Spinal Muscular Atrophy GI and Nutrition Care
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Overview of Gastrointestinal and Nutritional Complications in Spinal Muscular Atrophy
From Consensus Statement for Standard of Care in Spinal Muscular Atrophy
The key clinical problems associated with gastrointestinal and nutritional complications in spinal muscular atrophy are as follows:
- Feeding and swallowing problems. Bulbar dysfunction is universal in spinal muscular atrophy patients with severe weakness and can result in feeding and swallowing difficulties and aspiration pneumonia, which often results in death. The severity of bulbar dysfunction is variable in patients with spinal muscular atrophy of intermediate severity and rare in those who are mildly affected.
- Gastrointestinal dysfunction. Gastroesophageal dysmotility problems include constipation, delayed gastric emptying, and potentially life-threatening gastroesophageal reflux.
- Growth and undernutrition/overnutrition problems. Without optimal management, growth failure is universal in nonsitters, whereas excessive weight gain is more common in sitters and walkers.
- Respiratory problems. The presence of respiratory complications (weak cough, increased work of breathing, dyspnea, pneumonias, and cyanosis or desaturation with feeds) raises concern for gastrointestinal problems of aspiration and gastroesophageal reflux, which can be serious and life-threatening. Increased work of breathing may also result in increased energy expenditure.
Swallowing
Written for FightSMA by Robert T. Leshner, M.D., Professor, Neurology and Pediatrics, Children’s National Medical Center
This is a particularly sensitive issue in children with Type I (and some children with Type II) spinal muscular atrophy. Difficulty with chewing and swallowing may predispose to aspiration and pneumonia. A skilled speech pathologist may be able to identify certain foods which pose a particular hazard to the child. This is often done with the assistance of a special x-ray study called a “swallowing study and cine esophagram.” Direct observation of how a child swallows thin liquids, semisolid and solid foods often guide the therapist and parents to the safest diet. It is critical for children with neuromuscular disease to maintain adequate nutrition; a body deprived of calories and protein will often turn to its own muscles as a source of nourishment. Those children who can not safely swallow liquids or semisolids may be helped with alternative means of feeding including nasogastric (NG) tubes and gastrostomy tubes. The NG tube is inserted through the nose, down the esophagus (food pipe), and into the stomach. Parents can often learn how to place these tubes to assist their children’s nutrition. A gastrostomy tube (or PEG) is inserted by a surgeon or gastroenterologist. These devices allow nourishing liquids to be placed directly into the stomach. Although many parents find the concepts of an NG or PEG tube frightening, they are actually simple means of dealing with a potentially serious problem.
Feeding and Swallowing Problems
From Consensus Statement for Standard of Care in Spinal Muscular Atrophy
Feeding and swallowing difficulties are common in nonsitters and sitters but are rarely a concern in walkers. Key symptoms of feeding difficulties include prolonged mealtime, fatigue with oral feeding, and evident choking or coughing during or after swallowing. The presence of recurrent pneumonias is a potential indicator of aspiration, which may be silent (ie, without evident choking or coughing). Articles in the literature addressing the role of oral motor structures and specific chewing and swallowing impairments that impact oral feeding performance in spinal muscular atrophy are limited to class III and IV evidence. One review found a 36% prevalence of at least 1 feeding-related issue in children with spinal muscular atrophy. Several other population studies and case series report swallowing problems in patients with spinal muscular atrophy. Difficulties in the preoral phase included limited mouth opening and difficulties in getting food to the mouth for self-feeding. In the oral phase, difficulties included weak bite force, reduced range of mandibular motion limiting mouth opening, and increased fatigue of masticatory muscles. This affects biting and chewing abilities and can lead to prolonged mealtimes and fatigue, precluding sufficient intake. Masticatory and facial muscle weakness affects oral bolus control, chewing, and bolus propulsion, all of which contribute to reduced feeding efficiency. Difficulties with strength and efficiency are reported in the oral and pharyngeal phase of the swallow. Poor coordination of the swallow with airway closure can lead to penetration and aspiration of the airway. Poor head control may also be a factor in the development of feeding difficulties, precluding neck tuck or other compensatory postures to enhance the safety of swallowing. The psychosocial impact of feeding difficulties on these children and their family should not be underestimated. Prolonged mealtimes can put time pressure on other activities. In addition, their inability to feed themselves can make these children seem more dependent than their peers and lead to a sense of loss of control. In the weakest children, tube feeding can limit the nurturing role parents perceive from being able to orally feed their child.
