Neurology India, Vol. 50, (Suppl. 1), Dec, 2002, pp. S102-S108
Cognitive Rehabilitation in Stroke : Therapy and Techniques
S. Alladi, A.K. Meena, S. Kaul
Department of Neurology,
Nizam's Institute of Medical Sciences,
Hyderabad- 500 082, India.
Code Number: ni02170
Cognitive deficits following stroke are common and interfere with recovery. Cognitive rehabilitation incorporates principles of restorative neurology and neuropsychology and has now become an integral component of stroke rehabilitation strategy. The process of cognitive rehabilitation involves assessment of cognitive functions, identification of specific areas of impairment, goal setting and institution of appropriate rehabilitation techniques. Currently, there is enough evidence supporting the effectiveness of cognitive rehabilitation of neglect and aphasia in stroke. Apraxia, inattention and executive dysfunction may also improve with specific intervention. Compensatory strategies are the mainstay of managing patients with memory disturbances. In addition to specific cognitive deficits, physical and emotional disturbances as well as social support affect functional recovery. Comprehensive and holistic cognitive rehabilitation programs are necessary to improve daily life function in stroke patients.
Key words : Cognitive Rehabilitation, Stroke, Neglect, Aphasia, Apraxia.
With the recent growth in knowledge of neuropsychology and restorative neurology, cognitive rehabilitation has become an integral component of stroke management. Cognitive disturbances are frequent in patients with stroke and cause significant disability. Reported incidence of post-stroke cognitive impairment and dementia varies between 16.8- 31.8%.1 Aphasia, neglect, amnesia, apraxia, agnosia, inattention, visuospatial and visuoperceptual disturbances, impaired problem solving and executive functioning are the cognitive deficits which occur singly or in combination following stroke.
Cognitive disturbances impair recovery
Cognitive deficits generally underlie poor outcome of stroke and result in stroke rehabilitation 'failures'. Cognitive disability manifests as reduced efficiency and pace of functional recovery, decreased effectiveness in performing routine activities of daily living or failure to adapt to novel or problematic situations.2 Cognitive functions and not motor impairment predict psychosocial burden on the caregivers of elderly stroke victims.3 In addition, cognitive deficits also contribute to post stroke depression.4 Stroke rehabilitation programs therefore now incorporate interventions designed to promote recovery of cognitive functions.
What is cognitive rehabilitation
Cognitive rehabilitation is defined as a systematic, functionally oriented service of therapeutic activities that is, based on assessment and understanding of the patients brain behavioral deficits. Specific interventions may have various approaches, which include : i) Reinforcing, strengthening or reestablishing previously learned patterns of behavior. ii) Establishing new patterns of cognitive activity through compensatory cognitive mechanisms or impaired neurological systems. iii) Establishing new patterns of activity through external compensatory mechanisms such as personal orthoses or environmental structuring and support. vi) Enabling persons to adapt to their cognitive disability, even though it may not be possible to directly modify or compensate for cognitive impairments, in order to improve their overall level of functioning and quality of life.5
Regardless of the specific approach or area of intervention, cognitive rehabilitation services should be directed at achieving changes that improve each person's function in areas that are relevant to their everyday lives. Recovery from cognitive deficits caused by infarcts occurs by a process of brain plasticity and cortical reorganization.
Cognitive function assessment is essential
An understanding of stroke related neurobehavioral syndromes is essential for planning rehabilitation strategy. An early neuropsychological assessment should be done in all stroke patients.A comprehensive diagnostic protocol consists of the following areas of assessment: subjective complaints, background information, behavioral history, sensory motor screen, voice and speech evaluation, standard cognitive screen examining attention, orientation, memory, language, visuoperceptual and visuospatial skills, praxis and executive functions. The nature and severity of deficits are identified. The location of infarct may guide in predicting area of cognitive dysfunction. Assessment should be multi-dimensional and functioning in real life situations should be observed. The focus is on the individual's capacity to communicate and relate to his surroundings, rather than on specific deficits.
