Abstract
[Purpose] This study aimed to clarify the eating difficulties experienced by patients with spinal muscular atrophy type 2 in Japan. [Participants and Methods] This cross-sectional study was part of a larger survey of Japanese patients with spinal muscular atrophy that included the use of a questionnaire. The feeding questionnaire was developed by a medical professional and validated before survey administration. Of 221 patients who completed and returned the questionnaire, 62 had spinal muscular atrophy type 2. The average age of the study patients was 17.6 years (± 11.7 years). To identify feeding problems experienced by patients with spinal muscular atrophy type 2 by age, the participants were divided into the following three groups: 0–11 years, 12–19 years, and 20 years or older. [Results] The frequency of choking episodes during meals in Japanese patients with type 2 spinal muscular atrophy was 66.1% and increased with age. [Conclusion] Ongoing swallowing evaluation and feeding instructions are necessary for patients with spinal muscular atrophy type 2.
Keywords: Feeding, Choking episodes, Spinal muscular atrophy
INTRODUCTION
Spinal muscular atrophy (SMA) is a lower motor neuron disease characterized by muscle degeneration and progressive loss of muscle strength caused by motor neuron degeneration in the spinal cord1, 2). The prevalence of SMA is about 1 in every 10,000–20,000 live births3, 4). Childhood-onset SMA is classified as type 1, type 2, or type 3 based on the age when symptoms appear and maximum motor ability. The onset of SMA type 1 occurs within a half year, and motor function declines rapidly beginning from the early weeks of life. SMA type 1 patients experience difficulty supporting their neck, require continuous respiratory support, and often experience difficulty with oral intake5). Typically, SMA type 2 manifests by 1.5 years of age. The maximum motor ability achieved by patients with SMA type 2 is sitting; standing and walking are difficult for these patients6). Symptoms of SMA type 3 usually begin after age 1.5 years. Patients with SMA type 3 have the ability to walk; however, they fall easily and experience difficulty ascending and descending stairs7). In Japan, the most common type of SMA is type 28).
SMA is associated with motor neuropathy and complications such as muscle weakness, breathing problems, joint contractures, scoliosis, and difficulty eating. Eating difficulties and gastrointestinal symptoms are particularly important because of their associations with lifelong problems, such as inadequate weight gain, growth restriction, and food or liquid entering the airway. Eating disorders are most often observed in SMA type 2 patients who are able to sit up; however, they are rare among patients with SMA type 3 who have the ability to walk. While there have been systematic reports of feeding difficulty studies in SMA type 2 patients overseas9), no such reports exist in Japan. As dietary habits vary by region, understanding the unique feeding difficulties in SMA type 2 patients in Japan, considering its predominantly rice-based diet, is critical for tailoring interventions.
The purpose of this study was to investigate the eating difficulties experienced by patients with SMA type 2 in Japan. This study was also conducted as part of a large-scale survey10, 11). In our previous study, we conducted surveys on powered wheelchair creation and on chronic pain in patients with spinal muscular atrophy10, 11). In the current study, we assessed a new hypothesis that eating difficulties increase with age in patients with spinal muscular atrophy.
PARTICIPANTS AND METHODS
This survey was conducted as an observational cross-sectional study using a questionnaire from October 2017 to December 2017. The questionnaire was self-administered and anonymous. The secretariat of the Japan SMA Family Association distributed the questionnaire to 221 of its members. The questionnaires were returned to the person leading the research. Patients younger than 18 years were instructed to provide responses with the assistance of a parent or guardian. The survey was approved by the institutional review board of the institute to which the first author belongs. Consent of the participant was implied by the completion and return of the questionnaire.
The questionnaire was drafted by the researchers and discussed with physical therapists, pediatric neurologists, and physiatrists. The draft questionnaire was created by asking several patients with SMA to check and revise the included words and phrases. Data regarding age, sex, body weight, spinal surgery, tracheotomy, gastrostomy, nutritional status, and motor function were collected to evaluate the background characteristics of the patients. Data regarding meal times, eating postures, difficulty opening the mouth, difficulty chewing, and choking episodes were collected to investigate feeding issues.
To identify feeding issues experienced by SMA type 2 patients according to their life stage, the participants were divided into the 0 to 11 years, 12 to 19 years, and 20 years or older age groups. Clinical characteristics and feeding issues of patients in these age groups were compared using the χ2 test and one-way analysis of variance. Statistical analyses were performed using IBM SPSS Statistics for Windows (IBM Corp., Armonk, NY, USA), with significance set at <5%.
RESULTS
A total of 135 questionnaires were collected, resulting in a collection rate of 61.1%. Sixty-four respondents were patients with SMA type 2. Two of these 64 surveys were excluded because of missing data; therefore, a total of 62 valid questionnaires were evaluated. Table 1 shows the clinical characteristics and motor functions of SMA type 2 patients classified by age. Significant differences in body weight, spinal surgery, tracheostomy, and sitting were observed between groups; however, no differences in other characteristics were observed. Table 2 shows the feeding issues of SMA type 2 patients classified by age. Significant differences in meal times and choking episodes were observed between groups.
