Made by DATEXIS (Data Science and Text-based Information Systems) at Beuth University of Applied Sciences Berlin
Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
Funded by The Federal Ministry for Economic Affairs and Energy; Grant: 01MD19013D, Smart-MD Project, Digital Technologies
Agrammatism is a characteristic of non-fluent aphasia. Individuals with agrammatism present with speech that is characterized by containing mainly content words, with a lack of function words. For example, when asked to describe a picture of children playing in the park, the client responds with, "trees..children..run." People with agrammatism may have telegraphic speech, a unique speech pattern with simplified formation of sentences (in which many or all function words are omitted), akin to that found in telegraph messages. Deficits in agrammaticism are often language-specific, however—in other words, "agrammaticism" in speakers of one language may present differently from in speakers of another.
Errors made in agrammatism depend on the severity of aphasia. In severe forms language production is severely telegraphic and in more mild to moderate cases necessary elements for sentence construction are missing. Common errors include errors in tense, number, and gender. Patients also find it very hard to produce sentences involving "movement" of elements, such as passive sentences, wh-questions or complex sentences.
Agrammatism is seen in many brain disease syndromes, including expressive aphasia and traumatic brain injury.
Following are some precautions that should be taken to avoid aphasia, by decreasing the risk of stroke, the main cause of aphasia:
- Exercising regularly
- Eating a healthy diet
- Keeping alcohol consumption low and avoiding tobacco use
- Controlling blood pressure
If the symptoms of aphasia last longer than two or three months after a stroke, a complete recovery is unlikely. However, it is important to note that some people continue to improve over a period of years and even decades. Improvement is a slow process that usually involves both helping the individual and family understand the nature of aphasia and learning compensatory strategies for communicating.
After a traumatic brain injury (TBI) or cerebrovascular accident (CVA), the brain undergoes several healing and re-organization processes, which may result in improved language function. This is referred to as spontaneous recovery. Spontaneous recovery is the natural recovery the brain makes without treatment, and the brain begins to reorganize and change in order to recover. There are several factors that contribute to a person's chance of recovery caused by stroke, including stroke size and location. Age, sex, and education have not been found to be very predictive.
Specific to aphasia, spontaneous recovery varies among affected people and may not look the same in everyone, making it difficult to predict recovery.
Though some cases of Wernicke’s aphasia have shown greater improvements than more mild forms of aphasia, people with Wernicke’s aphasia may not reach as high a level of speech abilities as those with mild forms of aphasia.
In most individuals with expressive aphasia, the majority of recovery is seen within the first year following a stroke or injury. The majority of this improvement is seen in the first four weeks in therapy following a stroke and slows thereafter. However, this timeline will vary depending upon the type of stroke experienced by the patient. Patients who experienced an ischemic stroke may recover in the days and weeks following the stroke, and then experience a plateau and gradual slowing of recovery. On the contrary, patients who experienced a hemorrhagic stroke experience a slower recovery in the first 4–8 weeks, followed by a faster recovery which eventually stabilizes.
Numerous factors impact the recovery process and outcomes. Site and extent of lesion greatly impacts recovery. Other factors that may affect prognosis are age, education, gender, and motivation. Occupation, handedness, personality, and emotional state may also be associated with recovery outcomes.
Studies have also found that prognosis of expressive aphasia correlates strongly with the initial severity of impairment. However, it has been seen that continued recovery is possible years after a stroke with effective treatment. Timing and intensity of treatment is another factor that impacts outcomes. Research suggests that even in later stages of recovery, intervention is effective at improving function, as well as, preventing loss of function.
Unlike receptive aphasia, patients with expressive aphasia are aware of their errors in language production. This may further motivate a person with expressive aphasia to progress in treatment, which would affect treatment outcomes. On the other hand, awareness of impairment may lead to higher levels of frustration, depression, anxiety, or social withdrawal, which have been proven to negatively affect a person's chance of recovery.
The most common cause of expressive aphasia is stroke. A stroke is caused by hypoperfusion (lack of oxygen) to an area of the brain, which is commonly caused by thrombosis or embolism. Some form of aphasia occurs in 34 to 38% of stroke patients. Expressive aphasia occurs in approximately 12% of new cases of aphasia caused by stroke.
In most cases, expressive aphasia is caused by a stroke in Broca's area or the surrounding vicinity. Broca's area is in the lower part of the premotor cortex in the language dominant hemisphere and is responsible for planning motor speech movements. However, cases of expressive aphasia have been seen in patients with strokes in other areas of the brain. Patients with classic symptoms of expressive aphasia in general have more acute brain lesions, whereas patients with larger, widespread lesions exhibit a variety of symptoms that may be classified as global aphasia or left unclassified.
Expressive aphasia can also be caused by trauma to the brain, tumor, cerebral hemorrhage by extradural hematoma.
