The assessment of auditory function in CSWS: Lessons from long-term outcome

In Landau-Kleffner syndrome (LKS), the prominent and often first symptom is auditory verbal agnosia, which may affect nonverbal sounds. It was early suggested that the subsequent decline of speech expression might result from defective auditory analysis of the patient's own speech. Indeed, despite normal hearing levels, the children behave as if they were deaf, and very rapidly speech expression deteriorates and leads to the receptive aphasia typical of LKS. The association of auditory agnosia more or less restricted to speech with severe language decay prompted numerous studies aimed at specifying the defect in auditory processing and its pathophysiology. Long-term follow-up studies have addressed the issue of the outcome of verbal auditory processing and the development of verbal working memory capacities following the deprivation of phonologic input during the critical period of language development. Based on a review of neurophysiologic and neuropsychological studies of auditory and phonologic disorders published these last 20 years, we discuss the association of verbal agnosia and speech production decay, and try to explain the phonologic working memory deficit in the late outcome of LKS within the Hickok and Poeppel dual-stream model of speech processing.     

Episodic receptive aphasia in a child with Landau-Kleffner Syndrome: PET correlates

We report a four-year-old boy with Landau-Kleffner Syndrome (LKS) characterized by episodic receptive aphasia lasting for few weeks followed by gradual recovery of baseline language functions. Neuropsychological evaluation during an episode showed severe impairment in verbal skills and comprehension, but relative preservation of non-verbal skills. Although he could carry on a conversation during remission, neuropsychological evaluation demonstrated findings reflective of receptive language deficits. Prolonged EEG disclosed frequent sharp-wave activity in the left and right temporal regions but no electrographic seizures. Glucose metabolism PET scan during the fourth episode of aphasia revealed intense hypermetabolism in the left temporal neocortex. Awake EEG during the PET tracer uptake period showed 6.0 spikes/min in the left temporal region and 4.0 spikes/min in the right. A repeat PET scan during remission showed hypometabolism in the left temporal cortex. Awake EEG during the FDG uptake period showed 16.0 spikes/min in the right temporal region and 0.3 spikes/min in the left. During his fifth aphasic episode, EEG (without PET) showed 0.16 spikes/min in the right temporal region and none in the left. Intermittent short episodes of predominantly receptive aphasia with near-total recovery between episodes can be one of the clinical presentations of LKS. This case illustrates the dynamic changes of glucose metabolism in the temporal lobe during episodes of aphasia and remission in a case with LKS. The clinical course of our patient with transient EEG and PET findings suggest that glucose metabolism in LKS cannot be attributed solely to interictal epileptiform activities on scalp EEG.     

Revealing and quantifying the impaired phonological analysis underpinning impaired comprehension in Wernicke's aphasia

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.     

Changing perspectives on Landau-Kleffner syndrome

Landau-Kleffner syndrome (LKS) is a childhood disorder characterized by an acquired aphasia that emerges in association with epileptiform electroencephalographic abnormalities. The language loss is often characterized by a severe disturbance of auditory language comprehension (verbal auditory agnosia) combined with a substantial disruption of expressive language. Comorbid behavioral disturbances commonly involve hyperactivity and attentional problems but sometimes encompass a more pervasive pattern of difficulties resembling an autism spectrum disorder. Now one the most frequently described forms of acquired aphasia in children, LKS has had a profound influence on both neurological practice and cognitive neuroscience. Here, we review current conceptualizations of LKS, consider its pleomorphic manifestations and discuss existing and future diagnostic issues and dilemmas. The potential relevance of LKS to understanding other disorders, including autistic regression, is considered.     

获得性癫痫性失语综合征的临床特点分析

目的 研究中国人获得性癫痫性失语(Landau-Kleffner Syndrome,LKS)的临床、脑电图及治疗特点.方法 对中国大陆地区报道的文献中71例LKS患儿的临床资料进行回顾总结,并结合文献进行探讨.结果 获得性癫痫失语均发作于儿童期,临床均有失语及脑电图癫痫样放电,其中以混合性失语及腩电图棘-慢复合波为多见.多数临床有癫痫发作,听力均无异常,多数伴有精神行为异常.癫痫发作用抗癫痫药物控制良好,经皮质激素及免疫球蛋白的治疗,失语大多能改善.结论 中国儿童获得性癫痫性失语主要临床表现为获得性失语和癫痫发作,多伴有其它精神行为症状.EEG常见颞区的限局性放电,失语表现为听觉失认.早期诊断并采取包括抗癫痫药物和皮质激素应用的综合治疗,患者的预后总体良好.     

