CNS Infection Flashcards by Tim Resch

What is meningitis?

Inflammation of leptomeninges

-arachnoid/pia mater & underlying CSF

How well did you know this?

Not at all

Perfectly

What are the most common (70%) causes of acute bacterial meningitis?

Neisseria meningitidis
-classic petechial rash, small epidemics
Streptococcus pneumonia
-more common if skull fractures/ear disease/congenital CNS lesions

How well did you know this?

Not at all

Perfectly

What are the less common (30%) causes of acute bacterial meningitis?

Listeria monocytogenes (elderly/immunosuppressed)
Haemophilus influenzae
Staph aureus
TB

How well did you know this?

Not at all

Perfectly

What are the common viral causes of meningitis?

Enteroviruses (coxsackie A/B, echoviruses)
HSV
VZV

How well did you know this?

Not at all

Perfectly

What is the classic meningitic syndrome triad?

Headache
Neck stiffness
Fever

How well did you know this?

Not at all

Perfectly

What sx are present in acute bacterial meningitis?

Classic triad
High fever w/ rigors
Photophobia
Vomiting
Intense malaise
Confusion/seizures

How well did you know this?

Not at all

Perfectly

What signs are present in acute bacterial meningitis?

Kernig’s –> hip flexed, knee extension causes pain
Brudzinski’s –> passive flexion of neck causes flexion of knees/hip
Signs of raised ICP/CN palsies

How well did you know this?

Not at all

Perfectly

What are the common complications of acute bacterial meningitis?

Venous sinus thrombosis
Severe cerebral oedema
Hydrocephalus

How well did you know this?

Not at all

Perfectly

What sx/signs indicate complications in acute bacterial meningitis?

Progressive drowsiness
Lateralising signs
CN lesions

How well did you know this?

Not at all

Perfectly

What are the specific features of meningococcal meningitis?

Petechial rash (erythematous, non-blanching purpura)
Carried in nasopharynx
Caused by Men B/C
ACWY jab at 14yrs

How well did you know this?

Not at all

Perfectly

What are the specific features of viral meningitis?

Benign/self-limiting
Lasts 4-10days
Headache for some months, no serious complications

How well did you know this?

Not at all

Perfectly

What are the specific features of TB meningitis?

Insidious illness w/ fever, wt loss, progressive confusion/cerebral irritation –> coma
Treat w/ RIPE for 12mo w/ corticosterids
-decreases risk of cerebral oedema

How well did you know this?

Not at all

Perfectly

What is the clinical presentation of an epidural spinal abscess?

Fever
Back pain
Spinal root lesiosn

How well did you know this?

Not at all

Perfectly

What causes an epidural spinal abscess?

S. aureus from bloodsteam

How well did you know this?

Not at all

Perfectly

What is the management of an epidural spinal abscess?

Rule out osteomyelitis
Emergency imaging
A/b
Surgical decompression

How well did you know this?

Not at all

Perfectly

What is Encephalitis?

Inflammation of brain parenchyma, usually viral

How well did you know this?

Not at all

Perfectly

What are the common clinical features of viral encephalitis?

Headache
Drowsiness
Fever
Malaise
Confusion

What are the clinical features of more severe viral encephalitis?

High fever
Mood changes
Progressive drowsiness over hrs/days
Seizures/coma
Death (20%

What are the causative organisms of severe viral encephalitis?

HSV-1
-necrotising encephalitis affecting temporal lobes
HSV-2
-meningitis (in adults)

What investigations are appropriate in suspected viral encephalitis?

Head CT/MRI (diffuse oedema, temporal lobes)
LP (raised opening pressure, lympocytes, protein, normal glucose w/ +ve viral PCR)
Viral serology

What is the management of viral encephalitis?

IV acyclovir >10/7

What are the risk factors for TB meningitis?

Immunosuppression
Malnourishment
Multiple comorbidities
Recent contact w/ TB

What is the most common cause of TB meningitis?

Blood-borne spread of M. tuberculosis

Following 1o infection/miliary TB

What is the main risk factor for funal meningitis?

Immunosuppression

What investigations are appropriate in suspected meningitis?

Bloods - FBC, LFTs, U&Es, clotting, glucose, lactate Serum PCR (antigens) Blood cultures LP (MCS protein, glucose, meningo/pneumo/viral PCR) CT (prior to LP if suspected raised ICP) Throat swabs (1 for virology, 1 for bacteriology)

What CSF stains demonstrate which causative organisms of meningitis?

Gram +ve intracellular diplococci (Pneumococcus) Gram -ve cocci (Meningococcus) Ziehl-Neelsen stain (TB) Indian ink (Fungi)

What are the features of normal CSF?

Crystal clear <5 cells/mm3 (all lymphocytes/mononuclear cells) Low protein (0.2-0.4g/L) Low glucose (1/2 - 2/3 of blood levels)

What are the features of CSF in bacterial meningitis?

Turbid fluid High polymorphs Low glucose High protein

What are the features of CSF in viral meningitis?

Clear fluid High lymphocytes Normal glucose Normal protein

What are the features of CSF in TB meningitis?

Yellowish/viscous fluid High lymphocytes Low glucose High protein

What is the appropriate empirical antibiotic regimen if a non-blanching rash is present?

Benzyl-penicillin 1.2g IM immediately - 2-4mg 4hrly in hospital - cefotaxime in penicillin allergic pts

What is the appropriate empirical antibiotic regimen if <60yrs and NOT immunosuppressed?

IV ceftriaxone 2g BD IV dexamethasone -2 doses 6hrs apart, give w/ 1st a/b dose

What is the appropriate empirical antibiotic regimen for penicillin allergic pts?

IV chloramphenicol 25mg/kg IV

What is the appropriate empirical antibiotic regimen if >60yrs OR immunosuppressed?

IV ceftriaxone 2g BD IV amoxicillin 2g 4hrly IV dexamethasone

What agent should be added in suspected herpes encephalitis?

IV acyclovir

What agent should be given to close contacts as prophylaxis in meningococcal meningitis?

Ciprofloxacin, single dose | Eliminates pharyngeal cartilage

What are the acute complications of bacterial meningitis?

Sepsis/DIC Hydrocephalus Adrenal haemorrhage (Waterhouse-Friderichsen syndrome)

What are the long term complications of bacterial meningitis?

Brain abscess Seizure disorders CN palsies (sensorineural hearing loss or gaze palsies) Ataxia/muscular hypotonia

What are the risk factors for brain abscess formation?

Head trauma/neurosurgery Otitis media/Paranasal sinus infections 2o to bacterial endocarditis

What are the sx/signs of a brain abscess?

Features of expanding mass lesion Fever Systemic illness

What is the management of a brain abscess?

Surgical drainage Broad spectrum a/b High dose corticosteroids

What is the prognosis of a brain abscess?

Mortality 10% | Long-term sequalae greatest in pneumococcal disease