この博士論文は内容の要約のみの公開（または一部非公開）になっています筑波大学 (University of Tsukuba)201

KOZUKA Junko

狐塚 順子

Tsukuba Repository

Characteristics and the recovery process in
children with acquired aphasia
著者 KOZUKA Junko
内容記述 この博士論文は内容の要約のみの公開（または一部
非公開）になっています
発行年 2018
その他のタイトル 小児失語症の特徴ならびに改善経過に関する研究
学位授与大学 筑波大学 (University of Tsukuba)
学位授与年度 2017
報告番号 12102甲第8663号
URL http://hdl.handle.net/2241/00152338
  
〔博士論文概要〕 
 
 
 
Characteristics and the recovery process in children with acquired aphasia. 
 
（小児失語症の特徴ならびに改善経過に関する研究） 
 
 
 
 
平成 29 年度 
 
 
 
 
 
 
 
 
狐塚順子 
筑波大学 大学院 人間総合科学研究科 感性認知脳科学専攻
 1 
 
1. Introduction  
 
Aphasia is a loss or impairment of language functioning caused by brain damage 
(Benson, 1979), and is an acquired language impairment affecting all modalities of 
language including listening, speaking, reading, and writing. Although aphasia in 
adulthood develops after the completion of linguistic development, acquired childhood 
aphasia arises during normal linguistic development.  
There are some problems in studies of acquired childhood aphasia that are caused 
by its characteristics and the methodology used. First, acquired childhood aphasia is a 
rare language disorder (Robinson, 1991); the number of children with acquired aphasia 
is smaller than that of adults with aphasia. Most of the previous studies on childhood 
acquired aphasia were case studies, not group studies (Loonen et al., 1990; Van 
Dongen et al., 1994; Uno et al., 2004). The knowledge gained from these case studies 
may not be generalizable to groups of children with acquired aphasia. Moreover, only a 
limited number of studies have been performed examining the relationship between 
language symptoms and cerebral lesion areas, because it is difficult to control for the 
lesion areas as most of them are caused by head injury and are difficult to localize 
compared with those in adult aphasia, most of which are caused by cerebrovascular 
diseases (Van Hout, 1994; Chilosi, Cipriani, Pecini, Brizzolara, Biagi, Montanaro, 
Tosetti, & Cioni, 2008). 
   The second methodological problem for childhood aphasia research is that there is 
no language instrument developed specifically for patients with acquired childhood 
aphasia. There is only one screening test for children with acquired aphasia, that is, 
the Children’s Acquired Aphasia Screening Test devised by Whurr & Evans (1998). 
 2 
 
This screening test evaluates linguistic and non-linguistic function in brain-damaged 
children aged between 3 and 7 years, thus it is difficult to evaluate language symptoms 
of children aged over 7 years old. The Standard Language Test of Aphasia (SLTA) for 
Japanese speakers (Hasegawa et al., 1985), is a tool that can be used to evaluate 
language faculty, and not learning achievement, except for unlearned Kanji characters 
in children with acquired aphasia (Uno et al., 2002). 
The third methodological limitation of acquired childhood aphasia research relates 
to brain examinations. Methods to evaluate morphological changes, that is, methods to 
identify lesions and quantify their pathology, had not been established until recently. 
One of the cutting-edge methods for the analysis of morphological changes is 
voxel-based lesion-symptom mapping (VLSM), which was developed by Bates et al. 
(2003). VLSM provides statistical significance about the relationships between 
cerebral lesions at the spatial resolution of magnetic resonance imaging (MRI) and 
behavioral data at the voxel-level. Many studies of aphasia in adults have been 
performed using VLSM (Dronkers, Wilkins, Van Valin Jr., Redfern, & Jaeger, 2004; 
Baldo, Schwartz, Wilkins & Dronkers, 2006), but none have been applied to children, 
to the best of our knowledge.  
One of the methodological limitations in childhood aphasia research using cerebral 
blood flow Single Photon Emission Computer Tomography (SPECT) is that 
relationships between language symptoms and areas of low regional cerebral blood 
flow (rCBF) have not been investigated fully, because cerebral blood flow and blood 
distribution change over time as a child’s brain develops (Ogawa et al., 1987, Chiron et 
al., 1992). However, Ohnishi et al. (2000) and Fukushima et al. (2005) established a 
normal database (NDB) of cerebral blood flow, this database enabled the use of the 
 3 
 
Easy Z-score Imaging System, which was developed by Matsuda (2002), and has 
contributed to an increase in statistical analysis of imaging data derived from cerebral 
blood flow SPECT examinations of children. 
Therefore, upon improving the methodological limitations described above, the 
current study investigated the characteristics of childhood aphasia comparing with 
those in previous studies on adult aphasia. 
 