Landau-Kleffner syndrome: epileptic activity in the auditory cortex.

The Landau-Kleffner syndrome (LKS) is characterized by electroencephalographic spike discharges and verbal auditory agnosia in previously healthy children. We recorded magnetoencephalographic (MEG) spikes in a patient with LKS, and compared their sources with anatomical information from magnetic resonance imaging. All spikes originated close to the left auditory cortex. The evoked responses were contaminated by spikes in the left auditory area and suppressed in the right--the latter responses recovered when the spikes disappeared. We suggest that unilateral discharges at or near the auditory cortex disrupt auditory discrimination in the affected hemisphere, and lead to suppression of auditory information from the opposite hemisphere, thereby accounting for the two main criteria of LKS.     

Bilateral volume reduction of the superior temporal areas in Landau-Kleffner syndrome

No specific anatomic abnormalities have been detected in typical Landau-Kleffner syndrome (LKS), an acquired epileptic aphasia with language regression in children. In four children with typical LKS without obvious anatomic abnormalities, the authors performed MRI volumetric analysis of various neocortical regions and subcortical substructures. Volume reduction was detected in bilateral superior temporal areas (26 to 51%), specifically in planum temporale (25 to 63%) and superior temporal gyrus (25 to 57%), where receptive language is localized.     

Electrophysiological evidence of persisting unilateral auditory cortex dysfunction in the late outcome of Landau and Kleffner syndrome.

OBJECTIVES: In the late outcome of Landau and Kleffner syndrome (LKS), a childhood-acquired epileptic aphasia, most patients show after complete recovery of epilepsy a permanent one-ear extinction on dichotic listening tests contralateral to the temporal cortex previously affected by the epileptic focus. The pathophysiological significance of this dichotic extinction is not yet understood. It may be a consequence of a permanent dysfunction in the auditory system due to epileptic activity during the maturing period of the auditory system. Evoked potentials were used to check this hypothesis and to localize the level of the dysfunction along the auditory pathways. METHODS: Early, middle latency and late auditory evoked potentials were recorded in 5 right-handed children having recovered from LKS. They were compared with those of 5 control children paired for age and gender. RESULTS: In all 5 LKS patients, early and middle latency auditory evoked potentials were normal. But the amplitude of N1c (arising from associative auditory areas) was strongly reduced at temporal electrodes contralateral to the extinguished ear, whereas latency and amplitude of N1b (related to primary auditory areas) were in the normal range. CONCLUSIONS: Unilateral voltage reduction of late auditory evoked potentials over the temporal areas previously involved by epileptic discharges suggests a permanent dysfunction in the associative auditory cortex, the behavioral expression of which is the unilateral dichotic extinction.     

Verbal short-term memory deficits in Down syndrome: phonological,semantic, or both?

The current study examined the phonological and semantic contributions to the verbal short-term memory (VSTM) deficit in Down syndrome (DS) by experimentally manipulating the phonological and semantic demands of VSTM tasks. The performance of 18 individuals with DS (ages 11-25) and 18 typically developing children (ages 3-10) matched pairwise on receptive vocabulary and gender was compared on four VSTM tasks, two tapping phonological VSTM (phonological similarity, nonword discrimination) and two tapping semantic VSTM (semantic category, semantic proactive interference). Group by condition interactions were found on the two phonological VSTM tasks (suggesting less sensitivity to the phonological qualities of words in DS), but not on the two semantic VSTM tasks. These findings suggest that a phonological weakness contributes to the VSTM deficit in DS. These results are discussed in relation to the DS neuropsychological and neuroanatomical phenotype.     

