Impaired Auditory Comprehension Research Articles

Word picture verification performance reveals auditory comprehension deficits in primary progressive aphasia

Word/picture verification has been found to be a sensitive measure of lexical-semantic abilities in post-stroke aphasia and reveals information about disruptions in semantic and phonological processing. Exploration of the nature of auditory comprehension deficits using word/picture verification has not been replicated in primary progressive aphasia (PPA). We tested 108 individuals with PPA [logopenic variant PPA (lvPPA), n = 50; nonfluent agrammatic PPA (nfaPPA), n = 36; semantic variant PPA (svPPA), n = 22] on a spoken word/picture verification task and a spoken word/picture matching task. The spoken word/picture matching task identified 22 (20%) of individuals as impaired, whereas the spoken word/picture verification task identified 51 (47%) of individuals as impaired (two-tailed p < 0.001). Errors on spoken word/picture verification were due to semantic rather than phonologic foils in lvPPA (nouns, p < 0.001; verbs, p < 0.001), svPPA (nouns, p < 0.001; verbs, p < 0.001), and for nouns (p = 0.001) but not verbs in nfaPPA. Spoken word/picture verification was a more sensitive measure of single-word auditory comprehension deficits in PPA than word/picture matching. The error pattern, consistent with the distributed model of semantic knowledge, suggests that degradation of semantic representations for both nouns and verbs can occur in lvPPA, which may help to distinguish lvPPA versus nfaPPA and guide treatment for anomia. • We investigated picture verification and picture matching to assess auditory comprehension impairment in primary progressive aphasia (PPA). • Picture verification was a more sensitive measure of single-word auditory comprehension deficits in PPA than picture matching. • Errors on spoken word/picture verification were due to semantic rather than phonologic foils for nouns and verbs in logopenic variant and semantic variant PPA.

Correlation between focal lesion sites and language deficits in the acute phase of post-stroke aphasia.

Focal lesion sites can predict the language function of patients with aphasia during the subacute or chronic phases. However, the relationship between focal lesion sites and language deficits in the acute phase remains unclear. Therefore, our study aimed to investigate the relationship between focal lesion sites and fluency, auditory comprehension, repetition and naming deficits in patients with acute aphasia to further understand the pathophysiological mechanism of aphasia. We included a total of 52 patients with acute aphasia who had their first-ever stroke between June 2018 and June 2021 to investigate the association between focal lesion sites and fluency, auditory comprehension, repetition and naming deficits. Language function was assessed by the Western Aphasia Battery scale within one month of onset. The lesion sites were independently assessed by three professional speech and language pathologists according to the main sulcus of the brain within 1-2 days after stroke. Lesions involving the superior temporal gyrus, middle frontal gyrus, inferior frontal gyrus, precentral gyrus, postcentral gyrus, supramarginal gyrus, angular gyrus and insula were significantly associated with low fluency. Lesions involving the superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus, middle frontal gyrus, inferior frontal gyrus, supramarginal gyrus and angular gyrus significantly resulted in auditory comprehension impairment. Lesions involving the superior temporal gyrus, middle temporal gyrus, middle frontal gyrus, inferior frontal gyrus, precentral gyrus, postcentral gyrus, supramarginal gyrus, angular gyrus and insula significantly resulted in repetition and naming deficits. Our study suggests that focal lesion sites could lead to different language function impairments in the acute phase of post-stroke aphasia, which adds to our understanding of speech pathology and provides a direction for future research and treatment.

TRANSCORTICAL SENSORY APHASIA AS A MANIFESTATION OF ISCHEMIC STROKE WITH INTRACARDIAC THROMBUS

Transcortical sensory aphasia is characterized by impaired auditory comprehension, with intact repetition and uent speech. A 44-year-old right-handed patient with a history of hypertension on amlodipine and ischemic heart disease on aspirin was admitted to the neurology department for sudden onset of language impairment that started 2 days ago. The patient had features of transcortical sensory aphasia. Brain MRI showed an infarct in the territory of the left middle cerebral artery involving the tempo-parietal region. An apical thrombus was observed in the left ventricle on transthoracic echocardiography. This language impairment is thought to be caused by a disconnection between sensory language processes and semantic knowledge of objects. The prognosis is generally guarded and depends on the etiology and severity of the presentation

