Posttraumatic amnesia and outcomes

Having problems creating new memories after a TBI is termed anterograde amnesia or posttraumatic amnesia (PTA). The duration of PTA increases with TBI severity and is used along with other acute neurologic indicators, such as Glasgow Coma Scale (GCS) scores, and neuroimaging to help determine the severity of injury (mild, moderate, severe). The duration of PTA has been shown to be a good predictor of recovery and long-term cognitive outcomes.

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  PTA lasting up to 1 hour is seen with mild TBI (mTBI).

  
  
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  Outcomes: Expectations of full recovery; symptoms dissipate in days/weeks

  
  
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  PTA between 1 and 24 hours is seen in individuals with moderate TBI.

  
  
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  Outcomes: Expectations of full recovery for most; symptoms dissipate in weeks/months

  
  
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  PTA over 24 hours is associated with a severe TBI.

  
  
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  PTA between 1 to 14 days

  
  
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  Outcomes: Majority still attain good outcome but may not return to full baseline level of functioning; recovery most dramatic in first 3 to 6 months

  
  
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  PTA between 2 and 4 weeks

  
  
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  Outcomes: Up to 50% may experience moderate disability and protracted recovery

  
  
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  PTA greater than 4 weeks

  
  
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  Outcomes: Most will experience some degree of disability; severe disability for more than one-third of cases

PTA can be evaluated retrospectively by asking a patient about the first clear memory after their injury. More reliable assessment of PTA can be completed prospectively through serial administration of a standardized psychometric instrument.

Prospective assessment of posttraumatic amnesia

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  Galveston Orientation and Amnesia Test (GOAT)

  
  
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  Orientation Log (O-Log)

Although behavioral checklists/rating scales of agitation have been developed to assess individuals in PTA, more extensive assessment of cognitive abilities in this stage of recovery is unlikely to yield significant additional meaningful clinical information. Retrograde amnesia, loss of memory for the events immediately preceding a TBI, can also occur for some individuals with more severe TBI. Assessment of the duration of PTA and inquiry about potential retrograde amnesia should always be included as part of a clinical history in individuals with TBI.

Recovery of cognitive abilities after traumatic brain injury

Recovery of cognitive abilities varies based upon severity of TBI. The Institute of Medicine (IOM) concluded that there is inadequate or insufficient evidence of long-term cognitive impairments after mTBI. Individuals who sustain moderate TBIs demonstrate a slower recovery of cognitive abilities and less uniform cognitive outcomes. Individuals who sustain severe TBIs commonly display a diffuse pattern of cognitive impairments.

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  Limited evidence of cognitive impairment beyond days/weeks in mTBI/concussion

  
  
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  More protracted recovery in moderate TBI. Primary cognitive domains: information processing speed, declarative memory, and executive functions.

  
  
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  Long-term cognitive impairments are common in individuals who sustain severe TBI. Longer course of recovery with increased likelihood of residual cognitive impairments.

Table 33.1 summarizes several factors that have been empirically demonstrated to positively affect long-term cognitive outcomes after TBI.

Neuropsychological evaluation after traumatic brain injury

Objective evaluation of neuropsychological functioning is an important part of assessment and treatment, given the frequency of cognitive difficulties after TBIs. Neuropsychological testing is a standardized set of tests measuring multiple domains of cognitive functioning and other factors that have been shown to influence performance on cognitive tests. Common cognitive domains and neuropsychological tests are summarized in Table 33.2 .

TABLE 33.2

Neuropsychological Assessment After Traumatic Brain Injury

Domain of Functioning	Neuropsychological Tests
Serial monitoring after acute traumatic brain injury	JFK Coma Recovery Scale-Revised Orientation Log Galveston Orientation and Amnesia Test Agitated Behavior Scale
General cognitive functioning and full neuropsychological batteries	Wechsler Adult Intelligence Scale –4th Edition Neuropsychological Assessment Battery Repeatable Battery for the Assessment of Neuropsychological Status
Effort/validity	Dot Counting Test Test of Memory Malingering Green Word Memory Test Rey 15-Item Test (with recognition) Word Choice Test Embedded Measures of Performance Validity
Academic achievement	Wide Range Achievement Test–4th edition Woodcock-Johnson Tests of Achievement–4th edition
Sensory-motor functions	Grooved Pegboard Test Manual Finger Tapping Test
Language	Verbal Fluency Tests Multilingual Aphasia Examination Boston Naming Test
Visuospatial–constructional	Clock Drawing Test Rey-Osterrieth Complex Figure Test Judgement of Line Orientation Hooper Visual Organization Test
Learning and memory	California Verbal Learning Test–3rd edition Wechsler Memory Scale–4th Edition Rey Auditory Verbal Learning Test
Attention/Processing Speed	Trail Making Test Continuous Performance Tests Symbol Digit Modalities Test Paced Serial Addition Test Digit Span
Executive functions	Wisconsin Card Sorting Test Booklet Category Test Stroop Test Delis-Kaplan Executive Functions Test
Functional abilities	Texas Functional Living Scale Independent Living Scale
Emotional functioning and personality	Personality Assessment Inventory Minnesota Multiphasic Personality Inventory-2 Restructured Form

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