CNS Infections

Question 1

Describe 4 effects of cytokines in pathophysiology of acute bacterial meningitis

Answer 1

Bacterial invasion > production of cytokines >
1. Hypercoagulability
2. Reduced cerebral blood flow
3. Raised ICP compensated by raised BP
4. Increased blood brain barrier permeability

Question 2

Clinical signs of acute bacterial meningitis in an older child x4

Answer 2

Fever
Signs of raised ICP
Signs of meningeal irritation
Signs of cortical involvement

Question 3

Causative organisms of acute bacterial meningitis in neonates x5

Answer 3

E.coli
GB strep
Klebsiella
Enterobacter
L.monocytogenes

Question 4

When should Streptococcus pneumoniae be suspected x5

Answer 4

Skull fracture
Otorrhea
Paranasal sinuses
Frontal bone CSF leak
Sickle cell patient

Question 5

Describe Pathogenesis of purpura in meningitis x2

Answer 5

Dermal microvessels thrombosis that result in hemorrhagic skin necrosis

Question 6

Sequelae for haemophilus influenzae meningitis x5

Answer 6

Hearing loss
Epileptic fits
Subdural effusions
Mental retardation
Cerebral infarctions

Question 7

State the toxin produced in neisseria meningitidis and its 3 effects

Answer 7

Lipooligosaccharide
Causes septic shock, bilateral adrenal hemorrhage, DIC

Question 8

Define water-house Friderichsen syndrome and 3 causes

Answer 8

Massive bilateral hemorrhage into the adrenal glands
Caused by adrenal insufficiency, DIC, meningococcemia

Question 9

State 4 clinical features of acute bacterial meningitis in a neonate x4

Answer 9

Irritability
Poor feeding
Bulging fontanelle
Hypo or hyperthermia

Question 10

Complications of acute bacterial meningitis x5

Answer 10

Hydrocephalus
Epileptic fits
Brain abscess
Subdural effusions
Cerebral edema

Question 11

Which steroid is given in meningitis and when

Answer 11

Dexamethasone 10-15 minutes before Abx initiation in children> 2M

Question 12

Principles of treatment for meningitis x4

Answer 12

Antibiotics and steroids
Generalized care for unconscious child
Prevent or treat complications

Question 13

Clinical features of brain abscess x4

Answer 13

Headache, vomiting and papilloedema
Focal neurological signs with seizures
Sepsis and fever
Meningitis if it breaks into ventricles

Question 14

Define brain abscess and its predisposing factors x4

Answer 14

Localized suppuration within the brain tissue
1. CHD with R to L shunt
2. Otitis media
3. Mastoiditis
4. Sinusitis

Question 15

Management of a brain abscess x2

Answer 15

Abx with repeat CT
Surgical drainage when unresponsive to abx

Question 16

Subdural empyema is caused by sepsis originating from which conditions x5

Answer 16

Sinusitis
Meningitis
Mastoiditis
Brain abscess
Subdural hematomas

Question 17

Features of progressive encephalopathy due to direct HIV brain infection x3

Answer 17

Loss of developmental milestones
Intellectual fall off
Motor deficits

Question 18

Define encephalitis and its causes x2

Answer 18

Inflammation of the brain parenchyma
1. Invasion of the cns by virus
2. Immune reaction between the virus and host- post or para-infectious

Question 19

Clinical features of encephalitis x4

Answer 19

Seizures
Altered mental state
Altered consciousness
Focal neurological signs- paresis, aphasia

Question 20

Characteristics of Herpes simplex virus neuro infection x4

Answer 20

Focal hemorrhagic necrotic lesions
Site- temporal and orbital areas
Primary infection manifests with oral lesions
Disturbances of memory and behavioral changes
Focal fits and focal neurological signs

Question 21

State the 3 ways of spread in HSV encephalitis

Answer 21

1. From site of primary oro-pharyngeal infection to brain via trigerminal and olfactory nerves
2. CNS invasion by reactivation of infection in patients with history of recurrent infections
3. Reactivation of the latent HSV in situ within the brain

