The Neuroscience on the Web Series:
CMSD 636 Neuropathologies of Language and Cognition

CSU, Chico, Patrick McCaffrey, Ph.D.


Chapter 12. Traumatic Brain Injury: Recovery and Remediation


Recovery

In general, closed head injury (CHI) patients have a better prognosis than stroke victims. This is true in part because CHI patients are usually younger than those who suffer strokes and typically have healthier vascular system.

Abilities recovered

After CHI, some areas of functioning improve more rapidly than others. Verbal skills recovery more rapidly than visuomotor and visuospatial abilities. Short term memory seems to be resistant to trauma and is usually not affected much by CHI. Long term memory, on the other hand, appears to remain impaired for a considerable amount of time after CHI. One study found that 50% of a group who had received severe closed head injuriess continued to have memory deficits six to seven years after injury. According to Geschwind, the memory problems exhibited by CHI patients are the result of underlying attentional and information processing deficits (executive function). Because of the smooth interior of the skull near the primary language centers specific aphasia syndromes are relatively infrequent (Ylvisaker and Szekeres, in Chapey, 1994). Remediation therefore focuses on attentional and informational deficits and other aspects of executive function including disorientation and confused language.

Processes Involved in Recovery

According to Bach-y-Rita (1989), neural plasticity or the ability of the brain to relearn may account for recovery after head injury. Neural plasticity includes the processes of neural sprouting, neuronal unmasking, and denervation. All are aspects of the brain's ability to reorganize after an injury.

In monkeys and lower mammals with damage to the motor cortex progressive recovery within days or even hours of injury is attributable to changes in allegiance of cell columns near the lesion. These cells take on the function of the damaged cells. By injecting a gamma-amino butyric acid (GABA) antagonist drug into the cortex the motor territory can be enlarged (Fitz Gerald, 1996). Fast synaptic transmission is mediated by amino acids such as GABA (Bear et al. 2001).

Neuropharmacologic agents have ben used to help individuals return to work after injury. Stimulant and cognitive enhancing medications are used with individuals to attend to tasks, enhance concentration and heighten arousal levels. Medications are used to improve memory and speech/language skills. Amongst drugs used to increase attention are: Dexidrin (dexamphetamine), Ritalin ( metylphenidate), Symmetrel (amantadine),Parlodel (bromocriptine) and Sinemet (carbidopa-levodopa) and Cognex (tacrine). According to Ericksen etal, 2001 acetycholine levels can be increased in order to enhance memory by using tacrine and rivastigmine (Exelon) to block enzymes that degrade acetylcholine. This enables aceylcholine to be used as a neurotransmitter signal molecule. Physostigmine can produce similar effects.

Amantadine and Sinemet are used to enhance muscle movements by decreasing the rigidity and tremors seen in Parkinsons disease. These medications have also been used with TBI, although there is not enough research evidence to confirm their efficacy. (Ericksen et.al, 2001).

 

Neural Sprouting

There has been speculation recently as to whether the brain can produce new neurons. It would seem that it can. The hippocampus in the limbic system seems to be producing new cells all the time. This in important to the making of new memories. However, existing cells are able to sprout additional axonal branches which allow them to make new connections after an injury. (Think of sprouting as if it were an after effect of neural "pruning.")

Generally, neural sprouting is beneficial after an injury. If too much sprouting occurs, though, it can negatively affect brain functioning (Bach-y-Rita, 1989). According to Bhatnagar and Andy, 1995, P.114 "The proximal ends of axons in the CNS exhibit some growth (sprouting). However this growth is not significant because the regenerated axons cannot cross the astrocytic scars."

Neuronal Unmasking

Neurons which are normally quiescent may begin working again after others have been destroyed. This means that brain processes which are normally inhibited by higher level controls will be able to function. This may help in recovery. Negative effects of unmasking are reflexes and responses like the startle reflex which are usually only seen in young children. The Babinski reflex and the patella reflex may also be abnormal after head injury (Bach-y-Rita, 1989).

Denervation

After head injury, there may be an increase in neural sensitivity in the damaged area. To off-set this decrease, neurons that are still healthy may become hypersensitive or increase in number (Bach-y-Rita, 1989).

Remediation

Therapy with CHI patients will focus on improving attention, perceptual abilities, thought organization, and the performance of higher level cognitive processing tasks like problem solving. These deficit areas should be addressed in the order listed here for obvious reasons. (A patient who cannot attend will certainly be unable to organize his/ thoughts or solve hypothetical problems.) The techniques listed below could be therapeutic for any patient who has cognitive problems. They might be effective with some left CVA patients, but are especially likely to be useful with those who have right hemisphere damage (see below). (Adamovitch and Henderson, in La Pointe, 1990)

Improving Attention

Provide an environment in which distractions are minimized. Be aware of the types of attention deficits that you may encounter with right hemisphere involved patients. They include divided, sustained, focused and alternating. As you begin therapy, bear in mind that it may be necessary to limit the length and intensity of sessions. Therapy sessions can be longer and tasks can be made more difficult as the patient's tolerance increases. It is often helpful to integrate familiar and personally significant items into therapy tasks, especially during initial sessions. Sensory stimulation in all modalities can be used to stimulate attention.

