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Chapter 7

PSYC31 - Neuropsychological Assessment chapter 7

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Pare, Dwayne

PSYC31 – Chapter 7: Neuropathology for Neuropsychologists  in order to make diagnostic sense out of behavioral patterns that emerge in the neuropsychological assessment, the practitioner must be knowledgeable about the neuropsychological presentation of many kinds of neurological disorders and their underlying pathology  the knowledge gives the examiner a diagnostic frame of reference to identify, sort out, appraise, and put into a diagnostically meaningful context the many bits and pieces of observations, scores, family reports, and medical and social history that typically make up the material of a case  such a frame of reference should help the examiner know what additional questions need to be asked  the kind of info the examiner needs to know varies from person to person  a number of different kinds of disorders produce similar constellations of symptoms  many conditions with similar neuropsychological features can be distinguished by differences in other neuropsychological dimensions  with more than one brain disease process affecting brain function, the behavior presented is potentially complex with confusing set of symptoms  some conditions might increase the occurrence of other disorders  No single rule of thumb will tell the examiner what info he needs to make effective use of the examination data Traumatic Brain Injury (TBI)  an injury involving the brain resulting from some type of impact and/or acceleration/deceleration of the brain  TBI is defined to be an alteration in the brain function or other evidence of brain pathology, caused by an external force  Most injuries are closed in that the skill remains intact and the brain is not exposed (closed head injury = CHI) o Blunt head trauma or blunt injury as well o The skill can be fractured and the injury may still be a CHI as long as the meningeal covering of the brain or them brain itself is not breached by penetration through the skull  Penetrating head injuries (PHI) also called open head injuries (OHI) include all injuries from any source in which the skull and dura mater are penetrated by missiles or other objects  an acquired brain injury (ABI) refers to just about anything that can damage brain tissue and may be applied to TBIs  TBI is the most common cause of brain damage in children and young adults  Incidence of TBI also varies with the study site, as urban centers account for a higher incidence of TBI than rural areas  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  Most common causes of TBI are falls and transportation related injuries  More than half the injuries incurred by infants and young children and by persons in the 64 range are due to falls  Moving vehicle accidents account for half of all head injuries in the other age groups  Motorcyclists have a higher mortality rate than occupants of motor vehicles, but pedestrians in traffic accidents have the highest rate of all  Helmets have reduced head injuries although not all helmets reduce craniofacial injuries effectively  While helmets may protect the skull and surface of the head, the internal movement dynamics from the trauma still occur, producing shear-strain and mechanical deformation of the brain  Men sustain injuries about twice as frequently as women, with this sex differential greatest at the peak trauma years  Low economic status, unemployment, and lower educational levels are also risk factors, increasing the likelihood of TBIs due to fall and assaults more than for other groups  Typically TBI occurs in young working class males, who may have not have had a stable work history prior to injury  Violent TBI inflicted by oneself or another is higher for those who have less than a high school diploma, are unemployed, are male, and have a higher blood alcohol level at the time of injury and also for African Americans  Preexisting alcohol and substance abuse are major factors contributing to the incidence of TBI  Some form of brain imaging is performed on almost all patients presenting with acute TBI when medically indicated  the range of TBI severity begins with impacts so mild as to leave no behavioral trances, resulting in no lasting structural injury to the brain and producing only the briefest of transient and temporary changes in the neurological function  at the other end of the continuum are patients in prolonged coma or a vegetative state from catastrophic brain injury in which most regions of the brain have been damaged and where neuroimaging studies expose the most serious neuropathological abnormalities  neuropsychological assessment is concerned with patients between these 2 extremes  considering all levels of injury, it is observed that almost 40% of injured patients returned to work after 2 years  the diagnosis of TBI is defined by way of injury characteristics, not at some random point post status by way of severity of cognitive impairment o presence, degree and duration of coma, Glasgow Coma Scale (GCS) o coma duration alone is a poor predictor of outcome for the many patients who have brief periods of loss of consciousness (LOC) but it is good predictor for more severe injuries o Duration