Table 1. Clinical characteristics of spinal muscular atrophy type 2 patients.
| All patients n=62 |
0–11 years n=21 |
12–19 years n=21 |
20 years or older n=20 |
|
| Age, years | 17.6 ± 11.7 | 7.7 ± 2.6 | 17.3 ± 2.0 | 30.7 ± 10.8 |
| Male, n (%) | 29 (46.8) | 14 (53.8) | 8 (50.0) | 7 (35.0) |
| Body weight, kg* | 27.4 ± 13.0 | 19.1 ± 5.5 | 32.4 ± 12.1 | 34.3 ± 14.7 |
| Spinal surgery, n (%)† | 14 (23.0) | 0 (0) | 8 (50.0) | 6 (31.6) |
| Tracheostomy, n (%)† | 3 (4.9) | 0 (0) | 0 (0) | 3 (15.8) |
| Gastrostomy, n (%) | 7 (11.5) | 4 (15.4) | 2 (12.5) | 1 (5.3) |
| Oral intake only, n (%) | 54 (88.5) | 19 (90.5) | 17 (81.0) | 18 (94.7) |
| Motor function | ||||
| Rolling over or bottom shuffling, n (%) | 14 (23.0) | 12 (46.2) | 2 (13.3) | 0 (0) |
| Sitting, n (%)† | 34 (54.8) | 20 (76.9) | 7 (43.8) | 7 (35.0) |
*p<0.05: one-way analysis of variance, †p<0.05: χ2 test.
Table 2. Feeding issues experienced by spinal muscular atrophy type 2 patients.
| All patients n=62 |
0–11 years n=21 |
12–19 years n=21 |
20 years or older n=20 |
|
| Meal time, min* | 35.2 ± 18.6 | 31.0 ± 7.9 | 26.9 ± 12.5 | 48.2 ± 25.9 |
| Eating posture | ||||
| Sitting on a chair, n (%) | 16 (21.6) | 6 (23.1) | 6 (23.1) | 4 (18.2) |
| Sitting with a positioning device, n (%) | 33 (44.6) | 15 (57.7) | 10 (38.5) | 8 (36.4) |
| Sitting on a buggy, n (%) | 1 (1.4) | 1 (3.8) | 0 (0) | 0 (0) |
| Sitting on a bed, n (%) | 8 (10.8) | 1 (3.8) | 4 (15.4) | 3 (13.6) |
| Other, n (%) | 16 (21.6) | 3 (11.5) | 6 (23.1) | 7 (31.8) |
| Difficulty opening the mouth, n (%) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| Difficulty chewing, n (%) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| Choking episodes, n (%)† | 41 (66.1) | 14 (53.8) | 9 (56.3) | 18 (90.0) |
*p<0.05: one-way analysis of variance, †p<0.05: χ2 test.
DISCUSSION
During this study, we investigated feeding difficulties experienced by Japanese SMA type 2 patients and found that these patients experience more frequent choking episodes with increasing age. Previous systematic reviews have found an increased prevalence of dysphagia with increasing severity of the SMA phenotype and age12). Additionally, a survey of SMA type 2 patients in Italy indicated that nearly half of the patients in the 20 years or older age group experienced choking episodes9). Previous studies in Italy and the U.S. reported a similar trend in increasing choking episodes with age. However, dietary and rehabilitation differences may influence the severity of symptoms in Japan. Eating habits in Japan differ from those in Western countries13). Furthermore, the frequency of rehabilitation interventions, including feeding guidance, for SMA also differs14). Therefore, it is important to investigate dysphagia unique to Japan. In the present study, choking episodes at meal time occurred more frequently among Japanese patients with SMA who were 20 years or older. Japanese diets tend to be lower in fat and higher in carbohydrates and protein compared to those of Western countries, and rice is a major component of the Japanese diet15). Rice starch may affect chewing and swallowing because of the changes in firmness that occur as its concentration increases16).
Dysphagia in SMA type 2 patients is caused by neurological dysfunction. One study reported that a videofluoroscopic swallow study showed the presence of solid food residue on the upper esophageal sphincter of such patients17), which may cause aspiration. The increased frequency of chewing and increased time required to process food in the oral cavity to allow safe swallowing prolong the meal time18). The findings of this study indicated that many patients with SMA type 2 experience choking episodes during meals, and that these episodes increase with age. SMA type 2 patients should be evaluated using a videofluoroscopic swallow study to ensure safe and efficient eating. Future interventions should include multidisciplinary dysphagia assessments involving physical therapists, speech-language pathologists, and nutritionists to optimize feeding strategies for SMA type 2 patients.
A limitation of this study is that the results were not based on accurate genetic diagnosis or swallowing tests because the questionnaire was self-administered. Future studies should also consider the results of diagnostic swallowing function tests and postural assessments. Additionally, SMA is a rare disease and the number of participants in this study was small, so post hoc tests and multivariate analysis could not be conducted. In the future, we believe that a survey with a larger number of subjects, collected across a wider area including Asian regions, would be beneficial.
In conclusion, patients with SMA type 2 experience more frequent choking episodes as they age.
Funding
This study received funding from a research grant provided by the Tokyo Metropolitan Physical Therapy Association.
Conflict of interest
The authors declare no conflicts of interest.
Acknowledgments
We thank the respondents to the survey and the Japan SMA Family Association for research assistance. We also thank the physicians and physical therapists at our institutions for their help with collecting the questionnaires and advice regarding the research.
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