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Stroke in the language dominant hemisphere is the most frequent cause of aphasia. In the course of post-stroke aphasia different mechanisms can contribute to the recovery of language: recovery from ischemia, compensatory rerouting of language modalities and neuroplasticity occur at different time scales after the initial injury. These mechanisms may occur spontaneously or may be induced or influenced by various therapeutic interventions. This report contains a systematic review of the literature concerning the debated role of the right hemisphere in the recovery from stroke-related aphasia. The existing literature was approached using the PICOS principle and well-established inclusion and exclusion criteria. Although many gaps remain in the knowledge on the role of the right hemisphere, there is some evidence of a facilitation of spontaneous language recovery in the acute and subacute phase. In the subacute and chronic phase, the right hemisphere homologous language areas, along with memory and attention-related areas, facilitate treatment related improvement. In contrast, in therapy-free periods in the chronic stage, the right hemisphere no longer contributes to language recovery or may even be inhibitory. Injury-, language- and therapy-related variables impact on the role of the right hemisphere in aphasia recovery.

Predicting functional outcome in stroke is challenging to most clinicians, partly because of the complexity of the condition and also because of the lack of validated prognostic models. The strongest predictors of functional outcome are age and motor function at stroke onset. There is a growing literature on predicting recovery of upper limb after stroke; however, literature on prediction of language recovery remains sparse. This review covers the current status of predicting functional outcome after stroke focusing on recovery of activities of daily living, ambulation, upper limb use, and aphasia. Use of clinical factors, imaging, and neurophysiological measures are discussed.

The present case study aims to investigate whether the treatment of a third language (L3 French) in a trilingual chronic Wernicke-aphasic patient leads to the parallel improvement of the first (L1 German) and second (L2 English) languages. After a linguistic assessment in each language by means of the Bilingual Aphasia Test (BAT) [Paradis, M. (1987). The assessment of bilingual aphasia . Hillsdale: Lawrence Erlbaum], the patient was intensively treated in his L3 twice a day for 45 min for three and a half weeks. The treatment focussed on lexical–semantic deficits. Subsequent to the treatment, the patient was tested again in the three languages. The resulting recovery pattern shows that both L2 and L3 significantly improved after treatment with a larger effect for the treated language (L3) than for the L2. In contrast, L1 (German) did not show significant improvement, probably because the test results were already above-average for the first testing (T1). The present findings lend support to cognitive models of bilingual word recognition postulating that a bilingual's two languages share a common semantic–conceptual memory system.

Grafman, in this issue, discusses four forms of neuroplasticity that may account for development and recovery of functional neural networks in the human brain. These include homologous area adaptation, cross-modal reassignment, map extension, and compensatory masquerade. The following discussion focuses on these forms of neuroplasticity as they pertain to recovery of language function in aphasia. The first part of the paper presents data showing that two of the four forms, homologous area adaptation and map extension, are relevant to recovery from aphasia. The second part of the paper discusses factors related to neuroplastic activity during language recovery, including neurophysiological, subject, and environmental, that is, treatment variables. Data from animal studies as well as recent data from aphasia treatment studies will provide a basis for this discussion.

Background Poststroke aphasia recovery evolves in time. Increased perilesional activity associated with treatment-related language improvements has been confirmed in the chronic phase ( Fridriksson et al., 2011 ), but has not yet been systematically demonstrated during the early phases of stroke recovery. The pathophysiology of stroke suggests that perilesional reorganisation evolves within days, lasting for months after stroke, while increased neuronal excitability might provide a basis for perilesional neuroplasticity ( Schiene et al., 1999 ). Methods We compared fMRI BOLD response to speech (SP) and reversed speech (REV) using an auditory comprehension paradigm ( Saur et al., 2006 ) administered repeatedly (acute (t1) ⩽ 1 week, subacute (t2) = 1–2 weeks, chronic (t3) > 6 months post-onset) to patients with stroke affecting left frontal (FC, N = 17) or temporoparietal cortex (TPC, N = 17). Language activation (SP > REV) obtained from three perilesional ROIs expanding stepwise to 39 mm beyond the lesion (DISTANCE) was compared across TIME and to the improvement of language comprehension/production. Results An ANOVA revealed a significant TIME × DISTANCE interaction (F(4) = 2.9, p = .025) with increased activation from t1 to t3 and t2 to t3 (p). Conclusion To conclude, a remapping of cortical language representations in undamaged left cortices is likely to commence during subacute phase of recovery and improvements of specific language functions differentially involve frontal or temporal perilesional areas.

