Language Disorders Health Article

Definition

A language disorder is a deficit or problem with any function of language and communication.

Description

Speech and language disorders are extremely common. They can range from slow acquisition of language to sound substitution or stuttering to the inability to understand or produce and language at all. The federal Agency for Healthcare Research and Quality estimated in 2002 that communication disorders cost the United States between $30 and $154 billion annually in lost productivity and money spent on medical care, special education, and remediation.

Language disorders and the brain

Speech and language pathologists and neurologists (doctors who specialize in the brain and nervous system) have known for about 100 years that certain areas in the left hemisphere of the brain—Broca's area in the posterior frontal lobe and Wernicke's area in the temporal lobe—are centrally involved in language functions. Damage to Broca's area results in problems with language fluency: shortened sentences, impaired flow of speech, poor control of rhythm and intonation, and a telegraphic style with missing inflections. Damage to Wernicke's area produces speech that is fluent and often rapid, but with relatively senseless content, many invented words, and word substitutions.

With the invention of new technologies, including computed tomography (CT) scans and magnetic resonance imaging (MRI), several studies have looked at the language development in very young children with lesions in the traditional language areas of the brain. There is surprising agreement among the studies in their results: all find initial delays in language development followed by remarkably similar progress after about age two to three years. Lasting deficits have not been noticed in these children. Surprisingly, there are also no dramatic effects of laterality; lesions to either side of the brain seem to produce virtually the same effects. However, most of the data comes from conversational analysis or relatively unstructured testing, and these children have not been followed until school age. Nevertheless, the findings suggest remarkable plasticity and robustness of language in spite of brain lesions that would devastate an adult's language abilities.

Language disorders and hearing loss

Children with a hearing loss, either from birth or acquired during the first year or two of life, generally have a serious delay in spoken language development. The hearing loss occurs despite very early diagnosis and fitting with appropriate hearing aids. However, in the unusual case that sign language is the medium of communication in the family rather than speech, the child shows no delay in learning to use that language. Hearing development is always one of the first things checked if a pediatrician or parent suspects a language delay. The deaf child exposed only to speech will usually begin to babble ("baba, gaga") at a slightly later point than the hearing child. Recent work suggests that the babbling is neither as varied nor as sustained as in hearing children. However, there is often a long delay until the first words are spoken, sometimes not until age two years or older.

Depending on the severity of the hearing loss, the stages of early language development are also quite delayed. It is not unusual for the profoundly deaf child at age four or five years to only have two-word spoken sentences. It is only on entering specialized training programs for oral language development that the profoundly deaf child begins to acquire more spoken language. Often, such children do not make the usual preschool language gains until they reach grade school. Many deaf children learning English have pronounced difficulties in articulation and speech quality, especially if they are profoundly deaf, since they get no feedback in how they sound. A child who has hearing for the first few years of life has an enormous advantage in speech quality and oral language learning over a child who is deaf from birth or within his or her first year.

Apart from speech difficulties, deaf children learning English often show considerable difficulty with the inflection and syntax of the language, which marks their writing as well as their speech. The ramifications of this delayed language are also significant for learning to read, and reading proficiently. The average deaf high school student often only reads at fourth grade level.