BACKGROUND AND OBJECTIVES: It is important to understand the frequency region of cues used, and not used, by cochlear implant (CI) recipients. Speech and environmental sound recognition by individuals with CI and normal-hearing (NH) was measured. Gradients were also computed to evaluate the pattern of change in identification performance with respect to the low-pass filtering or high-pass filtering cutoff frequencies. SUBJECTS AND METHODS: Frequency-limiting effects were implemented in the acoustic waveforms by passing the signals through low-pass filters (LPFs) or high-pass filters (HPFs) with seven different cutoff frequencies. Identification of Korean vowels and consonants produced by a male and female speaker and environmental sounds was measured. Crossover frequencies were determined for each identification test, where the LPF and HPF conditions show the identical identification scores. RESULTS: CI and NH subjects showed changes in identification performance in a similar manner as a function of cutoff frequency for the LPF and HPF conditions, suggesting that the degraded spectral information in the acoustic signals may similarly constraint the identification performance for both subject groups. However, CI subjects were generally less efficient than NH subjects in using the limited spectral information for speech and environmental sound identification due to the inefficient coding of acoustic cues through the CI sound processors. CONCLUSIONS: This finding will provide vital information in Korean for understanding how different the frequency information is in receiving speech and environmental sounds by CI processor from normal hearing.
Acoustics ; Clinical Coding ; Cochlear Implants ; Cues ; Female ; Hearing ; Humans ; Male

BACKGROUND AND PURPOSE: Speech-in-noise perception deficits have been demonstrated in patients with mild cognitive impairment (MCI). However, it remains unclear whether the impairment of speech perception varies between MCI subtypes. The purpose of this study was twofold: 1) to compare speech perception performance among MCI subgroups, and 2) to identify the cognitive domains specifically related to speech-in-noise perception. METHODS: We studied 46 patients with MCI and 39 hearing-threshold-matched cognitively normal elderly (CNE) subjects. Two different patient classifications were used: 1) patients with amnestic mild cognitive impairment (aMCI) (n=21) or nonamnestic mild cognitive impairment (naMCI) (n=25), and 2) patients with frontal-executive dysfunction (FED) (n=16) or without FED (n=30). All of the subjects underwent audiometric, neuropsychological, and speech perception assessments. Speech-in-noise perception was measured using sentence recognition tests in the presence of two types of background noise at four levels. RESULTS: First, as the level of background noise increased, the MCI with FED group scored lower than both the MCI without FED and CNE groups under both types of noise. Second, both the naMCI and aMCI groups scored lower than the CNE group, but there were no differences between the naMCI and aMCI groups in sentence recognition under any noise conditions. Third, significant correlations were found between sentence recognition and executive function scores both in the MCI groups and in the CNE group. CONCLUSIONS: Our findings suggest that frontal-executive function is strongly related to speech-in-noise perception and that MCI patients with FED have greater deficits in speech-in-noise perception compared to other subgroups of MCI.
Aged ; Classification ; Executive Function ; Humans ; Mild Cognitive Impairment* ; Noise ; Speech Perception

BACKGROUND: Healthy aging is characterized by declines in language function and it is important to differentiate language comprehension difficulties due to pathological aging (i.e., mild cognitive impairment) from those due to normal aging. The purposes of this study were to review the literature on characteristics of language comprehension in normal elderly and the mild cognitive impaired, and to compare their performances on different language domains. METHODS: A comprehensive literature search identified numerous studies on language comprehension in both groups, and we analyzed them according to each language domain. RESULTS: The results indicated that the normal elderly show more difficulties in the comprehension of grammatically or lexically complex sentences and in text/discourse comprehension than words or simple sentences. Compared to normal elderly, MCI shows significantly lower performance on text/discourse comprehension and other tasks demanding higher cognitive function. In both groups, there are many different factors affecting language comprehension, such as hearing sensitivity, speech rate, literacy, and cognition. CONCLUSIONS: The results may provide insight into useful language comprehension tasks for differential diagnosis between normal aging and MCI. Further research on various compensatory strategies in daily life to facilitate language comprehension for both groups is warranted.
Aged* ; Aging ; Cognition ; Comprehension* ; Diagnosis, Differential ; Hearing ; Humans ; Mild Cognitive Impairment