Landau-Kleffner syndrome: long-term follow-up

Purpose

Landau–Kleffner syndrome (LKS) is a rare entity characterized by epilepsy and aphasia. It occurs in previously normal children, usually between three and seven years of age. The long-term outcome of LKS is not completely clear. The aim of this study is to verify the long-term follow-up of a group of patients with LKS, focusing on clinical and electroencephalographic (EEG) aspects, and quality of life. Methods: This was a transversal study. Between November 2006 and April 2007 seven patients with previous diagnosis of LKS were interviewed. They had had a follow-up of three to 16 years after their disease onset. They were all males between the ages of eight and 27 years old. All patients had normal MRI. Parents and/or patients were interviewed by one of the authors using a structured questionnaire. The Vineland Adaptive Behavior Scales, the Conner’s Rating Scales – Revised, and Short-Form Health Survey (SF 36) were used. Each patient had a prolonged interictal EEG recording. All patients had normal MRI. Results: The present investigation revealed that two patients still have seizures several years after epilepsy onset. One patient had total and three others had partial remission of language disturbance, while three patients still have aphasia and verbal auditory agnosia. With respect to quality of life, only one of our patients has a normal life at present. The remaining six patients with some sort of limitation consider the aphasia/agnosia to be the main difficulty in their lives. Five patients have normal EEGs. Conclusions: The long-term follow-up of patients with LKS shows that epilepsy and EEG abnormalities do not always disappear. Language disturbances tend to persist in most patients. The age of onset of language dysfunction does not seem to correlate with the prognosis for recovery of language function. Patients with LKS have an overall poor quality of life, mostly due to language difficulties.     

Landau-Kleffner Syndrome: Localization of Epileptogenic Lesion Using Wavelet- Cross-Correlation Analysis

Magnetoencephalographic findings in a 6-year-old patient suffering from acquired aphasia with convulsive disorder (Landau-Kleffner Syndrome, LKS) are presented. The data were analyzed using wavelet-cross-correlation analysis, a nonstationary analysis method developed to analyze the localization of an epileptogenic lesion and the propagation of epileptiform discharges. The results indicate that LKS might be a disorder of the primary temporal cortex, and that the auditory neural network may function as the circuit for the epileptic discharge propagation.     

Specific language impairment versus Landau-Kleffner syndrome

The occurrence of sleep electroencephalography (EEG) abnormalities in some children with specific language impairment (SLI), the various forms of language dysfunction patterns seen in children with benign childhood epilepsy with centrotemporal spikes (BECTS), and finally the acquired aphasia in Landau-Kleffner syndrome (LKS) indicate a large spectrum of interactions between language and epilepsy. As such, the question is whether SLI and LKS should rather be considered along a continuum or as two entirely distinct entities. In addition, the rationale for using antiepileptic medications in rare forms of SLI is discussed.     

Landau–Kleffner syndrome: A study of 29 patients

PurposeThe aim of the study was to retrospectively analyze the electroclinical features, etiology, treatment, and prognosis of 29 patients with Landau–Kleffner syndrome (LKS) with a long-term follow-up.MethodsInclusion criteria were a diagnosis of LKS with: (1) acquired aphasia or verbal auditory aphasia; (2) with or without focal seizures, secondarily generalized tonic-clonic seizures, absences, or atonic seizures.ResultsMean follow-up was 12 years. All cases except six had seizures. Before the onset of aphasia, developmental language and behavioral disturbances were present in 19 and 14 patients, respectively. All patients had verbal auditory agnosia. Aphasia was severe in 24 patients and moderate in five. Nonlinguistic cognitive dysfunctions were moderate in 14 patients. Behavioral disturbances were found in 16 patients. During the continuous spike-and-wave discharges during slow sleep phase, the spike-wave index was >85% in 15, 50–85% in eight, and 30–50% in four. In two patients, the EEG recording showed occasional bilateral spikes, without continuous spike-and-wave discharges during slow sleep. In this phase, the awake EEG recording showed more frequent interictal abnormalities, predominantly in the temporal regions. Eight patients recovered language completely, but the remaining patients continue to have language deficits of different degrees.ConclusionLandau–Kleffner syndrome is an epileptic encephalopathy characterized by acquired verbal auditory aphasia and seizures in most of the patients associated with continuous or almost continuous spike-and-wave discharges during slow wave sleep. The most commonly used treatments were clobazam, ethosuximide, sulthiame. High-dose steroids were also administered. Adequate and early management may avoid language and cognitive deterioration.     

Segregation of the neural correlates of language and phonological short-term memory

A left-handed patient is reported who developed a selective deficit of phonological short-term memory, but not aphasia, following an ischaemic lesion in the temporal parietal region of the left hemisphere The phonological short-term store was selectively damaged compared to the rehearsal system. The patient also showed impaired comprehension of spoken (but not written) connected language. This study suggests that language and phonological short-term memory may be mediated by segregated neural systems that develop independently in the two hemispheres. The relationship between phonological short- term memory and auditory comprehension is also discussed.     

