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NEUROLOGY > INFECTIONS OF THE CNS > Flashcards

INFECTIONS OF THE CNS Flashcards

1
Q

Infections of the CNS include

A

meningitis, encephalitis, meningoencephalitis, cerebral abscess and myelitis.

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2
Q

Review of meninges

A

from external to internal
Bone of the skull
Epidural space
Dura mater
Subdural
Arachnoid matter
Subarachnoid space
Pia mater

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3
Q

Bacterial meningitis

How can bacteria reach the brain?

A
  1. Hematogenous spread
  2. From contiguous structures
     Sinuses, middle ear or mastoid bone
  3. Directly:
     Congenital defects od cranial bones
     Cranial trauma
     Iatrogenic (neurosyrgery)
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4
Q

Bacterial Meningitis- Epidemiology

A

Adult population:
* Incidence: 5-10 cases / 100.000
* Predominate during cold season
* Common bacteria:
– Pneumococcus (vaccination possible for several serotypes)
– Meningococcus (vaccination possible for several serotypes)
– Haemophilus influenzae (incidence decreasing)
– Listeria monocytogenes
– Staphylococcus
– Hospital infections (staphyilococcus and gram- bacteria)

Children: the most common pathogens in children are:
1. H. Influenzae (vaccination)
2. Pneurmococco
3. Meningococco (vaccination)

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5
Q

Bacterial Meningitis - Risk Factors

A

o Age: 70% < 5 years
o Living in crowded communities: kindergarden, schools, caserme ecc
o hospitals
o Social and economical status

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6
Q

Bacterial Meningitis - Pathology

A
  1. Acute development of a purulent infection in the subarachnoid space; inflammation and hyperemia.
  2. Purulent material accumulates on the cerebral surface and sulci, Wirchow-Robin space, may also surround cranial nerves.
  3. Cortical edema
  4. Possibility of arterial and venous occlusions
  5. Purulent infection may recover; deposit of fibrinoid material in the subarachnoid space may follow.
  6. Spinal fluid circulation may then be impaired with development of hydrocephalus
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7
Q

Bacterial Meningitis - Clinical signs in children < 2 years of age:

A

o Irritability
o Weak weeping
o Vomiting
o Lethargy, stupor, coma
o Respiratory disturbances
o Rise of body temperature
o Fontanelle tension
o Skin Rash

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8
Q

Bacterial Meningitis - Clinical signs in older children and adults:

A

o Headache
o Vomiting
o Photophobia
o Rigor nucalis
o Hyperthermia
o Disturbances of vigilance
o Seizures
o Systemic manifestations: rush, arthritis, petechiae

Headache and rigor nucalis are due to activation of protective reflexes that tend to protect the spine.

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9
Q

BM - TYPICAL SIGNS

A

-Kernig sign (impossibility to extend the legs while hips are flexed

-Brudzinski sign (opposition to neck flexion).

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10
Q

BM NOTES

A

Seizures, confusion, stupor, coma, are due to the encephalopathy underlying the meningitis. Symptoms due to activation of cytokines and other toxic factors. Cerebral parenchymal lesions rare (exception: arteriolar or venous occlusion with infarcts).
Cranial nerves involvement:
* III,IV VI : diplopia, paralysis of ocular movements
* VII: peripheral facial paresis
* VIII: hypoacusia

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11
Q

BM DIAGNOSIS

A

CSF examination:
o Increase >CSF pressure (> 180 mm H2O)
o CSF non transapernt
o WBC > 1000/ml
o Proteins > 150 mg/dl
o Glucose < 30 mg/dl
CSF Sediment (Gram staining) may allow the identification of the bacteria; CSF culture RIA, latex-particle agglutination (LPA)-ELISA expensive may not be necessary.

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12
Q

BM IMAGING

A

Imaging: MRI + gadolinium  cortical reaction, inflammation of the meninges. Possible demonstration of infarcts

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13
Q

BM THERAPY

A

Antibiotics treatment can be:
* Empiric
* Specific

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14
Q

BM PROGNOSIS

A
  • Behavioral problems
  • hypoacusia
  • Language disturbances
  • Mental delay
  • Visual disturbances
  • Motor abnormalities
  • Epilepsia
  • Hydrocephalus
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15
Q

CHRONIC MENINGITIS

A
  • Slow - progressive course
  • Symptoms lasting > 4 weeks
  • Persistent inflammatory CSF
  • Usually in immunodepressed patients or patients with chronic disorders (TBC)
  • Variable ethiology
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16
Q

CM SYMPTOMS

A
  • Headache
  • Cervical pain
  • Cranial nerves involvement
  • Mild cognitive disturbances (attention deficit)
  • Behavioral changes
  • Hydrocephalus
  • Radiculopathies
17
Q

TBC OF THE CNS

A

Acute presentation is rare, while the subacute-chronic (weeks) presentation is more frequent.

Warning signs: fever, general discomfort, sub continuous headache.

Cranial nerves involvement is frequently observed (more often III, IV, V, VI, VII).

