Primary damage

Contusions—a bruise or bleeding on the brain—and lacerations can occur with or without skull fractures. Either an object hits the head, neck, or face, or the head hits an object. Damage can be to any area of the brain. Occipital blows are more likely to produce contusions than are frontal or lateral blows. Areas in which the cranial vault is irregular, such as on the anterior poles, undersurface of the temporal lobes, and undersurface of the frontal lobes, are commonly injured. Lacerations of blood vessels within the brain itself or of blood vessels that feed the brain from the neck or face reduce the flow of blood carrying oxygen to the brain. Contusions and lacerations can also injure the cranial nerves. The most commonly injured are the optic, vestibulocochlear, oculomotor, abducens, and facial nerves. Lacerations of the dura or in the arachnoid space may cause cerebrospinal fluid to discharge from the nose (cerebrospinal fluid rhinorrhea discharge increases with neck flexion, coughing, or straining).⁶ An example of a computed tomography (CT) scan of a cerebral contusion can be found in Chapter 37, Figure 37-17, B.

Epidural hematomas or hemorrhages occur mostly in adults when tearing of meningeal vessels results in blood collecting between the skull and dura. Skull fracture is present in the majority of cases. This is accompanied by intervals of lucidness and can result in death unless treated early.

Subdural hematomas occur with acceleration-deceleration injuries when bridging veins to the superior sagittal sinus are torn. Blood accumulates in the subdural space. Symptoms include weakness and lethargy. Symptoms such as weakness and lethargy that come on acutely are life-threatening. Symptoms caused by slow bleeding may not be present for several weeks. A CT scan of this problem can be found in Chapter 37, online image Figure 37-17, A. Also, note on the same figure the midline shift of the brain.

Diffuse axonal injuries, or shearing injuries, are among the most common types of primary lesions in patients with brain trauma.^7,8 Brain tissues that differ in structure or weight experience unequal acceleration, deceleration, or rotation of tissues during rapid head movement or during impact, causing diffuse axonal injury and changes in chemical processing. Refer to Chapter 37, Figure 37-17, D for an illustration of what axons are most affected by this shearing motion. Severing of the axons may be severe enough to result in coma. In milder forms, more spotty lesions are seen, including deficits such as memory loss, concentration difficulties, decreased attention span, headaches, sleep disturbances, and seizures. Damage often involves the corpus callosum, basal ganglia, brain stem, and cerebellum.^6,8 For a complete image of how the axons diffuse throughout the entire CNS, refer to Figure 37-17, C.

Penetrating objects with high velocities, such as bullets or shrapnel from explosives, can cause additional damage remote from the areas of impact as a result of shock waves. Foreign objects such as sticks and sharp toys cause low-velocity injuries, directly damaging the tissues they contact.

Blast injuries occur when a solid or liquid explosive material explodes, turning into a gas. The expanding gases form a high-pressure wave (overpressure wave) that travels at supersonic speed. Pressure then drops, creating a relative vacuum (blast underpressure wave) that results in a reversal of air flow, which is in turn followed by a second overpressure wave. Blast-related injury can occur through several mechanisms. The primary blast wave generates extreme pressure changes that can cause stress and shear injuries. For example, rupture of the tympanic membranes is very common after blast injury, and lung and gastrointestinal injuries also occur. The exact mechanism of injury to the brain is unknown, with speculation about both axonal shearing and shearing of vasculature.^9,10

Secondary damage

Secondary injuries are mainly caused by a lack of oxygen in the highly oxygen-demanding brain. Secondary problems may result from the following:

Motor, functional, sensory, and perceptual changes

Motor abnormalities after severe head trauma are common. More severe head injuries tend to manifest more persistent physical problems.⁶ In at least two studies^6,15 a fourth of the cases had no neurophysical sequelae. Changes in muscle tone may reflect the physiological effects of changes in the amount of tissue compression or irritation.¹⁶ Box 24-2 lists motor changes and provides symptoms of sensory and perceptive involvement.

Cognitive, personality, and behavioral changes

Cognitive and behavioral sequelae can result from generalized or focal brain injuries. Memory impairments are an aftermath of generalized lesions. Emotional changes may be seen with lesions in the orbitofrontal areas. Behavior may be excessive and disinhibited. Septal area lesions result in rage and overall irritability. Pseudobulbar injuries can result in emotional lability of involuntary laughing or crying not associated with feelings of emotions. Behavioral changes can be present even without cognitive and physical deficits. Although actual psychoses can be sequelae, they appear to be neither common nor definitively related to the brain injury.

The social consequences of inappropriate behavior can be disastrous and a stumbling block to achieving therapy goals. A correlation between preinjury personality and postinjury changes has not been established.⁶ It does seem reasonable, however, that factors within an individual’s psychological makeup may affect reaction to the injury. Brain trauma frequently happens to adolescents—an age group fraught with its own problems that may be aggravated by the injury. Outcomes at 1 year postinjury have shown the most common problems to be poor memory and problem solving, problems managing stress and emotional upsets, and an inability to control temper. Finally, managing money and paying bills were still a problem at the 1-year mark.¹⁷ Box 24-3¹⁸ lists both cognitive and behavioral changes resulting from brain injury.

