The essential feature of expressive language disorder is an impairment in expressive language development in a child as determined by scores on standardized individually-administered tests which measure both nonverbal intellectual capacity and receptive language development. The difficulties may occur in communication involving both verbal language and sign language.
The linguistic features of the disorder vary depending on its severity and the age of the child. These features include a limited amount of speech, limited range of vocabulary, difficulty acquiring new words, word-finding or vocabulary errors, shortened sentences, simplified grammatical structures, limited varieties of grammatical structures (e.g., verb forms), limited varieties of sentence types (e.g., imperatives, questions), omissions of critical parts of sentences, use of unusual word order, and slow rate of language development.
Non-linguistic functioning (as measured by performance intelligence tests) and language comprehension skills are usually within normal limits.
Expressive language disorder may be either acquired or developmental. In the acquired type, an impairment in expressive language occurs after a period of normal development as a result of a neurological or other general medical condition (e.g., encephalitis, head trauma, irradiation). In the developmental type, there is an impairment in expressive language that is not associated with a neurological issue. Children with this type often begin speaking late and progress more slowly than usual through the various stages of expressive language development.
The scores obtained from standardized individually-administered measures of expressive language development are substantially below those obtained from standardized measures of both nonverbal intellectual capacity and receptive language development. The disturbance may be manifest clinically by symptoms that include having a markedly limited vocabulary, making errors in tense, or having difficulty recalling words or producing sentences with developmentally appropriate length or complexity.
The difficulties with expressive language interfere with academic or occupational achievement or with social communication.
Criteria are not met for mixed receptive-expressive language disorder or a pervasive developmental disorder.
If mental retardation, a speech-motor or sensory deficit, or environmental deprivation is present, the language difficulties are in excess of those usually associated with these problems.