Settings goals for cognitive rehabilitation
On establishing a comprehensive diagnosis, variables affecting prognosis have to be identified; example: age, education, occupation, etiology of stroke, coexisting medical problems, severity and type of cognitive deficits, duration after onset, motivation, stimulability and environment. Whether treatment helps, what deficits should be treated, order of treatment and type of treatment will depend upon the overall prognosis of the patient.6 This information is invaluable to the rehabilitation team, patient and family as they move together towards achievement of rehabilitative goals. Although recovery of cognitive functions is maximal within the first 3 months after onset, long term improvement may be evident even one year after stroke.7
Rehabilitation of specific deficits
Cognitive disturbances although most severe at time of onset, may persist for longer periods. Time course of recovery is slower than the return of motor functions associated with self-care activities of daily living. At 3 months, memory deficits remained in 29% of a group of hemiparetics.8 Neglect persisted in 54% of right hemispheric strokes and 21% of left hemispheric strokes.9 A high frequency of executive function impairment has been observed in patients with subcortical lacunar infarcts.10
Unilateral neglect is a failure to respond, report or orient to a stimulus in one half of space and commonly follows right hemispheric stroke. Patients with neglect are unaware of their left side of space and may dress and groom only the right side of body, read only right half of page or run into things on their left side or inadvertently injure their left side. Neglect has an unfavorable impact on rehabilitative outcome. It is associated with significant difficulty in performing activities of daily living and results in slow, incomplete recovery.11 Associated anosognosia or denial of hemiplegia further interferes with the process of recovery.
Unilateral neglect improves with cognitive rehabilitation
There is clear evidence that cognitive remediation improves neglect after right hemispheric stroke.5 The various techniques listed below have been developed based on the understanding of the pathophysiology of neglect. i) Visual scanning in neglect is facilitated by reading and cancellation tasks where the left side of page is provided with a thick red vertical line (anchor). Alternatively the patient tracks a light moving across a screen.12 The principle here is that the damaged function is compensated for by preserved perceptual or motor functions. ii) Patients with visual inattention show significant improvement when trained to use the Lighthouse Strategy. In this technique, patients imagine that their eyes are horizon-sweeping beams of a lighthouse13 and use this visual image in functional and therapy training tasks. iii) Stimuli with cueing properties such as buzzers in left pocket and under left heel, colour coded edges to avoid collision and verbal cueing are used to direct attention of patients towards the neglected side.14 Patients are also encouraged to wear bright visual reminders like bracelets, scarves or the watch on the left side. iv) Unilateral neglect also improves by frequently touching the neglected side and asking the patient to 'find it' using video feedback. This technique increases somotosensory awareness of the neglected side.14 v) The use of prisms to produce rightward optical deviation15 also improves left hemispatial neglect. The principle used in this technique is that adaptation to a visual distortion can provide an efficient way to stimulate neural structures responsible for the transformation of sensorimotor coordinates. Similarly, improvement in visual inattention is observed following patching the right half of the visual field.16 vi) Activation of the limb contralateral to a cerebral lesion also seems to reduce visual neglect, either due to perceptual cueing or hemispheric activation. This principle is used in Limb Activation Training where small out-of-site movements of contra-lesional limbs provided improvement in neglect.17 vii) Nonspatial methods like phasic alerting by use of warning auditory tones was also able to overcome spatial neglect probably by increasing the patients' alertness.18 viii) Rehabilitative techniques such as vestibular stimulation and neck muscle vibration19 have spectacular although temporary effects and are more of theoretical interest.
A combination of these various techniques results in a more effective functional recovery. These techniques however have to be incorporated into functional tasks during therapy. Isolated use of microcomputer-based exercises does not appear effective in treating unilateral neglect.
Aphasia, an acquired language disorder is associated with dominant hemispheric stroke. Inability to understand language and articulate ideas and feelings isolate the patient from his environment. Aphasia also precludes active participation of patient in the stroke rehabilitation process.
Aphasia therapy restores communication skills
General guidelines while interacting with an aphasia patient are to show empathy and understanding of the patients and problem, to use facial expressions and voice intonation while speaking, to combine verbal statements with gestures, to use 'word board' or pictures and simplify communication by using short clear sentences. It is important to remember that even if a patient cannot speak he may understand all that is being said. Many aphasic patients are competent mentally.
