Stroke: Emergency Care and RehabilitationPage 17 of 27

15. Cognitive Changes After a Stroke

The human brain is responsible for all of the functions that define who we are and how we relate to one another—our talents, our intellect, our creativity, our ability to participate in sports, to communicate, and to understand and share in the emotions of others. Stroke can interfere with any or all of these functions. In fact, most of the brain supports cognitive and integrative processes underlying complex systems, such as attention, working memory, cognitive control, and language that are critical for these activities. Yet, stroke outcomes research traditionally has focused on recovery of the basic activities of daily living, such as feeding oneself and walking (Hillis & Tippett, 2014).

Studies that have investigated quality of life or health-related quality of life after stroke have focused on motor function, communication, and ADLs. These studies have found that age, nonwhite race, impaired upper-extremity function, and greater number of comorbidities are all associated with reduced health-related quality of life within the physical domain. A larger number of comorbidities are also associated with poorer health-related quality of life in the domain of memory and thinking, and stroke survivors whose hemiparesis affected the dominant side or had ischemic (rather than hemorrhagic) stroke reported poorer health-related quality of life in the domain of communication (Hillis & Tippett, 2014).

At the Stroke Cognitive Outcomes and Recovery (SCORE) Lab at Johns Hopkins University School of Medicine, researchers have noted that stroke survivors or their caregivers frequently reported problems that are not typically measured by stroke scales—difficulty in sleep or sex, overwhelming fatigue, change in personality, and so on (Hillis & Tippett, 2014). In an attempt to clarify problems and issues not captured by traditional outcome measures such as Modified Rankin Scale, the Barthel Index, and the National Institutes of Health Stroke Scale, researchers developed a survey tool focused on cognitive issues.

The single most frequently reported important/moderate consequence by both survivors of left hemisphere stroke and their caregivers was difficulty in spelling or writing. Word retrieval and mood problems were also frequently reported, as was right-sided weakness (Hillis & Tippett, 2014).

Right hemisphere stroke survivors reported fatigue, left-sided weakness, problems with mood, reading, writing, memory, and sexual function. The most frequently reported important/moderate consequence by caregivers of right hemisphere stroke survivors was impaired recognition of the emotions of others (loss of emotional empathy), identified by 50% of caregivers, followed by “other cognitive problems,” “change in personality and behavior,” and “walking” (Hillis & Tippett, 2014).

These results reveal that deficits in spelling and writing after left hemisphere stroke and loss of empathy after right hemisphere stroke are probably underestimated as residual consequences of stroke. Spelling has taken on new importance in a community that relies on email, texting, and online shopping and banking. The importance of empathy in communication and social relationship has been understood by social scientists for decades, but little attention has been given to impairments of empathy after stroke. Efforts to understand the variables that mediate these deficits and interventions to alleviate these problems are essential to improve quality of life after stroke (Hillis & Tippett, 2014).

Cognitive Impairment and Dementia

As many as two-thirds of stroke patients experience cognitive impairment or cognitive decline following a stroke; approximately one-third go on to develop dementia. The risk for cognitive impairment or decline is increased by a history of stroke. The risk for developing dementia may be 10 times greater among individuals with stroke than those without. Mortality rates among stroke patients with dementia are 2 to 6 times greater than among stroke patients without dementia (Teasell, McClure, Salter, Murie-Fernandez, 2014).

While cognitive decline may continue post stroke, about one-fifth of patients with cognitive impairment improve. Most improvement occurs in the first 3 months after a stroke although recovery may continue for up to a year (Teasell, McClure, Salter, Murie-Fernandez, 2014).

Cognitive impairment is associated with decreased ADL and independent ADL function and patients with impaired cognition may require longer-term, ongoing rehabilitation. Reduced cognition has been associated with a decreased ability to perform ADLs, with poorer physical functioning at discharge and with a greater likelihood of mortality within 1 year of discharge (Teasell, McClure, Salter, Murie-Fernandez, 2014).

The presence of cognitive impairment is strongly linked to post stroke outcomes. Estimates of cognitive function assessed 2 to 3 weeks post stroke strongly predict patients’ practical functioning after 13 months of post stroke recovery. In addition, cognitive impairment measured 3 months after first-ever stroke has been associated with increased risks of death and disability 4 years later (Han et al., 2014).

Cognitive rehabilitation focuses on several areas of cognition such as attention, concentration, perception, memory, comprehension, communication, reasoning, problem-solving, judgment, initiation, planning, self-monitoring and awareness (Teasell, McClure, Salter, Murie-Fernandez, 2014).