Working Memory in Aphasia: The Role of Temporal Information Processing

Aphasia is an acquired impairment of language functions resulting from a brain lesion. It is usually accompanied by deficits in non-linguistic cognitive processes. This study aimed to investigate in patients with aphasia the complex interrelationships between selected cognitive functions: auditory speech comprehension, working memory (WM), and temporal information processing (TIP) in the millisecond time range. Thirty right-handed subjects (20 males) aged from 27 to 82 years suffering from post-stroke aphasia participated in the study. Verbal working memory (VWM) and spatial working memory (SWM) were assessed with: (1) a receptive verbal test and (2) the Corsi Block-Tapping Test, respectively. Both these WM tests used the forward tasks (mainly engaging maintenance processes, i.e., storing, monitoring, and matching information) and backward tasks (engaging both maintenance and manipulation processes, i.e., reordering and updating information). Auditory comprehension was assessed by receptive language tests, and TIP efficiency was assessed by auditory perception of temporal order in the millisecond time range. We observed better performance of forward WM tasks than backward ones, independently of the type of material used. Furthermore, the severity of auditory comprehension impairment correlated with the efficiency on both forward and backward VWM tasks and the backward SWM task. Further analysis revealed that TIP plays a crucial role only in the latter task. These results indicate the divergent pattern of interactions between WM and TIP depending on the type of WM tasks. Level of verbal competency appeared to play an important role in both VWM tasks, whereas TIP (which is associated with manipulation processes) appeared to be important for SWM, but only on the backward task.

Verbal and non‐verbal auditory comprehension tests in early diagnosis of Alzheimer's disease

AbstractBackgroundThe purposes of this study are to correlate auditory comprehension impairment with AD early development and to evaluate the verbal and non‐verbal auditory comprehension tests for early diagnosis of AD.MethodThe 24 healthy controls (HC), 30 amnestic mild cognitive impairment (aMCI) and 27 mild AD (mAD) patients were recruited. The verbal (yes‐or‐no question, listening identification and oral instruction) and non‐verbal (sound categorization, emotion judgment, beat judgement, sound naming) auditory comprehension tests were adapted to evaluate the diagnostic ability of auditory comprehension. The receiver operating characteristic curves were used to analyze the diagnostic values.ResultAll tests except for yes‐or‐no question presented moderate or higher level of positive correlation in the scores with Mini‐Mental State Examination (MMSE) and Montreal Cognitive Assessment (MOCA), among which sound naming and oral instruction were the best. Statistical analysis identified a significant difference of sound naming and verbal auditory comprehension tests in aMCI group compared with the HC group. In addition, the mAD group exhibited statistically significant difference in sound categorization, sound naming, beat judgement and oral instruction when compared with the other two groups. Oral instruction sound categorization and naming benefited better in early diagnosis than the other subtests.ConclusionThe impairments of auditory comprehension emerge early in AD, or even aMCI patients, which worsen with the progression of the disease. The tests of sound categorization, sound naming and oral instruction exhibited better discriminative values, which might be beneficial for the early diagnosis of AD.

Test validity and performance validity: considerations in providing a framework for development of an ability-focused neuropsychological test battery.

Literature on test validity and performance validity is reviewed to propose a framework for specification of an ability-focused battery (AFB). Factor analysis supports six domains of ability: first, verbal symbolic; secondly, visuoperceptual and visuospatial judgment and problem solving; thirdly, sensorimotor skills; fourthly, attention/working memory; fifthly, processing speed; finally, learning and memory (which can be divided into verbal and visual subdomains). The AFB should include at least three measures for each of the six domains, selected based on various criteria for validity including sensitivity to presence of disorder, sensitivity to severity of disorder, correlation with important activities of daily living, and containing embedded/derived measures of performance validity. Criterion groups should include moderate and severe traumatic brain injury, and Alzheimer's disease. Validation groups should also include patients with left and right hemisphere stroke, to determine measures sensitive to lateralized cognitive impairment and so that the moderating effects of auditory comprehension impairment and neglect can be analyzed on AFB measures.

