CNS Pathology Flashcards
What is are the basic functional units for the nervous system?
Neurons, they are highly specialized cells
What is the purpose of the Blood Brain Barrier?
It is represented by the tight junctions that prevent larger and water soluble substances from entering the cells (infections, water soluble chemicals)
Water-soluble drugs have a hard time getting across the BBB
Do neurons divide in an adult?
No, neurons are nondividing, postmitotic, and permanent cells
What are glial cells?
They serve a supporting role. They are able to divide (unlike neurons)
How does damage to the brain affect its functions?
Specific loss of functions is associated with damage to specific areas of the Brian
What are the energy and nutrient demands of the brain?
Accounts for 2% of body weight, but its burden on metabolism is much greater
15% of cardiac output
20% of O2 consumption
25% of total body glucose utilization
Is the brain susceptible to toxicity despite the BBB?
Yes, largely due to the activity level of the brain. The brain is largely made form fats, so fat-soluble subsistences that are able to cross the BBB can build up in the brain
The brain also contains high amounts of sulfur-containing amino acids (can bind and transport heavy meals to the brain)
What are the reaction of neurons to injury?
The axon and/or cell body may become swollen upon injury. Rapid death results in phagocytosis. Axons may be regenerated
What happens to oligodendrocytes following brain injury?
These myelinating cells do not regenerate
What happens to astrocytes in response to brain injury?
Undergo hypertrophy and hyperplasia with just about any brain injury (this process is called gliosis)
What happens to ependymal cells following brain injury?
These cells line the ventricles (CSF container) and they do not regenerate
Does fibrosis occur in the brain?
No, there is no scarring. Rather a hole is left behind following a brain injury
What happens to microglia following a brain injury?
Transform into phagocytic cells once activated by chemotactic factors
What is global ischemia?
NOt enough oxygen gets to the brain tissue
Ex. Patients with chronic heart failure or due to atherosclerotic disease
What is a cerebral infarct?
This is a hemorrhagic stroke (clot blocks carotid artery)
What is intracerebral hemorrhage?
Bleeding in the brain such as a malformed vessel if that is weak (can be due to an aneurysm)
What is a fat embolism?
It is the presence of fat globules in the blood supply blocking flow
What is a mid-line shift in the brain?
This is the location of the corpus callousum
In forms of brain injury, the midline can shift towards one side due to injury on the other side
What are some risk factors associated with stroke?
HTN
Afib
Diabetes
Family history for stroke
High LDL
Increasing age
heart disease and poor blood flow
overweight, drinking heavily, eating too much fat or salt, smoking and cocaine, and other illegal drugs
What are the FAST symptoms seen in strokes?
FAST
Face: one side of the face is drooping
Arms: one or both arms have muscle weakness
Speech: difficult speaking
Time to call help and get EMS over to hospital
What are some factors that increase risk of dying following a hemorrhagic stroke?
Lots of intracranial bleeding
Coma
Advanced age
Oral anticoagulant use
Higher INR
What are some symptoms of a stroke?
Change in alertness
Changes in senses (impairment)
Clumsiness, confusion, or memory loss
Lack of control over bladder or bowels
Unilateral symptoms
Soured speech and/or trouble comprehending others
Trouble walking
What percentage of strokes are ischemic?
80% are ischemic, while the remaining 20% are hemorrhagic
How many hemorrhagic strokes are due to trauma?
Close to 25%, most hemorrhagic strokes are not due to external trauma
Does ischemia take a while to have an effect on brain tissue?
No, ischemia affects the brain rapidly because it does not store glucose (severely limits how long brain tissue can survive without constant perfusion)
What are some factors that can impact the severity of a stroke?
Duration of ischemia (longer is worse)
Collateral circulation (more is better)
BP affects overall perfusion (more is better)
Haematological factors (prone to more clotting is bad)
Temperature (cooler is better. Slows down brain metabolism and extent of injury)
Glucose metabolism (hyper or hypoglycemia may affect infarction size ) (more is better)
What happens to the appearance of brain tissues following a stroke?
No major changes are seen until about 5-6h after infarction. Then there is slight discolouration and a fuzziness of the usual clear border between gray and white matter
What happens to damaged brain tissue?
It necroses, which results in liquefaction and subsequent hole formation
What exactly causes cell death follwing ischemia?
Influx of Ca2+ and Na+; and activation of destructive processes that lead to cell death
These changes cause inflammation and endothelial cell reaction, leading to capillary plugging and increased vascular permeability
This results in cell death via necrosis and apoptosis
Review slide 23 for acute stroke treatment pathway
How is hemorrhagic stroke treated?
- BP control and supportive care to reduce intracranial
- Reduce further risk (reverse anti-clotting)
How are the different antiplatelet, antithrombotic, and thrombolytic agents reversed?
Antiplatelets: Platelet transfusion, Desmopressin
Warfarin: Vitamin K and fresh frozen plasma
Heparin: Protamine sulfate
Thrombolytics: Fresh frozen plasma and/or cryopreciptate
What are some types of physical brain injury?
Brain concussion: widespread, microscopic
Brain contusion: localized, macroscopic bruise and/or bleeding
Laceration: tearing of tissue
What are some types of neck and spinal cord injuries?