Changes in consciousness and coma

Coma and changes in consciousness result from conditions in which there are diffusely extensive and bilateral cerebral hemispheric depression of function, direct depression or destruction of the brain stem–activating system that is responsible for consciousness or a combination of the two. In moderate or severe head injury, unconsciousness can be prolonged. Plum and Posner’s definitions¹⁶ of various stages of acutely altered consciousness are briefly presented, intermingled with some insights from the descriptions offered by Gilroy and Meyer.¹¹ Plum and Posner¹⁹ do not equate the presence or absence of motor responses with the depth of coma. These authors point out that the neural structures regulating consciousness differ from and are more anatomically distant from those regulating motor function.

Other complications

A list of the complications that may accompany brain injury would be limitless. In addition to any concomitant injuries, some of the diagnostic, monitoring, and therapeutic procedures themselves carry hazards. So does prolonged bed rest. Catheters, nasogastric tubes, and tracheotomies can cause iatrogenic injuries. Infections, contractures, skin breakdown, thrombophlebitis, pulmonary problems, heterotopic ossification (HO), and surgical complications are but a few of the risks. Posttraumatic epilepsy is also a possible sequela. Depression occurs frequently after brain injury, and it can alter functional outcome. It appears that a combination of neuroanatomical, neurochemical, and psychosocial factors are responsible for the onset and maintenance of the depression.²⁶

Surgical interventions

Patients with epidural hematomas often undergo craniotomies with blood evacuation. Subdural injuries are frequently treated by removing the blood through bur holes.

Pharmacological interventions

Medications are chosen according to symptoms to be treated. Many of these recommendations are from a meta-analysis of management of severe TBI published in 2007.35–39

Lesion size and area

There is conflicting evidence regarding recovery outcomes on the basis of lesion size and area because the type of lesion and the rapidity with which lesions occur have an impact on both the deficits and the size. There is some evidence that lesion area rather than size is important. Van der Naalt and co-workers^54,55 looked at 67 patients with brain injuries in the mild to moderate injury categories and found that frontal and frontotemporal lesions were predictive of poorer outcomes than lesions in other areas. However, Kurth and colleagues⁵⁶ looked at number of acute hemorrhages, lesion volume, and location in TBI using neuropsychological outcome measures and found no relationship between the numbers of hemorrhages and the volume of injury. Brain MRI in 80 adult patients (6 to 8 weeks after injury) was predictive of nonrecovery from persistent vegetative states at 12 months when the client had corpus callosum and dorsolateral brain stem lesions.⁵⁷ Lesion location is not a significant predictor of GOS scores. Lesions in the brain stem do appear to cause poorer outcomes on the GOS than other lesions.^58,59

Time since lesion

Better functional outcomes were found in monkeys when rehabilitation occurred earlier after the lesion. Black and colleagues⁶⁰ created lesions in the motor cortices of 27 adolescent rhesus monkeys and then trained them in motor tasks involving the arm. Active postoperative training of the weak hand led to recovery of 82% of the preoperative function in 6 months if the therapy was initiated immediately. Recovery was only 67% of preoperative control if training was delayed 4 months.

Age

Age is an important factor in recovery. Beginning at age 40 years, older patients have significantly longer PTA and worse functional outcome at any severity.⁶¹

Posttraumatic amnesia

PTA duration is better related to outcome than either lesion area or size.⁶¹ Postinjury amnesia had a predictable relationship to length of coma in patients with diffuse axonal injury. Duration of PTA was strongly correlated with the GOS score at 6 and 12 months after injury in patients with diffuse axonal injury but poorly correlated in patients with primarily focal brain injury. Van der Naalt and colleagues’⁵⁴ study of the GCS indicates that this scale, applied 12 months after injury, is a simple and consistent predictor of outcomes in clients with a score of 9 to 11 (mild to moderate brain injury). PTA is a strong predictor of outcome as measured by the Functional Independence Measure (FIM) (an activity level measurement tool)⁶²; and when PTA is combined with age, sitting balance, and limb strength at admission, prediction of productive outcome is high.⁶³ Walker and colleagues⁶⁴ also found that when PTA lasted less than 4 weeks, a severe activity limitation was unlikely; and if longer than 8 weeks, a good recovery was unlikely when measured by GOS.

