Specific language impairment (SLI) is diagnosed when a child's language does not develop normally and the difficulties cannot be accounted for by generally slow development, physical abnormality of the speech apparatus, autism spectrum disorder, apraxia, acquired brain damage or hearing loss.
[4] Although difficulties with use and understanding of complex sentences are a common feature of SLI, the diagnostic criteria encompass a wide range of problems, and for some children other aspects of language are problematic (see below).
[5] The terminology for children's language disorders is extremely wide-ranging and confusing, with many labels that have overlapping but not necessarily identical meanings.
[10] Rapin is a child neurologist, and she refers to different subtypes as "syndromes"; many of those coming from the perspective of education or speech-language therapy reject this kind of medical label, and argue that there is not a clear dividing line between SLI and normal variation.
[12] Rapin's subgroups fall into three broad categories: Receptive/expressive phonologic/syntactic deficit syndrome is the most common form of SLI, in which the child's most obvious problems are a tendency to speak in short, simplified sentences, with omission of some grammatical features, such as past tense -ed.
[14][15] Verbal auditory agnosia is a very rare form of language impairment, in which the child appears unable to make sense of speech sounds.
It typically occurs as a symptom of Landau-Kleffner syndrome, in which case a diagnosis of SLI would not be appropriate, as there is a known neurological origin of the language difficulties.
There is much disagreement about diagnostic criteria, but the label most often used for children whose intelligibility declines markedly when they attempt complex utterances, compared to when they are producing individual sounds or syllables.
Children with DVD also typically have major literacy problems, and receptive language levels may be poor on tests of vocabulary and grammar.
[17] Phonologic programming deficit syndrome – the child speaks in long but poorly intelligible utterances, producing what sounds like jargon.
There has been a great deal of controversy about this category, which is termed pragmatic language impairment (PLI) in the UK.
Current evidence suggests that there are many different genes that can influence language learning, and SLI results when a child inherits a particularly detrimental combination of risk factors, each of which may have only a small effect.
Tombin et al. (1996) proposed the EpiSLI criterion, based on five composite scores representing performance in three domains of language (vocabulary, grammar, and narration) and two modalities (comprehension and production).
Some are restricted for use by speech and language professionals (therapists or SALTs in the UK, speech-language pathologists, SLPs, in the US and Australia).
A commonly used test battery for diagnosis of SLI is the Clinical Evaluation of Language Fundamentals (CELF).
For example, the SLP might look for whether the child introduces characters to their story or jumps right in, whether the events follow a logical order, and whether the narrative includes a main idea or theme and supporting details.
Contemporary approaches to enhancing development of language structure are more likely to adopt 'milieu' methods, in which the intervention is interwoven into natural episodes of communication, and the therapist builds on the child's utterances, rather than dictating what will be talked about.
[34] A radically different approach has been developed by Tallal and colleagues, who have devised a computer-based intervention, Fast ForWord, that involves prolonged and intensive training on specific components of language and auditory processing.
[35] The theory underlying this approach maintains that language difficulties are caused by a failure to make fine-grained auditory discriminations in the temporal dimension, and the computerised training materials are designed to sharpen perceptual acuity.
[38] In 2010, a systematic review of clinical trials assessing the FastForword approach was published, and reported no significant gains relative to a control group.
[45] For instance, Conti-Ramsden and Botting (2004) found that 64% of a sample of 11-year-olds with SLI scored above a clinical threshold on a questionnaire for psychiatric difficulties, and 36% were regularly bullied, compared with 12% of comparison children.
[46] In the longer-term, studies of adult outcomes of children with SLI find elevated rates of unemployment, social isolation and psychiatric disorder.
A major divide is between theories that attribute the difficulties to a low-level problem with auditory temporal processing,[51][52] and those that propose there is a deficit in a specialised language-learning system.