Convincing evidence exists to support the effectiveness of linguistic cognitive therapy for aphasia.5 Traditionally the aphasia syndrome is classified on the basis of comprehension, fluency and repetition into fluent and non-fluent aphasia. Various methods are used by speech therapists, which include re-education program to regain lost language skills and stimulation techniques to re-organize the access to preserve the language functions. Some techniques used by therapists are listed below. i) Melodic intonation therapy (MIT); Aphasics have preserved music and melody processing. This ability is used to enhance word production in nonfluent aphasia.20 ii) Helm elicited program for syntax (HELPSS); A story completion format incorporating different sentence types is used to train agrammatisms in nonfluent aphasia.21 iii) Voluntary control of involuntary utterances (VCIU); Patients with nonfluent aphasia can utter only a few stereotypic automatic words. Training patients to read the words and identify pictures representing the words can gradually increase the repertoire of utterances.22 iv) Treatment for Wernicke's aphasia (TWA); Patients with Wernicke's aphasia have impaired auditory comprehension. The use of word picture mapping results in the deblocking of auditory modality through visual modality23 and improves auditory comprehension.
Aphasia syndromes need reevaluation
The traditional division of patients into fluent and non-fluent aphasia is not informative about the underlying nature of language disorder. Instead of classifying aphasia into syndromes, a patient's deficits and retained abilities can be related to an informationprocessing model and therapy targeted more specifically.24
As the final goal of aphasia rehabilitation is to enhance communication skills in a natural environment, functional communication treatment which incorporates training in verbal and non-verbal skills,25 group treatment which focuses on encouraging stroke patients to communicate with each other in a group26 and promoting aphasics communicative effectiveness (PACE)27 where the clinician and patient communicate with each other in response to stimuli are some of the popular methods used.
Computers in aphasia rehabilitation
Computer based techniques have been implemented in aphasia rehabilitation. Software programs have been designed where graphics and text stimuli can be presented to patients. Simple and complex exercises train patients in naming, comprehension, syntax, numbers, situations etc. Programs adjust automatically to the patient's level of performance while providing continuous feedback to support the patient and guide his work. Majority of aphasic patients show improvement in performance especially when treatment is supplemented with traditional speech therapy. Interactive multimedia therapy programs containing videos with prototypical situations taken from daily life are being developed to promote daily life functioning of stroke patients.28
Amnesia following stroke is severely disabling. Cognitive rehabilitation programs for amnesia provide either memory retraining or teach patients strategies to cope despite memory impairment.
In the limited studies available where amnestic population studied is of mixed etiology, direct methods that involve repetitive practice have not been successful.29 Training in compensatory strategies by using mnemonics, visual imagery, systematic cueing and rhymes have some effect on memory tests but failed to generalize to every day situations.30 A more recent approach has been to capitalize on the commonly spared procedural memory to teach patients specific skills.31 Environmental manipulation and use of external aids are currently the most effective way of circumventing problems related to amnesia.32 Patients disoriented to time can be helped by the use of timers, pagers, diaries, personal organizers or reminders from care givers. Place disorientation can be managed by the use of signs, color-coding of doors and identification of high visibility structures at strategic points. Badges and distinctive clothing help to orient patients to people.