Mismatch negativity (MMN) reveals inefficient auditory ventral stream function in chronic auditory comprehension impairments

BackgroundAuditory discrimination is significantly impaired in Wernicke's aphasia (WA) and thought to be causatively related to the language comprehension impairment which characterises the condition. This study used mismatch negativity (MMN) to investigate the neural responses corresponding to successful and impaired auditory discrimination in WA. MethodsBehavioural auditory discrimination thresholds of consonant-vowel-consonant (CVC) syllables and pure tones (PTs) were measured in WA (n = 7) and control (n = 7) participants. Threshold results were used to develop multiple deviant MMN oddball paradigms containing deviants which were either perceptibly or non-perceptibly different from the standard stimuli. MMN analysis investigated differences associated with group, condition and perceptibility as well as the relationship between MMN responses and comprehension (within which behavioural auditory discrimination profiles were examined). ResultsMMN waveforms were observable to both perceptible and non-perceptible auditory changes. Perceptibility was only distinguished by MMN amplitude in the PT condition. The WA group could be distinguished from controls by an increase in MMN response latency to CVC stimuli change. Correlation analyses displayed a relationship between behavioural CVC discrimination and MMN amplitude in the control group, where greater amplitude corresponded to better discrimination. The WA group displayed the inverse effect; both discrimination accuracy and auditory comprehension scores were reduced with increased MMN amplitude. In the WA group, a further correlation was observed between the lateralisation of MMN response and CVC discrimination accuracy; the greater the bilateral involvement the better the discrimination accuracy. ConclusionsThe results from this study provide further evidence for the nature of auditory comprehension impairment in WA and indicate that the auditory discrimination deficit is grounded in a reduced ability to engage in efficient hierarchical processing and the construction of invariant auditory objects. Correlation results suggest that people with chronic WA may rely on an inefficient, noisy right hemisphere auditory stream when attempting to process speech stimuli.

Effectiveness of melodic intonation therapy in a case of aphasia following right hemisphere stroke

Background: The use of Melodic Intonation Therapy (MIT) in the clinical setting is suggested to be based on several criteria; however, some persons with aphasia not meeting these criteria may still benefit from this approach.Aims: The purpose of this research was to explore the effectiveness of utilising MIT to improve expressive language in a person with global aphasia following right hemisphere stroke.Methods & Procedures: A participant with global aphasia following right hemisphere haemorrhagic stroke completed a 7-week treatment programme utilising MIT. Sessions were held 5 days a week, for two and a half hours per day. Non-linguistic cognitive activities (COG) were also utilised briefly in each session as a break (BRK) from MIT. The Aphasia Diagnostic Profiles (ADP), American Speech-Language-Hearing Association-Functional Assessment of Communication Skills and the Stroke and Aphasia Quality of Life Scale-39 were administered pre- and post-treatment to assess for the treatment-related change.Outcomes & Results: The participant responded well to MIT, completing the elementary level in 25 sessions and progressing through the intermediate level until the end of the treatment period at session 30. Performance on the ADP suggested decreased aphasia severity characterised by improved auditory comprehension, repetition, average phrase length and elicited gestures. Functional communication was slightly improved, whereas quality of life did not change. It was reported by the spouse, caregiver and clinician that the participant began using several novel phrases in appropriate context over the course of the treatment.Conclusions: The MIT may be a valid treatment of global aphasia following right hemisphere stroke, providing more options to practising clinicians working with this population. It is likely that the criteria ruling out those with impaired auditory comprehension and those with right hemisphere lesions, regardless of lesion location, are too restrictive. Most likely, good and poor candidates for MIT can better be identified using intrahemispheric lesion location information, rather than interhemispheric.

Electrophysiology Correlates of Successful and Impaired Auditory Discrimination in Acquired Comprehension Impairments

Wernicke's aphasia is a condition which results in severely disrupted language comprehension following a lesion to the left temporo-parietal region. A phonological analysis deficit has traditionally been held to be at the root of the comprehension impairment in Wernicke's aphasia, a view consistent with current functional neuroimaging which finds areas in the superior temporal cortex responsive to phonological stimuli. However behavioural evidence to support the link between a phonological analysis deficit and auditory comprehension has not been yet shown. This study extends seminal work by Blumstein, Baker, and Goodglass (1977) to investigate the relationship between acoustic?phonological perception, measured through phonological discrimination, and auditory comprehension in a case series of Wernicke's aphasia participants. A novel adaptive phonological discrimination task was used to obtain reliable thresholds of the phonological perceptual distance required between nonwords before they could be discriminated. Wernicke's aphasia participants showed significantly elevated thresholds compared to age and hearing matched control participants. Acoustic?phonological thresholds correlated strongly with auditory comprehension abilities in Wernicke's aphasia. In contrast, nonverbal semantic skills showed no relationship with auditory comprehension. The results are evaluated in the context of recent neurobiological models of language and suggest that impaired acoustic?phonological perception underlies the comprehension impairment in Wernicke's aphasia and favour models of language which propose a leftward asymmetry in phonological analysis. Highlights ? This study provides the first positive evidence of a link between impaired auditory comprehension in Wernicke's aphasia and disrupted auditory?phonological analysis. ? A novel test of nonword auditory discrimination is introduced. This test enables differentiation of abilities within severely impaired participants. ? Results support traditional theories of Wernicke's aphasia.

