Text B Aphasia

Definition

Aphasia is a disorder of language at the conceptual level．Aphasics may have difficulty with producing language，comprehending language，or both．

Pathobiology

In more than 99％of right－handed individuals，language is localized to the left hemisphere．In left－handed individuals，language is also predominantly localized to the left hemisphere，although varying degrees of bilateral or rarely right hemispheric dominance may be seen．The hemisphere involved in language is referred to as the dominant hemisphere．1 Anatomic differences in the temporal and parietal lobes of the dominant hemisphere versus the other hemisphere also reflect the specialization for language．

In clinical practice，lesions in the dominant hemisphere's auditory association areas cause receptive language dysfunction．The critical regions are located in the superior temporal lobes adjacent to the primary auditory cortex and in the adjacent supramarginal and angular gyri of the inferior parietal lobule，an area known as Wernicke's area．Lesions in the dominant hemisphere's lateral inferior posterior frontal lobes，often referred to as Broca's area，result in expressive language deficits．Loss of access to one's vocabulary for either understanding spoken language or expressing oneself results from lesions in any portion of the region of the dominant hemisphere around the sylvian fissure， including the lateral posterior inferior frontal lobe，the inferior parietal lobule， and the superior and middle temporal gyri．2 Coronal and axial MRI scans give a detailed view of the critical language regions．

Clinical Manifestations

The language comprehension difficulties in aphasia must be distinguished from hearing disorders，and the motor speech dysfunction in aphasia must be distinguished from dysarthria．Errors of articulation in aphasia reflect altered conceptual selection of what is to be said．In aphasia，mispronunciation of a sound within one word may be followed by perfect pronunciation of the same sound in a different word．In dysarthria，by comparison，the errors in articulation or phonation are consistent．

Aphasia has three principal components：impaired verbal comprehension， disordered verbal expression，and impaired naming．Disorders of reading，writing， and sentence repetition are additional elements of the aphasia syndrome． Disordered verbal comprehension may range from profound to mild．When profound，patients are unable to grasp the meaning of single words．In milder forms of disordered comprehension，patients may be able to follow one－step，but not two－or three－step commands．Usually，the comprehension difficulty involves both spoken and written language，but each can be affected separately． Anomia，which is an inability to produce names of people or objects，is common in almost all aphasic syndromes．

In expressive aphasic syndromes，written material and spoken speech are most often affected in parallel．In the expressive aphasias，speech is labored， and it lacks the normal melody and variation in intonation that characterize normal speaking．Melody and intonation are referred to as the prosody of speech．Speech is often grammatically impoverished．The number of words per utterance is greatly reduced，thus giving the speech a choppy，staccato character．These features are referred to as speech apraxia．Nonfluency is a related term that describes the reduced number of words and the terseness of verbal output．In some aphasic syndromes，speech is often degraded by anomia and paraphasic errors（word or syllable substitutions），even when fluency， melody，and intonation are preserved．

Specific Aphasic Syndromes

Specific，common aphasic syndromes exhibit various combinations of receptive and expressive difficulty．

Wernicke's aphasia．In Wernicke's aphasia，verbal comprehension of both written and verbal language is severely impaired．Patients with Wernicke's aphasia have difficulty understanding the meaning of individual words and may not be able to follow any command of greater than one step．Their speech is fluent but marred by paraphasia and anomia．Wernicke's aphasics tend to lack awareness of the extent of their communicative difficulties and are often unaware that the words they are uttering are fundamentally incorrect．3 The location that typically causes Wernicke's aphasia is the dominant posterior superior temporal lobe or inferior supramarginal gyrus．

Broca's aphasia．Broca's aphasia is a syndrome in which expressive language is prominently affected．Patients with Broca's aphasia have nonfluent，labored speech．The lesion location that typically causes Broca's aphasia is the dominant posterior inferior frontal lobe．Patients with Broca's aphasia have largely preserved comprehension and，as a result，are acutely aware of their difficulties and become frustrated with them．Depression is common in Broca's aphasics．