Serial MEG change in a boy with Landau-Kleffner syndrome

We report a 7-year-old boy with Landau-Kleffner syndrome (LKS), with emphasis on the effect of therapy and serial MEG. The equivalent current dipoles (ECDs) of spike discharges accumulated in the bilateral Heschl gyri, predominantly on the right. Although spike discharges on the scalp EEGs disappeared by treatment with clonazepam and sodium valproate, the auditory agnosia did not improve. Therapeutic trials with conventional antiepileptic drugs were unsuccessful. A high-dose corticosteroid was effective, with disappearance of ECDs, appearance of auditory evoked fields (AEF) in the bilateral Heschl gyri on MEG, and improvement of behavioral problems and amelioration of acquired aphasia. The clinical course of this patient suggests that MEG findings are useful not only in making precise diagnosis of LKS but also in assessing and predicting the effects of treatment.     

Auditory identification of frequency-modulated sweeps and reading difficulties in Chinese

BackgroundIn Chinese Mandarin, lexical tones play an important role of providing contrasts in word meaning. They are pitch patterns expressed by frequency-modulated (FM) signals. Yet, few studies have looked at the relationship between low-level auditory processing of frequency signals and Chinese reading skills.AimsThe study aims to identify the role of auditory frequency processing in Chinese lexical tone awareness as well as character recognition in Chinese-speaking children.MethodsChildren with (N = 28) and without (N = 27) developmental dyslexia (DD) were recruited. All participants completed two linguistic tasks, Chinese character recognition and lexical tone awareness, and two auditory frequency processing tasks, frequency discrimination and FM sweep direction identification.ResultsThe results revealed that Chinese-speaking children with DD were significantly poorer at all tasks. Particularly, Chinese character recognition was significantly related to FM sweep identification. Lexical tone awareness was significantly associated with both auditory frequency processing tasks. Regression analyses suggested the influence of FM sweep identification on Chinese character recognition contributed through lexical tone awareness.Conclusions and implicationThis study suggests that poor auditory frequency processing may associate with Chinese developmental dyslexia with phonological deficits. In support of the phonological deficit hypothesis, what underlies phonological deficit is likely to be auditory-basis. A potential clinical implication is to reinforce auditory perception and sensitivity through intervention for phonological processing.     

The mismatch negativity (MMN) response to complex tones and spoken words in individuals with aphasia

Background: The mismatch negativity (MMN) is a fronto-centrally distributed event-related potential (ERP) that is elicited by any discriminable auditory change. It is an ideal neurophysiological tool for measuring the auditory processing skills of individuals with aphasia because it can be elicited even in the absence of attention. Previous MMN studies have shown that acoustic processing of tone or pitch deviance is relatively preserved in aphasia, whereas the basic acoustic processing of speech stimuli can be impaired (e.g., auditory discrimination). However, no MMN study has yet investigated the higher levels of auditory processing, such as language-specific phonological and/or lexical processing, in individuals with aphasia. Aims: The aim of the current study was to investigate the MMN responses of normal and language-disordered subjects to tone stimuli and speech stimuli that incorporate the basic auditory processing (acoustic, acoustic-phonetic) levels of non-speech and speech sound processing, and also the language-specific phonological and lexical levels of spoken word processing. Furthermore, this study aimed to correlate the aphasic MMN data with language performance on a variety of tasks specifically targeted at the different levels of spoken word processing. Methods & Procedures: Six adults with aphasia (71.7 years ±3.0) and six healthy age-, gender-, and education-matched controls (72.2 years ±5.4) participated in the study. All subjects were right-handed and native speakers of English. Each subject was presented with complex harmonic tone stimuli, differing in pitch or duration, and consonant-vowel (CV) speech stimuli (non-word /de:/ versus real word /deI/). The probability of the deviant for each tone or speech contrast was 10%. The subjects were also presented with the same stimuli in behavioural discrimination tasks, and were administered a language assessment battery to measure their auditory comprehension skills. Outcomes & Results: The aphasic subjects demonstrated attenuated MMN responses to complex tone duration deviance and to speech stimuli (words and non-words), and their responses to the frequency, duration, and real word deviant stimuli were found to strongly correlate with performance on the auditory comprehension section of the Western Aphasia Battery (WAB). Furthermore, deficits in attentional lexical decision skills demonstrated by the aphasic subjects correlated with a word-related enhancement demonstrated during the automatic MMN paradigm, providing evidence to support the “word advantage effect”, thought to reflect the activation of language-specific memory traces in the brain for words. Conclusions: These results indicate that the MMN may be used as a technique for investigating general and more specific auditory comprehension skills of individuals with aphasia, using speech and/or non-speech stimuli, independent of the individual's attention. The combined use of the objective MMN technique and current clinical language assessments may result in improved rehabilitative management of aphasic individuals.     

