Speech therapy for children with dysarthria acquired before three years of age
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
1. To assess whether direct intervention aimed at improving the speech of children with dysarthria is more effective than no intervention at all.
2. To assess whether individual types of intervention are more effective than others in improving the speech intelligibility of children with dysarthria.
Background
Dysarthria denotes an articulatory disturbance which arises when neuromuscular impairment affects the tone, power and coordination of any or all of the muscles of used for speech. The changes to tone, power and co‐ordination influence the speed, range, strength and durability of movements, leading to loss or inaccuracy of articulatory movements. When this happens listeners perceive the distortion or omission of sounds and syllables and the alterations to voice quality characteristic of dysarthria. For example, changes to lip and tongue movement may cause 'tip' to be heard as 'sip', 'hip' or 'sieve'; 'beach' to be heard as 'eats'; 'decide' as 'sigh' or 'say.' Changes in tone, power and coordination affecting the larynx alter the quality of phonation (sound made when air passes through vibrating vocal folds) and the control of pitch and loudness. This may give an impression of loss of normal intonational rises and falls (sometimes termed monopitch) and blurring of contrasts between stressed and unstressed syllables (monoloudness). Inco‐ordination of movement can lead to other alterations of the normal flow of speech, in the shape of perceived changes in rhythm. The speaker sounds as if they are stuttering or talking syllable by syllable. Voice may be quiet or there may be inappropriate swings in pitch and loudness. Such changes can also be associated with changes to respiratory function. The air needed to produce speech is insufficient, is poorly regulated and/or escapes too quickly. Apart from the consequences this has for phonation and articulation (as described above), it may also have a knock‐on effect on the length of utterances a speaker can produce. Involvement of the soft palate typically leads to perceptions of excess nasality in a person's speech. Symptoms of dysarthria can range from mild slurring of speech sounds and slightly low pitch to complete inability to produce any intelligible words.
Dysarthria in childhood is associated with congenital disorders such as cerebral palsy (Lepage 1998; Kennes 2002; Bax 2006; Odding 2006) and with acquired aetiologies such as brain tumours (van Mourik 1996; Cornwell 2003; Richter 2005) and traumatic brain injury (Chapman 2001; Netsell 2001; Cahill 2002). At present there is a dearth of information of the prevalence of dysarthria in children. In cerebral palsy, estimates of speech disorder in middle to late childhood range from 40% to approximately 50% (Kennes 2002; Bax 2006). However, precise prevalence figures are not known as previous research has used measures that amalgamate speech and communication. Given that cerebral palsy occurs in approximately two per thousand live births, approximately one in a thousand may have dysarthria. How many additional children have dysarthria arising from other causes is not known. However, cerebral palsy and head injury remain two of the most common medical causes of referral to speech and language therapy (Petheram 2001). As the speech impairments are neurologically based they do not resolve. Intervention seeks to maximise children's speech performance, teaching them how to use different movements and lay down new motor programmes for those movements. The acquisition of new motor programmes requires intensive practice (Schmidt 2005) and hence considerable therapy input over long time periods. Dysarthria therapy, therefore, potentially carries considerable costs to health services even though the prevalence of the disorder in childhood may be small.
Therapy to reduce the motor speech impairments experienced by children, and the intelligibility limitations these impairments impose, has been advocated in textbooks on dysarthria (e.g. Love 1992; Hayden 1994; Strand 1995; Hodge 1999; Yorkston 1999). An approach that targets all subsystems of the vocal tract: breathing, nasal resonance, articulation and pitch control; is commonly described, and is similar to intervention for adults with dysarthria acquired following neurological insults (e.g. following a stroke). Treatment focusing on one or more subsystem in speech production may for example aim to help children control their breathing and maintain adequate pressure for speech across a phrase. This may involve teaching children how to start to speak at the beginning of exhalation and how to split utterances into smaller phases in which they can maintain adequate volume. Intervention also involves slowing children's speech rate, to allow more precise movement of muscles in the oral tract. Strand (Strand 1995) and Yorkston and colleagues (Yorkston 1999) also advocate increasing respiratory effort and making jaw movements bigger in speech to increase oral cavity volume, and the use of speech and non‐speech exercises to help close the airway to the nose during speech. Treatment for articulation has only been advised when other aspects of speech production have been/are being addressed, as imprecise "production of speech sounds (which is the most common perceptual characteristic of dysarthria) is not simply an oral articulatory problem, and is usually the result of laryngeal, velopharyngeal, respiratory and oral articulatory problems" (Strand 1995, p134). Thus, more precise articulation and improved intelligibility is thought to be achieved through developing control of breathing for speech, increasing background effort and slowing speech rate (Love 1992; Strand 1995; Yorkston 1999). Treatment for prosody (intonational contours of speech) and pitch control has been described by Yorkston and colleagues (Yorkston 1999) and Strand 1995 and comprises exercises to control the rate or words spoken and pauses used, increase volume and possibly the use of pitch change.
