
• Dissemination & CNS invasion (via cerebral microvascular endothelial cells, choroid plexus epithelium, spread along olfactory nerve)
• Symptoms due to inflammatory spread in CNS

Question 4

What are the general features presented in viral meningitis?

Answer 4

• Fever
• Meningism (headache, neck stiffness, photophobia)
• Sometimes viral prodrome
• Difficult to distinguish between viral & bacterial
• NEONATES: look for nuchal rigidity, bulging anterior fontanelle

Question 5

What are the signs of meningitis when examining a patient?

Answer 5

• Kernig’s sign: Hip & knee flexed cannot be extended due to pain/stiffness in hamstrings
• Nuchal rigidity: resistance to flexion of neck
• Brudzinski’s sign: flexing neck causes hip & knee to flex

Question 6

What investigations are required?

Answer 6

• Blood test (U&E, FBC, CRP, clotting)
• CT head
• Lumbar puncture (protein, glucose, viral pathogens)
• Serology (mumps, EBV/CMV, HIV)
• Throat swab/ stool sample (enterovirus)

Question 7

What are the usual CSF findings in viral meningitis?

Answer 7

• CRP: normal
• Glucose: normal/slightly low
• Protein: Normal/slightly high
• White cell count: pleocytosis= white cells in CSF

Question 8

What is the treatment for viral meningitis?

Answer 8

• Appropriate antibiotics if risk of bacterial
• Mainly supportive therapy (analgesia & antipyretics)
• Good prognosis (some long term problems)
• Notifiable to local public health department

Question 9

Describe enteroviral meningitis

Answer 9

• Commonest cause
• Classically late summer/autumn
• Fever, vomiting, rash, anorexia, upper resp symptoms
• No specific treatment, full recovery normal

Question 10

What are the 2 forms of Herpes Simplex virus and what can they cause?

Answer 10

HSV1= cold sores & viral encephalitis
HSV2= genital herpes & meningitis (2nd commonest of viral meningitis)

Question 11

What is Mollaret’s meningitis?

Answer 11

• Recurrent aseptic meningitis

- Wide differential but major cause HSV2

Question 12

How is varicella zoster virus associated with meningitis?

Answer 12

• Primary= chickenpox (varicella)
• Secondary= shingles (zoster)
• Meningitis unusual but can occur during chickenpox/shingles/ after vaccination
• No treatment & complete recovery

Question 13

Describe mumps meningitis

Answer 13

• 10-30% cases
• CNS symptoms 5 days after onset of parotitis
• Abdo pain & orchitis
• No treatment & full recovery
• Preventable with vaccine

Question 14

What are the clinical features of meningitis associated with HIV?

Answer 14

• Can occur as part of primary infection
• Associated features: fever, lymphadenopathy, rash, pharyngitis, like glandular fever
• Self-limiting

Question 15

What is the aetiology of viral encephalitis?

Answer 15

• HSV1&2 (1=90%)
• Mumps
• Measels
• Adenovirus
• Enteroviruses (inc polio)
• VZV, EBV, CMV
• Rubella’
• HIV
• Influenza
• Arboviruses
• Bacterial
• Autoimmune
• Malignancy
• Acute disseminated encephalomyopathy

Question 16

What is the clinical presentation for viral encephalitis?

Answer 16

• Altered mental state (confusion/bizarre behaviour, coma)
• Fever
• Headache
• Meningism (maybe absent)
• +/- focal neurology
• Seizures
• Weakness
• Ataxia
• Cranial nerve palsy
• Dysphasia/aphasia

Question 17

What investigations need to be carried out for potential encephalitis?

Answer 17

• Blood test (FBC, CRP, U&E, clotting)
• CT
• MRI
• Lumbar puncture (protein/glucose)
• EEG (abnormal temporal lobe activity)

Question 18

How is viral encephalitis treated?

Answer 18

-High dose IV aciclovir 10mg/kg 14-21days

Question 19

Describe herpes simplex encephalitis

Answer 19

• Rare but high mortality 70%
• Equal male & female
• inflammation/swelling of brain tissue
• Acute focal necrotising encephalitis
• Primary infection (direct transmission of virus along neural/olfactory pathway)
• Reactivation (in trigeminal ganglia)
• In survivors frequent neuro consequences: paralysis, personality change, speech loss

Question 20

Describe acute disseminated encephalomyelopathy (ADEM)?

Answer 20

-Immune mediated CNS demyelination
Follow viral illness/ vaccination (influenza)
-Treatment: steroids/ immunosuppressants
-Presents same as encephalitis
-CSF findings= viral meningitis

Question 21

What is acute hypertensive encephalopathy

Answer 21

• Diffuse cerebral dysfunction
• Confusion, vomiting, convulsions, coma & death
• Intervention to reduce raised intracranial pressure