A unique modality‐specific domain for the production of neologisms: Recurrent perseveration and oral reading

Background: Two commonly prevalent neurolinguistic constructs that have been clinically challenging are neologisms and perseveration. Both are integral parts of the language deficit that are seen in the spontaneous verbal output of patients with paragrammatism and neologistic jargon types of anomia. Both can appear in modality‐specific domains and usually co‐occur, adumbrating verbal output impairments. These are also known to occur in selected phases of the restitution, usually in the acute and sub‐acute periods, generally disappearing with recovery. Both constructs have been extensively investigated but largely as isolated phenomena. We show here that neologisms can occur in oral reading and that perseveration can be a major factor in the genesis of neologism. Aims: To date, most patients observed to have neologistic jargon aphasia also exhibited anomia and impaired auditory comprehension. Traditionally, neologisms have been studied in spontaneous verbal output, or at confrontation naming or repetition contexts. This study focuses on oral reading of a patient with aphasia who produced neologisms, but who nevertheless demonstrated good comprehension for the spoken language. There was no neologism present in her spontaneous verbal output. Methods & Procedures: The patient studied was a 76‐year‐old woman post removal of temporal lobe mass with subsequent haemorrhagic CVA. Neurolinguistic data were obtained from a standardised assessment and five treatment sessions in a 2‐month period. Transcription and analysis of the patient's oral reading revealed a profound disassociation in grapheme‐to‐phoneme conversion resulting in the production of neologisms in single‐word reading, which was further contaminated by perseveration. Outcomes and Results: An analysis of the neologisms in reading aloud revealed that not just one process had contributed to their production; rather there were multiple mechanisms that were noted to be operational in the genesis of neologisms. Conclusions: Neologisms can occur independently of impaired auditory comprehension; they can also extend beyond spontaneous verbal output and there are many linguistic processes that contribute to the genesis of neologism, with recurrent perseveration serving a crucial productive role in constructing the surrogate words that “mask” the deep retrieval blocks of words.

A pilot study transitioning children onto levetiracetam monotherapy to improve language dysfunction associated with benign rolandic epilepsy

Benign rolandic epilepsy (BRE) and Landau–Kleffner syndrome (LKS) are similar epilepsy syndromes with sleep-accentuated epileptiform activity, sporadic seizures, and language dysfunction. Levetiracetam has been associated with improved language function in LKS and seizure reduction in BRE. We hypothesized levetiracetam would improve language function in children with BRE. A pilot study was performed with six children (aged 6–12) with BRE and evidence of impaired auditory comprehension and verbal memory. Children were transitioned from their current anticonvulsant to 40 mg/kg/day levetiracetam over a 2-week period and retested at 6 months. At 6 months, three of four children with baseline auditory comprehension impairments performed normally ( P = 0.06), and five had improved auditory verbal memory ( P = 0.08). Seizures improved in five, decreasing from 2.7 to 1.0 seizure per 6 months ( P = 0.11). Results from this pilot study suggest that levetiracetam may have a beneficial effect on language in children with BRE.

Successful syllable detection in aphasia despite processing impairments as revealed by event-related potentials

BackgroundThe role of impaired sound and speech sound processing for auditory language comprehension deficits in aphasia is unclear. No electrophysiological studies of attended speech sound processing in aphasia have been performed for stimuli that are discriminable even for patients with severe auditory comprehension deficits.MethodsEvent-related brain potentials (ERPs) were used to study speech sound processing in a syllable detection task in aphasia. In an oddball paradigm, the participants had to detect the infrequent target syllable /ta:/ amongst the frequent standard syllable /ba:/. 10 subjects with moderate and 10 subjects with severe auditory comprehension impairment were compared to 11 healthy controls.ResultsN1 amplitude was reduced indicating impaired primary stimulus analysis; N1 reduction was a predictor for auditory comprehension impairment. N2 attenuation suggests reduced attended stimulus classification and discrimination. However, all aphasic patients were able to discriminate the stimuli almost without errors, and processes related to the target identification (P3) were not significantly reduced. The aphasic subjects might have discriminated the stimuli by purely auditory differences, while the ERP results reveal a reduction of language-related processing which however did not prevent performing the task. Topographic differences between aphasic subgroups and controls indicate compensatory changes in activation.ConclusionStimulus processing in early time windows (N1, N2) is altered in aphasics with adverse consequences for auditory comprehension of complex language material, while allowing performance of simpler tasks (syllable detection). Compensational patterns of speech sound processing may be activated in syllable detection, but may not be functional in more complex tasks. The degree to which compensational processes can be activated probably varies depending on factors as lesion site, time after injury, and language task.

