Botulinum toxin for swallowing disorders

Many people have problems swallowing because of an impairment of the upper oesophageal sphincter (UOS), a high pressure zone within the tube that carries food from the mouth to the stomach. Many people with neurological conditions such as stroke, traumatic brain injury, Parkinson's disease or multiple sclerosis can have UOS impairment. This results in difficulty swallowing food and liquids, resulting in choking and food entering into the lungs (aspiration). This has serious consequences for the patient and can cause dehydration, malnutrition and aspiration pneumonia. The person's quality of life can be affected as they are unable to have food or liquids safely by mouth. Tube feeding and hospitalisation is often required.

Many interventions are used to improve UOS function. These include surgery, medications including botulinum toxin, rehabilitation exercises, diet modification and other compensatory techniques.

There is no clear consensus on whether botulinum toxin is safe and effective in managing UOS dysfunction in people with neurological conditions. This makes it hard to decide which intervention will be safest and most effective to improve swallowing and quality of life.

Only randomised controlled trials were sought for inclusion in this review. Trials were looked for through electronic searches of databases, searches of clinical trials registers, from peer reviewed journals, published conference proceedings and reference lists of relevant articles. No trials met the inclusion criteria for the review.

There is insufficient evidence to support the use of botulinum toxin to improve swallowing in people with UOS dysfunction and neurological disease. The lack of trials does not mean that this intervention is ineffective. Adequately powered well designed trials are required. In addition to using sensitive measures looking at changes in swallow function, measures are needed that examine client and caregiver satisfaction, changes in quality of life, psychological well-being and unwanted symptoms associated with the intervention.

Authors' conclusions: 

It was not possible to reach a conclusion on the efficacy and safety of botulinum toxin as an intervention for people with UOS dysfunction and neurological disease. There is insufficient evidence to inform clinical practice. Directions for future research are provided.

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Background: 

Adequate upper oesophageal sphincter (UOS) opening is critical to safe and efficient swallowing due to the close proximity of the UOS to the airway entrance. Many people with neurological conditions, progressive and non-progressive, present with UOS dysfunction. The consequences for the person include difficulty swallowing food with subsequent choking and aspiration (passage of material into the trachea beyond the level of the true vocal cords). Clinical complications include aspiration pneumonia, weight loss, dehydration and malnutrition. Tube feeding is often indicated but is associated with increased mortality. Quality of life is also frequently impacted. A range of interventions exist that aim to improve UOS function and swallowing. These include compensatory strategies, rehabilitation techniques, pharmacological interventions and surgery. Over the last two decades, botulinum toxin has been gaining popularity as an intervention for UOS dysfunction, with some evidence to suggest that it is successful in improving swallow function. Despite a number of studies investigating its efficacy, there is a lack of consensus regarding whether this intervention is effective in improving swallowing for individuals with UOS dysfunction associated with neurological disease.

Objectives: 

To establish the efficacy and safety of botulinum toxin use aimed at improving UOS dysfunction in people with swallowing difficulties (dysphagia) associated with non-progressive and progressive neurological disease.

Search strategy: 

We searched the following electronic databases for published trials: the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (1950 to 2013); EMBASE (1980 to 2013); AMED (Allied and Complementary Medicine) (1941 to 2013); CINAHL (Cumulative Index to Nursing and Allied Health Literature) (1937 to 2013). We also searched major clinical trials registers: CCT (http://www.controlled-trials.com); Clinical Trials (http://www.clinicaltrials.gov); Chinese Clinical Trial Register (www.chictr.org); ACTR (http://www.actr.org.au/. We examined the reference lists of all potentially relevant studies to identify further relevant trials. We handsearched published abstracts of conference proceedings from both the Dysphagia Research Society and the European Society of Swallowing Disorders. Digestive Disease Week (published in Gastroenterology) was also handsearched. Additionally, we searched ProQuest Dissertations & Theses for dissertation abstracts.

Selection criteria: 

Only randomised controlled trials were sought.

Data collection and analysis: 

Independent searches were completed by JR, AM, MC and MW. Two review authors (JR and MW) independently inspected titles, abstracts and key words identified from the literature search.

Main results: 

No randomised controlled studies were retrieved. Twenty-nine studies were excluded, mainly on the basis of trial design.

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