The present retrospective analysis reports two studies. In Study 1, clinical aspects of aphasia are compared in right-handed (RH) and non-right-handed (NRH) patients; in Study 2, recovery from aphasia is compared in RH and NRH aphasic patients with a minimum of 5 months of daily language rehabilitation. From a continuous series of 1200 brain-damaged subjects, 24 NRH patients with a vascular lesion documented by computerized tomography were selected. In 19 cases the lesion was in the left hemisphere and in 5 cases in the right hemisphere. For 14 NRH patients, a RH subject with similar lesion, matched for age, education, length of illness, etiology (ischemic vs. hemorrhagic), and, when possible, sex was found. Presence and type of aphasia were compared in the two patients of the same pair and were found similar except for Pair 14; the RH subject had global aphasia and the NRH had conduction-like aphasia. Fifteen NRH patients were rehabilitated and reexamined at least 5 months after the first examination. Recovery of the 12 patients with a left-hemisphere lesion was compared with recovery of a group of RH subjects and no significant differences were found. Recovery of the three patients with right-hemisphere lesions is described. It is concluded that differences in type of aphasia and recovery between RHs and NRHs have been overemphasized in the past and must be reconsidered.

This investigation studied the patterns of ear preference of a group of 25 aphasic adults through the administration of two verbal dichotic tests and retests over a 2-month interval of time. These dichotic tests were a Dichotic Digits Test (DDT) and a Dichotic Animal Names Test (DANT). Schuell's short test of aphasia was given twice over this interval to assess language recovery. Results indicated that as aphasics improve in language, cerebral dominance becomes more firmly established in the right cerebral hemisphere. The data in this study tend to support a dominance shift hypothesis in the recovery of language after aphasia.

The paper presents a daily analysis of the language recovery of a patient who was globally aphasic at the time of her first observation and who had recovered language, as measured by the Western Aphasia Battery, at the time of her discharge 14 days later. The paper emphasizes the relatively regular growth of normal syntactic, lexical, and pragmatic features coupled with similar regular decreases in aphasic features. Observations of both phenomena are necessary to describe language recovery.

Language recovery in aphasic patients who received one of three types of speech and language treatment was compared with that in aphasic patients who received no treatment. One hundred aphasic patients were followed from 2 to 4 weeks postonset for 1 year or until recovery, using a standardized test battery administered at systematic intervals. Both treatment methods provided by trained speech-language pathologists were efficacious, while the method provided by trained nonprofessionals approached statistical significance. Small group size prevented resolution of the question of whether one type of treatment was superior to another.

Longitudinal dichotic scores were obtained for aphasic patients for whom extensive language and memory data were also available. Severity of language impairments was related to ear advantage, but this occurred because larger lesions yielded more severe language impairments and were more likely to involve Heschl's gyrus. Extent of language recovery was not related to changes in ear dominance. Relationships that occurred generally supported a functional-anatomical interpretation which stressed the importance of the integrity of the posterior superior temporal lobe to performance both on dichotic tests and on specific language or memory tests.

A neurobiological model for recovery of function in aphasia is proposed. Clinical features and contributing factors are systematically reviewed: aphasia type, time course, etiology, sex, age, handedness, cerebral asymmetries, depression, epilepsy, perseveration. The role of the right hemisphere is investigated: language recovery and the right hemisphere, crossed aphasia, transfer of language dominance, right hemisphere language. Mechanisms of recovery are considered: localizationist theories (redundancy, vicarious function, multiple control, substitution) and diaschisis (anatomy and physiology, experimental evidence). Evidence for a new theory of recovery of function in aphasia is then provided: sprouting, supersensitivity., chemical anatomy (noradrenergic and serotonergic systems, mesocortical dopaminergic system), release of right hemisphere potential, latent synapses (pharmacological deblocking, environmental deblocking). A more active intervention into recovery from aphasia is suggested.