2. Purposes 
 
The aim of Study 1 was to investigate the relationships among language symptoms, 
cerebral lesions, and functional lesions in childhood aphasia. 
The aim of Study 2 was to examine the relationship between the change of language 
symptoms and the change of rCBF while controlling for age-related changes in the 
recovery process of two children with acquired aphasia. 
Through Studies 1 and 2, we aimed to determine whether the characteristics of 
childhood aphasia were similar or different from those in previous studies on adult 
aphasia. 
 
3. Methods 
 
Study 1 was a group study of 10 children with acquired aphasia and focal lesions 
due to cerebrovascular events. That was investigating associations between lesion 
location and language functioning. Furthermore, using 7 children with acquired 
aphasia who underwent SPECT examinations as part of their clinical care, the 
 4 
 
relationships between language symptoms and regions of focal hypoperfusion, which 
can be interpreted as regions of reduced functioning, were examined.  
Study 2 was a case study of 2 children with acquired aphasia who had a similar age 
at onset, underlying illness, and lesion location. The age at onset was 8 years and both 
underwent multiple SPECT examinations as part of their clinical evaluation. With 
regard to their language symptoms, the scores of the SLTA, which was administered 
approximately at the same time as the cerebral blood flow SPECT examinations, were 
transformed into z-scores by comparing their scores against those of healthy children 
of the same age group. With regard to rCBF, z-scores were computed that represent a 
comparison against data from the corresponding age group in the NDB.  
 
4. Results  
 
4.1 Results of Study 1 
 
   Nine of the participants in the first study exhibited language fluency. The results 
of these 9 fluently speaking participants indicated lesions in the area from the left 
temporal lobe to the parietal lobe. Conversely, the non-fluent participant exhibited 
lesions in the pars opercularis of the left frontal lobe, precentral gyrus, postcentral 
gyrus, supramarginal gyrus, Roland pars opercularis, insular, Heschl transverse gyrus, 
superior temporal gyrus, middle temporal gyrus, and temporal pole.  
All 7 of the participants in rCBF study exhibited fluent language. The regions in 
which the participants’ blood flow was significantly lower than in healthy children 
included the left posterior parts of the inferior, middle, and superior temporal gyrus to 
 5 
 
the inferior parietal lobe, including the supramarginal gyrus and angular gyrus. 
The lesion and rCBF results both showed overlapping relevance to 4 of the SLTA 
subtest results: “Oral commands,” “Picture naming,” “Explanation of activities in a 
picture,” and “Repetition of sentences.”  In both analyses, the “Oral commands” result 
was associated with the left posterior parts of the superior and middle temporal gyri to 
the inferior parietal lobe (angular gyrus and supramarginal gyrus). The “Picture 
naming” result was associated with the left superior and middle temporal gyri and the 
temporal pole. The “Explanation of activities in a picture” result was associated with 
the left temporal pole. In addition, the “Repetition of sentences” result was associated 
with the left posterior parts of the superior and middle temporal gyri to the inferior 
parietal lobe. 
 
4.2 Results of Study 2 
 
For Case A, a statistically significant difference among the time points was found 
only for rCBF reduction in the left hemisphere (χ2＝12.771, df = 3, p <0 .01). The 
reduction z-score in the left hemisphere was significantly smaller at the first time 
point compared to all other time points (Z = -2.521, p = 0.012) and no other statistically 
significant difference was observed. In Case B, a statistically significant difference 
among the assessment time points was detected only in the right hemisphere increase 
z-scores (χ2 = 19.286, df = 3, p < 0.01). The right-hemisphere increase z-score was 
significantly greater at the first time point relative to the other time points, and the 
z-score at the 4th time point was significantly smaller (Z = -2.366, p = 0.018). 
In both cases, strong correlations were seen between some language regions in the 
 6 
 
left hemisphere and their homologous regions in the right hemisphere. Conversely, 
there were differences between the two cases in the time course of rCBF changes 
during their recovery process. In Case A, strong correlations were seen within left 
hemisphere between adjacent regions or regions that are connected by neuronal fibers. 
However, in Case B, significant correlations were not seen between rCBF changes 
within left hemisphere. 
About the change of the z-score on the SLTA subtests, Case A showed a significant 
difference among the time points (χ2 =11.743, df = 3, p < 0.01), with the performance 
at the first time point being significantly lower than at the second time points (Z = 
-2.521, p = 0.018). Case B showed a significant difference in SLTA performance among 
the time points (χ2 ＝14.440, df = 3, p < 0.01), with the performance at the first time 
point being significantly lower than at the other time points (Z = -2.521, p = 0.012). 
On the analysis of change in language performance and change in rCBF z-score in 
the language regions at the 4 time points, in Case A, strong correlations were found 
between performance changes in the SLTA subtest “Oral commands” and rCBF 
changes in the left 7 language regions, and right BA21, BA22 and BA45, and between 
performance changes on SLTA subtest “Picture naming” and rCBF changes in the left 7 
language regions, and right BA21, BA22, and BA45, and between performance changes 
on SLTA subtest “Enumeration of animal names” and rCBF changes in the left BA20, 
and BA21. In Case B, strong correlations were found between SLTA subtest 
performance changes “Oral commands”, “Explanations of activities in picture” and 
“Explanation of a comic strip” and rCBF changes in the right BA39. However, no 
statistically significant correlations were found between language symptoms changes 
and rCBF changes in the language regions in the left hemisphere.  
 7 
 