Sitting and standing balance

Age younger than 50 years had a significant association with normal sitting and standing balance. Measures of severity of TBI, including admission Glasgow Coma GCS score, length of PTA, length of coma, and acute care length of stay, were also each significantly related to impaired sitting and standing balance. Initial abnormalities in pupillary response, respiratory failure, pneumonia, soft tissue infections, and urinary tract infections had a significant relationship with impairment of sitting but not standing balance. Presence of intracranial hemorrhages did not have a significant relationship with either sitting or standing balance. Intracranial compression had a significant relationship with standing balance. Discriminant functional analysis showed no relationship between balance ratings and neurological or radiological findings, injury severity, or medical complications.⁶⁵

Other factors

Finally, several studies have reported that absence of previous TBI,⁴² a higher level of educational achievement, and stable work history also are positive preinjury variables for a better prognosis.⁶⁶ The Wechsler Adult Intelligence Scale (WAIS)—Revised IQ test may correlate with prognosis according to other studies.⁶⁶

Motor disturbances resulting from brain injury generally have a good prognosis.¹⁴ Of the physical deficits encountered, dysfunctions in the cerebral hemispheres and of the cranial nerves are the most common disorders, and these may partially resolve. Losses of these functions can be more permanent,^11,14 especially without skilled rehabilitation interventions. Complete recovery is rare except with hearing, vestibular function, and smell. In one Glasgow study, some degree of hemiparesis was present 6 months after injury in 49% of the 150 clients who regained consciousness after severe brain injury.⁶

Psychosocial outcomes vary after severe brain injury.⁶⁷ Psychosocial variables that significantly increased life satisfaction for persons with TBI were total family satisfaction, being employed, being married, having memory, bowel independence, and not blaming oneself for the injury. Those who do not blame themselves show a greater number of functional activities as indicators for their self-satisfaction.⁶⁸

See Box 24-6 for factors that can influence recovery and management.

Characteristics of A learned skill (motor pattern).

In learning a new skill, movement begins with a “gross approximation” of the movement that includes agonist-antagonist co-contraction. As movement is refined, reciprocal movement replaces co-contraction.⁷¹ In electrophysiological studies of skill acquisition, less electrical activity is seen on electromyography (EMG) and less time to peak activation of the muscle is noted in motor tasks after they become skillful. In addition, fewer muscles are recruited for the same movement.⁷² PET scans have confirmed these EMG findings, demonstrating decreasing areas of brain activity after skill acquisition. Neuronal changes brought about through long-term potentiation and long-term depression are a basis for learning new tasks and developing motor patterns and behavioral changes.⁷³ As neurons are repetitively fired at the same time, networks develop. These neuronetworks, or cell assemblies, are formed with increasing complexity and self-organization. The more they are used, the stronger and more permanent are the changes that occur. Finally, a specific stimulus now provokes a learned or skilled response as an organized synergy. The output of the networks is not a summation of individual functions but has “emergent properties” that are more than the sum of the output of individual neurons.

The best understood motor patterns are the balance and reaching patterns. Both appear to be basic innate synergies. Quiet standing in humans is maintained by somatosensory, visual, and vestibular inputs (see Chapter 22). It requires the coordination of many muscles, especially those of the hips, knees, and ankles, to maintain the body’s center of gravity over its base of support. This complex coordination of muscle control is accomplished by sequences of stereotyped patterns mediated through the brain stem, cerebellum, and spinal cord. Somatosensory input during body sway stimulates the response in which posture is stabilized by small changes in the angle between the foot and the leg. For small and slower center of gravity movements, these synergies are sequenced in a distal to proximal manner. The direction of sway determines the particular synergy elicited to correct for the shift in the center of gravity. In forward losses of balance, the posterior extensor muscles of the legs and trunk respond at about 100 ms. In backward losses the anterior muscles respond, including the anterior tibialis, hip flexors, and abdominals. The timing between muscle contractions and the proximal-to-distal sequence are preset. The amplitude of contraction varies with the environmental demands and the amount and velocity of sway. In larger or more rapid sway, a different synergy is used; the person may bend at the hips and knees, or a hip strategy or a combination of hip and ankle strategies is used. If the balance loss is great enough, the person takes a step to maintain upright balance.⁷⁴ (For additional information, see Chapter 22A on balance and 22B on vestibular dysfunction). In gait, weight shifts from one leg to the other and stability after the weight shift are other aspects of dynamic balance performed through motor patterns. The movement pattern of the swing leg in gait is limited in the number of degrees of freedom at each joint and the sequence of movement by motor patterns. There is also a specific coordination and timing of swing leg movement in relation to the stance leg movement (interlimb timing and coordination) accomplished through motor patterns. In gait, the sequence of contraction of the leg muscle from ankle to hip, the time of onset of the contraction of each muscle, and a ratio of force for each muscle is preset in the motor control program of the brain or spinal cord. If an increase in speed is needed, step length, cadence, and force can be increased within the synergy, but the basic synergies, or motor patterns, are what give identity to a gait pattern. Whether the person is walking quickly or slowly, there is an individually recognizable pattern.

In the reaching and grasping pattern, three components have been identified: the reaching portion (transport), the grasping or prehension portion, and the maintenance of balance. Reaching and maintenance of balance are accomplished through motor patterns.^75,76 The target determines the reaching pattern. Characteristics of the reaching synergy include a distal-to-proximal sequence of firing, and movement is in a straight line with a bell-shaped velocity curve.⁷⁷ The prehension portion of reach and grasp is not a synergistic movement, and the motor-sensory cortex helps with force production and selection of muscles⁷⁸ during hand movement to meet task demands. This may be why more severe deficits are seen in the hand after cortical injury.

