4. Attention

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What is Being Tested?

Level of consciousness is severely impaired in damage to the brainstem reticular formation and in bilateral lesions of the thalami or cerebral hemispheres (see Neuroanatomy Through Clinical Cases 3e, Figure 2.23). It may also be mildly impaired in unilateral cortical or thalamic lesions. Toxic or metabolic factors are common causes of impaired consciousness because of their effects on the structures mentioned here. Generalized impaired attention and cooperation are relatively nonspecific abnormalities that can occur in many different focal brain lesions; in diffuse abnormalities such as dementia, delirium, or encephalitis; and in behavioral or mood disorders.