Module 7 CNS: Stroke, Encephalopathy, Abscess, Meningitis Flashcards
(35 cards)
Next topic for CNS is Ischemic Stroke/Cerebral Infarction. there are three types each card will go through the types. What is the first?
Thrombotic/Ischemic Stroke (more common)
HTN — atherosclerosis — unstable plaque —thrombosis —bland infarct (white infarct due to 100% occlusion of lumen)
Risk factors for atherosclerosis:
-smoking, DM, hypercholesterolemia (most common under 40) , HTN (most common over 40)
The second etiology for an ischemic stroke is embolic stroke. What are some features?
Embolic Stroke: (less common but more serious)
–atrial fibrillation + mural thrombus in left heart — legs (DVT) or brain (Red infarct bc lumen not completely occluded)
The third etiology for an ischemic stroke is carotid artery dissection. What are some features?
Carotid Artery Dissection: young and middle aged
- mild trauma — occludes lumen and causes stroke
- -extension to the adventitia may cause subarachnoid hemorrhage
What is the most common affected vessel?
Middle cerebral artery
–watershed between MCA and ACA
What is the presentation of a patient with an Ischemic stroke?
Contralateral hemiparesis and sensory loss (again for any stroke) Aphasia if Broca's Affected Cerebellum affected: D (dysmetria) D (Dysdiadokinesia) A (ataxia) N (nystagmus) I (intention tremor) S (Slurred speech) H (hypotonia)
In an ischemic stroke what does the CT show?
Non contrast CT: shows no abnormalities so that rules out hemorrhage but does not rule out ischemic
MRI: much more sensitive
What changes are seen in the brain for an ischemic stroke?
0-12 hrs: nothing
12-24 hrs: coagulative necrosis
24 hours: PMNs
–stroke is a permanent neurological deficit after 24 hours (legs recover before arms)
–before 24 hours (transient ischemic attack but can still have perm neuro damages)
over 48 hours: microglia – liquefactive necrosis
2 weeks: astrocytes — glosis
Moving on to Hypoxic-Ischemic Encephalopathy, what is this?
Widespread injury to neurons
- -neurons are more vulnerable to hypoxia/ischemia than other cells (4 minute rule on CPR)
- -usually due to cardiorespiratory arrest with resuscitation
What are the pathological changes in order of severity for Hypoxic-Ischemic Encephalopathy?
- Selective Neuronal Necrosis (unpredictable distribution)
- Laminar Necrosis: necrosis of all neurons in a given neocortical layer
- Pseudolaminar Necrosis: necrosis of all cytological elements in neocortical layers 2 thru 6
- Watershed Infarcts
- Multifocal grey matter infarcts
What CNS changes are expected in a patient that is dead at a scene?
Massive craniocerebral trauma
Vertebrospinal trauma
Diffuse post traumatic vascular injury
Idiopathic cardiorespiratory dysfunction following milder head injury
What CNS changes are expected in a patient that is in a persistent coma/vegetative state (often with disproportionately mild imaging findings)
Diffuse axonal injury
Post traumatic hypoxic-ischemic encephalopathy (thalamic involvement)
What CNS changes are expected in a patient with a lucid interval (patients who talk and die)?
Acute peridural hemorrhage (epidural hemorrhage)
Post traumatic brain swelling
What CNS changes are expected in a patient with a post traumatic epilepsy, cognitive and/or motor dysfunction?
Contusion
Mild diffuse axonal injury
Chronic Subdural
Residual effects of evacuated peridural hematomas
The next topic will be brain abscess, what is the etiology?
Two routes of spread:
- Hematogenous spread: usually due to sepsis or septic emboli from left sided endocarditis (IV drug users that has tetralogy of fallot)
- Direct/Contigual Spread (more common): sinusitis, mastoiditis, otitis media and dental infections
- -example: Chrug Strauss – CANCA positive with chronic sinusitis
What is the pathogenesis for a brain abscess?
Collection of infection in the parenchyma (liquefactive necrosis with PMNs and cellular debris)
What is the presentation of a brain abscess?
Spiking Fevers
Confusion
Projectile vomiting (increased ICP)
Focal neurological deficits
What do you see on biopsy and lumbar puncture in a patient with a brain abscess?
Biopsy best investigation: Mixed flora or Polymicrobal flora (combination of anaerobes and aerobes)
Lumbar Puncture: Elevated WBC, elevated protein and normal glucose (b.c the problem is in the brain not the CSF)
What is seen on CT scan in patient with brain abscess?
CT scan with contrast:
Ring Enhancing lesion
What are the 5 conditions that give you a ring enhancing lesion on CT?
Glioblastoma Multiform Mets Abscess Lymphoma Toxoplasmosis
What are the complications of a brain abscess?
Rupture into ventricles —– ventriculitis —- obstruction of ventricles —- hydrocephalus (non communicating)
Also from broad spectrum abx = CDIFF or toxic megacolon
A quick review on Meningitis, what are the bacterial causes for the various age groups?
Bacterial:
- Neonate: E.coli or strep
- –Children: H.influenza or N.meningitides
- Adolescents: N. meningitides
- Adults: S. pneumoniae or L. monocytogenes
What is seen on histology and CSF for meningitis?
Histology: Exudates covering the leptomeninges and engorgement of the meningeal vessels
CSF: increased WBCs, increased protein and decreased glucose
Fungal Meningitis usually occurs in the immunocompromised, what are the various bugs?
Meningeal: -cryptococcosis: soap bubble appearance -candida: microabscesses Vasoinvasive --- thrombotic occlusion--infarction and hemorrhage --aspergillus -mucomycosis
The last meningitis to be discussed is Tuberculous meningitis. What are some features?
- -TB granulomas in the parenchyma (TB)
- -May complicate primary hematogenous dissemination
- -Cell mediate immunity – formation of Rich’s/Gohn’s Focus – depression of CMI — reactivation and rupture of focus into subarachnoid space