Knowledge of results

Information on how successful the movement was in meeting the task goal is basic to learning. Knowledge of results (KR) consists of extrinsic information over and above that provided by the task itself.⁸⁷ During the practice portion of most tasks, increasing any type of feedback appears to improve task performance.⁸⁸ But long-term learning may be improved when KR is provided less often. The relative frequency with which KR is provided in relation to the number of trials is important in learning. Bandwidth KR, in which information is given about trials falling outside a certain range, and a random schedule of feedback appear to be effective for many learning situations in therapy. Delaying KR also improves learning.⁸⁷

Practice type

The type of practice is important for clients who are learning new skills. A commonly used technique to simplify a task by practicing at a slower speed or practicing a part of a motor task is often not effective. For example, weight shifting is often practiced as a component of gait before walking is initiated. Winstein and colleagues⁸⁹ demonstrated that this part practice did not transfer to gait in a group of clients who had had a stroke. In a study by Man and colleagues,⁹⁰ a complex task was broken down into adaptive training methods (e.g., slower motions) and part-task training (on components of the task). Subjects who practiced the whole task had better performance than either of the other groups. A finding that practicing small components of a task does not make one better at the whole task is not too surprising. Many of us can jump, have good shoulder power, and can throw overhead but cannot, without practice, put this together to play basketball. A minimum basic amount of strength, range of motion (ROM), and interlimb sequencing is necessary to play basketball but is not adequate to play without the actual practice of the sport.

However, practicing other than the whole task may be possible. By use of the same task as that used by Man and colleagues,⁹⁰ Newell and colleagues⁹¹ showed that part-task training was effective when it was conducted in natural subtasks of the whole. These subtasks are part of the whole task but are distinguished by changes in speed or direction. This area of skill acquisition has not been studied adequately to identify subtasks of most common movements. A recent meta-analysis reviews use of part practice and methods of part practice for the most effective motor learning.⁹² Whole practice appears best for tasks low in complexity and high in organization as well as for discrete or serial tasks with high organization. An example might be a golf swing. Part practice appears effective for tasks high in complexity and low in organization, for example, dancing.

Finally, many therapy techniques that improve a client’s immediate performance inhibit learning because they are based on the external controls and support provided by the therapist’s manipulations, markedly changing the basic task. The types of feedback and the methods by which they are provided are critical to learning new motor skills. For example, when the hip stabilization component of walking is externally provided by the therapist during gait training, the client has no need to develop his or her own hip stabilization patterns, and feedback lacks a basic component of gait. Therefore the manual guidance may give the client a feeling of the movement pattern, but to continue to provide the hands-on control deprives the client of learning the balance and anticipatory components himself or herself.

To review, the conceptual framework for the evaluation and intervention of clients with TBI is based on distributed motor control theory, which states that movement is task or goal oriented and a result of combined systems working together to produce synergistic movement (motor pattern). Synergistic movement has an anticipatory component that is matched with sensory feedback and previous experience to contribute to task refinement through adaptation. Changes in motor behavior may be determined by how “set” the patterns are (dynamic pattern theory). They are influenced by the type of practice, knowledge of the effectiveness of the results, and how the motor skills are broken down for practice.

Examination of the client with brain injury

Cognitive, behavioral, and communication deficits.

Figure 24-1 depicts the close association of cognitive, behavioral, and physical functioning soon after injury. The three domains gradually become more distinguishable in later stages of recovery and can be assessed more independently; however, their interrelationships remain exceedingly complex. Cognition includes many aspects of function, including memory, learning, information processing, attention span, motivation, and initiation. Cognitive impairment was the primary contributor to activity limitation in most clients with TBI who scored at moderate to severe levels on the GOS.⁹⁶ Neuropsychologists, speech pathologists, and occupational therapists all perform testing of cognitive function. These tests may include word association, written word fluency, figural fluency, and card-sorting tests. Attention can be tested with the digit span and arithmetic tests on the WAIS⁹⁷ and by serial counting by 7. Information processing is reflected in reaction time tests and digit symbol tests. Choice reaction time is an indicator of information processing and commonly remains below normal in clients with brain injury.⁹⁸ Testing of intellectual functions is often done with the WAIS. However, formal testing of intellectual function can be hampered by inadequate perceptual, visual, and motor performance. Memory can also be tested with the WAIS and with the Galveston Orientation and Amnesia Test.⁹⁹ The Mini-Mental State Exam¹⁰⁰ is a memory screen often used by health care providers to determine whether further testing is indicated. Language and cognitive problems are frequently examined by speech pathologists and/or neuropsychologists using naming tests, aphasia examinations, and tests of auditory comprehension and speed of comprehension. A widely used system of cognitive function at the activities level is based on numerous observations of clients with brain injuries at Rancho Los Amigos Hospital. This has resulted in a descriptive categorization of various stages of “cognitive function,” as shown in Appendix 24-A, with use of the Rancho Los Amigos Levels of Cognitive Functioning Scale.