Understanding lateralization of brain function is important for understanding what areas of the brain cause expressive aphasia when damaged. In the past, it has been believed that the area for language production differs between left and right-handed individuals. If this were true, damage to the homologous region of Broca's area in the right hemisphere should cause aphasia in a left-handed individual. More recent studies have shown that even left-handed individuals typically have language functions only in the left hemisphere. However, left-handed individuals are more likely to have a dominance of language in the right hemisphere.
In relation to other types of aphasia, TMoA occurs less frequently, so there is less information on its prognosis. In general, for individuals with aphasia, most recovery is seen within 6 months of the stroke or injury although more recovery may continue in the following months or years. The timeline of recovery may look different depending on the type of stroke that caused the aphasia. With an ischemic stroke, recovery is greatest within the first two weeks and then diminishes overtime until the progress stabilizes. With a hemorrhagic stroke, the patient often shows little improvement in the first few weeks and then has relatively rapid recovery until they stabilize.
In a study involving eight patients with border zone lesions, all patients presented with transcortical mixed aphasia initially after the stroke. Three of these patients made a complete recovery within a few days post-stroke. For three other patients with more anterior lesions, their aphasia transitioned to TMoA. All participants in the study regained full language abilities within 18 months following their stroke. This suggests a positive long-term prognosis for patients with TMoA. However, this might not be the case for all patients and more research is needed in order to solidify these findings. Another study found that prognosis of TMoA is affected by lesion size. Smaller lesions typically cause delays in speech initiation; whereas, larger lesions lead to more profound language abnormalities and difficulty with abstract language abilities.
Research has shown that treatment has a direct effect on aphasia outcomes. Intensity, duration and timing of treatment all need to be taken in to consideration when choosing a course of treatment and determining a prognosis. In general, greater intensity leads to greater improvement. For duration, longer-term treatment produces more permanent changes. As for timing, beginning treatment too early may be difficult for the system which has not recovered enough to do intensive therapy, but beginning too late may result missing the window of the opportunity in which the most change can occur. Neuroplasticity, the brain's natural ability to reorganize itself following a traumatic event, occurs best when treatment connects simultaneous events, maintains attention, taps into positive emotion, utilizes repetition tasks, and is specific to the individual's needs.
Other factors affecting prognosis includes location and site of lesion. Since the lesion that results in TMoA usually occurs in the watershed area and does not directly involve the areas of the brain responsible for general language abilities, prognosis for these patients is good overall. Other factors that determine a patient’s prognosis include age, education prior to the stroke, gender, motivation, and support.
Transcortical motor aphasia (TMoA), also known as commissural dysphasia or white matter dysphasia, results from damage in the anterior superior frontal lobe of the language-dominant hemisphere. This damage is typically due to cerebrovascular accident (CVA). TMoA is generally characterized by reduced speech output, which is a result of dysfunction of the affected region of the brain. The left hemisphere is usually responsible for performing language functions, although left-handed individuals have been shown to perform language functions using either their left or right hemisphere depending on the individual. The anterior frontal lobes of the language-dominant hemisphere are essential for initiating and maintaining speech. Because of this, individuals with TMoA often present with difficulty in speech maintenance and initiation.
Damage in the watershed region does not directly harm the areas of the brain involved in language production or comprehension; instead, the damage isolates these areas from the rest of the brain. If there is damage to the frontal lobe, executive functions related to language use are often affected. Executive functions relevant to language include activating language responses, controlling syntax (grammar), and narrative discourse. Difficulties in these areas can lead to supplementary deficits involving difficulties forming complex sentences, choosing which words to use appropriately, and initiating speech in conversation.
The extent and location of the brain damage will impact the degree and variety of language functioning characteristics (i.e. damage deep to the frontal lobe and/or damage across multiple regions will greatly impair language). Right hemiparesis, or right-sided paralysis, may coincide with TMoA if the lesion in the anterior frontal lobe is large enough and extends into the posterior frontal lobe.
There are some other forms of aphasia that relate to TMoA. For instance, adynamic aphasia is a form of TMoA that is characterized by sparse speech. This occurs as a result of executive functioning in the frontal lobe. Another form of aphasia related to TMoA is dynamic aphasia. Patients with this form of aphasia may present with a contiguity disorder in which they have difficulty combining linguistic elements. For dynamic aphasia, this is most apparent when the patient is asked to sequence at the sentence level whereas for other aphasias contiguity disorder can be seen at the phoneme or word level.
There is no curative treatment for this condition. Supportive management is helpful.
Agrammatism was first coined by Adolf Kussmaul in 1887 to explain the inability to form words grammatically and to syntactically order them into a sentence. Later on, Harold Goodglass defined the term as the omission of connective words, auxiliaries and inflectional morphemes, all of these generating a speech production with extremely rudimentary grammar. Agrammatism, today seen as a symptom of the Broca's syndrome (Tesak & Code, 2008), has been also referred as 'motor aphasia' (Goldstein, 1948), 'syntactic aphasia' (Wepman & Jones, 1964), 'efferent motor aphasia' (Luria, 1970), and 'non-fluent aphasia' (Goodglass et al., 1964).
