Language Versus Speech

Bitterroot Neurology
Stuart Kieran, MD
1019 West Main Street
Hamilton, MT 59840
(406) 375-9310

A common complaint that people experience and physicians see often is slurred speech. While this is certainly descriptive, there are a number of varied conditions that can cause this and it is important to discern the cause, as treatment of the underlying condition can be very different.

First we must differentiate between language and speech. Language is the activity that the brain does to express and understand words and writing. Speech is what sounds come out of a person's mouth and is a combination of functions of the lungs, trachea, larynx or voice box, throat, tongue and lips. It is therefore the mechanical ability to express words. Language however is the thinking part of that process i.e. mental functioning that goes into producing speech. Writing is the graphic equivalent of talking and although it removes the necessity of the mouth, the mental apparatus that goes into writing is very similar to speech production. Likewise reading is the mental ability to understand print and is comparable to listening to words. Some of the descriptions discussed above seem obvious but when, for example someone presents to the emergency room with slurred speech it is important to differentiate whether it is a mechanical problem of forming words versus a brain dysfunction, both of which can cause words to come out in a slurred fashion. Technically the inability to mentally form or comprehend language is called aphasia while the difficulty forming words with the mouth and larynx i.e. mechanical inability to talk, is called dysarthria.

A common example of dysarthria without aphasia is Bell's palsy. This is where the facial muscles on one side become weak, the mouth and muscles of the eye droop downward and a person's speech is slurred. People often are afraid that they're having a stroke and will go to the emergency room or their physician. While there are some subtle clues with regard to which face muscles per se to help differentiate Bell's palsy from other conditions. One of the key differences is that with Bell's palsy, speech production is impaired but the actual content of the speech i.e. the grammar, ability to think of and comprehend words are all normal. In other words the words sound jumbled and are difficult to understand but if one were to transcribe the words there would be perfectly normal English grammar and content. This is different from the slurred speech from a stroke; for example where the words sound jumbled also, but if one were to directly transcribe them there would be a number of mistakes in grammar, decreased or confused content, missing words or even the inability to produce any cogent information at all.

Aphasia can be a complicated condition where various aspects of language are impaired and others are preserved. A condition called Broca's aphasia, also called a nonfluent aphasia, is where speech production is severely impaired or even absent, but comprehension is normal or near normal. This is typically due to a lesion, often a stroke, in the left frontal area of the brain. Another type is called Wernicke's aphasia which is the opposite of this where comprehension is severely impaired but the person is talking fluently. Because the person cannot even understand their own speech, the sentences that come out are often unusual and not even real English words. Naming of objects is also a characteristic of language even though we often take it for granted. It is, however, a left hemisphere function. It is also one of the more fragile language functions of the brain. Difficulty naming things is called dysnomia. It can have many causes. As we get older we often have difficulty naming and this can be a normal aging phenomenon, as can mild decreased short-term memory, both of which in and of themselves do not necessarily imply dementia, Alzheimer's, or even any serious brain function especially if all other mental functioning is normal. This naming ability can be temporarily impaired with various medical conditions, for example someone is very ill in the hospital, certain medications, infections, intoxications or head injuries.

At the far end of the language spectrum is mutism. This is where no speech production occurs at all. At this level however it may be difficult to differentiate dysarthria from aphasia. It also has many causes that can involve the brain, mouth, larynx and more. Commonly however, other than Bell's palsy and stroke, most all of these conditions tend to come on slowly over weeks, months and sometimes even years so the exact cause can be determined and hopefully treated or at least addressed.
A therapy that is often underutilized is speech therapy. These professionals are very skilled at evaluating the cause of speech and language dysfunction, and treating that particular cause.

This health column was provided by Stuart Kieran, MD at Bitterroot Neurology, Hamilton, MT 59840. To schedule an appointment please contact your primary care physician for a referral. Working together to build a healthier community!


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