Examination of motor functions

Although most of the following sections describe motor function, motor function is only a small part of the problem of the client with TBI. Social and family problems will likely be the most devastating in the long term. Motivation, attention skills, emotional instability, memory, learning, and social deficits are all cognitive processes that prevent or retard clients’ progress in the therapy program as well as in home and work environments. Working with professionals who specialize in these areas will improve the client’s chances to escape deficits that are permanently handicapping.

Impairments

Once the task has been analyzed, the impairments leading to poor performance of the task are identified. Breaking motion down to its most basic components may be helpful, but two caveats are necessary. First, improvement in abnormal components may not lead to improvement in activity limitations.

Impairments can be identified and evaluated for their contribution to an activity or participation limitation. Some critical impairments will have more influences on an activity than will others. For example, in children with cerebral palsy who have gait disabilities, Olney and colleagues¹⁰² demonstrated that poor force output by ankle plantarflexors during the late stance phases of gait was the most important factor in poor gait performance within this population. Another example comes from Perry and colleagues,¹⁰³ who showed that for normal walking velocity to be attained, although cadence and stride length are important, a strength level of 3+/5 is a critical component in the ankle muscles. Deficiencies of timing, strength, or sequencing can contribute to poor hand function, but sensory deficits at the hand level may be the critical impairment related to poor manipulation skills. In addition, impairments in the circulatory, respiratory, integumentary, and musculoskeletal systems can account for activity limitation in the client with TBI (Figure 24-2). Relative contributions of the impairments to the activity limitation or participation limitation are addressed by the therapist’s task analyses, hypothesis, subsequent evaluation, and diagnosis,¹⁰⁴ which will determine the focus of the intervention program. Second, treating the individual impairments will not necessarily result in the client learning a skill. Skills result from an organization of many motor functions together and require whole task practice. Conversely, not having a critical component, such as arm strength, may be the one factor preventing a person from learning to perform a skill (e.g., enough force cannot be generated to throw a ball 5 feet in the air to hit a basket).

Many examinations address the impairment level. These include muscle strength tests, flexibility (ROM) tests, speed of motion, reaction time, sensation, vision, vestibular, tone, and proprioceptive examinations (see Chapter 7).

Flexibility

Flexibility at the muscle and joint level is important. Muscle atrophy occurs rapidly¹⁰⁶ and changes in muscle fiber type and function can be seen as early as 3 days. Viscoelastic properties change with paralysis so that the muscle feels stiffer.^113,114

Examinations should determine the contribution of both tone and tissue factors in limiting flexibility. Active and passive motion should be compared because stiffness (not contracture) often prevents good function. For example, active dorsiflexion is often limited in clients who have full passive ankle ROM because stiffness begins at neutral. The functional result is foot drop or toe catch in the early part of the swing phase of gait because the anterior tibialis muscle cannot generate adequate force production to overcome the stiffness in the gastrocnemius and soleus. This restriction also may limit forward movement of the tibia over the foot during the stance phase of gait, resulting in hip retraction or an apparent balance loss. Knee hyperextension also can result from lack of forward motion of the tibia.

Flexibility measurements are done with goniometers, motion analysis systems, tape measures, inclinometers, photographs, or electronic devices. Taking both passive and active measurements is critical in identifying intervention approaches.

Tone

In the motor learning theories of today, many of the behaviors and resulting motor patterns after brain injury are seen as attempts by the CNS to compensate for loss. For example, spasticity (increased tone) may be the result of an attempt to compensate for the client’s inability to increase force. When the amplitude of a contraction cannot be increased because of the injury, the CNS may increase the length of time the muscle fires or may recruit muscles not normally used in a particular pattern of movement; both are characteristics seen in spasticity.

Whatever the cause of increased tone, the therapist can evaluate tone at two levels: is it interfering with function, and, if so, can it be changed? Spasticity is not a single problem.107–110^{,113,115–119} Spasticity can have any or all of the following characteristics:

Examination begins with identifying whether there is increased or decreased muscle tension at rest. If it is increased, is the tension at the muscle level (stiffness or sarcomere involvement) or the neurological level? Muscle stiffness resulting from tissue changes is common in the client with brain injury. If there is increased tone during movement, EMG may be beneficial to determine the nature of the tone. Is it a problem of co-contraction of agonist and antagonist at a joint? Is it a problem of prolonged contraction? Or is it poor sequencing, either temporally or spatially, of other muscles involved in the movement?

Spatial sequencing of movement involves the contraction of a preset group of muscles. Temporal sequencing involves muscles contracting in a fixed sequence. EMG and video analysis provide additional depth of information regarding the sequence and timing of movement patterns (Figure 24-3). For example, is the normal temporal sequencing in the distal-to-proximal manner present in the upper extremity during a reaching task? In a balance reaction, are the ankle, hip, and back extensors (spatial sequencing) all contracting in response to a forward perturbation? The most commonly used tool in examination of tone is the Ashworth Scale or Modified Ashworth Scale¹²⁰ (Box 24-10). The Tardieu Scale¹²¹ is similar, but testing is done at three different velocities and may provide a clearer picture of what is caused by tone versus muscle shortening. Testing of deep tendon reflexes identifies problems with stretch reflexes, and surface EMG (sEMG) can determine the presence of co-contraction, prolonged contraction, sequence and timing problems, and increased latencies.