Although therapy for dysarthria in childhood has been described in textbooks and review articles only one investigation has been undertaken to review its general effectiveness and this review was not undertaken systematically (Yorkston 1996). Speech and language therapists therefore have little evidence on which to base treatment decisions. Some may provide intervention as there is no evidence to show that the treatment does not work or causes harm. Others may withhold treatment because there is no evidence showing its effectiveness.
We aim to conduct a systematic review of the studies of speech therapy for children who have acquired dysarthria early in life and to investigate the relative effectiveness of different types of treatment.
Objectives
1. To assess whether direct intervention aimed at improving the speech of children with dysarthria is more effective than no intervention at all.
2. To assess whether individual types of intervention are more effective than others in improving the speech intelligibility of children with dysarthria.
Methods
Criteria for considering studies for this review
Types of studies
Randomised controlled trials and studies using quasi‐experimental designs in which children are allocated to groups using non‐random methods will be considered in this review.
Types of participants
Any child under 20 years of age who acquired dysarthria below three years of age. No exclusions will be made on the basis of additional impairments (intellectual or sensory impairments, the presence of epilepsy) or prior receipt of speech and language therapy. This age range was selected as people who have identified special needs are entitled to statutory education provision up to 19 years of age in England, which could specify speech and language therapy. Children who acquired dysarthria above three years of age will be excluded from this review as they may differ from children with earlier acquired pathologies in terms of: their neural development, plasticity and recovery patterns; memories of fluent speech; retrieval of previously developed motor programmes; self image (seeing themselves as a fluent speaker rather than a person with a speech disorder) and patterns of communication development. Children with early acquired dysarthria may never have developed motor programmes for fluent speech, have no memories of non‐dysarthric speech, or see themselves as an intelligible speaker. Furthermore, children with severe speech and motor impairments arising from congenital pathologies or those acquired in early infancy have highly unusual patterns of communication development. They take a mainly responsive role in communication and often fail to develop a full range of conversational skills (Pennington 1999). Interventions for children who acquire dysarthria at three years of age and above are the subjects of a separate review (Morgan 2006)
Types of interventions
Any therapy aimed at improving children's speech, whether provided individually or in groups, or in the child's home, school or health service settings, except where it is provided as part of a holistic approach (for example, as in conductive education where there is no specific speech interventions). Therapy can be provided directly by speech and language therapists (also known as speech‐language pathologists, speech pathologists) or by other personnel under the direction of a speech and language therapist.
Types of outcome measures
Primary outcome measures
Primary outcome measures relate to children's speech production: respiration, phonation, nasality, articulation, sound pressure level, intelligibility. These are classified as voice, articulation, fluency and rhythm of speech, production of notes and respiratory functions in the World Health Organisation International Classification of Functioning, Disability and Health (ICF). ICF activities of speaking, conversation, and discussion will also form primary outcome measures for this review. Measures used may be, for example: rating scales, oro‐motor skills tests, articulation tests, phonology tests, acoustic measures of pitch and loudness, physiological tests e.g. of respiration and nasal emission, intelligibility rates, coding schemes developed for individual research studies that include validity and reliability data.
Secondary outcomes
Satisfaction of participant and family with treatment; non‐compliance with treatment; direct costs of treatment; adverse events, including time missed from education.
