Aphasiology

Aphasiology is the study of aphasia, which is a communication impairment that occurs as a result of brain injury. In most cases, aphasia is a product of brain damage caused by strokes and other neurological events, but it can also be caused by injuries related to trauma, infection, or tumors. The effects of aphasia can vary depending on the nature and extent of brain damage involved. Generally, patients with aphasia exhibit some sort of difficulty in speaking or understanding words. While those with milder cases may simply have a hard time finding the right words or putting words together in coherent sentences, those with more severe cases may be entirely unable to communicate. Physicians have been studying aphasia for thousands of years. Although relatively little meaningful progress in understanding the condition was made until the nineteenth century, modern aphasiologists have made great strides in defining, diagnosing, and treating aphasia.

Background

The earliest evidence of aphasia and aphasiology dates back to ancient Egypt. Archeologists found a papyrus believed to have been written between 3000 and 2500 BCE that describes the case of a patient who apparently developed communication problems after suffering a traumatic head injury. Beyond that, the idea that mental processes were controlled by the brain first began to emerge in ancient Greece and Rome. It was not until the first century CE, however, that this theory first gained real traction in the scientific community thanks to the Greek physician Galen's work with Roman gladiators who suffered traumatic brain injuries.

While cases of aphasia continued to occur, little progress was made in truly understanding the condition or its causes until the nineteenth century. It was during the nineteenth century that physicians first outlined the concept of cerebral localization, which is the idea that special functions, such as vision and speech, are controlled by specific parts of the brain. At the forefront of the study of cerebral localization was Paul Broca, a French physician who determined that aphasia could be caused by injuries to the part of the frontal lobe that controls linguistic abilities. Broca worked primarily with a patient dubbed "Tan," who had severe aphasia and could say little beyond the word tan. After his patient's death, Broca performed an autopsy. He found that Tan had a lesion on his left anterior lobe and determined that this lesion was responsible for Tan's aphasia. In recognition of Broca's accomplishments, part of the brain was named Broca's area and the type of aphasia he described became known as Broca's aphasia.

Another key researcher who studied aphasia was German physician Carl Wernicke. Wernicke further refined the map of which areas of the brain affected language development, production, and expression. Like Broca, he too had a part of the brain and a form of aphasia named after him in recognition of his work.

In the twentieth century, localizationist theory was largely supplanted by interactionist theory, which held that though basic functions are localized, there are also redundancies built into the brain so that an injury to a particular part will not necessarily impair a person's higher-level behaviors. In the years since, high-tech imaging techniques like computed tomography (CT) scans and magnetic resonance imaging (MRI) have allowed physicians to get an even better look at how the brain works and how aphasias affect brain activities.

Overview

Aphasia is a medical disorder that occurs when the parts of the brain that control language are damaged. The most common cause of aphasia is brain damage caused by stroke. Strokes occur when a blood clot or a burst blood vessel interrupts blood flow to part of the brain. When the blood supply is interrupted, brain cells do not receive the oxygen and nutrients they need to survive and begin to die. The death of brain cells in this manner often leads to impairment in higher-level behaviors. When a stroke effects the portion of the brain that controls language, the damage may cause aphasia. Similar damage can also occur as a result of trauma, infections, or tumors.

People who have aphasia usually present with an impaired ability to understand and express themselves through language. While it most often interferes with speech, people with aphasia may also have difficulty with reading or writing. Depending on the type and severity of their condition, people with aphasia may speak in short, incomplete, or incoherent sentences. They may also unintentionally substitute one word or sound for another or use entirely recognizable words. In some cases, these same problems may occur in writing as well.

There are six main types of aphasia, including global aphasia, nonfluent aphasia, mixed nonfluent aphasia, fluent aphasia, anomic aphasia, and primary progressive aphasia. Global aphasia is the most severe type of aphasia. Patients with global aphasia typically have an extremely limited ability to produce any recognizable words, are often unable to understand spoken language, and cannot read or write. In nonfluent aphasia, which is also known as Broca's aphasia, speech output is reduced, vocabulary is limited, and the production of sound is difficult and clumsy. Most people with Broca's aphasia can read, but writing ability may be limited. In mixed nonfluent aphasia, speech is somewhat limited and effortful. Patients also typically exhibit limited speech comprehension and restricted reading and writing ability. In fluent aphasia, which is also known as Wernicke's aphasia, the ability to speak is relatively unaffected, but speech comprehension is limited. Most patients also experience difficulty in forming coherent speech and have a severely impaired ability to read and write. In anomic aphasia, patients have little to no problem in producing speech but usually have difficulty in finding the right words to describe their thoughts. Primary progressive aphasia is a neurological syndrome that causes language abilities to become increasingly impaired over time. It is most often associated with conditions like Alzheimer's disease.

Treatments for aphasia depend on the cause, type, and extent of the condition. Aphasias caused by a tumor, for example, can resolve if the tumor is removed. Stroke-related aphasias sometimes resolve on their own as the brain recovers. In other cases, aphasia symptoms may improve with speech therapy aimed at helping the patient to use his or her remaining language abilities and restoring lost abilities to the greatest extent possible. People with aphasia can also use gestures, electronic devices, or other means of communicating without speaking.

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