Speed of motion

Research shows that seemingly different movements may actually be spatially the same (same muscles involved) but may appear different because of pauses within the movements, velocity, or speed.¹²²

Measurements include how quickly a joint can be moved actively. Recording the number of repetitions of a movement in a specific time frame provides an easy clinical measurement. Isokinetic instruments can measure partial- and whole-extremity motion speed. Speed of movement at each joint in a synergistic movement (videotaped or movement analysis systems) can help with analysis of function. Is poor performance the result of speed of movement problems in just one part of the motor pattern or in all parts? Computerized motion analysis techniques can also help examine speed of motion relationships between and among limb segments, which is particularly useful in assessing upper-limb movements such as reaching and grasping activities.

Reaction time

How fast can the client begin motion? This parameter can be measured by EMG or with other computerized equipment.

Simple reaction time examination gives insight into the time for neurological processing because it is the measurement of time from a stimulus to a response. Rapid reaction times may be critical for many patterns to be effective, but especially for automatic patterns such as balance responses. Simple reaction times appear impaired even long after TBI (moderate to severe),¹²³ although there is conflicting literature in this area.

Testing of reaction times is usually performed with computerized testing with a visual or auditory cue used as a stimulus, then the time to a motor response (usually at the hand or foot) is measured.

Endurance and fatigue

Fatigue, which is separate from impaired endurance, may result from increased energy requirements resulting from less efficient motor patterns or from more CNS activity. Fatigue is a common complaint after TBI¹²⁴ and is associated with insomnia.¹²⁵ Testing for fatigue is difficult. There are a few paper and pencil tests, including the Chalder fatigue scale.¹²⁶

Muscle endurance refers to the ability of a muscle to produce the same level of contraction over time. The subjective feeling of effort and weakness after fatiguing exercise may be related to the need to recruit more motor units and to increase the mean firing frequency of the motor units to maintain constant force output.¹²⁷ EMG with medium-frequency analysis can test this type of fatigue. Fatigue can also be assessed by measurement of maximal voluntary force, maximal voluntary shortening velocity, or power.¹²⁷ Decreased force production, prolonged time to relaxation of muscle fibers, and recruitment of additional muscles during an activity are characteristic of fatigue.¹²⁸ Although repeated muscle testing can pick up decreased strength in specific muscles, in most instances overwork fatigue is first noted by an altered pattern of movement of body segments during activity.

Cardiovascular endurance determines how effectively the body can use oxygen and how soon fatigue sets in. This type of endurance can be measured with several bicycle tests^129,130 and with a treadmill using the Bruce¹³¹ protocol or a branching protocol for clients with less endurance. A simple test is heart rate before and after activity; the less change and the more rapid the return to resting rate, the better the client’s fitness level. The 3- and 6-minute walk tests are also reliable and valid for endurance testing.¹³²

Incoordination

Ataxia was one of the most common findings among military personnel who had sustained TBI,¹⁰⁵ with 32% of clients showing ataxia initially and 14% at the 2-year follow-up. There are many subcategories of ataxia, including dysmetria, rebound, diadochokinesia, and intention tremor. Many clinical tests are available. Common tests include having the client touch an index finger to the examiner’s finger and back to the client’s nose. Running the heel up and down the opposite shin is a test for ataxia in the lower extremity. For a list of coordination tests see Chapter 21.

Sensory function

Various sensations can be impaired. Problems in the sensory system are often reflected in the motor system, creating distorted movement through faulty information in the feed-forward or feedback processes.

Two broad categories of sensations can be defined on the basis of the type of information: primary sensations and cortical (or integrative) sensations. This arbitrary division is useful functionally but it is not anatomically based. Primary sensations include exteroception and proprioception. The exteroceptors of smell, sight, and hearing are sometimes referred to as teloreceptors. Vision, hearing, olfaction, gustation, pain, touch, temperature, position sense, and kinesthesia are commonly checked primary sensations. Sensations cannot be clinically tested definitively without client participation. Further evaluations of sensation are provided in specific systems.

Vision and visual perception.

Vision is critical in recovery of many motor functions because it is responsible for much of the feed-forward or anticipatory control of movement as well as the initial development of a movement pattern. For example, balance can be maintained through the visual system by modifying synergies before surface change occurs. Feedback through the peripheral field through the movement of the visual array on the retina can also trigger balance responses. Campbell¹³³ found problems with visual functions in most clients with mild to moderate TBI; these problems involved poor visual acuity (48%) and problems with vergence (85%), which can cause blurring and doubling of vision, and smooth pursuit (63%), which can cause a “jumping” of the visual image.

Some clients are able to use their hands for grasp and release, in spite of severe somatosensory deficits, when they are able to use vision to guide the motion; therefore many of the standard movement tests should be performed with and without vision.

General visual functions can be screened by the physical or occupational therapist as follows:

1. Tracking is assessed by use of an H pattern of movement of the object being tracked. The examiner observes any nystagmus or refixation saccades. Eye muscle paralysis can be observed during tracking if the client cannot move the eye(s) laterally, up, down, or medially.

