Aphasias and Related Disorders

Aphasias are disturbances in the comprehension or production of spoken or

written language. Clinical examination should assess naming,spontaneous

speech,comprehension,repetition,reading,and writing. A classification scheme

is presented in Table 42-1; the most common aphasias are summarized below.

Wernicke’sAphasia

Clinical Manifestations Although speech sounds grammatical,melodic,

and effortless (“fluent”),it is virtually incomprehensible due to errors in word

usage,structure, and tense and the presence of neologisms and paraphasia (“jargon”).

Comprehension of written and spoken material is severely impaired,as

are reading,writing,and repetition. The pt usually seems unaware of the deficit.

Associated symptoms can include parietal lobe sensory deficits and homonymous

hemianopia. Motor disturbances are rare.

Etiology Lesion located in posterior perisylvian region. Most common

cause is embolic occlusion of inferior division of dominant middle cerebral

artery (MCA); less commonly hemorrhage,tumor, encephalitis, or abscess is

responsible.

Broca’sAphas ia

Clinical Manifestations Speech output is sparse,slow, labored, interrupted

by many word-finding pauses,telegraphic, and usually dysarthric; output

may be reduced to a grunt or single word. Naming and repetition also impaired.

Most patients have severe writing impairment. Comprehension of written and

spoken language is relatively preserved. Patient is often aware of and visibly

frustrated by deficit. With large lesions,a dense hemiparesis may occur, and

the eyes may deviate toward side of lesion. More commonly,lesser degrees of

contralateral face and arm weakness are present. Sensory loss is rarely found,

and visual fields are intact. Buccolingual apraxia is common,with difficulty

imitating movements with tongue and lips or performing these movements on

command.

Etiology Lesion involves dominant inferior frontal convolution (Broca’s

area),although cortical and subcortical areas along superior sylvian fissure and

insula are often involved. Commonly caused by vascular lesions involving the superior division of the MCA; less commonly due to tumor,abscess, metastasis,

subdural hematoma,encephalitis.

Global Aphasia

All aspects of speech and language are impaired. Patient cannot read,write, or

repeat and has poor auditory comprehension. Speech output is minimal and

nonfluent. Usually hemiplegia,hemisensory loss, and homonymous hemianopia

are present. Syndrome represents the combined dysfunction of Wernicke’s and

Broca’s areas,usually resulting from occlusion of MCA supplying dominant

hemisphere (less commonly hemorrhage,trauma,or tumor).

Conduction Aphasia

Comprehension of speech and writing is largely intact,and speech output is

fluent,although paraphasia is common. Repetition is severely affected. Lesion

spares,but functionally disconnects,Wernicke’s and Broca’s areas. Most cases

are embolic,involving supramarginal gyrus of dominant parietal lobe, dominant

superior temporal lobe,or arcuate fasciculus.

Laboratory Studiesin Aphasia

CT scan or MRI usually identifies the location and nature of the causative lesion.

Angiography helps in accurate definition of specific vascular syndromes.

TREATMENT

Speech therapy may be helpful in treatment of certain types of aphasia.