Word Deafness Research Articles

“I could see, and yet, mon, I could na’ see”: William Macewen, the agnosias, and brain surgery

Two little noticed cases in which William Macewen used symptoms of visual agnosia to plan brain surgery on the angular gyrus are reviewed and evaluated. Following a head injury, Macewen’s first patient had an immediate and severe visual object agnosia that lasted for about 2 weeks. After that he gradually became homicidal and depressed and it was for those symptoms that Macewen first saw him, some 11 months after the accident. From his examination, Macewen concluded that the agnosia clearly indicated a lesion in “the posterior portion of the operculum or in the angular gyrus.” When he removed parts of the internal table that had penetrated those structures the homicidal impulses disappeared. Macewen’s second patient was seen for a chronic middle ear infection and, although neither aphasic nor deaf, was ‘word deaf.’ Slightly later he became ‘psychically blind’ as well. Macewen suspected a cerebral abscess pressing on both the angular gyrus and the first temporal convolution. A large subdural abscess was found there and the symptoms disappeared after it was treated. The patients are discussed and Macewen’s positive results analysed in the historical context of the dispute over the proposed role of the angular gyrus as the visual centre.

Clinical Management of Agnosia

Agnosia is a neurological recognition deficit that affects a single modality. Visual agnosias include pure object agnosia, prosopagnosia, akinetopsia, and pure alexia. Auditory agnosias include pure word deafness, phonagnosia, and pure sound agnosia. New neuroimaging tools have permitted scientists to better understand the loci of lesions that cause various agnosias and from that knowledge to develop theories about the processing networks that contribute to perception and recognition in each modality. These research data, in turn, inform the rehabilitation process. By utilizing current knowledge about neuroprocessing networks, clinical professionals can differentially diagnose agnosias from aphasia and other cognitive deficits. Practical approaches to treatment of agnosia will follow once the diagnosis is established.

Formant Interaction as a Cue to Vowel Perception: A Case Report

Accumulating evidence indicates that cerebral processing of consonants and vowels is separable. It has been shown that disordered temporal acuity leads to disturbed consonant perception in cases with pure word deafness. In contrast, there has been no clear explanation of how vowel perception is impaired. We examined a patient with auditory agnosia, who showed a differential ability to identify the five Japanese vowels after bilateral cerebral lesions. He correctly identified the vowel [a] in more than 70% of auditory presentations, whereas he identified [i] in only about 30% of presentations. The difference between the first and second formant frequencies “F2–F1” and an artificially defined value “F1–(F2–F1)” for each vowel correlated significantly with the percentage of correct identifications. These findings support the hypothesis that vowel perception is based on formant interactions.

A Clinical Guide to Epileptic Syndromes and their Treatment: Based on the New ILAE Diagnostic Scheme

A Clinical Guide to Epileptic Syndromes and their Treatment: Based on the New ILAE Diagnostic Scheme

Cortical auditory disorder caused by bilateral strategic cerebral bleedings. Analysis of two cases

The authors present the anatomical and clinical features of cortical auditory dysfunction in two patients, in whom hypertensive bleedings destroyed the cortical auditory centres in both hemispheres. The second haemorrhage occurred four years after the first bleeding in both cases. The bleedings isolated the cortical hearing centres due to the destruction of the right and left temporal white matter. During the clinical course the symptomatology has changed in both patients: pure word deafness has transformed to cortical deafness and generalised auditory agnosia. Normal pattern of brain stem auditory evoked potentials suggested intact auditory pathways. Authors conclude that transformation of clinical forms of cortical auditory disorder can be explained by the tissue reaction to the subcortical bleeding in the cortical auditory centres.

Analysis of lexical-semantic processing and extensive neurological, electrophysiological, speech perception, and language evaluation following a unilateral left hemisphere lesion: Pure word deafness?

Background : Theoretical models of lexical-semantic processing that explicate the relationships between spoken word comprehension, repetition, and writing to dictation are discussed in relation to pure word deafness (PWD). Various theories relative to the neuroanatomical sites and pathophysiological/electrophysiological mechanisms that cause the speech perception deficit seen in PWD are reviewed, as well as case studies that have identified variables that facilitate comprehension of spoken language for individuals with PWD. Aims : A case study of an individual with an extensive and complex neurological history and a constellation of symptoms suggestive of PWD is presented. Extensive evaluation, including experimental tasks developed to test a theoretical lexical processing model, was undertaken to determine whether this case fitted the criteria for a diagnosis of PWD. Methods & Procedures : Extensive neurological, electrophysiological, speech perception, and language testing was undertaken to confirm site of lesion, assess neurophysiological processes underlying speech perception, and determine overall language status. Experimental tasks based on a lexical-semantic processing model assessed word and nonword repetition and writing to dictation under two conditions: presentation with and without facial cues. Outcomes & Results : MRI confirmed a lesion in the participant's left frontoparietal area. Electrophysiological measures indicated his auditory nerve and auditory brainstem functions were intact, middle latency response (MLR) was normal over his right hemisphere and absent over his left hemisphere, and a significant mismatch negativity (MMN) response was elicited by pitch, but not phonetic, differences. Speech perception testing indicated he had difficulty with spectral or spectro-temporal discrimination and combining phonological and semantic information, as well as decreased ability to use formant motion in sentence perception and to perceive speech in noise. Language testing revealed relatively intact spontaneous language production and reading comprehension. The participant's performance on experimental tasks indicated an effect of syllable length and presentation mode for both words and nonwords. That is, as the number of syllables increased, his performance decreased; however, repetition and writing to dictation reflected superior performance with facial cues regardless of word and nonword length when compared to presentation without cues. Relative to the lexical processing model, the participant's performance suggested impoverished phonetic processing in the auditory analysis system. Conclusions : The results of extensive evaluation revealed a selective impairment in acoustic phonetic perception that is consistent with a diagnosis of PWD. The findings of this study support other studies that have demonstrated that speech perception involves cortical areas other than the temporal lobes.

