Interventions for speech problems (dysarthria) after stroke or other non-progressive brain injury

Review question
Does any type of treatment help people who have difficulty speaking clearly after a stroke or other types of brain injury acquired during adulthood?

Brain damage caused by stroke, injury or other non-progressive disease can make speech unclear and difficult for listeners to understand. This condition is known as dysarthria and it occurs when face, tongue, and throat muscles are weak, slow, and unco-ordinated. Dysarthria can cause people who are affected to lose confidence when talking and become socially isolated, even if others see symptoms as mild. People with dysarthria do not have difficulties thinking, remembering, or retrieving words.

Treatment is usually provided by a speech and language therapist or speech pathologist and involves advice and education plus strategies and exercises to increase clarity of speech and to cope with social interaction. Other types of treatment used include acupuncture or brain stimulation.

We wanted to find out if any treatments work, if the effects are long lasting, and if so, which works best, when treatment should start, how frequent treatment should be, and for how long. To find out we searched for, evaluated, and summarised the quality of the existing research on this topic.

Search date

We searched the literature up to May 2016.

Study characteristics
We included five small trials that randomised only 234 people, almost all with stroke. Two trials investigated dysarthria treatment versus an attention control and three compared one treatment with usual care. There were no trials that compared one treatment to no treatment.

Key results
We found few randomised controlled trials of dysarthria treatment, and those that have been conducted involved small numbers of participants, or were not adequately designed or had serious reporting flaws.

We compared many different measures at various time points after treatment, so caution is recommended when interpreting results. We found no evidence of effectiveness on most measures, including long-lasting improvement in every day communication abilities. A positive finding was short-term improvement in muscle movement, such as tongue and lip control. However, this result is not reliable because it was based on small numbers of people, and we found concerns about the conduct and reporting of some trials. This finding needs to be investigated in a bigger, better designed trial.

We found insufficient evidence to tell us whether any one treatment is better than any other or whether treatment is better than general support, or no treatment. We found no studies that examined timing, duration, or intensity of treatment. This is a clinically important question and should be considered in future trials.

Quality of the evidence
The included trials varied in quality but all included small numbers of participants. Overall, studies were rated as low to very low quality evidence.

Authors' conclusions: 

We found no definitive, adequately powered RCTs of interventions for people with dysarthria. We found limited evidence to suggest there may be an immediate beneficial effect on impairment level measures; more, higher quality research is needed to confirm this finding.

Although we evaluated five studies, the benefits and risks of interventions remain unknown and the emerging evidence justifies the need for adequately powered clinical trials into this condition.

People with dysarthria after stroke or brain injury should continue to receive rehabilitation according to clinical guidelines.

Read the full abstract...

Dysarthria is an acquired speech disorder following neurological injury that reduces intelligibility of speech due to weak, imprecise, slow and/or unco-ordinated muscle control. The impact of dysarthria goes beyond communication and affects psychosocial functioning. This is an update of a review previously published in 2005. The scope has been broadened to include additional interventions, and the title amended accordingly.


To assess the effects of interventions to improve dysarthric speech following stroke and other non-progressive adult-acquired brain injury such as trauma, infection, tumour and surgery.

Search strategy: 

We searched the Cochrane Stroke Group Trials Register (May 2016), CENTRAL (Cochrane Library 2016, Issue 4), MEDLINE, Embase, and CINAHL on 6 May 2016. We also searched Linguistics and Language Behavioral Abstracts (LLBA) (1976 to November 2016) and PsycINFO (1800 to September 2016). To identify further published, unpublished and ongoing trials, we searched major trials registers: WHO ICTRP, the ISRCTN registry, and We also handsearched the reference lists of relevant articles and contacted academic institutions and other researchers regarding other published, unpublished or ongoing trials. We did not impose any language restrictions.

Selection criteria: 

We selected randomised controlled trials (RCTs) comparing dysarthria interventions with 1) no intervention, 2) another intervention for dysarthria (this intervention may differ in methodology, timing of delivery, duration, frequency or theory), or 3) an attention control.

Data collection and analysis: 

Three review authors selected trials for inclusion, extracted data, and assessed risk of bias. We attempted to contact study authors for clarification and missing data as required. We calculated standardised mean difference (SMD) and 95% confidence interval (CI), using a random-effects model, and performed sensitivity analyses to assess the influence of methodological quality. We planned to conduct subgroup analyses for underlying clinical conditions.

Main results: 

We included five small trials that randomised a total of 234 participants. Two studies were assessed as low risk of bias; none of the included studies were adequately powered. Two studies used an attention control and three studies compared to an alternative intervention, which in all cases was one intervention versus usual care intervention. The searches we carried out did not find any trials comparing an intervention with no intervention. The searches did not find any trials of an intervention that compared variations in timing, dose, or intensity of treatment using the same intervention. Four studies included only people with stroke; one included mostly people with stroke, but also those with brain injury. Three studies delivered interventions in the first few months after stroke; two recruited people with chronic dysarthria. Three studies evaluated behavioural interventions, one investigated acupuncture and another transcranial magnetic stimulation. One study included people with dysarthria within a broader trial of people with impaired communication.

Our primary analysis of a persisting (three to nine months post-intervention) effect at the activity level of measurement found no evidence in favour of dysarthria intervention compared with any control (SMD 0.18, 95% CI -0.18 to 0.55; 3 trials, 116 participants, GRADE: low quality, I² = 0%). Findings from sensitivity analysis of studies at low risk of bias were similar, with a slightly wider confidence interval and low heterogeneity (SMD 0.21, 95% CI -0.30 to 0.73, I² = 32%; 2 trials, 92 participants, GRADE: low quality). Subgroup analysis results for stroke were similar to the primary analysis because few non-stroke participants had been recruited to trials (SMD 0.16, 95% CI -0.23 to 0.54, I² = 0%; 3 trials, 106 participants, GRADE: low quality).

Similar results emerged from most of the secondary analyses. There was no evidence of a persisting effect at the impairment (SMD 0.07, 95% CI -0.91 to 1.06, I² = 70%; 2 trials, 56 participants, GRADE: very low quality) or participation level (SMD -0.11, 95% CI -0.56 to 0.33, I² = 0%; 2 trials, 79 participants, GRADE: low quality) but substantial heterogeneity on the former. Analyses of immediate post-intervention outcomes provided no evidence of any short-term benefit on activity (SMD 0.29, 95% CI -0.07 to 0.66, I² = 0%; 3 trials, 117 participants, GRADE: very low quality); or participation (SMD -0.24, 95% CI -0.94 to 0.45; 1 study, 32 participants) levels of measurement.

There was a statistically significant effect favouring intervention at the immediate, impairment level of measurement (SMD 0.47, 95% CI 0.02 to 0.92, P = 0.04, I² = 0%; 4 trials, 99 participants, GRADE: very low quality) but only one of these four trials had a low risk of bias.