Personality factors influence recovery and psychotherapy aimed at increasing expectations of improvement and raising self-belief may prove beneficial.33
Limb apraxia is characterized by a disturbance in performing gestures, which cannot be explained by intellectual deterioration, poor comprehension and uncooperativeness or by a deficit in elemental motor or sensory systems.34 Although limb apraxia tends to ameliorate in the course of the first months of stroke onset, ideomotor apraxia can persist to some extent in 45% of patients one year after stroke onset,35 delaying return to work.36
Limb apraxia affects rehabilitation negatively as patients cannot be involved in action planning activities. About 80% of patients with limb apraxia are also aphasic37 and loss of gesture communication results in further reduction in social interaction. Patients with apraxia undergo an intensive gesturetraining program, which uses visual, verbal and tactile cues to perform a wide variety of gestures, both transitive and intransitive. Praxic defects are amenable to this form of therapy.38 Although in earlier studies patients showed no generalization of training effects,39 use of a wider range of gestures under different contexts did result in generalization of improvement.38
Agnosias and other perceptual defects
Agnosia is the loss of recognition although visual, tactile and auditory systems are unimpaired. Patients may have impaired visual recognition (visual agnosia), tactile recognition (astereognosis) and inability to recognize sounds (auditory agnosia). Visuoperceptual and visuospatial problems like object agnosia, prosapognosia, impaired depth perception, defective topographic orientation and construction although subtle, can sometimes interfere significantly with patient's activities. Similarly unawareness or denial of disease (anosognosia, alien limb phenomenon, cortical blindness) are not only potentially dangerous but also prevent active participation in rehabilitation process, delaying recovery.
Activities of patients with agnosia must be structured and monitored closely. Living situation should be made free of harmful objects and poisonous substances. Patients should be encouraged to utilize perceptive functions that are preserved, in order to compensate for affected abnormal perception.40
Motor recovery, 2 years after stroke was directly related to indicators of sustained attention assessed at 2 months after stroke,41 demonstrating the importance of attention in stroke rehabilitation outcome. Interventions to treat inattention are mainly exercises designed to improve attention focus and processing speed using stimulus- response paradigms. Paper and pencil tasks as well as computer assisted reaction training have demonstrated beneficial effects on attention.5 However, the effects are task-specific and there is a need to assess the impact of treatment on ADL.
Executive dysfunction and impaired problem solving commonly occur in patients with infarcts in the frontal-subcortical circuits. These patients are unable to initiate behavior, anticipate the consequences of action, plan and formulate goals.
Training in problem solving provides patients with techniques to break down complex problems into manageable steps based on a social problem-solving model. Patients are encouraged to define the problem, formulate goals, generate alternatives, make decisions and verify solutions. Improvement in intelligence subtests and planning ability was demonstrated in a group of patients of stroke and traumatic brain injury.42
Comprehensive-holistic cognitive rehabilitation
In addition to specific cognitive deficits, physical, emotional disturbances as well as social support affect functional recovery. Comprehensive and holistic programs provide intensive individual and group therapies and facilitate adjustment and acceptance of residual cognitive disability.
Drugs as an adjunct to cognitive therapy
Many neurotransmitters are involved in the performance of cognitive functions. These systems have been manipulated pharmacologically in an attempt to produce therapeutic benefit. While drug therapy is unlikely to revolutionize the treatment of cognitive disorders, it holds some promise in aphasic disorders.
Various drugs have been tried in the treatment of aphasia. Although studies evaluating the use of the dopamine agonist bromocriptine have demonstrated variable results, fluency was found to have improved when used in conjunction with speech therapy. Amphetamine, a noradrenergic agent also facilitated recovery from aphasia.43 Other drugs like sodium amytal, propranolol and meprobamate have not shown any benefit. Amantidine44 by acting as a dopaminergic agent was found to improve perseverations in stroke patients. A recent study has revealed that methylphenidate is safe and effective in early post stroke rehabilitation expediating recovery.45 Methylphenidate also improved reaction time in a patient with subcortical infarcts who had severe apathy.46
Piracetam, a neuroprotective agent was found to increase cerebral blood flow in stroke. Various domains of speech improved with the use of piracetam.47 It is recommended as an adjunct to language therapy in aphasia.48 However effects on perceptual deficits and activities of daily living could not be demonstrated.49 Acetylcholinesterase inhibitors are currently under evaluation for improving memory and cognition in vascular dementia.
Considerable progress has been made in the development of cognitive rehabilitation methods that improve practical, daily life function in stroke patients. Overall, support exists for the effectiveness of cognitive rehabilitation of neglect and aphasia in stroke. However compensatory strategies are the mainstay of managing patients with memory disturbances. Cognitive scientists and rehabilitationists must work ever more closely to fulfill their potential for furthering scientific understanding of the brain and improving the lot of patients.
Copyright 2002 - Neurology India. Also available online at http://www.neurologyindia.com