Neuropsychological Outcome Of Severe Traumatic Brain Injury

All aspects of recovery and outcome after traumatic brain injuries (TBI) are affected by injury severity. Severe injuries may result in persistent neuropsychological impairments, functional disability, and poor return to work rates. Severe TBI can result in temporary, prolonged, or permanent neurocognitive and neurobehavioral impairments. Cognitive impairment is highly individualized but there is a linear relationship between injury severity and the magnitude and number of cognitive abilities affected. Neurobehavioral changes include personality changes, problems regulating emotions, apathy, disinhibition, and anosognosia. From a neurocognitive perspective, impairments are most notable in attention, concentration, working memory, and speed of processing. As injury severity increases, there is a greater likelihood of global cognitive deficit that may include motor skills, verbal and visual-spatial ability, reasoning skills, poor balance and dizziness, visual impairments, cranial nerve impairments, headaches, sexual dysfunction, fatigue and sleep problems. Severe TBI may result in poor return to work rates. This delayed return to work in turn will result in interpersonal problems for the patients and their families, economical stress for the individual, and productivity loss for the society.

A combination of assessment procedures, including standardized tests, informant and self-rating inventories, naturalistic observations, and thorough interview of patients and caregivers, is essential to evaluate all consequences of TBI. Attention is commonly impaired following severe TBI and it is more apparent in higher-order tasks involving divided attention, working memory, and cognitive flexibility and likely to be attributed to speed of information processing. Learning and memory (retrograde and anterograde) are also frequently impaired. New learning on episodic memory tasks with a delayed recall component may be markedly impaired with difficulty learning verbal information, and inability to utilize organizational strategies such as clustering of semantical/ related words. Diffuse TBIs have typically been associated with language impairments including anomic aphasias, poor sentence repetition, followed by deficits in confrontation naming, word generation, and receptive language. It has been associated with semantic dissociations that make formation of language structure difficult.

Dyspraxia and dysartheria may also be present in severe cases. Assessment of pragmatics such as turn-taking, staying on topic, listening skills, interference control, responding to the speaker, and appropriateness of subject topic is also essential in measuring language disturbance in those patients. Visual disturbances such as decreased acuity, visual field deficits, and oculomotor disturbances can be an issue particularly during the acute phases of recovery. Formal visuospatial deficits are less commonly observed following TBI. Due to diffuse damage, however, attention-related visuospatial neglect may occur. Impairment in constructional activity, such as drawing a design or assembling a figure is a common deficit after severe TBI. Executive dysfunction may manifest as perseverative language or behaviour, decreased cognitive and behavioural initiation, decreased self-monitoring, poor planning, and compromised problem solving. Set-switching and cognitive flexibility appear in particular to be significantly impaired after a variety of severe brain injuries and can be used to predict post-injury outcome. Individuals with more severe brain injuries may lose the ability to carry out goal-directed behaviourdue to problems with modulation of attention and behavioural action, as well as a lack of initiation manifested in both inappropriate and impoverished verbal and behavioural activities.

In summary, the long term neurological, neuropsychiatric, functional, and neurocognitive deficits associated with severe brain injuries result in adverse effects for the injured person, his/her families and society. TBI is not an event but an ongoing process in any patient, and neuropsychological evaluations must reflect this. The assessment battery in general should be tailored to the stage of recovery of the patient and must be dynamic in nature to accommodate the evolving nature of TBI. Therefore, serial evaluation will be necessary to adjust patient and caregiver expectations and to help plan future treatments.