2. Focus or accommodation can be checked by observing constriction and dilation of the pupil. Constriction occurs as an object is moved toward the nose, and dilation as the object is moved away from the nose.

3. Binocular vision is controlled through feedback from blurred or doubled vision. This reflex signals whether the eyes and fovea are focused on a single point or target, as the images in both eyes fall on the same retinal points. A “cover test” can screen for binocular vision. The client stares at an object at about 18 inches from the nose. The therapist covers one eye. If there is movement to adjust the remaining uncovered eye back to the object, both retinas may not be focusing on the same point. Observing whether light reflections fall on exactly the same place on both pupils is useful in evaluating binocular eye focus. Vergence testing can also be an indicator of binocular visual functions.

4. Visual fields can be grossly tested by having the client look forward at a point (observer sits in front of the client to be sure the client remains focused straight ahead [Figure 24-4]). The client indicates when he or she first sees an object coming into the peripheral field from behind, or the “spotter” notes when the client looks toward the object.

5. Vergence is tested by having the client observe an object or pen tip as it is brought from about 20 inches away. The client is told to follow the object with his or her eyes. The object is moved at a moderate speed toward the bridge of the nose, and the client reports when the object becomes blurred or doubles. When typical convergence is present, there will be no blurring or doubling until the object is 2 inches away or closer, and when the object is moved back out, the client will report the object as single within 4 inches.

6. Visual interactions with the vestibular system are assessed through the vestibuloocular reflex (VOR). This reflex maintains a fixed gaze on a target as the head moves. The object should not appear to blur, move, or double during head motion at various speeds.

7. Perceptual tests that evaluate how visual information is used include visual memory tests, cancellation tests, and figure-ground tests.

8. Visual acuity is tested using a Snellen eye chart. Poor acuity can affect balance responses.

Neuro-optometrists and neuro-ophthalmologists are appropriate referrals for clients needing in-depth visual workups, especially when visual perception is involved. See Chapter 28 for additional information on vision and visual testing.

Anticipatory reactions

Anticipatory reactions are dependent on learning. They require combining past information with present information to make motor responses appropriate to internal and external needs. Forces that stabilize limbs or the trunk during movements occur before the firing of the prime mover. The disruption of balance that would occur before moving must be anticipated and counterbalanced before the movement even begins. For example, does the gastrocnemius muscle contract before forward-reaching activities to prevent forward movement of the center of gravity? Does the client shape the hand for picking up objects? Almost all motor functions have an anticipatory component. Use of sEMG can help determine the presence of common anticipatory responses. Visual observation may provide some information about anticipatory responses also. For example, does the client walk smoothly over or around objects, or does he or she need to stop, slow down, or make corrective responses? When reaching or stepping during sitting or standing, does the client fall or lean in the direction the limb moves?

Adaptation

Feedback is used to modify and fine-tune responses. Observation is often used by providing the client with an unexpected perturbation after several expected perturbations. The initial response is usually poor, but as the same perturbation is repeated, the response improves. Other observations can include whether the activity is corrected to meet changing environmental conditions. When not successful at task performance, does the client use the information to modify or adapt subsequent responses? Is the adaptation appropriate, or does it result in poorer performance?

Sitting balance

Brown and colleagues¹³⁸ found sitting balance to be impaired in 52% of the clients with TBI at initial examination in their review. Testing includes static sitting without arm support and dynamic sitting with the client reaching in multiple directions.

Standing balance

Standing balance after TBI is usually affected in mild, moderate, and severe injuries, with 82% of clients showing standing balance problems. Problems include both motor strategy problems and appropriate use and integration of somatosensory, visual, and vestibular information. Newton¹⁴⁰ reported that clients with moderate and severe TBI showed significantly impaired reaction times to perturbation in standing. Although they could grade their responses to the perturbations appropriately, the responses were often asymmetrical.

Balance is tested with feet shoulder width apart, feet together (Romberg), and feet in tandem (sharpened Romberg) with eyes open and eyes closed. A Clinical Test of Sensory Interaction on Balance (CTSIB) test¹⁴¹ is used to test sensory balance components. Perturbations to balance can be used to examine motor components of ankle, hip, and stepping strategies. See Chapter 22.

Gait

People with TBI walk with a significantly slower speed than matched healthy controls. There is a significant difference between groups for cadence, step length, stance time on the affected leg, double support phase, and width of base of support. The most frequently observed biomechanical abnormality is excessive knee flexion at initial foot contact. Other significant gait abnormalities are increased trunk anterior and posterior amplitude of movement, increased anterior pelvic tilt, increased peak pelvic obliquity, reduced peak knee flexion at toe-off, and increased lateral center of mass displacement. Walker¹⁰⁵ found that testing of clients using the tandem gait identified the most frequent physical impairment remaining at a 2-year follow-up in a group of people with TBI. He suggests using tandem gait as one part of the clinical examination for all clients with TBI.