BACKGROUND: Speech production requires accurate coordination of the speech musculature, and is dependent upon cooperation among cortical and subcortical structures. Multiple subcortical structures, including the basal ganglia, thalamus, and cerebellum, are involved in several parallel and segregated cortical-subcortical-cerebellum circuits. These circuits serve critical functions in integrating neural networks that modulate speech motor behaviors. Previous studies on speech disorders linked to subcortical lesions have been limited to perceptual evaluations of speech in patients with lesions. However, more recent studies using neuroimaging have confirmed the results of the lesion studies and provided further evidence of the important contributions of the subcortical structures to speech motor control. METHODS: We reviewed recent research literature on both behavioral and functional neuroimaging to reveal the role of subcortical structures in speech production. A review of this topic was conducted by searching the literature and electronic databases. RESULTS: Based on numerous articles, we found that the basal ganglia, thalamus, and cerebellum make different contributions to the modulation of speech-related variables. The cerebellum is the structure that is most strongly associated with speech rate, complexity, and timing. CONCLUSIONS: We conclude that the subcortical structures may play critical functions in speech production. The function of each structure involves the stimulation of cortical regions through the neural circuits and neurotransmitters. Thus, the function of the subcortical structures should be understood within the paradigm of neural networks.
Basal Ganglia ; Cerebellum ; Electronics ; Electrons ; Functional Neuroimaging ; Humans ; Neuroimaging ; Neurotransmitter Agents ; Speech Disorders ; Thalamus

BACKGROUND: The term "transcortical aphasia" is applied to primary lesions not involving the receptive and expressive language areas, but rather the areas connected to the association cortex. By definition, patients with transcortical aphasia can repeat what they have heard, but they have difficulty producing spontaneous speech or understanding speech. This paper reports the clinical features of stroke patients with transcortical aphasia to delineate the language profiles of its subtypes. METHODS: Eighty patients with stroke were divided into three subtypes of transcortical aphasia: transcortical sensory aphasia, transcortical motor aphasia, and mixed transcortical aphasia. A Korean version of the Western Aphasia Battery was used to compare the subdomains of language ability among the three groups. RESULTS: The patients showed a relatively preserved repetition ability, but the performances in repetition and generative naming, and the aphasia quotient were highest in the transcortical sensory aphasic group, followed by the transcortical motor aphasic and mixed transcortical aphasic groups. CONCLUSIONS: The present study provides detailed information on the language profiles of the three subtypes of transcortical aphasia, which can be differentiated based on the aphasia quotient and generative naming scores.
Aphasia ; Aphasia, Broca ; Aphasia, Wernicke ; Humans ; Language ; Stroke

PURPOSE: Recently, the incidence of early gastric cancer (EGC) patients is rapidly increased in Korea. However, they're often not perceptible by surgical palpation or inspection. The aim of this study is 1) to develope a software that can locate the tumor and measure the mucosal distance from an anatomic landmark to the tumor using CT gastrography and 2) to compare the distance measured by the developed software with the distance measured by the pathologic findings. MATERIALS AND METHODS: Between January 2004 and September 2005, sixty patients (male=45, female=15, mean 57.8 years old) estimated for EGC with preoperative CT scans and undergone gastrectomies in Kyungpook National University Hospital were enrolled in this study. Preoperative CT scans were performed after insufflations of room air via 5 Fr NG tube. The scans included the following parameters: (slice thickness/reconstruction interval: 0.625 mm, kVp: 120, mAs: 200). 3D volume rendering and measurement of the surface distance from the pylorus to the EGC were performed using the developed software. RESULTS: The average difference between the lesion to pylorus distances measured from pathologic specimens and CT gastrography was 5.3+/-2.9 mm (range 0~23 mm). The lesion to pylorus distance measured from CT gastrography was well correlated with that measured from the pathologic specimens (r=0.9843, P<0.001). CONCLUSION: These results suggest that the surface distance from an anatomic landmark to the EGC can be measured accurately by CT gastrography. This technique could be used for preoperative localization of early gastric carcinomas to determine the optimal extent of surgical resection.
Anatomic Landmarks ; Gastrectomy ; Gyeongsangbuk-do ; Humans ; Incidence ; Insufflation ; Korea ; Palpation ; Pylorus ; Stomach Neoplasms* ; Tomography, X-Ray Computed

BACKGROUND: The purpose of this study was to investigate the effects of the subthalamic nucleus (STN) deep brain stimulation (DBS) on the phonation and articulation of patients with Parkinson's disease (PD). METHODS: Seven PD patients who underwent bilateral STN DBS were included. The patients were asked to make and sustain the vowel sounds /a/ and /i/ as long as possible and to repeat nonsense syllables, /pa/, /ta/, /ka/ and /pataka/ as quickly as possible for 3 seconds. When the patients were administered levodopa `on' and `off' treatments, we evaluated the effect of DBS on the maximum phonation time (MPT), jitter (pitch perturbation), shimmer (intensity perturbation), tremor index and diadochokinetic rate (DDK). In each condition, using a Unified Parkinson's Disease Rating Scale score, we also measured the motor disability of the patients. RESULTS: During levodopa `off', both the DBS and levodopa treatment caused significant prolongation of the MPT of the vowels /a/ and /i/. Acoustic analysis showed that DBS had an effect on shimmer only when the patients were levodopa `off'. At the articulatory level, no significant changes were found in the diadochokinetic rate under any conditions. However, there was a correlation between the amount of improvement of voice tremor and sum of UPDRS scores measuring `tremor at rest' and `postural tremor'. CONCLUSIONS: In patients with advanced PD, STN DBS improves phonation, but had limited effects on articulation.
Acoustics ; Deep Brain Stimulation* ; Humans ; Levodopa ; Parkinson Disease* ; Phonation* ; Subthalamic Nucleus* ; Tremor ; Voice