Question 22

Define subacute sclerosing panencephalitis SSPE

Answer 22

A progressive fatal neurological disorder that usually occurs months or years after a measles infection

Question 23

State initial (4) and advanced (death) symptoms of SSPE

Answer 23

Initial- mild cognitive decline, changes in behavior, seizures, disturbances in motor function
Advanced- losing ability to walk, deterioration of comatose state, persistent vegetative state

Question 24

Pathophysiology of neurocysticercosis x4

Answer 24

Ingestion of ova of taenia solium
Larva lodge in the CNS vascular area
Surrounding inflammation and edema
Dead cysts induce intense inflammation

Question 25

Clinical features of neurocysticercosis x5

Answer 25

Obstructive hydrocephalus Focal seizures + neurological signs Raised ICP Psychotic symptoms Headache, coma

Question 26

Treatment of neurocysticercosis and doses x4

Answer 26

Albendazole 15mg/kg/d for 8 days Praziquantel 50mg/kg/d for 14 days Anticonvulsants if seizures present Steroids to prevent systemic reaction caused by release of endotoxin like substances when large numbers of cysts are killed

Question 27

Pathophysiology of cryptococcosis x3

Answer 27

Occurs in immunocompromised patients Fungus found in soil and pigeon Primary respiratory infection which reaches brain via hematogenous spread

Question 28

Clinical manifestations of cryptococcosis x4

Answer 28

Cranial nerve palsies Impaired level of consciousness Raised ICP and papilledema Headache and meningeal irritation

Question 29

CSF characteristics of cryptococcosis x5

Answer 29

High pressure Elevated lymphocytes Increased proteins Low sugar Indian ink - clear halo around yeast wall

Question 30

Treatment of cryptococcosis x3 and duration

Answer 30

Duration 6 weeks Amphotericin B 1mg/kg/d Fluorocytosine 15mg/kg/d Fluconazole - prophylaxis in HIV

Question 31

Describe the Kernigs sign

Answer 31

Position the patients supine with their hips flexed to 90°. This test is positive if there is pain on passive extension of the knee

Question 32

Describe Brudzinskis sign

Answer 32

Position the patients supine and passively flex their neck. This test is positive if this manoeuvre causes reflex flexion of the hip and knee.

Question 33

Risk factors of acute bacterial infection in neonates x4

Answer 33

Low birth weight Male babies Premature rupture of membranes Difficulty delivery with extensive manipulations

Question 34

Normal csf parameter ranges x3

Answer 34

White cells : 0 neutrophils, 0-6 lymphocytes Glucose : 3.6-5.6 mmol/dL Protein : 0.15-0.45 mg/L

Question 35

CSF parameter ranges for bacterial infection x3

Answer 35

White cells : 100-50000 neutrophil predominant Glucose : 1.1-1.6 mmol/dL Protein : mild to moderately increased

Question 36

CSF parameter ranges in viral meningitis

Answer 36

White cells: 25-500 lymphocytes predominant Glucose: 3.6-5.6 normal Proteins : mildly increased

Question 37

Csf parametric ranges for Tb meningitis

Answer 37

White cells : 25-500, lymphocyte predominant Glucose : 2.2-2.7 Proteins: moderately increased

Question 38

Prophylaxis for N meningitidis close contacts x2

Answer 38

Rifampicin 10mg/kg twice a day for 2 days Ceftriaxone 125mg imi stat

Question 39

Prophylaxis for H influenza

Answer 39

Rifampicin 20mg/kg twice a day for 4 days

Question 40

Clinical features of HSV x6

Answer 40

Fever and malaise Mucosal lesions Memory and behavioral changes Focal fits and focal neurological signs Lethargy, coma

Question 41

CT characteristics of HSV infection x3

Answer 41

Attenuation in temporal lobes Temporal lobe atrophy Temporal lobe cysts

Question 42

State 4 CT scan findings in cryptococcosis

Answer 42

Hydrocephalus Mass lesions- granulomas Cerebral edema Basilar enhancement

Question 43

State 3 CT scan findings for neutocysticercosis

Answer 43

Solitary or multiple cysts Single multiple calcified lesions Patches of hypodensity with ring enhancement