Global aphasia．Global aphasia occurs when both expressive and receptive problems are present．Global aphasia often appears acutely after a major dominant hemisphere infarction，hemorrhage，or traumatic brain injury．

Anomia．Anomia is at the milder end of the spectrum of language disorders． Some anomic aphasics also have difficulty with sentence repetition，even in the presence of relatively preserved comprehension and verbal expressive abilities． There is some controversy whether this latter syndrome，called conduction aphasia，represents a disconnection between the perisylvian centers for comprehension and expression or whether it represents a lesion in the cortical auditory areas involved in immediate auditory memory．4

Ideomotor apraxia．Ideomotor apraxia is a disorder at the interface between comprehension and execution of facial or limb motor actions．Patients with ideomotor apraxia have no paresis of the face or limb musculature and are able to carry out simple tasks，but they are unable to execute more complex tasks or commands．For example，in a woman who is able to name a comb and use her right hand to point to parts of her body，ideomotor apraxia can be demonstrated if she is unable to indicate through her actions how she would use the comb．

Diagnosis

The diagnosis of aphasia is made by listening to the patient speak and by examining comprehension，naming ability，reading，and writing in a standardized fashion．Often，the diagnosis of aphasia is made during attempts to obtain a history from the patient．It is helpful to prompt patients to speak about a neutral topic，such as what they had for their last meal or what they did the previous day．Listening to their spontaneous speech allows the examiner to characterize its fluency，grammatical form，articulation，melody，and intonation，as well as difficulty finding words，the presence of paraphasias， and the overall information content．5

Comprehension should be examined formally by asking the patient to perform tasks that range from one to at least three steps．Naming can be tested by asking the patient to name a series of common objects，such as the parts of the hand and arm（e．g．thumb，palm，knuckles，wrist，elbow）．In general，the more commonly a word is used in the language，the easier it will be to name， whereas infrequent words are harder for aphasics．Reading and writing should also be tested．

Portions of the dominant perisylvian cerebral cortex may be damaged by infarction，hemorrhage，and other space－occupying brain lesions such as neoplasm or abscesses．Aphasia secondary to stroke has an abrupt onset，usually with some subsequent improvement．Recovery from aphasia after a stroke may occur as ischemic zones around an infarction eventually regain function．Regions remote from the infarction may also be synoptically depressed acutely after a stroke （“diaschisis”）but eventually regain function．Finally，regions in the nondominant hemisphere may become more active over the course of recovery．Aphasia that has a gradual and slowly progressive onset occurs in the degenerative dementia syndromes of progressive aphasia and semantic dementia．