Search methods for identification of studies
Electronic searches
The following data bases will be searched from inception: Cochrane Central Register of Controlled Trials (CENTRAL) published in the Cochrane Library; MEDLINE; CINAHL, EMBASE; ERIC; Psych INFO; Linguistics and Language Behaviour Abstracts (LLBA); Dissertation Abstracts.
The search strategy below (developed from Robinson 2002) will be used for MEDLINE and modified for other databases.
1. dysarthria/rh, th [rehabilitation, therapy]
2. articulation disorders/rh,th [rehabilitation, therapy]
3. speech disorders/rh, th [rehabilitation, therapy]
4. voice disorders/rh, th [rehabilitation, therapy]
5. 1 or 2 or 3 or 4
6. child/ or adolescent/ or infant/ or child, preschool/
7. 5 and 6
8. randomized‐controlled trial.pt.
9. controlled‐clinical trial.pt.
10. randomized controlled trials/
11. random allocation/
12. double‐blind method/
13. single‐blind method/
14. or/8‐13
15. animal/ not human/
16. 14 not 15
17. clinical trial.pt.
18. exp clinical trials/
19. (clinic$ adj25 trial$).tw.
20. ((singl$ or doubl$ or trebl$ or tripl$) adj (mask$ or blind$)).tw.
21. placebos/
22. placebo$.tw.
23. random$.tw.
24. research design/
25. (latin adj square).tw.
26. or/17‐25
27. 26 not 15
28. 27 not 16
29. comparative study/
30. exp evaluation studies/
31. follow‐up studies/
32. prospective studies/
33. (control$ or prospectiv$ or volunteer$).tw.
34. cross‐over studies/
35. or/29‐35
36. 35 not 15
37. 36 not (16 or 28)
38. 16 or 28 or 37
Other searches
We will handsearch the following journals from their inception or from 1980 onwards: International Journal of Language and Communication Disorders; Augmentative and Alternative Communication; Child Language Teaching and Therapy; Developmental Medicine and Child Neurology; Child: Care, Health and Development and the Ambulatory Child; Journal of Child Psychology and Psychiatry and Allied Disciplines; Topics in Language Disorders; European Journal of Special Needs Education; Journal of Communication Disorders; Journal of Psycholinguistic Research; Journal of Special Education; International Journal of Rehabilitation Research; Folio Phoniatrica; Applied Psycholinguistic Research; Journal of Speech, Language and Hearing Research; Australian Journal of Communication Disorders; American Journal of Speech‐Language Pathology; International Journal of Disability, Development and Education; Speech, Language and Hearing in Schools; Journal of Medical Speech‐Language Pathology; Advances in Speech Pathology; Asia Pacific Journal of Speech Pathology. (The current titles are given for journals experiencing name changes since 1980)
Published conference proceedings of the following organisations will be checked: European Academy of Child Development (1996 to 2007), International Society for Alternative and Augmentative Communication (1996 to 2006), American Speech and Hearing Association (1999 to 2007), Royal College of Speech and Language Therapists (1998 to 2007).
Reference list of all studies selected for possible inclusion will be checked for other possible eligible studies.
We will contact authors of included trials for unpublished studies.
We will include studies reported in any language; translations will be sought if necessary.
Data collection and analysis
Title and selection of trials
Two of the three review authors (LP, SR, NM).will independently screen for inclusion each title and abstract. If inclusion is uncertain the full text of the paper will be obtained and the two review authors will independently review the full text regarding inclusion. Two of the three review authors (LP, SR, NM) will independently review papers fitting the inclusion criteria. In the event of disagreement regarding inclusion the third review author will independently review the paper and consensus will then be formed by all three review authors re‐assessing the inclusion criteria together. Agreement on inclusion will be calculated using the Kappa statistic.
Data extraction
Two members of the research team (LP, SR, NM) will independently extract data into RevMan 4.2.