The Barthel Index,¹⁴² FIM,¹⁴³ Tinetti assessment,¹⁴⁴ Gait Assessment Rating Scale,¹⁴⁵ and Motor Assessment Scale¹⁴⁶ also examine different components of gait but more at the activity limitation level. Speed of walking for functional activities such as crossing a street at a stoplight and endurance can be measured by distance and a stopwatch.¹⁴⁷ Endurance can be measured with a 6-minute walk test.¹³²

Reach and grasp

Numerous problems occur during reaching and grasping. Tests such as the Nine-Hole Peg Test and the Purdue Pegboard Test provide a standardized means of measuring reach and grasp using a timed method. The Motor Assessment Scale has an upper-extremity component that is validated to use alone. The Frenchay Arm Test measures functional use of a dominant hand.

Are basic motor patterns available, accessible, and used appropriately?

Are the three basic components of movement all present? They are as follows¹⁴⁸:

Starting at the reflex level, are reflexes such as swallowing, visual tracking, and smiling intact? Injury at this level may affect basic motor program production and sequencing. Are automatic movement patterns present (e.g., balance synergies, walking, and running)? Are volitional or voluntary movements present?

Are the basic motor patterns being selected or modified to meet specific task requirements?

Many of these functions are associated with cerebellar functions, which provide tone, timing, coordination, and amplitude of motions. The synergistic system smooths out the motor program and provides adaptability. One of the contributions of synergy use is the ability to limit the degrees of freedom in a movement. Is the client able to use the basic motor patterns in a functional manner? Is the client able to modify and then accomplish activities such as rolling over, coming from sitting to standing, standing, walking, reaching, picking up objects, and ball catching? Is there good interlimb coordination as demonstrated by coordinated two-handed activities, good timing between limbs in walking, and jumping? Does the client appear to have the ability to coordinate motions (decrease the degrees of freedom), or are they limited by too few degrees of freedom? Does the client respond correctly to environmental changes or stimuli such as stepping over or around objects or being able to walk on different terrain? When motor patterns are used, are they appropriate for the stimulus? For example, is the ankle strategy used for standing on a firm surface and when stopping walking?

Variability of performance

The plastic nervous system can adapt and change its motor output to meet different requirements. VanSant¹⁴⁹ showed that children and adults vary in the way they stand from supine, even under the same environmental conditions. She states that the most striking observation in nondisabled individuals is this variability of performance. The lack of variability has been suggested as a sign of system damage.⁸⁶ When the client with brain injury is assessed, the therapist should look for variability of performance in basic motor acts. Can the client accomplish the same task in several ways? Can the client adapt to different task demands? As the complex task is being performed, keep in mind that the extent of deficit is important. To what extent is the observed motor behavior involved? Is the behavior totally absent, is it deficient, or are there signs of substitution of function or adaptation?

Following is an example of the examination process. The client complains of difficulty in walking and is experiencing several falls daily. Walking requires several complex elements including extensor strength, postural control, and balance.¹⁵⁰ First, a task analysis is performed, and in this case the therapist would look at the gait pattern, perhaps using the Rancho Los Amigos Observational Gait Analysis to analyze the kinematic aspects of the pattern. The therapist then hypothesizes about specific problems observed during the task (gait) analysis. For example, if the client is dragging his toe in swing and does not have adequate knee flexion in this phase, the therapist might hypothesize that the thigh is advancing too slowly (speed of motion impairment) to promote good knee flexion and that dorsiflexion is limited because of poor anterior tibialis activation (force production problem). Timing the speed of hip flexion and doing MMT might confirm or rule out these hypotheses.

If postural control appears to be the problem, the therapist observes the client in standing, noting that the client leans to the left. The therapist may hypothesize that head-righting reflexes are not intact. This might be tested by leaning the client to the side with eyes closed to determine head-on-body righting. Is the head righted to the body or to gravity (as is normal in adults)? Examination for verticality would include lying, sitting, or standing with the body vertical, both with eyes open where vision can control verticality and with eyes closed to examine somatosensory and vestibular control of posture and verticality. If the walking problem appears to be in the client’s balance system, then use of sEMG on the leg muscles will determine whether the client is using balance synergies with a temporal sequence of distal to proximal contraction (ankle strategy) during small perturbations. Does the client use only the appropriate muscles in balance responses (spatial sequence)? Or is the client co-contracting, indicating a temporal or spatial sequencing problem that disrupts the normal motor patterns? Is there efficient movement in the swing leg? Does it move in a straight line, and is foot placement on the floor appropriate (coordinated movement)? Does closing the eyes change the character of the movement? If it does, the client may be controlling movement by vision without regard to vestibular and somatosensory input. The therapist may hypothesize that sensory influences on balance are impaired and choose to do the CTSIB to confirm this hypothesis. Does the client step over objects placed or rolled in front of him (anticipatory and adaptation)? If not, was it because the client misjudged the height of the object (visual anticipatory responses) or misjudged the distance to move the leg (modification of the locomotion synergy at the amplitude level)? Is movement too disorganized (uncoordinated) to clear the object? The therapist may hypothesize a problem in timing of the leg movements and confirm the hypothesis diagnosis with sEMG.