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Pathophysiology 2 > Neuro units > Flashcards

Neuro units Flashcards

1
Q

What is the neural tube?

A

The neural tube develops at week 3 of gestation when the embryo’s ectoderm thickens and forms the neural plate which then folds in on itself to form the neural tube

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2
Q

What are the two ends of the neural tube?

A

cranial end–> brain
caudal end–> spinal cord

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3
Q

What are the causes of neurodevelopmental disorders?

A

-genetic disease
-neural tube defect
-neurotoxin exposure
-infectious disease
-physical trauma
-multifactorial cause

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4
Q

Describe Huntington Disease

A

-rare genetic disease that affects the brain and causes progressive impairment of movement, cognition, and behaviour
-caused by CAG repeats in the gene

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5
Q

What is the pathogenesis of Huntington Disease?

A

neuronal dysfunction and death

basal ganglia degeneration–> loss of motor control

cerebral cortex degeneration–> loss of cognition

neurochemical changes associated with HD are decreased GABA and increased DOPA

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6
Q

What are the clinical manifestations of Huntington disease?

A

Basal ganglia degeneration:
-chorea (random muscle movements)
-dystonia (random sustained muscle contractions)
-bradykinesia
-dyarthria and involuntary vocalizations
-dysphagia

Cerebral cortex degeneration:
-irritability, apathy, anxiety and depression
-paranoia, delusions, hallucinations
-suicidal ideations
-executive dysfunction
-dementia

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7
Q

What are the complications of Huntington Disease?

A

-injuries due to falls
-malnutrition
-swallowing difficulties
-choking
-aspiration pneumonia

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8
Q

What can occur when the neural tube doesn’t close completely during development?

A

-called a neural tube defect
-causes impairment such as paralysis, hydrocephalus, bladder and bowel dysfunction and learning difficulties

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9
Q

What causes a neural tube defect?

A

-maternal folic acid deficiency (most common)
-obesity, poorly controlled DM, and taking medications that interfere with folate metabolism (ex. some anti-seizure meds)

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10
Q

Describe anencephaly

A

when the soft, bony component of the skill and part of the brain are missing– occurs in about 1 in 5000 births each year
-the baby is stillborn or dies within a few days

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11
Q

Describe encephalocele

A

a developmental defect in which a herniation or protrusion of brian and meninges through a defect in the skill, resulting in a saclike structure– occurs in about 1 in 10,000 live births

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12
Q

Describe spina bifida occulta

A

the most common and mildest form of spina bifida– when the spinal cord and surrounding meninges lie within an incomplete lumbosacral vertebral column
-the spinal cord and nerves are undamaged, asymptomatic and are often unaware that they have the disorder
-patch of hair, dimple, or birthmark in the lumbar region might overlie the affected spinal region

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13
Q

Describe meningocele

A

-rare and mild neural tube defect
-meninges protrude through an incomplete vertebral column
-does not involve the spinal cord or nerve roots and may produce no neurologic deficit or symptoms
-can occur in the cervical, thoracic or lumbar spine

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14
Q

Describe myelomeningocele

A

-also called spina bifida cystica
-neural tube defect where a cyst containing meninges and spinal cord protrudes through an incomplete vertebral column
-one of the most common developmental anomalies of the nervous system, with an incidence rate of 1 in 1000 pregnancies
-often located in the lumbar region

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15
Q

What is a provoked seizure?

A

one with a known cause

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16
Q

What is an unprovoked seizure?

A

one with an unknown cause

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17
Q

What is the pathogenesis of a seizure?

A
  1. seizure initiation
  2. tonic phase– excitation
  3. clonic phase– inhibition
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18
Q

What is status epilepticus?

A

A continuous global seizure lasting more than 5 minutes or a series of rapidly recurring seizures that prevent a return of consciousness

–a medical emergency
– NOT epilepsy

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19
Q

Describe an absence seizure

A

lapses in consciousness that rarely last longer than 10 seconds– staring blankly then returning to being alert
-more common in children and usually doesn’t lead to lasting injury

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20
Q

Describe a tonic-clonic seizure

A

a sudden loss of consciousness, stiffening of the body with arching of the back followed by convulsions
-usually lasts 2-5 minutes
-pt may experience changes in sensation, mood or emotion leading up to the seizure
-pt may lose control of their bladder or bowel

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21
Q

Describe an atonic seizure

A

a sudden loss of postural muscle tone
mild– head dropping
severe– falling

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22
Q

What is the difference between a primary and secondary brain injury?