Auditory perception in auditory neuropathy: Clinical similarity with auditory verbal agnosia

The precise features of auditory perception in patients with auditory neuropathy have not been well described. In the present study, we examined auditory perception in a patient with auditory neuropathy. The patient was a right-handed 7-year-old boy. His chief complaint was delayed speech and suspected of verbal learning disability. He could talk, read and repeat rather fluently but could not understand fully what was asked. V-IQ, P-IQ and F-IQ of Wechsler Scale for Children III-R were 53, 118 and 81, respectively. Pure tone audiogram was completely normal. His speech discrimination ability was very poor. He could identify environmental sounds with visual matching. He could differentiate intensity difference but not time difference. This phenomenon was reported in patients with hemispheric symptoms. These clinical features are very similar to verbal auditory agnosia. ABR showed no response at 90dBnHL alternating clicks and tone bursts. Click evoked and distortion product otoacoustic emissions (OAE) were normal. Electrocochleogram was also normal. Motor and sensory nerve conduction velocity was completely normal. Pa of MLR and N1 of SVR were present. His diagnosis should be ‘pure type’ of auditory neuropathy or auditory nerve disease. Importance of both ABR and OAE examination should be widely announced and auditory neuropathy must be campaigned stressed to be clinical entity among personnel who take care of children with speech delay.

A Case Study of Pure Word Deafness: Modularity in Auditory Processing?

AL, a woman with an acquired disturbance of auditory processing beginning in the second decade, was originally diagnosed as having pure word deafness. Recent analysis with a wide range of stimuli suggests that her comprehension deficit also extends to a subset of musical and non-verbal environmental sounds. The perceptual demands of the different auditory stimuli appear to account for part of the apparent material specificity. Additionally, over the years, the presumed temporal lobe cortical pathology has been supplemented by a mild to moderate, peripheral low-frequency hearing loss and evidence of dysfunction in lower level auditory processing pathways. The current peripheral dysfunction closely resembles cases recently labeled as auditory neuropathy. The diagnosis of pure word deafness should not be based on a limited set of auditory stimuli; additionally, a careful assessment using modern audiological techniques should be performed to evaluate peripheral auditory functions.

A case study of pure word deafness: modularity in auditory processing?

A case study of pure word deafness: modularity in auditory processing?

A Case Study of Pure Word Deafness: Modularity in Auditory Processing?

A Case Study of Pure Word Deafness: Modularity in Auditory Processing?

Pure word deafness in two patients with subcortical lesions

We report two patients with pure word deafness (PWD) with tumour in the III ventricle region with obstructive hydrocephalus. A diagnosis of PWD was made in these two patients in view of impaired verbal comprehension in the presence of adequate hearing, intact acoustic stapedius reflex and well preserved environmental sound perception. Return of verbal comprehension following the radiation therapy observed is probably due to the reduction of the tumour mass and the release of thalamocortical auditory pathways from its compressive effect. Our findings support the hypothesis of the presence of discrete auditory pathways for mediation of verbal and non-verbal stimuli independently.

Pure word deafness and the bilateral processing of the speech code

The analysis of pure word deafness (PWD) suggests that speech perception, construed as the integration of acoustic information to yield representations that enter into the linguistic computational system, (i) is separable in a modular sense from other aspects of auditory cognition and (ii) is mediated by the posterior superior temporal cortex in both hemispheres. PWD data are consistent with neuropsychological and neuroimaging evidence in a manner that suggests that the speech code is analyzed bilaterally. The typical lateralization associated with language processing is a property of the computational system that acts beyond the analysis of the input signal. The hypothesis of the bilateral mediation of the speech code does not imply that both sides execute the same computation. It is proposed that the speech signal is asymmetrically analyzed in the time domain, with left-hemisphere mechanisms preferentially extracting information over shorter (25–50 ms) temporal integration windows and right mechanisms over longer (150–250 ms) windows.