18
Q

CEREBRAL ABSCESS

A

It can be secondary to cranial fracture (< 10% of cases); more often it can be secondary to focal infections
* 40%: paranasal sinuses infections (frontal and sphenoidal sinuses) can lead to frontal and parieto-temporal abscesses
* Middle ear infections can lead to cerebellar abscesses
* Secondary to pulmonitis, bacterial endocarditis

19
Q

CEREBRAL ABSCESS SYMPTOMS

A

Symptoms:
* Headache
* Somnolence
* Confusion
* Seizures (focal, generalized, focal-generalized)
* Focal signs (signs depend on the site of abscess)
* > WBC, fever: not always, systemic symptoms may be absent

20
Q

Viral diseases of the nervous system

A

HIV-1; HIV-2, HSV-1, HSV-2, VZV, EBV, CMV, poliovirus, rabies virus.Viruses may have specific tropism for specific cells:
– Poliovirus: motoneurons;
– VZV: peripheral sensitive neurons;
– Rabie: brainstem neurons.
– JC virus: oligodendrocytes (progressive multifocal leukoencephalopathy).
– Herpes simplex: may cause severe encephalitis with loss of selectivity (grey matter, white matter, arteries, meninges)

21
Q

How do viruses enter the CNS?

A

 Respiratory
 Oro-fecal
 Genital
 Mucosae
 Animals-insects bites
 Transplacental

22
Q

Viruses can lead to:

A
  • Acute aseptic meningitis
  • Meningoencephalitis
  • Ganglionitis (herpes zoster)
  • Chronic diseases (AIDS)
  • Poliomyelitis
  • Chronic infetions: Progressive multifocal leucoencephalopathy (PML)
23
Q

VIRAL EPIDEMIOLOGY

A
  • Incidence: 11 per 100.000
  • Males>female
  • Any age. More frequent in children < 1 year
  • More common in hot season
24
Q

VIRAL SYMTOMS

A
  • Acute onset of fever (38 - 40°), headache, rigor nucalis (often mild)
  • Photophobia, pain during ocular movements
  • Rash, exanthema
    The virus is identified in only 11% of cases, and the viruses are: enterovirus, virus parotite, arbovirus, HSV, HIV.
25
Q

VIRAL DIAGNOSIS

A
  • Clinical suspect if other family members or community members have similar symptoms
  • CSF:
    – Colorless, > WBC (usually lymphocytes)
    – Protein: mild increase < 130 mg
    – Glucose: usually normal
  • MRI: picture below
26
Q

Encephalitis

A

It is an acute onset disease. It presents with fever plus a combination of several symptoms and signs:
* Cognitive problems: delirium, confusion, stupor, coma;
* Motor symptoms, ataxia, involuntary movements, myoclonus
* Cranial nerves paralysis
* Meningeal signs
The disease has a variable etiology:
* Infections: Bacteria, fungi
* Autoimmune diseases

27
Q

Herpetic Encephalitis

A

Most cases of encephalitis are herpetic encephalitis.
– HSV 1: oral lesions (typical, more ferequent encephalitis in adults)
– HSV2: genital lesions. Neonatal encephalitis from the mother (transplacentar)
– HHV3: varicella virus
– CMV: citomegalovirus

HSV stays quiescent in CNS, and then undergoes reactivation, possibly causing encephalitis. Possible direct transmission from peripheral nerves to CNS. The infection is sporadic, can occur at any age, in any season, and in any geographical area.

28
Q

HERPETIC ENCAPHALITIS CLINICAL MANIFESTATIONS

A

Clinical Manifestation
1. Prodromic symptoms: malasie, nausea, headache, fever
2. Acute encephalopathy (confusion, delirium, stupor, coma)
3. Headache, seizures, focal signs

Site of infection: temporal lobes in 60% of cases.

It is potentially lethal in 7-14 days. Sequelae:
o Epilepsy: 45%
o Cognitive disturbances: 25%

29
Q

HERPES DIAGNOSIS

A

This is the typical neuroradiological presentation of herpetic encephalitis: temporal lobes and frontal lobes are the most affected. (WHITE AREAS)

This is why patients with this disease develop epileptic seizures originating from the temporal lobe, they have disorders of consciousness, of behavior, memory, mood changes, speech problems and others.

30
Q

HERPES TREATMENT

A

Acyclovir IV 14 days. We need to start treatment asap even when diagnosis is not confirmed. This drug is effective, safe, and it decreases mortality and sequelae.

31
Q

Limbic Encephalitis

A

Autoimmune attack of the CNS: a number of antibodies can lead to it. An example is antibodies against VGKC but we can also have antibodies against GABAergic receptors or NMDA receptors, we can have specific clinical features according to the specific antibodies. We can have patients with cancer that is preceded by this condition.

32
Q

LIMBIC ENCEPHALITIS RADIOLOGY

A

also here (like Herpetic encephalitid) we have prominent localization of the lesions in the temporal lobe, in particular in the medial aspect of the temporal pole. Sometimes it’s bilateral. Hard to distinguish from herpetic enc. Because they are in the same location

33
Q

LIMBIC DIAGNOSIS

A

Diagnosis can be reached by looking at CSF

NEUROLOGY (7 decks)

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