A

primary– sudden and profound injury to the brain at the time of impact (ex. car accident)

secondary– indirect consequence of primary injury and involves both brain and systemic responses (ex. ischemic neuron injury)

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23
Q

What are the clinical outcomes of a focal brain injury compared to a global?

A

focal– more likely to be fatal
global– lower mortality rate but more likely to cause severe disability in survivors

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24
Q

What is the GCS score for mild, moderate and severe TBI?

A

mild >13
moderate 9-12
severe <8

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25
Q

What causes a focal brain injury?

A

blunt or penetrating trauma

26
Q

Describe coup vs contrecoup injury

A

coup– the site of impact

contrecoup– the rebounding of the brain (hitting the opposite side)

27
Q

What is a brain contusion

A

-brain bruise
-blunt trauma compresses the skill and underlying brain tissue at the point of impact and the compression lacerates blood vessels within the affect brain tissue
-blood leaks out of the damaged vessels to cause a brain contusion

28
Q

When does the maximal effects of closed brain injury peak?

A

18-36 hours after severe head injury– diffuse brain injury and secondary brain injury is likely

29
Q

What is a brain hemorrhage?

A

when blood pools in the skull to form a brain hematoma– caused by damage to intracranial blood vessels during closed head injury

30
Q

What are the types of hematomas?

A
  1. epidural hematoma
  2. subdural hematoma
  3. intracerebral hematoma
31
Q

Where is an epidural hematoma located?

A

between the dura mater and the skull

32
Q

Where is a subdural hematoma located?

A

between the dura mater and arachnoid mater

33
Q

Where is an intracerebral hematoma located?

A

within the brain parenchyma

34
Q

Describe a diffuse axonal injury (DAI)

A

when the brain rapidly moves inside the skull due to a blunt force and damages axons– is the leading cause of morbidity and mortality in pts with TBI

-characterized by extensive damage to the axons of neurons, which leads to impaired neuronal function and neurologic deficits

35
Q

What are the types of DAI?

A

mild– microscopic axonal damage but no apparent functional deficits

moderate– more extensive axonal damage with altered LOC and focal neurologic deficits

severe– widespread axonal damage with coma

36
Q

What are the manifestations of DAI?

A

-altered LOC
-memory loss
-headache
-dizziness
-nausea and vomiting
-seizures
-muscle weakness and paralysis

37
Q

What are the potential complications of DAI?

A

-cognitive impairment
-motor deficits
-sensory impairment
-behavioural impairments
-epilepsy
-coma
-brain death or cerebral death

38
Q

What are the potential long-term consequences of brain injury?

A

-brain ischemia and hypoxia
-cerebral edema
-excitotoxicity
-neuroinflammation
-brain atrophy
-intracranial hypertension

39
Q

What are the types of post-traumatic brain syndromes?

A
  1. post-concussion syndrome
  2. post-traumatic seizure
  3. chronic traumatic encephalopathy
40
Q

Describe post-concussion syndrome

A

-occurs with mild TBI
-symptoms are nonspecific, including headache, dizziness, fatigue, anxiety, irritability, insomnia, photophobia, depression, inability to concentrate, and forgetfulness
-may last weeks to months

41
Q

Describe post-traumatic seizures

A

-occurs in about 10% of TBIs, especially among open brain injuries
-seizures can occur within days and up to 2-5 years or longer after the trauma

42
Q

Describe chronic traumatic encephalopathy

A

-progressive dementing disease that develops with repeated brain injury associated with sporting events, blast injuries in soldiers, or work-related head trauma
-Tau neurofibrillary tangles are present
-associated with violent behaviours, loss of control, depression, suicide, memory loss and cognitive change

43
Q

Define cord concussion

A

-minor spinal cord injury that results in temporary disruption of cord-mediated functions
-temporary loss of spinal cord function

44
Q

Define cord contusion

A

-a relatively minor spinal cord injury
-bruising of neural tissue causes swelling and temporary loss of cord-mediated functions
-temporary loss of spinal cord function

45
Q

Define cord compression

A

-more severe than cord concussion or contusion
-pressure on the spinal cord damages it directly and may cause local cord ischemia
-pressure on the spinal cord must be relieved (decompressed) to prevent permanent damage to it
-may cause local cord ischemia and permanent loss of spinal cord function

