CNS Infections Lecture Powerpoint Flashcards
Meningitis
Inflammation of the meninges any part or all 3 layers, most often the arachnoid mater and CSF in the subarachnoid space initially, caused by bacterial or viral exposure most often, common in newborn in elderly
3 vaccines that have drastically decreased rate of meningitis
- HIB
- meningococcal
- pneumococcal
Pathogenesis of meningitis
-Infection enters body, invades bloodstream, crosses BBB, invades meninges, and multiplies in the CSF
Most common ways meningitis can spread (3)
- Mother to child during birth
- cough or sneezing
- food prep
Neisseria meningitis characteristic appearance
Rash (bleeding under skin), poor prognosis
Bacterial vs viral meningitis
Bacterial is much more severe and fatal than viral
When a patient has suspected bacterial meningitis, need…
….immediate antibiotic treatment ASAP to improve prognosis
Most common organisms that cause bacterial meningitis (5) and what is the leading cause?
- Neisseria meningitidis
- strep pneumonia (leading cause in US)
- Listeria monocytogenes (in children and elderly)
- Group B streptococcus (children)
- E coli (children)
Clinical presentation of bacterial meningitis (3)
-Fever
-nuchal rigidity
-mental status change
(sudden acute onset of this)
Kernigs sign
Place patient supine with hip flexed at 90 degrees, attempt to extend leg at knee, positive when there is resistance to extension or pain in lower back or posterior thigh
Brudzinski sign
Place patient in supine and passively flex the head toward the chest, positive when there is flexion of the knees and hips in response
Viral meningitis usually preceded by a ___. It is usually ___
URI, self limiting
1 cause of acute viral meningitis
-Enterovirus
Symptoms of viral meningitis vs bacterial
Viral is same as bacterial but much less severe except sometimes in immunocompromised patients
How to differentiate between viral vs bacterial meningitis? (3)
- Blood cultures (start antibiotics after empirically and don’t take them after giving medication otherwise false neg)
- Lumbar puncture with CSF analysis
- Polymerase chain reaction viral testing
How many tubes of CSF are typically sent for analysis? What about in suspected subarachnoid hemorrhage with blood tinge?
3 tubes, 4 tubes
CSF findings in bacterial vs viral meningitis
Bacterial: cloudy appearance, leukocyte count is high, glucose low, protein high
Viral: CSF is clear, wbc count lower predominant lymphocytes, glucose normal range
Before getting Lumbar puncture with any concern of increased intracranial pressure, need to get…
….CT
Examethasone in meningitis treatment
Used in viral and bacterial, reduces cerebral edema, increases ICP, and decreases neurological complications and mortality
Antibiotics for meningitis treatment (2)
- <1 month use ampicillin (listeria concern)
- vancomycin + 3rd gen cephalosporin (cefatoxine in <1 month or cephtriaxone in >1 month)
Post exposure prophylaxis for meningitis (3)
- rifampin
- single dose quinolone
- ceftriaxone
Encephalitis
Acute inflammation of the brain parenchyma associated with neurological dysfunction, often co-occurring with meningitis
1 organism causing encephalitis
-Arbovirus
Signs/symptoms of encephalitis (1)
-Very similar to meningitis
Diagnostic testing for encephalitis (3)
- CT/MRI if evidence of increased intracranial pressure
- Lumbar puncture if no contraindications
- Blood culture
Brain abscess definition
Focal collection of pus within the brain parenchyma that can arise from a variety of infections, trauma, or surgery
Space occupying lesions increase….
…intracranial pressure (dont do an LP on em!)
Diagnostic studies for brain abscess and which is the gold standard (3)
- MRI
- CT
- Aspiration and culture (gold standard)
Venous sinus thrombosis definition
Uncommon but life threatening condition where clot forms in cavernous sinus (unknown what causes propensity to form) resulting in increased pressure, decreased perfusion, and leaking of blood into interstitial space
Signs/symptoms of venous sinus thrombosis (3)
- New onset headache
- intracranial hypertension
- encephalopathy
Diagnostic studies for venous sinus thrombosis (3)
- MRI/MRV
- CBC
- Coag panel
Treatment for venous sinus thrombosis (4)
- early anticoag
- antibiotics if infection present
- corticosteroids
- surgery if needed
Transverse myelitis definition
Demyelination of both sides of one section of spinal cord due to inflammatory process that leads to sensory and motor changes below the lesion as well as autonomic dysfunction, often idiopathic
Transverse myelitis diagnosis (3)
- MRI with contrast
- CSF
- autoimmune tests
Transverse myelitis treatment (2)
- Short course high dose corticosteroids
- methotrexate alternative
If pressure is above __ on opening pressure of lumbar puncture, withdraw and do immediate CT
18 mmH2O
Ways to avoid spinal headache following lumbar puncture (5)
- lay supine 2-3 hours
- fluids
- no heavy lifting 2-3 days
- tyelonol
- blood patch
Electroencephalogram (EEG) (what is it primarily indicated for?)
Tool to assess physiological electrical activities of brain not used to screen but as a diagnostic aid to evaluate seizure activity
EEG measurement
MEasures synchronous summation of millions of neurons discharging electrical activity at a given frequency in a specific spatial area of brain (called a montage) and done under certain activities (sleep, awake, etc) at any given age (infants thru adults)
EEG types (4)
- Awake (stimulus evoked with strobes, sounds, or smells)
- Sleep/sleep deprived
- Ambulatory (for more than one day)
- Video monitored (over a few days in hospital
Limitations to EEG (4)
- Poor spatial resolution (does not localize foci accurately)
- Measures only gyri
- thick hair
- patient cooperation
EEG alpha wave
Located posterior, present when patient is relaxed with eyes closed, if abnormal think coma
EEG Beta wave
Located symmetrical anterior, present when patient is alert, active, busy, if abnormal think of medication cause
EEG Theta wave
Located somatosensory cortex parietal lobe, present in sleep at any age, if abnormal think cognitive decline
EEG delta wave
Located frontal lobe in adults and occipital in children, present in deep sleep, if abnormal think lesions (tumor) or hydrocephalus
Difference between nerve conduction study and electromyography
NCS detects problem with nerve while EMG detects whether muscle is functioning properly in response to nerve stimulus and can be much more painful/uncomfortable
Nerve conduction study and electromyography indications (4)
- Paresthesias
- numbness
- tingling
- pain
3 types of evoked potential and a brief description about each
- brainstem auditory evoked potential (noninvasive to evaluate hearing loss with clicks, beneficial to localize lesions distal to cochlea CN VIII and distal)
- visual evoked potential (screening to evaluate optic neve damage that affects sight)
- somatosensory evoked potential (Measure response from stimuli to the spinal cord to help determine causes of numbness to the arms or legs thru tiny electrical shocks delivered by an electrode to a nerve indicated for spinal cord injury)