Data will include:
Participants: age; gender; age of onset of disorder; diagnosis of underlying disorder; type of dysarthria; severity of dysarthria (measures relating to speech production): respiration; phonation; nasality; articulation; sound pressure level; intelligibility
Co‐morbidity
Intervention: type of intervention; duration; frequency provider: SLT/other
Focus of intervention: respiration, phonation, nasality, articulation, sound pressure level, intelligibility
Comparator intervention
Type of intervention
Duration
Frequency
Provider: SLT/other
Focus of intervention: respiration, phonation, nasality, articulation, sound pressure level, intelligibility
Quality assessment
The two review authors who extract data on an individual study will also independently assess the study's methodological quality. Disagreements will be resolved with the third review author. Agreement on methodology assessment will be calculated using the Kappa statistic. Individual criteria will be rated according to the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2006):
(A) adequate,
(B) component not reported or unclear
(C) component reported but inadequate
1. Method of allocation (assignment of participants to group)
(A) Well described randomised process.
(B) Allocation is not described or description leads to uncertainty in quality of allocation and possibility of bias.
(C) Non‐random method (e.g. days of the week, alternate).
2. Allocation concealment
In the case of speech and language therapy interventions neither participant nor provider can be blind to the type of treatment given. Blinding in studies in this review will refer to blinding of study research team and treatment provider to allocation process.
(A) Allocation will be classed as adequately concealed if allocation was done using a centralised system independent of research team, use of pre‐numbered opaque sealed envelopes, generation of allocation by computer by person not in charge of allocation.
(B) Methods of concealment are not described or description does not allow bias to be ruled out.
(C) Providers of intervention undertake allocation or research team allocate participants and have access to participant characteristics.
3. Blinding of outcome assessors
(A) Reports state that assessors were blind to allocation.
(B) No information on blinding of assessors.
(C) Reports suggest that assessors are likely to know the group to which the participant was allocated (e.g. provided treatment, worked with person delivering treatment).
4. Loss to follow up
(A) Attrition is similar in both conditions, and no greater than 25% than participants entering the trial.
(B) Loss of participants to follow up is not reported.
(C) Loss of participants to follow up is greater than 25% or is distributed unevenly across groups. Studies showing uneven loss to follow up will be considered separately in sensitivity analyses.
5. Intention to treat analysis
(A) All trial participants entered into the analysis in the group to which they were originally allocated.
(B) Intention to treat analysis not reported.
(C) Trial participants who did not complete their originally allocated treatment removed from the analysis.
Data management
Data extraction sheets for the review, which will include a methodological assessment table for application of the codes above, will be developed and piloted for the study. Paper copies of the form will be used with the included studies. Data from the forms will be entered into RevMan 4.2. Review authors will contact authors of studies to request missing data.
Data synthesis
Continuous data
For studies using similar outcome measures with continuous data, data will be summarised using standardised mean differences.
Binary data
Binary data (e.g. reaching normal loudness: yes or no) may be used in early reports. For binary data, we will calculate a standard estimation of the odds ratio, with a 95% confidence interval.
Heterogeneity
Meta‐analysis will be undertaken when studies investigate similar interventions, use similar outcome measures and include groups of participants who are clinically homogeneous. If studies are heterogeneous a narrative review will be undertaken. If studies are similar in intervention, outcome measurement and participants, possible inconsistency across studies will be assessed using the I‐squared (I2) statistic (Higgins 2003). If studies are heterogeneous (Q‐statistic = 0.1 and I2 value of 25% or greater) the review authors will consider conducting subgroup analysis only. If the primary studies are considered to be heterogeneous even within subgroups, narrative reviews rather than meta‐analysis will be undertaken.
Subgroup analyses
Subgroup analyses will be undertaken if studies fitting the criteria for meta‐analysis can be further grouped according to participants' type of dysarthria, severity of dysarthria, age.
Sensitivity analyses
We will undertake sensitivity analyses to assess the robustness of review findings by investigating the impact of study quality: effects of randomisation; inadequate concealment; blinding of outcome assessors; unequal loss to follow up; failure to employ intention to treat design.
Assessment of bias
We will investigate associations between effect size and study precision in terms of sample size using funnel plots. Relationships observed may be due to differences between studies involving large and small samples or systematic biases, such as publication bias.