P3-008: Assesment OG language functions on patients with Alzheimer’s disease and Pick’s diseases

Although language disturbances in dementia were recognized earlier, the exact nature and extent of language impairment in Alzheimer's and Pick's diseases has been the subject of much recent research, giving rise to more systematic study of the nature of communication deficits. Some authors have linked language dysfunction these types of dementia to aphasia, while others have emphasized the differences in language behavior of demented and aphasic patients. In this work, we report three cases with Alzheimer–type dementia and three cases with Picks disease in order to estimate the profile of language disorders. MMSE, BDAE and BNT tests have been used. The obtained results have shown that patients with Alzheimer's disease have severe language disturbances manifested by anomia, impaired auditory comprehension, word–finding difficulties and a lack cohesion in discourse, agraphia and dyslexia. Besides, they have exibited memory disorders, apraxia and agnosia. On the other side, two patients with Pick's diseases have semantic aphasia and the other has nonfluent aphasia. Although those patients have progressive language functions damage, memory, praxia and gnostic functions are not severely damaged.They have been treated for one year with antycholinergic inhibitors (Exelon and Aricept). Positive effects were found in patients with Alzheimer's disease, while patients with Pick's diseases did not show any improvement. We confronted language disturbances profile of patients with Alzheimer's disease and patients with Pick's diseases againts classical aphasics syndromes.

Transcortical sensory aphasia: revisited and revised.

Transcortical sensory aphasia (TSA) is characterized by impaired auditory comprehension with intact repetition and fluent speech. We induced TSA transiently by electrical interference during routine cortical function mapping in six adult seizure patients. For each patient, TSA was associated with multiple posterior cortical sites, including the posterior superior and middle temporal gyri, in classical Wernicke's area. A number of TSA sites were immediately adjacent to sites where Wernicke's aphasia was elicited in the same patients. Phonological decoding of speech sounds was assessed by auditory syllable discrimination and found to be intact at all sites where TSA was induced. At a subset of electrode sites where the pattern of language deficits otherwise resembled TSA, naming and word reading remained intact. Language lateralization testing by intracarotid amobarbital injection showed no evidence of independent right hemisphere language. These results suggest that TSA may result from a one-way disruption between left hemisphere phonology and lexical-semantic processing.

Word Meaning Deafness: Spelling Words That Are Not Understood

We describe a patient (KW) w ho show s impaired auditory comprehension of words in the presence of relatively intact written comprehension. His ability to perform auditory discrimination, repetition, and lexical decision tasks for words he cannot understand indicates that he has a word meaning deafness. It has been proposed that this deficit results from an impairment in the mappings between auditory lexical and semantic representations. A pure deficit of this nature w ould predict intact spelling to dictation for words that cannot be comprehended by way of a direct lexical, nonsemantic route betw een auditory and orthographic lexicons. In the case of KW, ability to write to dictation is relatively well-preserved for both regular and irregular words, relative to auditory comprehension. The nature of KW 's spelling errors was considered. In particular, w e reflect on the origin of his spelling errors since these may provide evidence regarding the nature of the lexical nonsemantic route that mediates w riting to dictation. KW 's performance is discussed in terms of current models of the spelling process.

Global aphasia due to thalamic hemorrhage: A case report and review of the literature

A 55-year-old patient was admitted with weakness in the right extremities and with significant language deficits. Both computed tomography (CT) and positron-emission tomography (PET) using 2-fluoro-2-deoxy-D-glucose were done within 1 month and repeated at 10 months after onset. Language evaluation was done using parts of the Western Aphasia Battery (WAB) and the Boston Diagnostic Aphasia Examination (BDAE) at 1 month after admission, at 3 months, and at 10 months. The initial CT scan revealed hemorrhage in the left thalamus with edema surrounding the hemorrhage. A follow-up CT scan after 10 months showed an old hemorrhage in the left thalamus with no new lesions. The initial PET scan revealed hypometabolism in the left thalamus, and a repeat PET scan at 10 months showed reduced uptake in the left frontal, left parietal, and left temporal cortex. An initial language evaluation showed impaired auditory and reading comprehension, poor verbal expression, impaired repetition, and difficulty with naming and with sentence completion. The patient was diagnosed with global aphasia. Follow-up language evaluation at 3 months and 10 months showed only minimal improvement in his communication. Global aphasia due to lesions in the thalamic region is rare and the prognosis is poor.