Receptive prosody in nonfluent primary progressive aphasias

IntroductionProsody has been little studied in the primary progressive aphasias (PPAs), a group of neurodegenerative disorders presenting with progressive language impairment.MethodsHere we conducted a systematic investigation of different dimensions of prosody processing (acoustic, linguistic and emotional) in a cohort of 19 patients with nonfluent PPA syndromes (11 with progressive nonfluent aphasia, PNFA; five with progressive logopenic/phonological aphasia, LPA; three with progranulin-associated aphasia, GRN-PPA) compared with a group of healthy older controls. Voxel-based morphometry (VBM) was used to identify neuroanatomical associations of prosodic functions.ResultsBroadly comparable receptive prosodic deficits were exhibited by the PNFA, LPA and GRN-PPA subgroups, for acoustic, linguistic and affective dimensions of prosodic analysis. Discrimination of prosodic contours was significantly more impaired than discrimination of simple acoustic cues, and discrimination of intonation was significantly more impaired than discrimination of stress at phrasal level. Recognition of vocal emotions was more impaired than recognition of facial expressions for the PPA cohort, and recognition of certain emotions (in particular, disgust and fear) was relatively more impaired than others (sadness, surprise). VBM revealed atrophy associated with acoustic and linguistic prosody impairments in a distributed cortical network including areas likely to be involved in perceptual analysis of vocalisations (posterior temporal and inferior parietal cortices) and working memory (fronto-parietal circuitry). Grey matter associations of emotional prosody processing were identified for negative emotions (disgust, fear, sadness) in a broadly overlapping network of frontal, temporal, limbic and parietal areas.ConclusionsTaken together, the findings show that receptive prosody is impaired in nonfluent PPA syndromes, and suggest a generic early perceptual deficit of prosodic signal analysis with additional relatively specific deficits (recognition of particular vocal emotions).     

Efficacy of very high dose steroid treatment in a case of Landau-Kleffner syndrome

Landau-Kleffner syndrome (LKS) is an acquired childhood aphasia associated with paroxysmal bitemporal electroencephalogram (EEG) abnormalities and, sometimes, clinical seizures. We report the case of a female aged 5 years 6 months who presented clinically with apparent hearing loss, deterioration in speech, and seizure activity over 12 days. The female had previous detailed speech/language assessments at 3 to 4 years of age due to articulation delay. LKS was diagnosed on EEG with bitemporal spike and wave activity during sleep. The patient was treated with high dose prednisolone 3mg/kg/day, intensive speech/language therapy, and followed a modified educational program. We recorded a marked regression in receptive and expressive language skills, as well as her speech, language, and cognitive profiles before and during treatment with prednisolone, during an 18-month follow-up period. The patient demonstrated an excellent clinical response highlighting the importance of a multidisciplinary approach to management of LKS.     

Epileptiform Activity in Aphasia of Childhood:An Epiphenomenon?

Isolated aphasia with associated EEG epileptiform activity is a recognized syndrome in children. The relationship of the EEG abnormality and the type and severity of the speech impairment has not been well described. This relationship was studied in two children with severe expressive and receptive aphasia with generalized spike-wave discharges on EEG using prolonged EEG FM radiotelemetry and video recording (TEEG-VR). Speech was compared with 10 children with absence seizures with similar EEG abnormalities also evaluated using TEEG-VR. In addition, 43 cases of aphasia with epileptiform activity on the EEG reported in the English literature were reviewed. Speech abnormalities in absence seizures consisted of speech arrest, decreased speed of speech, and brief periods of partial or complete receptive and expressive aphasia, always directly associated with a spike-wave ictus. Speech abnormalities in acquired or congenital aphasia were not related to epileptiform activity and were characterized by severe articulation difficulties, syntactic transformation, paraphasia, and receptive and expressive aphasia. Anticonvulsants did not alter speech. Based on these two cases and the 43 others reviewed in the literature, it is proposed that epileptiform activity in this syndrome is an epiphenomenon reflecting underlying abnormalities of speech areas rather than the cause of the aphasia.