Aphasia comes from the Greek root word, “aphatos”, meaning “speechless”. It is a language disorder in which there is an impairment of any language modality which may include difficulty in producing or comprehending spoken or written language. Aphasia occurs in men and women alike and although it is more common in middle-aged adults it may also occur in children. Depending on the area and extent of the brain damage, someone suffering from aphasia may be able to speak and not write, or vice versa. Aphasia may also display a wide variety of other language deficiencies in language comprehension and production such as the ability to sing and not speak. Aphasia may also co-occur with speech disorders such as dysarthria or apraxia of speech, which is now a disorder in itself ((Risser, Anthony H.; Spreen, Otfried (2003). Assessment of aphasia. Oxford [Oxfordshire]: Oxford University Press).). Both resulting from brain damage. Dysarthria is a motor speech disorder resulting from a neurological injury and characterized by poor articulation. Apraxia is a disorder caused by damage to specific areas of the cerebrum and is characterized by loss of the ability to execute or carry out learned purposeful movements, despite having the desire and ability to perform the movements (wikopedia). One can understand how both of these disorders correlate closely to the language disorder aphasia, rather taking an in depth look or just an overview.
Aphasia is caused by damage to one or more language areas of the brain. Many times, the cause of brain injury is a stroke but other causes include severe blows to the head, brain tumors, brain infections, dementia, and other brain conditions. Aphasia may also develop after an individual sustains a brain injury from infections such as herpes encephalitis. As a result of the injuries, the pathways for language production and comprehension are disrupted or destroyed. For most people, 95 percent of right-handed and 60-70 percent of left-handed, this means damage to different parts of the left hemisphere of the brain which controls functions such as grammar and vocabulary in language (http://neurology.health-cares.net/aphasia-causes.php).
There are different types of aphasia and they all range from mild to more severe. The more common types of aphasia are: Expressive (Broca’s aphasia), Receptive (Wernicke’s), and Global aphasia. With expressive aphasia, the person knows what he or she wants to say but has difficulty communicating it to others whether the sufferer is trying to say it or write it. Receptive aphasia is when the person can hear a voice or read a print but may not understand the meaning of the message. Oftentimes, individuals with receptive aphasia take figurative language literally. Global aphasia is the most severe type and is often seen after a stroke. The person has difficulty speaking and understanding words and also reading and writing. (http://www.webmd.com/brain/aphasia-causes-symptoms-types-treatments)
Pierre Paul Broca was a French physician, anatomist, and anthropologist who was best known for his research on the Broca’s area which is a region of the frontal lobe that was named after him (Jay V (March 2002). "Pierre Paul Broca". Archives of Pathology & Laboratory Medicine 126 (3): 250–1). This part of the brain is important for putting words together to form complete sentences. When injury occurs and this part of the brain is damaged, individuals may develop expressive aphasia. These people have difficulty forming complete sentences. They may get out basic words to get their message across but will leave out words such as “in” or “the” and often they will say things that don’t resemble a sentence. They may also have trouble understanding sentences and following directions like “left”, “right”, “under”, or “after”. Comprehension is commonly retained but issues with disjointed sentences and poor speech still continue.
Global aphasia is basically a severe combination of both Broca’s and Wernicke’s aphasia. There is almost a total loss of all aspects of language, spoken and written and in expression as well as comprehension. Patients with global aphasia still have other cognitive skills remaining though such as memory and recognition. Global aphasia, because of the effects, may seem to be the “last stage” in someone who suffers from aphasia due to an injury. In actuality, when an injury initially occurs, the progression begins with global aphasia. This is due to the brain swelling and happens in the first two days. Then for about 1-3 months it turns into Broca’s or Wernicke’s aphasia. Studies have shown that some improvements happen within six months but a full recovery is rare (Risser, Anthony H.; Spreen, Otfried (2003). Assessment of aphasia. Oxford [Oxfordshire]: Oxford University Press).