Language Disorders 247Differential diagnosis and assessment
Hearing impairment is the most important differential diagnosis since it
is common, there are effective treatments and delaying these treatments
can seriously disadvantage the affected individual. It is essential, therefore,
that everyone with language delay should have their hearing properly
assessed. Language delay can be part of an intellectual disability, and this
possibility can only be ruled out by suitable tests of general mental ability,
which obviously need to be judged by tests of non-verbal ability in the
presence of severe language problems. Likewise, tests of general mental
ability are helpful in distinguishing between the selective loss of language
skills in Landau-Kleffner syndrome and the general loss of cognitive skills
in progressive childhood dementias (see Chapter 24). A general psychiatric
assessment is also important since autistic spectrum disorders (see Chapter
4) characteristically involve language delay or deviance, and may even
begin with a developmental ‘setback’ in which established language skills
are lost. Selective mutism (see Chapter 16) refers to a relatively rare group
of children who are able to understand what other people say, but who
restrict their own speech to a small group of very familiar people in specific
circumstances; social anxiety is probably the key factor in most cases, but
this anxiety may be aggravated by co-existent minor language problems.
If a speech or language problem is likely to be present, referral to a speech
and language specialist should be considered. There are many specific
tests of articulation, expressive language and receptive language, with the
Clinical Evaluation of Language Fundamentals (CELF) being widely used
by speech-language therapists in the UK and the USA both for screening
and for the diagnosis of specific language impairment.
Interventions for language disorders
There have been a few randomised controlled trials of speech and language
therapy, which show:
There is a significant effect of intervention when children have phono-
logical or expressive language disorders.
The results for children with receptive language difficulties are incon-
clusive, but the few studies that are available do not show a significant
effect of therapy.
For children with expressive language difficulties, treatment admin-
istered by parents under professional guidance seems as effective as
treatment administered by clinicians.
By contrast, treatment administered by clinicians may be more effective
for children with phonological or receptive language difficulties.Prognosis for language development
The prognosis for language development depends both on the type
of language disorder and also on the presence of associated cognitive