Abstract word meaning deafness

Abstract We report the case of a patient, DRB, who shows impaired auditory comprehension of abstract but not concrete words, in the context of preserved comprehension of all types of written words. Good performance on auditory lexical decision for abstract words indicates that DRB is able to access these lexical entries. This pattern may be termed “abstract word meaning deafness.” Repetition is also more impaired for abstract words than concrete words. DRB is unable to repeat nonwords or write them to dictation. He makes semantic errors in real word repetition, which is compatible with the view that his repetition is semantically mediated. Exactly the same pattern of semantic errors and a particular difficulty with abstract words is found in tasks where DRB is required to write to dictation. DRB's auditory comprehension and repetition impairments are not affected by word frequency. Performance on specific words is inconsistent, and is improved following a written cue.

Theodor Meynert′s Contribution to Classical 19th Century Aphasia Studies

Carl Wernicke (1848-1905) is traditionally considered the first to have described the features of, and the brain pathology underlying, impaired auditory comprehension and related symptoms. Although Wernicke (1874) clearly and repeatedly indicates his indebtedness to Theodor von Meynert (1833-1892). this is usually understood as an acknowledgment that Meynert taught Wernicke neuroanatomy (Eggert, 1977); Wernicke′s own words in part support this interpretation. A more sophisticated historical analysis notes that, prior to Wernicke, both Johann Schmidt in 1871 and Charlton Bastian in 1869 had described the concept of receptive aphasia, but neither had supported their analyses with autopsy evidence as did Wernicke, thus not dislodging Wernicke′s claim of priority. However, a virtually unknown work by Theodor von Meynert, published in 1866, has recently been rediscovered by us ["Ein Fall von Sprachstörung, anatomisch begründet." Medizinische Jahrbücher. XII Band der Zeitschrift der K. K. Gesellleschaft der Ärzte in Wien, 22.Jahr. Pp. 152-189]. In this paper Meynert analyzes the anatomical basis for localizing the comprehension of language in the superior temporal gyros, he argues that lesions in this area should (by analogy to Broca′s earlier observations on language expression) cause impairments in language comprehension, and he presents a case of receptive aphasia with autopsy evidence of destruction of the superior temporal gyros in the left hemisphere. The patient′s aphasia was classic: impaired auditory comprehension, and fluent speech with paraphasias. It is clear that Meynert should be given historical credit for his work.

Diazepam Therapy of Verbal Auditory Agnosia

A 7-year-old girl suffered from a gradual loss of her ability to understand speech. But she had normal hearing and understood various environmental sounds. Brain computerized axial tomography showed normal, but electroencephalogram revealed spike and wave activity from temporal leads, especially on the left side. She was diagnosed as having verbal auditory agnosia. The treatment consisted of diazepam therapy. One year after the onset, her impaired auditory comprehension dramatically improved with the use of diazepam. The dichotic listening test revealed a left ear advantage for both environmental sounds and spoken words. The results seemed to suggest that in this patient the right hemisphere might be functioning as a speech center instead of the left one.

Evoked potential measures of auditory cortical function and auditory comprehension in aphasia

This study investigated the relation between severity of auditory comprehension impairment in aphasia and the functional integrity of the posterior superior temporal region as evaluated by middle- and long-latency auditory evoked potentials and dipole source analysis. AEPs were studied in 20 stroke patients and in age-matched controls. AEPs and language data were collected 1 year or more post onset, and were compared to performance early after onset. Patients were differentiated in a group with severe and a group with moderate to recovered auditory comprehension impairment. Significant asymmetries of auditory evoked dipole source potentials were more frequent in the severely impaired group. However, a severe auditory comprehension deficit was not incompatible with normal AEPs. The results confirm the importance of the posterior superior temporal region for auditory language comprehension, but the correlation between AEP asymmetry and auditory comprehension seems due to the close spatial relation of AEP generating substrate and posterior language area rather than to partial overlap. Dipole source analysis of AEPs proved to be a valuable method for the assessment of interhemispheric asymmetries, enhancing the sensitivity of AEPs to unilateral damage of auditory cortex.