The early accounts of agrammatism involved cases of German and French participants. The greater sophistication of the German school of aphasiology at the turn of the 20th century and also the fact that both German and French are highly inflected languages, might have been triggers for that situation (Code, 1991). Nowadays, the image has slightly changed: grammatical impairment has been found to be selective rather than complete, and a cross-linguistic perspective under the framework of Universal Grammar (UG) together with a shift from morphosyntax to morphosemantics is à la page. Now the focus of study in agrammatism embraces all natural languages and the idiosyncrasies scholars think a specific language has are put in relation to other languages so as to better understand agrammatism, help its treatment, and review and advance in the field of theoretical linguistics.
There is little written about agrammatism in Catalan. The beginnings of the field should be encountered in the work of Peña-Casanova & Bagunyà-Durich (1998), and Junque et al. (1989). These papers do not describe case reports, they are rather dealing with more general topics such as lesion localization or rehabilitation of agrammatic patients. The most updated studies could be found in the work of Martínez-Ferreiro (2009). The work of Martínez-Ferreiro is under the so-called Tree Pruning Hypothesis (TPH) of Friedmann & Grodzinsky (2007). Such a hypothesis is somewhat lagging behind after the findings in Bastiaanse (2008) have been proved by means of a re-analysis of data from Nanousi et al. (2006) and Lee et al. (2008), and the work of Yarbay Duman & Bastiaanse (2009). Other rather updated work for agrammatism in Catalan should be found in Martínez-Ferreiro et Gavarró (2007), in Gavarró (2008, 2003a, 2003b, 2002), Balaguer et al. (2004), in Peña-Casanova et al. (2001), and in Sánchez-Casas (2001).
From a cross-linguistic perspective under the framework of Universal Grammar (UG), grammatical impairment in agrammatism has been found to be selective rather than complete. Under this line of thought, the impairment in tense production for agrammatic speakers is currently being approached in different natural languages by means of the study of verb inflection for tense in contrast to agreement (a morphosyntactic approach) and also, more recently, by means of the study of time reference (which, in a sense, should be seen closer to morphosemantics). The type of studies this paper should be related with are those dealing with tense impairment under the framework of time reference. Prior to explaining that, to help understand the goals of such research, it is good to give a taste of the shift from morphosyntax to morphosemantics the study of agrammatism is undergoing.
The main clinical features are signature language progressive difficulties with speech production. There can be problems in different parts of the speech production system, hence patients can present with articulatory breakdown, phonemic breakdown (difficulties with sounds) and other problems. However, it is rare for patients to have just one of these problems and most people will present with more than one problem. Features include:
- Hesitant, effortful speech
- Speech 'apraxia'
- Stutter (including return of a childhood stutter)
- Anomia
- Phonemic paraphasia (sound errors in speech e.g. 'gat' for 'cat')
- Agrammatism (using the wrong tense or word order)
As the disease develops, speech quantity decreases and many patients will become mute.
Cognitive domains other than language are rarely affected early on. However, as the disease progresses other domains can be affected. Problems with writing, reading and speech comprehension can occur as can behavioural features similar to frontotemporal dementia.
Cerebellar cognitive affective syndrome (CCAS), also called "Schmahmann's syndrome" is a condition that follows from lesions (damage) to the cerebellum of the brain. This syndrome, described by Dr. Jeremy Schmahmann and his colleagues refers to a constellation of deficits in the cognitive domains of executive function, spatial cognition, language, and affect resulting from damage to the cerebellum. Impairments of executive function include problems with planning, set-shifting, abstract reasoning, verbal fluency, and working memory, and there is often perseveration, distractibility and inattention. Language problems include dysprosodia, agrammatism and mild anomia. Deficits in spatial cognition produce visual–spatial disorganization and impaired visual–spatial memory. Personality changes manifest as blunting of affect or disinhibited and inappropriate behavior. These cognitive impairments result in an overall lowering of intellectual function. CCAS challenges the traditional view of the cerebellum being responsible solely for regulation of motor functions. It is now thought that the cerebellum is responsible for monitoring both motor and nonmotor functions. The nonmotor deficits described in CCAS are believed to be caused by dysfunction in cerebellar connections to the cerebral cortex and limbic system.
There is much research that needs to be conducted on CCAS. A necessity for future research is to conduct more longitudinal studies in order to determine the long-term effects of CCAS. One way this can be done is by studying cerebellar hemorrhage that occurs during infancy. This would allow CCAS to be studied over a long period to see how CCAS affects development. It may be of interest to researchers to conduct more research on children with CCAS, as the survival rate of children with tumors in the cerebellum is increasing. Hopefully future research will bring new insights on CCAS and develop better treatments.