Cognitive rehabilitation aims to:

  • Reinforce, strengthen, or reestablish previously learned patterns of behavior
  • Establish new patterns of cognitive activity through compensatory cognitive mechanisms for impaired neurological systems
  • Establish new patterns of activity through external compensatory mechanisms such as personal orthoses or environmental structuring and support
  • Enable persons to adapt to their cognitive disability (Teasell, McClure, Salter, Murie-Fernandez, 2014)


As mentioned earlier, apraxia is the loss of the ability to organize a movement or perform a purposeful act. It is a disorder of the execution of movement that cannot be attributed to weakness, incoordination, sensory loss, poor language comprehension, or attention deficit. Apraxia is a weakening of the top-down formulation of an action—the inability to sustain the intent to complete a movement. As a result, the nervous system is easily influenced by irrelevant input—a sort of pathologic absent-mindedness.

Apraxia is common in patients with left hemispheric strokes, especially in lesions involving the left frontal and parietal lobes. It can be spontaneous during everyday activities (difficulty with dressing, using utensils, starting the car, turning keys to open doors). In can cause difficulty when performing motor tasks and becomes evident when the patient is asked to do something and appears unable to initiate or complete the task (Teasell, McClure, Salter, Murie-Fernandez, 2014).

Visual-Perceptual Disorders

[This section taken largely from Teasell, MClure, Salter, Murie-Fernandex, 2014.]

Unilateral spatial neglect is a visual-perceptual disorder that can be one of the most disabling features of a stroke. Neglect is a sensory dysfunction caused by damage to the parietal lobe in which a person is unaware of the contralateral (opposite) side of the body, including half of the visual field. It causes a disruption of a person’s body schema and spatial orientation and adversely affects a person’s balance and safety awareness. Those suffering from neglect are often unaware that the second half of the body exists and will deny that anything is wrong.

Clinically, the presence of severe unilateral spatial neglect is apparent when a patient collides with his or her surroundings, ignores food on one side of the plate, and attends to only one side of the body. However, symptoms of unilateral spatial neglect have to be quite severe for this impairment to be observed easily during the performance of functional activities. More subtle forms of unilateral spatial neglect may go undetected in a hospital setting but are a major concern for client function and safety upon discharge. Mild symptoms of unilateral spatial neglect become apparent during high-level activities such as driving, riding a bicycle, working with tools, or while interacting with others.

Unilateral spatial neglect has been reported to have a negative impact on functional recovery, length of rehabilitation stay, and the need for assistance post discharge. While the majority of patients diagnosed with visuospatial inattention post stroke recover by 3 months, those with severe visuospatial inattention on initial presentation have the worst prognosis. The presence of unilateral spatial neglect has been associated with poorer functional outcome, poorer mobility, longer length of stay in rehabilitation, and a greater chance of institutionalization upon discharge from rehabilitation.

There are currently more than sixty standardized and non-standardized assessment tools available to assess unilateral neglect. Line bisection test, Albert’s test, single letter cancellation test, star cancellation test, and Bell’s test are all examples of simple, pencil-and-paper tests used to detect the presence of unilateral spatial neglect. All can be administered at the bedside in just a few minutes. However, the patient must be able to follow instructions as well as hold and use a pencil with reasonable accuracy in order to complete these types of tests reliably. In 2006 the Canadian Stroke Rehabilitation Outcomes Consensus Panel selected the line bisection tool as its preferred standard for the identification of unilateral spatial neglect.

In general, rehabilitation interventions to improve neglect may be classified into those that (1) attempt to increase the patient’s awareness of or attention to the neglected space and; (2) those that focus on the remediation of deficits of position sense or body orientation.

Examples of interventions that attempt to improve awareness of or attention to the neglected space include the use visual scanning retraining, arousal or activation strategies, and feedback to increase awareness of neglect behaviors.

Interventions that attempt to improve neglect by targeting deficits associated with position sense and spatial representation include the use of prisms, eye-patching and hemi-spatial glasses, caloric stimulation1, optokinetic stimulation2, TENS, and neck vibration.

1Caloric stimulation: a procedure in which cool or warm water is introduced into the ear canal.

2Optokinetic stimulation: the use of visuospatial patterns such as moving white vertical stripes, random black dots, or other moving patterns to produce nystagmus.


Aphasia is an acquired language disorder that affects a person’s ability to comprehend and produce language. The most common form of aphasia occurs because of damage to the left cerebral hemisphere; the left hemisphere is dominant for language in 99% of right-handed people (93% of the population). Aphasia can occur in left-handed people as a result of damage in the right hemisphere—about 30% of left-handed people with post stroke aphasia have right hemispheric strokes (Teasell et al., 2014).