Korean written language is composed of ideogram (Hanja) and phonogram (Hangul), as Japanese consists of Kanji (ideogram) and Kana (phonogram). Dissociation between ideogram and phonogram impairment after brain injury has been reported in Japanese, but few in Korean. We report a 64-yr-old right-handed man who showed alexia with agraphia in Hanja but preserved Hangul reading and writing after a left posterior inferior temporal lobe infarction. Interestingly, the patient was an expert in Hanja; he had been a Hanja calligrapher over 40 yr. However, when presented with 65 basic Chinese letters that are taught in elementary school, his responses were slow both in reading (6.3 sec/letter) and writing (8.8 sec/letter). The rate of correct response was 81.5% (53 out of 65 letters) both in reading and writing. The patient's performances were beyond mean-2SD of those of six age-, sex-, and education-matched controls who correctly read 64.7 out of 65 and wrote 62.5 out of 65 letters with a much shorter reaction time (1.3 sec/letter for reading and 4.0 sec/letter for writing). These findings support the notion that ideogram and phonogram can be mediated in different brain regions and Hanja alexia with agraphia in Korean patients can be associated with a left posterior inferior temporal lesion.
Cerebral Infarction/*complications/radiography ; Dyslexia/*etiology ; Humans ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Task Performance and Analysis ; Temporal Lobe/*injuries/radiography ; *Writing

BACKGROUND: Determining the mechanism for aphasia following a subcortical infarct involving the striatum and internal capsule has been controversial. The aim of this study was to determine the underlying mechanism, which might clarify the relationship between the severity of aphasia and the cortical hypoperfusion in a striatocapsular infarct. METHODS: We included 33 patients with striatocapsular infarcts in the dominant hemisphere on precontrast CT/MRI. A MR angiography (MRA) was done in all patients. Contrast enhanced MRI and/or triphasic perfusion CT (TPCT) were performed in 26 patients to identify slow collateral blood flows. The regional cerebral blood flow was evaluated in 14 out of 33 patients by perfusion SPECT. The index of aphasia severity was the aphasia quotient, measured by the Korean version-Western Aphasia Battery. RESULTS: Twenty-five of 33 patients (75.7%) showed aphasia with different degrees of severity. The four aphasic subgroups were mild (n=9), mild-to-moderate (n=8), moderate-to-severe (n=3), and severe (n=3) groups. Six patients with moderate-to-severe or severe degree of aphasia showed larger infarcts, occlusions of the middle cerebral artery (MCA) stem or internal carotid artery (ICA) on MRA, and abnormal delayed cortical vascular enhancements on MRI and/or TPCT. The severity of aphasia correlated strongly with the degree of perisylvian cortical hypoperfusion on SPECT. Focal perisylvian cortical atrophy on follow-up MRI was found in two patients with greater than moderate-to-severe aphasia. CONCLUSIONS: Aphasia of greater than moderate-to-severe degree following a striato-capsular infarct may be explained by selective neuronal loss of the perisylvian cortex due to the occlusion of the MCA stem or ICA and insufficient collateral blood flow. (J Korean Neurol Assoc 19(1):10~18, 2001
Angiography ; Aphasia* ; Atrophy ; Carotid Artery, Internal ; Follow-Up Studies ; Humans ; Internal Capsule ; Magnetic Resonance Imaging ; Middle Cerebral Artery ; Neurons ; Perfusion ; Tomography, Emission-Computed, Single-Photon

Apraxia of speech (AOS) is a speech disorder due to an impaired ability to program the positioning of the speech musculature and the sequencing of muscle movements. It differs from dysarthria because speech errors are inconsistent depending on the locus of the sound. We report a 66-year-old man who presented with AOS which evolved into frontotemporal dementia 5 years later. Initial neuropsychological test showed mainly buccofacial apraxia and frontal lobe dysfunction. Brain FDG-PET disclosed hypometabolism in frontotemporal region.
Aged ; Apraxias* ; Brain ; Dysarthria ; Frontal Lobe ; Frontotemporal Dementia* ; Humans ; Neuropsychological Tests