WORD DEAFNESS PRESENTING AS A SUDDEN HEARING LOSS

SUMMARYSudden hearing loss is a condition frequently seen in ENT departments and is usually due to otological pathology. We present a patient who described symptoms of a sudden inability to hear but who, on further questioning and investigations, had 'word deafness' due to bilateral temporoparietal infarcts. We discuss the clinical syndromes associated with these infarcts and the specific management of word deafness.

Disorder in Sequential Speech Perception: A Case Study on Pure Word Deafness

We described disorders of a patient which were uniquely restricted to speech perception of syllable sequences after brain damage. The results of series of experiments using syllable sequences showed “negative recency effect,” in which the subject's repetition performance at the latter syllable position was remarkably poor. Experimental analyses suggested that the “negative recency effect” could be due to dual factors: the lower rate of processing of speech sounds and the memory load of holding processes of preceding syllables imposed on the succeeding phonological processing. The results also suggested that the holding processes which imposed the memory load on the succeeding auditory phonological coding processing were modality nonspecific.

Perception of Dynamic Acoustic Patterns by an Individual with Unilateral Verbal Auditory Agnosia

Previous studies have found that subjects diagnosed with verbal auditory agnosia (VAA) from bilateral brain lesions may experience difficulties at the prephonemic level of acoustic processing. In this case study, we administered a series of speech and nonspeech discrimination tests to an individual with unilateral VAA as a result of left-temporal-lobe damage. The results indicated that the subject's ability to perceive steady-state acoustic stimuli was relatively intact but his ability to perceive dynamic stimuli was drastically reduced. We conclude that this particular aspect of acoustic processing may be a major contributing factor that disables speech perception in subjects with unilateral VAA.

The influence of premorbid language skills and behavior on language recovery in children with verbal auditory agnosia.

Previous studies of children with Landau-Kleffner syndrome and related language-epilepsy syndromes have focused on the relationship of seizure control to language recovery. We examined the effect of premorbid language skills and behavior, as well as some characteristics of clinical seizures and electroencephalograms, on language recovery in a retrospective study of 67 children with the severe receptive and expressive language disorder, verbal auditory agnosia. Fifty-eight percent of these children had seizures, 76% were autistic, and 24% had a history of language regression after showing previously normal language skills. The duration of language loss was not influenced by the persistence of clinical seizures. Premorbid language and behavior were more predictive of language recovery in these children. Most children with normal early language (acquired verbal auditory agnosia) had onset of language loss after age 3 years, in contrast to those with abnormal early language. Children with acquired verbal auditory agnosia were more likely to show fluctuations in language skills than those in other groups. Autistic children were more likely to begin having seizures before age 3 years, and had a longer duration of language loss and lower educational placement at time of last follow-up than those with normal behavior. This study emphasizes the importance of assessing premorbid language and behavior in predicting recovery of language skills in children with language-epilepsy syndromes.

In Process Citation

Pure word deafness (auditory verbal agnosia) is characterized by an impairment of auditory comprehension, repetition of verbal material and writing to dictation whereas spontaneous speech production and reading largely remain unaffected. Sometimes, this syndrome is preceded by complete deafness (cortical deafness) of varying duration. Perception of vowels and suprasegmental features of verbal utterances (e.g., intonation contours) seems to be less disrupted than the processing of consonants and, therefore, might mediate residual auditory functions. Often, lip reading and/or slowing of speaking rate allow within some limits to compensate for speech comprehension deficits. Apart from a few exceptions, the available reports of pure word deafness documented a bilateral temporal lesion. In these instances, as a rule, identification of nonverbal (environmental) sounds, perception of music, temporal resolution of sequential auditory cues and/or spatial localization of acoustic events were compromised as well. The observed variable constellation of auditory signs and symptoms in central hearing disorders following bilateral temporal disorders, most probably, reflects the multitude of functional maps at the level of the auditory cortices subserving, as documented in a variety of non-human species, the encoding of specific stimulus parameters each. Thus, verbal/nonverbal auditory agnosia may be considered a paradigm of distorted "auditory scene analysis" (Bregman 1990) affecting both primitive and schema-based perceptual processes. It cannot be excluded, however, that disconnection of the Wernicke-area from auditory input (Geschwind 1965) and/or an impairment of suggested "phonetic module" (Liberman 1996) contribute to the observed deficits as well. Conceivably, these latter mechanisms underly the rare cases of pure word deafness following a lesion restricted to the dominant hemisphere. Only few instances of a rather isolated disruption of the discrimination/identification of nonverbal sound sources, in the presence of uncompromised speech comprehension, have been reported so far (nonverbal auditory agnosia). As a rule, unilateral right-sided damage has been found to be the relevant lesion.

Clinical picture and morbid anatomy in case of `pure word deafness'

Clinical picture and morbid anatomy in case of `pure word deafness'

Verbal auditory agnosia with focal EEG abnormality: an unusual case of a child presenting to an ENT surgeon with 'deafness'

Verbal auditory agnosia with focal EEG abnormality: an unusual case of a child presenting to an ENT surgeon with 'deafness'

An analysis of speech perception in word deafness

An analysis of speech perception in word deafness