Ch. 12 - Infections of CNS Flashcards Preview

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Flashcards in Ch. 12 - Infections of CNS Deck (37)
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1
Q

Common organisms causing bacterial meningitis in neonates/infants? Adults?

A

Neonates - GBS, E. coli

Infants - GBS, Strep pneumo

Kids/adults - Strep pneumo, Neisseria meningitides

2
Q

3 main routes of infectious spread to meninges and CSF

A
  1. Hematogenous
  2. Retrograde via infected thrombi from infections adjacent to CNS (sinusitis, otitis, mastoiditis)
  3. Direct spread into subarachnoid space from skull or paranasal sinus infections
3
Q

Why is phagocytosis impaired in CSF?

A

Has low opsonic activity

4
Q

Major presenting features of meningitis

A

High fever + meningismus (HA, neck stiffness, photophobia, vomiting, AMS)

Often preceded by URI

5
Q

How does meningitis presentation differ in infants, elderly, and immunocompromised?

A

Neck stiffness and fever are often absent; usually present with irritability, confusion, obtundation

6
Q

CSF features in bacterial meningitis

A

Cloudy CSF, elevated WBC (esp. PMNs), elevated protein, low glucose, positive Gram stain in over 70%

7
Q

Which abx is the mainstay of bacterial meningitis tx?

A

Ceftriaxone; add a penicillin as needed for appropriate coverage

8
Q

Major complications of bacterial meningitis

A

Cerebral edema, seizures, communicating hydrocephalus, subdural effusion (esp. in kids), subdural empyema (rare), brain abscess (rare)

9
Q

Where do brain abscesses arising by hematogenous dissemination frequently develop?

A

Usually multiple at the junction of white and grey matter; specific region is proportional to blood flow - most occur in distribution of MCA (i.e. parietal lobe)

10
Q

What is the most common pathogen isolated from brain abscesses?

A

Streptococcus (80%); Staph aureus when infection results from trauma or postoperatively

11
Q

CT appearance of brain abscess

A

Contrast-enhancing ‘ring’ lesion

12
Q

What is the most sensitive imaging modality for diagnosing a brain abscess?

A

MRI

13
Q

When should surgical excision of brain abscesses be considered?

A

Persistent reaccumulation of pus despite repeated aspirations, in accessible site, well-formed fibrous capsule, cerebellar location

14
Q

What abx should you use for postoperative brain abscess?

A

Vancomycin

15
Q

Clinical features of epidural brain abscess?

A

Primarily those of osteomyelitis (acute localizing pain, pitting edema of scalp)

16
Q

Pott’s puffy tumor

A

Localized pitting edema of scalp over area affected by epidural abscess

17
Q

Classic presentation of subdural abscess

A

Patient with history of acute frontal sinusitis who develops severe headaches and high fever, has rapid neurological deterioration with seizures

18
Q

What will CSF show in TB meningitis?

A

Lymphocytic pleocytosis, elevated protein, low glucose, low chloride, acid-fast bacilli in 20%

19
Q

Definitive diagnosis of TB meningitis

A

Culture of M. tuberculosis which can take up to 6 weeks

20
Q

Tx of TB meningitis

A

Isoniazid, rifampin, ethambutol, pyrazinamide

21
Q

How does intracranial tuberculoma present?

A

Similar to intracranial tumor (raised ICP, focal neurologic signs, seizures)

Systemic sxs of TB in less than 50%

Preoperative dx is usually appreciated only after recognition of TB foci ELSEWHERE

22
Q

How does cerebral cryptococcosis present?

A

Patient with underlying condition (AIDS, IV drug use, sarcoidosis) hung out with pigeons

23
Q

Dx of Cryptococcus

A

Cryptococcus seen on India ink prep

Positive latex cryptococcal agglutination test

24
Q

Cryptococcus tx

A

Amphotericin B, 5-fluocytosine, or fluconazole

25
Q

Why should great care be taken when excising intracerebral hydatid cysts?

A

Spilled contents can induce anaphylactic shock

26
Q

Medical tx of hydatid cyst

A

Albendazole

27
Q

How is cerebral toxoplasmosis treated?

A

Sulfadiazine and pyrimethamine

28
Q

Common cerebral infections in AIDS?

A

Toxoplasmosis > Cryptococcus > TB, Candida, HSV, progressive multifocal leukoencephalopathy

29
Q

Most common parasitic dx of CNS

A

Neurocysticercosis caused by Taenia solium (tapeworm)

30
Q

CSF appearance in neurocysticercosis

A

Lymphocytosis, eosinophilia, positive complement fixation test, occasionally see cysts

31
Q

Tx of neurocysticercosis

A

Surgical intervention + albendazole or praziquantel

32
Q

Presentation and causative organism of herpes simplex encephalitis

A

HSV-1; acute necrotizing encephalitis (meningitis, progressive deteriorating neurologic state, seizures)

33
Q

EEG in herpes simplex encephalitis

A

Focal slowing, periodic spikes or sharp and wave patterns

34
Q

What is seen on MRI with herpes simplex encephalitis? In CSF?

A

Signal changes within temporal lobe with edema and hemorrhage

CSF with mononuclear cells and viral DNA

35
Q

Herpes simplex encephalitis tx

A

Acyclovir

36
Q

Identify the lesion

A

Ring-enhancing cerebral abscess with surrounding edema

37
Q

Identify the lesion

A

Herpes simplex encephalitis in right temporal lobe