Aphasia 91There are four impor tant factors in understanding aphasia; each is discussed in detail next.
First, aphasia is not a speech impediment; it is the loss or disruption of language (Darley, 1982;
Darley, Aronson, & Brown, 1975). Second, aphasia impairs to vari ous degrees all modalities of
language— speaking, gestures, writing, reading, and understanding the words of others. Aphasia
also may impair the ability to perform and understand simple mathe matics. Third, aphasia can
be separated into predominantly expressive and predominantly receptive disorders. Although
aphasia cuts across all modalities of language, most patients have either predominantly expressive
or predominantly receptive deficits. Fi nally, aphasia includes several psychological components,
such as excessive emotional reactions, catastrophic reactions (anxiety attacks), and depression.
Table 5-1 pres ents the general classification of aphasia and related disorders.
Etiology of Aphasia
Aphasia can be caused by a wide range of diseases and disorders. According to the National
Aphasia Association (2015), strokes or cerebrovascular accidents are the most common causes
of aphasia, and about 33% of them result in the communication disorder. A stroke occurs when
parts of the brain are deprived of blood, causing anoxia (lack of oxygen) and the sudden death
of tissue (infarct). There are two types of strokes: occlusive and hemorrhagic. An occlusive
stroke occurs when an artery supplying blood to the brain is blocked. In one type of occlusive
stroke, an embolus, an obstruction that originates elsewhere in the body, moves and eventu-
ally lodges in the brain. By contrast, the occlusive type of stroke known as thrombosis develops
when the obstruction originates in the brain. A hemorrhage is the rupture of an artery to the
brain, with subsequent bleeding and buildup of pressure in the cranial cavity. According to
Marquardt (2000, pp. 462–463): “The prevalence and morbidity vary with each of the etiologies
of stroke. Thromboses occur more frequently than hemorrhages, but individuals with throm-
bosis are more likely to survive the stroke.”