Spinal cord gets pinched by vertebral bones due to jerking motion:
Hyperextension injury
Hyper flex ion injury
What are some symptoms of concussions?
May be fatigued, confused, and have headaches for a long period of time. Recovery is a long process in concussions.
How are intracranial hemorrhages classified?
Location (epidural, subdural, subarachnoid or intracebral)
What are some causes of intracerebral hemorrhages?
Common complication of head trauma
Rupture of intracerebral vessels
Gunshot wounds
Non-traumatic forms
Common in hematologic diseases (leukaemia)
What are some types of CNS infections?
Encephalitis
Myelitis
Cerebral abscess
Meningitis
Neurosyphillis
AIDS-related CNS lesions
What is encephalitis?
It is an inflammation of the brain and spinal cord usually caused by viral infection
Can be caused by diseases such as rabies, polomelitis, and herpes encephalitis are all caused by a viral infection
Measles, mumps, and rubella are childhood illnesses that can lead to secondary encephalitis
West NIle, La Crosse, St. Louis, western and eastern equine encephalitis care all caused by mosquito-borne viruses
HSV-1 (Herpesvirus encephalitis) can cause encephalitis in the very young and very old
What is the clinical presentation of encephalitis?
Flu-like symptoms and headache
Severe cases: Severe headache, sudden high fever, drowsiness, vomiting, confusion, seizures, abnormal sensations (visual, auditory, olfactory) or movements
What are the different types of encephalitis?
Infectious encephalitis (viral infection)
Post-infectious: (inflammation due to immune system reactions to previous infection or vaccine)
Autoimmune: inflammation due to immune system reacting to a non-infections cause)
Chronic: inflammation build slowly over many months (can be due to HIV or unknown cause)
What are some severe symptoms of encephalitis?
Respiratory arrest
Coma
Death
What are some chronic symptoms of encephalitis?
Fatigue
Mood disorders
Memory problems
Intellectual disabilities
Lack of muscle coordination
Paralysis
Hearing or vision loss
Speech impairments
What causes “Covid-19 related brain fog”?
Severe inflammation outside the brain (lungs and other organs) while enduring Covid-19, causes immune system activation
This activation causes brain fog, anosmia/dysguesia (loss of taste), impaired cognition, memory, and mood
These symptoms can persist for many months after the infection
What are some factors that can improve the outcomes of neurogenerative disease?
Hearing aids, continual education, physical activity, and social interactions all help stave off neurogenerative disease
What is dementia?
It is a general, non-specific term to describe the cognitive, memory, and communication impairment associated with neurogenerative diseases
What are some specific skills that can become impaired n dementia?
Focus, reasoning, judgement, control of emotions, and motor skills can also become impaired
Is dementia a normal part of aging?
No, not everyone does not develop dementia
How are dementias diagnosed?
In addition to a medical history, family history and physical exam the following can be performed
Special tests of memory, language skills, math ability, and mental functioning
Lab tests to rule out infection, vitamin deficiency, or tumour
Psychiatric evaluation to rule out depression and other affective disorders
Genetic testing for specific disorders like Huntington’s
What are some neurodegenerative diseases?
Alzheimer’s disease
Parkinson’s disease
Amyotrophic lateral sclerosis
Pick’s disease
What is Alzheimer’s disease (AD)?
It is a degenerative brain disorder that develops in mid-to-late adulthood. It results in a progressive and irreversible decline in memory and deterioration of various other cognitive abilities
Who does Alzheimer’s disease disproportionately affect?
Usually elderly citizens and urban populations
What are some factor that increase the risk of Alzheimer’s disease?
HEavy MEtals
Environmental factors (Tobacco, Smoke, PEsticides)
Genetics (mutations in APP, PSEN1, and PSEN2)
Aging
CV disease
What is the physiopathology of Alzheimer’s disease?
Atrophy of the cortical parts of the frontal and temporal regions of the brain (cognitive and judgement impairment)
What is dementia?
Progressive loss of cognitive functions and a functional decline (loss of memory predominates)
What are some modifiable risk factor for Alzheimer’s disease?
Social engagement
Physical activity
Educational level
Mental actvity
What are some non modifiable risk factors for Alzheimer’s disease?
Family history
Genetics (Apo E2 gene)
Is there a connection between CV risk factors and Alzheimer’s disease risk?
The following are under investigation for their impact on Alzheimer’s disease:
Vascular disease
Heart disease
Stroke
HTN
Diabetes
Obesity
What is the pathology of Alzheimer’s disease?
The development of neurofibrillary tangles. They contain amyloid protein. Amyloid protein is toxic, compressing, and destroys normal brain tissue
Do amyloid plaques also cause damage that can lead to the development of Alzheimer’s disease?
They are not the direct cause of neuronal dysfunction. Some patients with amyloid plaques do not have dementia
What areas of the brain are particularly affected by Alzheimer’s disease?
Hippocampus (new memories)
Frontal lobe (behaviour, cognition, judgement)
Parietal lobe (language)
Review slide 47 to examine the differences between normal and early Alzheimer’s symptoms