46
Q

Define spinal cord laceration

A

-occurs when fragments of fractured vertebral bone tears the spinal cord
-severe, cord laceration may result in permanent loss of cord-mediated functions
-the effects of this injury may be reversible if only slight damage to the spinal cord sustained
-may result in permanent loss of spinal cord function

47
Q

Define cord transection

A

-occurs when fragments of fractured vertebral bone sever the spinal cord, causing permanent loss of function

complete transection– all spinal cord tracts are completely severed and all cord-mediated functions below transection are completely and permanently lost (paralysis)

incomplete transection– some spinal cord tracts (and the functions they mediate) remain intact, while others are damaged, some functions are lost but may return over time

48
Q

What is the general pathogenesis of a secondary spinal cord injury?

A
  1. hemorrhage
  2. local edema and ischemia
  3. cord swelling
  4. neuroinflammation
  5. necrosis
  6. glial scarring
49
Q

Define spinal shock

A

-temporary cessation of spinal cord function below injury
-flaccid paralysis
-dysreflexia/areflexia
-loss of sensation

50
Q

Describe neurogenic shock

A

-life-threatening condition that can occur following a spinal cord injury
-due to loss of sympathetic tone and uninhibited parasympathetic tone
-more common in spinal cord injuries above T5

Consequences include:
-hypotension
-bradycardia
-hypothermia
-multi-organ failure
-death

51
Q

Describe autonomic dyreflexia

A

-a potentially life-threatening medical emergency that can occur in individuals who have suffered a spinal cord injury at or above the T6 level
-a condition in which the autonomic nervous system responds excessively to stimuli below the level of injury, leading to a sudden and dangerous increase in BP

S/Sx:
-increase in BP
-severe headaches
-flushing of the skin
-sweating above the injury
-bradycardia
-feeling of anxiety
-can cause a stroke, seizures or even death

52
Q

Describe focal brain ischemia

A

-caused by localized infarction of brain tissue
-results in focal neurological deficits typically without altered consciousness
-extent of damage dependent on volume of collateral blood flow and location of infarct
-common causes: cerebral thrombosis and cerebral embolisms

53
Q

Describe global brain ischemia

A

-caused by inadequate blood flow to large sections of or the entire brain
-results in unconsciousness within seconds
-if circulation is not restored immediately, severe and permanent brain damage is likely, or even death
-common causes: cardiac arrest, shock and carotid stenosis

54
Q

Define cerebral thrombosis

A

caused by a blood clot that forms in a brain artery or vein

55
Q

Define cerebral embolism

A

caused by a blood clot (or foreign substance) that travels through the bloodstream and lodges in a brain artery

56
Q

What is a watershed infarct?

A

-occurs in the border zone between the territories of two major arteries that supply blood to the brain
-happens when blood flow to the brain is reduced due to a decrease in blood pressure or a decrease in the oxygen-carrying capacity of the blood, for example, in cases of hypotension, hypoxemia or shock
-can lead to weakness or numbness in the limbs or difficulty speaking or understanding speech

57
Q

What is laminar necrosis?

A

-a type of infarct that occurs in the deeper layers of the brain cortex due to a lack of blood flow
-often caused by prolonged and severe hypoxia and occurs in conditions such as carbon monoxide poisoning, cardiac arrest, or prolonged hypotension
-blood flow to this area is from short penetrating arteries, which is why the necrosis is penetrating
-can cause changes in cognition, personality and movement disorders

(lots of ischemia deep in the brain because it has the least blood flow normally)

58
Q

Describe the penumbra

A

-a central core of dead or dying cells
-a “halo” of borderline ischemic tissue
-if the penumbra dies, the infarct enlarges, and the issue surrounding it becomes ischemic (ie. a new penumbra is formed)

59
Q

What does the survival of the penumbra depend on?

A

-successful and timely reperfusion
-degree of excitotoxicity and neuroinflammation
-degree of cerebral edema
-availability of collateral circulation
-degree of vascular remodeling (angiogenesis)

60
Q

What are the mechanisms of an ischemic stroke?

A

-embolism
-thrombus formation
-vessel stenosis from atherosclerosis
-brain hypoperfusion

61
Q

Define neurodegeneration

A

the progressive loss of neuron structure or function, leading to neuron injury and death

62
Q

Define inclusions

A

misfolded protein deposits– can be intraneuronal or extraneuronal

Pathophysiology 2 (3 decks)

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