Aphasia affects about one-third of the stroke population, and roughly 40% continue to have significant language impairment a year and a half after the stroke (Bronken et al., 2013). Impairment ranges from mild, involving difficulties in finding words, to severe, involving severe impairment of all language modalities (expression and comprehension of speech, reading, and writing and the use of language as a flexible tool in everyday life) (Bronken et al., 2013).

There is a large body of evidence suggesting the brain undergoes tremendous recovery and reorganization of structure and function following a stroke. Specific linguistic impairments, such as phonological disorders1, lexical semantic impairments2, and syntactic impairments3, can show substantial recovery in the first few months following a stroke (Kiran, 2012).

1Phonological disorders: A type of speech disorder also known as an articulation disorder. Can be caused by changes in the structure or shape of the muscles and bones that are used to make speech sounds. Also can be related to damage to parts of the brain or the nerves that control how the muscles and other structures work to create speech.

2Lexical semantic impairments: A disruption in a person’s ability to recognize word forms (sound, spelling, and word properties), and perceive and understand their meaning. Traditionally associated with Wernicke’s aphasia.

3Syntactic impairments: Speech that lacks structure—traditionally associated with Broca’s aphasia. Typically involves word substitutions and omissions, reduced sentence length, and reduced sentence complexity.

Recovery of language function after stroke is thought to occur in three overlapping phases, each with a unique set of underlying neural phenomenon:

  • Acute phase—lasts for about 2 weeks after the onset of the lesion.
  • Second phase—the subacute phase—usually lasts up to 6 months after onset.
  • Chronic phase begins months to years after stroke, and it may continue for the remainder of the person’s life (Kiran, 2012).

Although each of these phases is accompanied by a tremendous amount of physiologic change, much is unknown about the precise mechanisms underlying language recovery in post stroke aphasia. There have been several recent reviews examining advances in neuroimaging of recovery from aphasia, and all of them underscore the need for further careful and systematic research in this topic. Even in situations when language is recovered, it is not known whether the regions of activation observed are truly due to reorganization of language abilities to other functionally capable regions or due to utilization of abnormal cognitive strategies (Kiran, 2012).

The conventional treatment for aphasia usually begins during hospitalization in the intensive rehabilitation unit. The therapeutic management of aphasia is a long-term process that frequently does not end with a complete recovery of language and communication functions. For many patients the progress toward functional communication is steady but slow, while other patients need to be assisted to learn compensatory strategies for an effective communication. After discharge, the complex issues associated with stroke often reduce a patient’s autonomy and can affect their ability to continue with outpatient rehabilitation (Agostini et al., 2014).

In a large study of chronic aphasia recovery, researchers found that the single most important determinant of recovery of speech production was time since onset of stroke, indicating that improvement continues over time, even in the chronic stage. The brain recovers from a focal lesion like stroke through a variety of mechanisms that take place at different times after onset (Hillis & Tippett, 2014).

Bilingual Aphasia

[This section taken largely from Ansaldo & Saldi, 2014.]

The bilingual population is large and growing worldwide, and bilingual aphasia is becoming more and more frequent. The behavioral patterns observed in bilingual aphasia are complex, involving two (or more) languages, whose recovery does not always follow monolingual patterns. Given the almost endless possible combinations of language pairs, the issue of bilingual aphasia therapy is a big challenge. Even the most avant garde educational policies aimed at training bilingual speech-language pathologists are likely to provide only partial solutions to the clinical management of this population.

Bilingualism imposes challenges regarding the assessment and intervention provided to bilingual clinical populations, particularly those who suffer from cognitive impairment. The complexity of this issue extends well beyond the linguistic knowledge required to interact with the patient. Beyond language, there is communication, which is essential for the understanding—what is normal and what is not—in the context of a given culture.

The issue of language impairment in bilingual people has interested cognitive neuroscientists for more than a century. This has led to the development of bilingual aphasia tests for a variety of language pairs, among which the Bilingual Aphasia Test (BAT)—developed for more than 59 languages—and the Multilingual Aphasia Examination developed in six languages. Additionally, there are tests normalized in several languages, such as the Aachen Aphasia, and the Boston Diagnostic Aphasia Examination. These tests provide a linguistically valid assessment of bilingual aphasia.

Recently, researchers have focused on the complex issue of bilingual aphasia language therapy, with the purpose of developing the most efficient procedures for triggering language recovery in this population. This is a relatively new field, and a complex one, given that it requires juggling the complexities of bilingual language processing, which amounts to more than simply the additive processing of two languages.