5. Discussion 
 
5.1. Discussion of Study 1 
 
In Study 1, as the children with acquired aphasia demonstrated fluent verbal 
output while also showing impaired auditory comprehension and repetition, it was 
considered that they examined had a type of aphasia analogous to Wernicke’s aphasia 
in adults. The regions identified both as a structural lesion and an area of reduced 
functioning were the posterior part of the superior and middle temporal gyri and the 
inferior parietal lobe (supramarginal and angular gyri) including Wernicke’s area. 
Therefore, our results suggest that the relationship between an aphasia subtype and 
the location of structural and functional damage observed in our patients with 
child-onset aphasia was similar to that in adult aphasia cases. 
In addition, associations of SLTA subtest performance with structurally and 
functionally impaired regions reported in previous studies on adult aphasia were also 
observed in our patients with acquired childhood aphasia, namely, associations 
between auditory phonological processing and the posterior left superior temporal 
gyrus, between sentence repetition and the posterior left superior and middle temporal 
gyrus and inferior parietal lobe, and between naming and the left superior and middle 
temporal gyrus and temporal pole. Conversely, associations between syntax 
comprehension and Brodmann area 44/45, and between attention during a sentence 
repetition task and the performance of verb generation and the frontal lobe were not 
observed in the current study. 
Language function is still under development in children’s brains, and different 
 8 
 
brain regions mature at different rates. Therefore, we suggest that the associations of 
language performance with structurally and functionally impaired regions were 
similar between child-onset cases and adult-onset cases for language function that had 
already localized in the brains in children, while those associations were different from 
adult cases for language function for which the processing neural network is still under 
construction in developing brains. 
 
5.2. Discussion of Study 2 
 
   In Study 2, we followed the prognoses of 2 patients with acquired childhood 
aphasia while controlling for age-related changes. The changes in rCBF over time 
within the 7 regions related to language functions in the left hemisphere and their 
corresponding regions in the right hemisphere were highly correlated among the areas 
surrounding the lesion, or between the areas connected by nerve fibers within each 
hemisphere in case A, and within right hemisphere in Case B. Between the right and 
left hemispheres, strong correlations were observed regarding some of the 
corresponding regions in both cases. Consistent with previous reports on adult aphasia, 
the current study suggested that both hemispheres were involved in the long-term 
process of recovery from aphasia symptoms. Conversely, rCBF changes during the 
recovery process, as well as the relationship between the changes in language 
symptoms and changes in rCBF, were different between both cases. We suggest that 
the status of the brain prior to the onset of aphasia, and the timing and side of the 
revascularization operation contributed to the differences observed in both cases. 
However, due to the strong correlations between changes in rCBF and changes in 
 9 
 
language symptoms, rCBF measurement has the potential to serve as a biomarker for 
capturing the changes of language symptoms. Although both cases showed an 
improvement in language symptoms, there were some residual symptoms at 5 years 
after onset, which suggests that compensatory abilities were limited despite the high 
plasticity of children’s brains. 
 
5.3 General Discussion 
 
Through Studies 1 and 2, many findings were obtained from children with acquired 
aphasia that are consistent with those of previous studies on patients with adult 
aphasia, including the relationships between language symptoms and lesion location, 
between language symptoms and areas of functional reduction, and recovery process 
from aphasia. Conversely, the present study provided several findings that were 
inconsistent with previous studies on adult aphasia, for example, the results on 
language function, for which the neural network still be under development in 
children’s brains, were only partially consistent with the results reported for adult 
cases.  
The limitations of study 1 were that the number of participants was small, that was 
a bias for the fluent type of aphasia, and the time period from onset to testing was not 
controlled precisely among the patients. In addition, the present study did not acquire 
direct evidence showing that the neural networks for language processing were still 
under development in the children’s brains. Additional studies, especially ones using 
diffusion tensor imaging, need to be performed to examine the development of 
language processing networks. 


小児失語症の特徴ならびに改善経過に関する研究

https://tsukuba.repo.nii.ac.jp/?action=repository_action_common_download&item_id=46976&item_no=1&attribute_id=17&file_no=1

小児失語症の特徴ならびに改善経過に関する研究

Abstract

Similar works

Full text

Available Versions

Tsukuba Repository