Aging Begins at 30

From Thought to Word and Back Again

Aphasia is difficulty with understanding and expressing language caused by brain damage. Transforming thought into language or other people's language into thought is a fragile skill. For speech, one needs in the brain a word dictionary, grammar skills, and the ability to integrate sounds into words and words into sentences.

Aphasia disease is usually on the left side of the brain in over 95% of right-handed individuals and is most often blood vessel blockage. It used to be thought to be in localized language centers but is now known to be in networks connecting many areas of the brain. Presently there are six recognized groups of aphasia: Broca's, Wernicke's, conduction, global, transcortical and atypical.

Pierre Broca, a French surgeon in the 1860's described patients with difficulty in speaking words, although they understood written and spoken words. The speech is often called telegraphic (nouns and action verbs only) and is flat, unmelodic, and distorted. They are surprised to be unable to repeat a simple phrase. Their nerve network for integrating voice fragments into words and words into sentences has gone.

Carl Wernicke, a German neurologist in 1875, described fluent, unintelligible speech with misconstructed words and sentences. There was poor naming and poor repetition. There was usually no limb paralysis, although due to a stroke. Their processor of speech sounds was damaged.

Conduction aphasia patients can comprehend sentences and can produce intelligible speech but they have trouble assembling sounds and naming objects, such as using "the thing you write with" for pen,. The right side of their face may be weak but there is no major paralysis. There may be contamination by word or letter substitutions.

In global aphasia speech is reduced to a few words which may be a repetitive "Ah, Ah, Ah" or expletives such as "God damn it." There is associated right face and limbs weakness and hemianestheia. This comes from a large area of brain damage.

Transcortical (across the rind of the brain) aphasia has two separate subtypes, nonfluent or explosive, and fluent or scant speech but a capacity to repeat sentences is preserved.

New techniques in the past 20 years such as CAT scanning or MRI have allowed us to map the brain and uncover language related areas deep below the surface. Speech control from the left temporal lobe (side brain above the cheek bone) operates in finding words or naming objects. Damage can occur to the basal ganglia or to the frontal lobes (behind the brow) which control initiation of speech, causing mutism when damaged. Story and joke telling may be controlled by the non-dominant hemisphere (the right half in the right-handed person).

Speech therapists and neuropsychologists construct a performance profile in 3 hour interviews which defines the type of aphasia and helps to delineate undamaged areas that help in relearning. The profile also records the patient's and family's intelligence, emotional balance and support. Aphasia treatment generally works. Music or melodic intonation therapy, word and phrase construction (syntax) training and visual action therapy can be useful. Pharmacotherapy (replacement of the nerve transmission chemicals of the brain) such as dopamine as stimulation by bromocryptine can help a few.

Eighty-five thousand new cases of aphasia occur yearly, mainly from stroke, but head injury adds a significant number, both common in the elderly.

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