The essential feature of selective mutism is the persistent failure for at least one month (but not limited to the first month after the start of school) to speak in specific social situations where speak-ing is expected, despite speaking in other situations (most com-monly in the home). Children with this disorder become impaired in social and educational settings. Selective mutism must not be diagnosed when there is a lack of knowledge or comfort speak-ing, for example, when a child is an immigrant.
Previously referred to as elective mutism, in DSM-IV-TR the condition was renamed selective mutism, so as to be less judg-mental. The prevalence is usually reported as 0.6 to seven per 1000, with higher incidence in females rather than males. When subjects failing to speak in the first few weeks of school (a DSM-IV-TR requirement) are excluded, rates do not exceed two per1000. Onset is usually in the preschool years, but the peak age of presentation and diagnosis is between 6 and 8 years. A high in-cidence of insidious onset of refusal to speak with anyone except family members is reported. The other typical picture is one of acute onset of mutism on starting school.
Three basic theories have been proposed to explain the etiology of selective mutism: children who are negative, oppositional and controlling; traumatized children; and children who have severe anxiety, chiefly social phobia. Although early psychodynamic theorists described an enmeshed relationship between mother and child, the father being distant and ineffectual, and a conflicted re-lationship between the parents, the only two controlled studies of selective mutism did not find family functioning worse compared with the families of other emotionally disturbed children (Kolvin and Fundudis, 1981; Wilkins, 1985). Associated features include a history of delayed speech and articulation problems, and possi-bly increased incidence of enuresis and/or encopresis. There may be a family history of general shyness, or of elevated levels of anxiety in the parents.
Prior to making a diagnosis of selective mutism, a comprehen-sive evaluation should be conducted to rule out other explana-tions for mutism and to assess important comorbid factors. For obvious reasons, the parental interview will form the mainstay of evaluation but, as discussed below, direct observation (and interview if it is possible) of the child can afford important di-agnostic information important to obtain information of the nature of the onset (insidious or sudden), any uncharacteristic features (i.e., not talking to family members, abrupt cessation of speech in one setting, absence of communication in all set-tings) suggestive of other neurological or psychiatric disorders (e.g., pervasive developmental disorders, acquired aphasias), and any history of neurological insult/injury, developmental delays, or atypical language and/or speech. The assessment should also include the degree to which nonverbal communication or non-face-to-face communication is possible, the presence of anxiety symptoms in areas other than speaking, social and behavioral inhibition, medical history including ear infections and hearing deficiencies. Parents will be able to give information on where and to whom the child will speak, the child’s speech and lan-guage complexity at home, articulation problems, use of non-verbal communication (e.g., gestures), any history of speech and language delays, and the possible importance of bilingualism (where primary language is not English). It can be useful to have the parents provide an audiotape of the child speaking at home. The child evaluation can assess the presence of anxiety and so-cial inhibition (willingness to communication through gesture or drawing). Physical examination of oral sensory and motor ability may provide evidence of neurological problems (i.e., drooling, asymmetry, orofacial weakness, abnormal gag reflex, impaired sucking or swallowing). Specialist audiometry (pure tone and speech stimuli as well as tympanometry and acoustic reflex test-ing) may provide evidence of hearing and/or middle ear prob-lems that can have a significant effect on speech and language development. Cognitive abilities may be difficult to assess, but the performance section of the WISC-R or Raven’s Progressive Matrices as well as the Peabody Picture Vocabulary Test may be useful in the nonverbal child.
Treatment has long been regarded as difficult and the prognosis poor. Approaches have included behavioral therapy, family ther-apy, speech therapy and, more recently, pharmacological agents. Unfortunately most published studies are single case reports, with very few controlled studies.
Behavioral treatment focuses on mutism as a means of get-ting attention and/or escaping from anxiety. A controlled study (Calhoun and Koenig, 1973) of eight subjects with random as-signment to treatment (teacher and peer reinforcement of ver-bal behavior) or control showed significant increases in mean number of vocalizations after 5 weeks of treatment. These gains were not, however, maintained at 12-month follow-up. Other techniques have included graded exposure, shaping and mod-eling. The goal of a treatment program should be to decrease the anxiety associated with speaking whilst encouraging the child to interact verbally.
Regarding pharmacotherapy, the use of SSRI medication in cases of selective mutism with associated anxiety (principally social phobia) has promise. An open trial of 21 children using a mean dose of 28.1 mg/day of fluoextine showed improvement in 76% of cases (Dummit et al., 1996). A placebo-controlled double-blind study showed mixed results, though both groups remained highly symptomatic. More chronic (.14 weeks) treatment was recommended (Black and Uhde, 1994).