Oral-peripheral stimulation

Many of the same techniques used with swallowing patients can be applied to therapy with CHI patients if necessary. For example, if a patient is ignoring one side of his mouth, a lollipop could be used to encourage him to move his tongue into that area.

Auditory stimulation

Bells or other simple auditory stimuli could be used at first. As the patient's ability to attend improves, present more complicated stimuli like music or speech.

Tactile stimulation

Contrasts like hot and cold or soft and rough could be used to stimulate attention.

Visual stimulation

Different colors might be used. Also, light might be contrasted with dark.

Taste

Again, contrasts such as sweet vs. sour may cause the patient to attend.

Olfactory stimulation

Start with strong, noxious smells like ammonia, which really command attention, and then present more pleasant scents, such as perfume.

Improving perception

According to Henderson and LaPointe (1990), the clinician should identify the sensory modality in which perception is most impaired and begin therapy by presenting stimuli in that modality. The least affected modality should be used for cueing. Other sources disagree with this technique and suggest initially presenting stimuli in the most intact modality.

To improve visual tracking, the patient could be asked to follow a light with his eyes. To address auditory tracking, ask him to point in the direction of a sound source with his eyes closed.

Shape recognition

Patients could be asked to trace or copy shapes.

Word recognition

Read a passage to the patient. Ask him to raise his hand every time he hears you say a particular target word.

Discrimination/Matching

First, the clinician should ask the patient to match two identical objects. Next, s/he might match pictures with objects and pictures with other pictures. Letters, words, sentences and geometric forms can be incorporated into therapy tasks as the patient's abilities improve.

Thought Organization/Information Processing

Patients can be asked to sort items by size, shape, color, etc. Also, they might be asked to name the item that does not belong in a particular group.

Closure

To improve visual closure, the patient might practice completing pictures with missing parts. Tasks like completing sentences or words with phonemes missing can be used to work on auditory closure.

Sequencing

For example, the patient might be asked to order objects from small to large or light to dark. Also, he might practice unscrambling words or sentences. As the patient improves, introduce more practical activities like sequencing the steps in daily activities or following complex directions.

Executive Function/Problem Solving

According to Ylvisaker, Szekeres and Feeney, 2001 .page 276, "a functional operational definition of the executive system is

1. Awareness of strengths and weaknesses and associated understanding of the difficulty level of tasks.

2. Based on this awareness, an ability to set reasonable goals, plan and organize behavior designed to achieve the goals, initiate behavior towards achieving goals, inhibit behavior incompatible with achieving those goals, monitor and evaluate performance in relation to the goals, flexibly revise plans and strategically solve problems in the event of difficulty or failure.

3. Ability to assume a non-egocentric perspective. (and)

4. Ability to think abstractly and transfer skills from training to application contexts."

The following remedial guidelines are suggested:

Convergent thinking

Convergent problems require one specific answer. For example, the clinician might ask the patient to identify the attribute that a group of objects have in common (Chapey, 2001).

Divergent thinking

Divergent problems have numerous potential solutions and therefore stimulate flexible, creative thinking. For example, the patient might be asked to list all the ways that an everyday object, like a brick, might be used. Other divergent thinking tasks include explaining all the meanings of words with multiple definitions (e.g., knot, to, board), and explaining proverbs and idioms (Chapey, 2001).

Deductive reasoning

Ask the patient to complete syllogisms. For example, the patient could be given the premises "all children go to school" and "Bob and Jane are children," then have to decide whether or not Bob and Jane go to school. As the patient improves, ask him/her to practice deducing the consequences and causes of everyday problems (Chapey, 2001).

Inductive reasoning

To improve the patient's inductive reasoning abilities, ask him/her to finish stories, answer why questions or listen to short stories and then guess what kinds of emotions the characters in the story might be experiencing (Chapey, 2001).

Multi-process reasoning

Ask the patient to devise solutions for everyday kinds of problems. For example, the clinician might present a hypothetical argument between two people then require the patient to explain the pros and cons of both points of view and suggest a compromise that might be used to settle the debate (Chapey, 2001).

Working memory

Although working memory (it is measured by digit span) is not a very common memory impairment in CHI, it is sometimes impaired. Ylvisaker and Szekeres (1994) suggest increasing functional capacity through the use of grouping by meaningful units (semantic grouping), or grouping syntactically or by melodic chunking.

Orientation training

When patients are beyond the confused and agitated stage of recovery, orientation training should begin. It is comprised of environmental prompts and systematic stimulation, training, and behavior management (Brookshire, 1997). Environmental prompts are strategies that help compensate for cognitive deficits. They can include memory note books, calendars of daily events/appointments, maps, alarm clocks or clock radios, simple maps to help then find their way around, etc. (Ylvisaker and Szekeres, 1994). Orientation to place, person, and time must be considered. I have always liked to use photographs of the patient's neighborhood (orientation to place), and of family members and friends (orientation to person). Orientation to all of the above should be accomplished through involving as many people as possible in the effort. It should include hospital staff, friends and family. Occasionally I get patients who are in extreme denial and with very poor prognosis. I think that in some situations orientation to reality may not be in their best interests.

 
 
 


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Other courses in the Neuroscience on the Web series:
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