PSYC31H3 Chapter Notes - Chapter 7: Vascular Dementia, Impulsivity, Transient Ischemic Attack

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Chapter 7 - Neuropathology for Neuropsychologists
-In order to make diagnostic sense out of the behavioural patterns that emerge in
neuropsychological assessment, the practitioner must be knowledgeable about the
neuropsychological presentation of many kinds of neurological disorders and their underlying
pathology
-knowledge of these disorders gives the examiner a diagnostic frame of reference that helps
to identify, sort out, appraise, and put into a diagnostically meaningful context the many bits
and pieces of observational, scores, family reports, and medical and social history that typically
make up the material of a case
Neurological Disorders (exemplified)
-head trauma
-vascular disorders
-degenerative disorders
-multiple sclerosis
-normal pressure hydrocephalus
-toxic conditions
-infectious processes
Traumatic Brain Injury (TBI)
-defined as an alteration in brain function, or other evidence of brain pathology, caused by an
external force
-generally refers to injury involving the brain resulting from some type of impact and/or
acceleration/deceleration of the brain
-traumatic brain injury is the most common cause of brain injury
-head injuries resulting from “falls” are most likely to be incurred by infants and young children
-accident involving moving vehicles account for approximately half of all head injuries in the
other age groups
-head injury is still synonymous with TBI, but in some cases it refers to injury of other head
structures such as the face or jaw
-brain damage typically occurs in two stages
-primary injury: damage that occurs at time of impact
-secondary injury: physiological processes set in motion by the primary injury
-the primary injury
-coup
-the blow at the point of impact
-countercoup lesions
-when the brain sustains a bruise (contusion) in an area opposite the blow,
occurs in most cases of occipital injury
-coup and countercoup lesions account for specific and localizable behavioural
behavioural changes that accompany closed head injuries
-the movement of the brain within the skull puts strains on delicate nerve fibers and
blood vessels that can stretch them to the point shearing
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-shearing effects
-microscopic lesion that occur throughout the brain tend to be concentrated in the
frontal and temporal lobes and the interfaces between gray and white matter
-hence the diffuse damage and neuropsychological effects
-the more severe the injury, the more likely it is that the patient will display deficits characteristic
of frontal and temporal lobe injuries along with behavioural abnormalities and the more
prominent these deficits will be
-impairments in information processing speed, attention, and learning and consequent retrieval
is most common neuropsychological profile in mild and moderate TBI, as well as severe TBI,
although extent of executive disturbances is more prominent in these patients
Closed vs Open Head Injuries
-closed head injuries (CHI) are referred to as blunt head trauma or blunt injury
-the skull can be fractured and the injury may still be a CHI as long as the meningeal
covering of the brain itself is not breached by penetration through the skull
-account for most head injuries
-Penetrating head injuries (PHI) a.k.a. open head injuries (OHI) include all injuries from any
source in which the skull and dura are penetrated by missiles or other objects
-account for less than 10% of all documented head trauma in the civilian population
-there are commonalities between CHI and PHI, the nature of the injury along with the
pathophysiological processes set in motion by damage to the brain may differ in these two types
of injuries
-acquired brain injury (ABI) refers to just about anything that can damage brain tissue and may
be applied to TBIs
-concussion: considered a mild form of TBI
-secondary or delayed injuries are sometimes more dangerous than the primary cause of the
TBI
-hemorrhage, hypoxia (insufficient oxygen), ischemia (insufficient or absent blood
supply), elevated intracranial pressure (ICP), and changes in metabolic function, coagulopathy
(blood clotting), and pyrexia (fever)
-prevalence estimates and incidence reports in epidemiological studies vary depending on
such decisions as whether to include all grades of severity, to count deaths, to limit the study to
hospitalized patients, etc
-for the most common type of CHI, mild TBI, many of the injured may never seek medical care
-peak ages for TBI are in the 15 - 24 year range with high incidence rates also occurring in the
first five years and for elderly persons
-helmets have reduced head injuries in sports such as bicycling, hockey, horseback riding, and
football although not all helmets reduce craniofacial injuries effectively
-low socioeconomic status, unemployment, and lower educational levels are also risk factors,
increasing the likelihood of TBIs due to falls or assaults more than for other groups
-TBI: young working class males, limited educational attainment, lack of previous stable
work prior to injury
-Violent TBI: less than high school, unemployed, male, high blood alcohol level at time of
injury, and african americans
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-the behavioural effects of all brain lesions binge upon a variety of factors, such as severity,
age, site of lesions, premorbid personality, and the mechanisms of the injury
Diagnosis of TBI
-how a TBI is categorized depends on the injury characteristics, not some random point post
status by way of “severity” of cognitive impairment
-glasgow coma scale (GCS): not appropriate for many cases, and it largely meaningless
without other form of supplementary material
-duration of lost consciousness: good predictor for severe injuries
-post traumatic amnesia: brief or no PTA associated with with mild injury with increasing
PTA duration associated with more severe injury
-neuroimaging
-neuropsychological testing
-retrograde amnesia (RA) usually involving the minutes, sometimes hours and more rarely days
immediately preceding the accident, frequently accompanies PTA
-frontal and temporal regions, as well as the anterior cingulate gyrus implicated in RA
-visual field defects are stone indicators of severity
-anosmia (loss of smell) can be a marker of not only damage to olfactory regions but also the
orbitofrontal damage
Severity Classifications and Outcome Prediction
-patients whose injuries seem mild, as measured by most accepted methods, may have
relatively poor outcomes both cognitively and socially
-patients classified as moderately to severely injured have enjoyed surprisingly good outcomes
Glasgow coma scale (GCS)
-classification system based on elcation of depth and duration of altered consciousness
-good predictor of injury outcome
Mild Traumatic Brain Injury
-GCS: 13 - 15
-duration of lost consciousness corresponds to less than 20 minutes
-post traumatic amnesia corresponds to less than 24 hours
-Islands of memory
-temporal/continuous memory
-no evidence of intracranial injury on neuroimaging examination
-Complicated Mild Traumatic Brain Injury: same as above, except THERE IS intracanial injury
present
Moderate Traumatic Brain Injury
-GCS: 10 - 12
-duration of lost consciousness corresponds to greater than 20 minutes and less than 36 hours
-duration of post traumatic amnesia is greater than 24 hours and less than seven days
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