（1，202 words）

New Words and Phrases

aphasia［ə'feɪzɪə］n． 失语症

temporal lobe 颞叶

cortex［'kɔːteks］n． 皮质

supramarginal［suːprə'mɑːdʒɪnəl］ 上缘板

gyrus［'dʒaɪrəs］（［复］gyri）n． 脑回

lobule［'lɒbjuːl］n． （肝、肺等的）小叶

fissure［'fɪʃə］n． （如大脑皮质的）裂隙

coronal［kə'rəʊnəl］a． 冠状的

dysarthria［dɪs'ɑːθrɪə］n． 构音障碍

articulation［ɑːtɪkjʊ'leɪʃən］n． （清晰的）发音

phonation［fəʊ'neɪʃən］n． 发声

anomia［ə'nəʊmɪə］n． 失命名症，命名不能

prosody［'prɒsədɪ］n． 韵律结构

apraxia［ə'præksɪə］n． 运用不能症，失用症

paraphasic［,pærə'feɪsɪk］a． 言语错乱的

substitution［,sʌbstɪ'tjuːʃən］n． 代替

paraphasia［,pærə'feɪzɪə］n． 言语错乱，错语症

supramarginal gyrus 缘上回

traumatic［traʊ'mætɪk］a． 外伤的

perisylvian［,perɪ'sɪlvɪən］ 外侧裂周区

ideomotor［,aɪdɪə'məʊtə］a． 观念性动作的；意念性动作的

paresis［'pærɪsɪs］n． 局部麻痹，轻瘫

knuckle［'nʌkl］n． 指节

space－occupying 占位性

abscess［'æbsɪs］n． 脓肿

diaschisis［daɪ'æskɪsɪs］n． 神经功能丧失

degenerative［dɪ'dʒenərətɪv］a． 变性的；衰退的

dementia［dɪ'menʃɪə］n． 痴呆

Notes

1．The hemisphere involved in language is referred to as the dominant hemisphere．

参考译文：涉及语言的半球被称为优势半球。

此句中过去分词短语involved in language作后置定语，修饰the hemisphere；is referred to as是谓语，意为“被称为”。

2．Loss of access to one's vocabulary for either understanding spoken language or expressing oneself results from lesions in any portion of the region of the dominant hemisphere around the sylvian fissure，including the lateral posterior inferior frontal lobe，the inferior parietal lobule，and the superior and middle temporal gyri．

参考译文：位于大脑优势半球颞横裂周围任何部位的病变都可导致理解口语或表述自己能力的丧失，这些部分包括侧后下额叶、顶下小叶、颞上回和颞中回。

Loss of access．．．or expressing oneself为句子主语，results from为谓语， including．．．gyri为现在分词短语做状语，是对前面病变区域的补充说明。

3．Wernicke's aphasics tend to lack awareness of the extent of their communicative difficulties and are often unaware that the words they are uttering are fundamentally incorrect．

参考译文：韦尼克失语症（皮质感觉性失语症）患者往往意识不到他们在语言交流上的困难，也不会觉察到其言语表达基本上是错误的。

此句的主语为Wernicke's aphasics，tend to．．．and are unaware是两个并列谓语部分；that引导表语从句，they are uttering为定语从句，修饰限定the words。

4．There is some controversy whether this latter syndrome，called conduction aphasia，represents a disconnection between the perisylvian centers for comprehension and expression or whether it represents a lesion in the cortical auditory areas involved in immediate auditory memory．

参考译文：被称为传导性失语症的后一种综合征究竟是负责语言理解和表达的外周侧裂中心之间不存在联系所致，还是与即时听觉记忆有直接关系的皮质听觉区域存在病变所致，这一点目前还存有争议。

此句为there be句型；whether．．．or whether．．．是whether引导的两个并列同位语，解释句子主语controversy。

5．Listening to their spontaneous speech allows the examiner to characterize its fluency，grammatical form，articulation，melody，and intonation，as well as difficulty finding words，the presence of paraphasias，and the overall information content．

参考译文：通过倾听患者自发的言语，检查者可以准确掌握患者语言流利度、语法形式、发音清晰度、语言节奏和语音语调等方面的特征，也可发现其选词困难、言语错乱以及信息内容完整性受损的程度。

Listening to their spontaneous speech是动名词短语，做句子的主语；as well as连接并列宾语，意为“也，又，以及”。

Exercises

Ⅰ．Answer the following questions．

1．What is Broca's area？If lesions happen in Broca's area，what will they result in？

2．What are three principal components in aphasia？

3．Can you give out the features of speech apraxia？

4．How may we diagnose aphasia？

5．What are specific aphasic syndromes of Wernicke's aphasia，Broca's aphasia，global aphasia anomia and ideomotor apraxia？

Ⅱ．Decide whether the following statements are True or False．

1．In left－handed individuals，language is also predominantly localized to the right hemisphere，although varying degrees of bilateral or rarely right hemispheric dominance may be seen．

2．Lesions in the dominant hemisphere's lateral inferior posterior frontal lobes，often referred to as Wernick's area，result in expressive language deficits．

3．Patients with Wernicke's aphasia have difficulty understanding the meaning of individual words and may not be able to follow any command of greater than one step．

4．The lesion location that typically causes global aphasia is the dominant posterior inferior frontal lobe．

5．Recovery from aphasia after a stroke may occur as ischemic zones around an infarction eventually regain function．