of posttraumatic amnesia (PTA) can also help determine the presence and severity of a TBI. Brief or no PTA is associated with mild injury with increasing PTA duration associated with more severe injury o neuroimaging o once it has been determined that an individual has sustained a brain injury, at whatever severity level, that person should be considered a candidate for neuropsychological assessment Mild Traumatic Brain Injury  concussive brain injury induces an acute physiological effect but probably no lasting structural injury  90% occur in this range  Symptoms such as dizziness, drowsiness, irritability, and sleep disturbances; attentional deficits, verbal retrieval problems, headaches, emotional distress/fatigue, depression and anxiety  Needs to be diagnosed by relevant history  most commonly used scale for assessing the presence and initial severity of TBI is the GCS, recorded by paramedics at the site of injury or in the ED or hospital  defined GCS of 13-15; a single GCS score without data on when it was determined and the status of other pertinent variables at the time can lead to an inaccurate assessment of the severity of injury  it is based on evaluation of the presence, depth and duration of altered consciousness  it is a good predictor for severe injuries but poor for patients who have brief periods of LOC  duration of LOC corresponds to less than 20 minutes  some clinicians rely on the PTA to measure the severity of the injury; duration of PTA correlates well with GCS ratings  PTA corresponds to less than 24 hours; retrograde amnesia usually accompanies PTA  Many patients with mild TBI are discharged home while still in PTA or never seek emergency medical care in the first place. An examiner at some later date can only estimate PTA duration from reports by the patients or family members who often have less than reliable memories (islands of memories)  length of PTA tends to be more accurate than coma duration in predicting long-term cognitive status and relates more directly to long-term neuroimaging findings  there is no evidence of intracranial injury on neuroimaging examination; negative CT and MRI but EEG and SPECT abnormalities of right temporal dysfunction with parallel dissipation of retrograde amnesia and SPECT findings at 3 months o MRI-identified metabolites were indicative of tissue disruptions in the white matter Complicated Mild Traumatic Brain Injury  characterized by same injury characteristics with exception of intracranial injury being present Moderate Traumatic Brain Injury  GCS corresponds to 10-12  Duration of LOC corresponds to greater than 20 minutes and less than 36 hours  Duration of PTA is greater than 24 hours and less than 7 days  Involves injury to both gray and white matter  8-10% fall in this category  Suffer disturbances at 3 months of post-injury  Headaches, memory problems, and difficulties with everyday living, slow processing speed  Women have better outcomes than men  Frontal damage can be seen in people that have become more impulsive or subject to temper outburst; temporal lobe damage makes it appear as a learning disorder  Planning ability and automatic self-monitoring are often compromised Severe Traumatic Brain Injury  GCS corresponds to 9 or less  Duration of LOC is greater than 36 hours  Duration of PTA is greater than 7 days  Has significant cognitive effects even decades after the injury  Fewer than 10%  Becoming a major and growing problem because their rehab needs are very costly and not all can return to normal living and functioning  Attentional deficits are common along with memory impairments, working memory deficits, deficits associated with frontal lobe injury, language deficits, visuospatial, visuoperceptual and constructional deficits, and basic motor deficits  The outcome for each type of TBI depends on many factors such as age, repeated TBIs, multiple injuries, alcohol abuse, academics, work history, social support, any legal difficulties (criminal history), financial status  Outcomes also depends on the injury characteristics themselves defined by the GCS, LOC, PTA, and presence/absence of intracranial injury Outcomes from each type of TBI Mild TBI  Cumulative research on the outcome of a single uncomplicated mTBI shows that neuropsychological impairments may persist for up to 3 months but the norm is full recovery with no long term residual deficits  It was seen that patients returned to a baseline level of normal cognitive performance within 1- 3 months of post-trauma  There was 97% overlap of control and mTBI injury test performance by 1 month post-trauma and 95% confidence intervals of effect size estimates at both 30-89 days and more than 89 days post-trauma included 0 (suggesting no difference in test performance)  The overall cognitive test performance of those with mTBI was essentially indistinguishable from that of matched controls by 1 month post-trauma (the patients returned back to normal functioning after 1 month and were not distinguishable from normal people that hadn’t had the injury)  Maximum prevalence of deficit after 3 months is likely to be little to none and the neuropsychological assessment is likely to have positive predictive value of less than 50% (there is less than a 50% chance
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