Viral CNS Infections

Question 1

What are the clinical features of a viral Meningitis

Answer 1

Fever,
Signs of raised intracranial pressure: headache( often relieved by LP), vomiting
Signs of Menigeal irritation: neck stiffness
Usually no focal neurological signs to find
Prolonge course but benign

Question 2

Prognosis of a viral meningitis

Answer 2

Benign in the vast majority of cases

Question 3

By which two methods does an encephalitis occur

Answer 3

Direct invasion of the CNS by the virus

Due to the subsequent immune reaction i.e. postinfectious/parainfectious

Question 4

Clinical features of an encephalitis

Answer 4

Altered mental state
Seizures
EEG shows generalised and diffuse slowing

Question 5

What are the primary causes of a direct encephalitis

Answer 5

Herpes simplex virus
Rabies virus
Varicella zoster virus
Enterovirus
Arbovirus

Question 6

What are the causes of the parainfectious encephalitis

Answer 6

Measles,mumps. Rubella 
Chickenpox
EBV
Adenovirus 
Influenza A
Para influenza

Question 7

What is subacute Sclerosing osiepanencephalitis

Answer 7

SSPE is a chronic encephalitis usually from a prior measles infection

Question 8

What are the clinical features of SSPE

Answer 8

Slow onset of personality changes
Intellectual deterioration progressing to dementia
Aphasic apraxic agnostic predominance
In voluntary movements progressing to pyramidal and extra pyramidal signs (spasticity and dystonia)

Question 9

Major characteristic of an HSV encephalitis

Answer 9

Focal haemorrhagic necrosis lesions with the predilection for the temporal and orbital areas of the brain

Question 10

Pathogenesis of HSV encephalitis

Answer 10

Reactivation of latent virus situated in the trigeminal ganglion
Virus enters brain by speeding along:
– Branches of meningeal nerves
– Nasal mucosa through cribriform plate
Primary infection of the CNS is unusual exceptions are:
– Neonates sand young infants

Question 11

Clinical features of an HSV encephalitis

Answer 11

Pre-seeding prodrome of fever and malaise followed by:
– Memory and behavioural changes
– Focal seizures
– Focalneurological signs
– lethargy and coma
Mucosal lesions may or may not be present

Question 12

Management of HSV encephalitis

Answer 12

Acyclovir as soon as possible

Steroids and not recommended

Question 13

In what ways can HIV affect the brain

Answer 13

Directly:
– Progressive encephalopathy
– – Regression with loss of milestones, intellectual fall-off and motor deficits e.g. spasticity, Ataxia and weakness
Indirectly:
– Opportunistic infections e.g. cryptococcal meningitis
– NeoplasmsE.g. lymphoma
– Cerebrovascular disease e.g. strokes