Evaluation of Feeding and Swallowing Problems
Assessment of feeding problems should be performed by a feeding specialist, most commonly a speech or occupational therapist. Routine clinical evaluation of feeding and swallowing difficulties should include a feeding assessment. Videofluoroscopic swallow studies should be performed when indicated. A feeding case history with mealtime observation is desirable. Examination of oral structures that influence feeding efficiency and consideration of the effect of positioning and head control on feeding and swallowing are essential. Videofluoroscopic swallow studies should be carried out after initial assessment if there are concerns about swallow safety. Laryngeal aspiration requires specific assessment, as it is sometimes silent (ie, no clearing cough is triggered). In severely affected children, vocal fold paralysis and consequent inability to protect the airway may be a diagnostic sign. A videofluoroscopic swallow study is not simply a diagnostic test of aspiration but is an opportunity to evaluate therapeutic strategies, such as adapted food texture and positioning, to assess impact on swallow function. As position and consistency can affect swallow physiology, it is important that the videofluoroscopic swallow studies procedure is as representative of the child’s usual meal and feeding position as possible.
Management of Feeding and Swallowing Difficulties
Treatment should aim at reducing the risk of aspiration during swallow and optimizing efficiency of feeding and promote enjoyable mealtimes. A Cochrane review of treatment of swallowing difficulties in chronic muscle disease concluded it was not possible to determine the benefit or otherwise of dietary and feeding advice, surgical intervention (cricopharyngeal myotomy or upper esophageal dilatation), and enteral feeding. Changing food consistency and optimizing oral intake are appropriate treatment strategies. The literature suggests there is currently widespread use of consistency modification in helping to optimize oral intake. A semisolid diet can be used to compensate for poor chewing and reduce length of mealtimes. Thickened liquids may protect against aspiration of thin fluids. Preferably, this intervention would be evaluated objectively on videofluoroscopic swallow studies. In 1 study, complete restriction orally to eliminate risk of aspiration during swallowing was not found to significantly affect the clinical course in severe spinal muscular atrophy. This study failed to consider the risk of aspiration due to concomitant gastroesophageal reflux. Positioning and seating alterations and orthotic devices (eg, Neater Eater, elbow support, valved straw) to enhance self-feeding ability may improve swallow safety and efficiency. Such interventions should be planned in liaison with an occupational therapist and/or physiotherapist as required. There is currently no supporting evidence that oral motor treatment programs impact safety or efficiency of oral feeding.
The gastrointestinal/nutrition working group did not reach consensus regarding when to refer a patient with spinal muscular atrophy for consideration for gastrostomy tube placement and whether one should supplement or replace oral feeding with tube feeding in a nonsymptomatic patient. Some practitioners prefer a proactive approach, particularly in the nonsitters, whereas others believe that exposing such patients to the risk of surgery is inappropriate prior to the onset of symptoms. However, 1 clear consensus is that optimal management requires proactive nutritional supplementation as soon as inadequate oral intake is recognized. Whether a gastrostomy tube is placed in a particular child often requires extensive discussion with multiple caregivers. It usually takes time to schedule a surgical procedure like gastrostomy tube placement. In the interim, nutritional supplementation via nasogastric or nasojejunal feeding is desirable. Nasojejunal feeding may be preferable in circumstances when gastroesophageal reflux with aspiration is a concern, especially when the patient is on ventilatory support. However, technical difficulty may prevent its feasibility. Gastrostomy tube feeding is the optimal method of feeding when insufficient caloric intake or unsafe oral feeding is of concern. It prevents the potential morbidity associated with prolonged use of either nasogastric or nasojejunal tubes. The presence of a nasojejunal or nasogastric tube may also result in a less-than-ideal mask fit when there is a need for the use of noninvasive ventilation such as bilevel positive airway pressure.
There are several options for gastrostomy tube placement, including insertion via percutaneous methods with endoscopic guidance, or placement via open or laparoscopic surgical techniques together with an antireflux procedure such as Nissen fundoplication. The open surgical technique is associated with a relatively large upper abdominal incision, increased postsurgical pain, and risk for respiratory complications due to diaphragmatic splinting. A laparoscopic surgical technique provides the best possible setting for immediate or early postoperative extubation. Such procedures are typically performed with general anesthesia, although placement using percutaneous methods with endoscopic guidance is performed in some centers with conscious sedation and local anesthesia. Care should be taken to minimize the amount of fasting preoperatively and to resume full nutritional support as quickly as possible following the procedure. Possible pulmonary complications of sedation should be anticipated and may require treatment with noninvasive ventilation (see “Pulmonary Care”).
Gastrointestinal Dysfunction
From Consensus Statement for Standard of Care in Spinal Muscular Atrophy
Children with spinal muscular atrophy suffer from the following gastrointestinal problems: gastroesophageal reflux, constipation, and abdominal distension and bloating. Gastroesophageal reflux is an important determinant of mortality and morbidity in patients with spinal muscular atrophy. It can be associated with silent aspiration and results in pneumonias and, at times, life-threatening events. Frequent “spitting up” or vomiting after meals, complaints of chest or abdominal discomfort, bad breath, or obvious regurgitation of feeds may indicate gastroesophageal reflux. Some children may refuse feeds when they develop discomfort with swallowing, placing them at risk for undernutrition. High-fat foods delay gastric emptying and increase the risk of gastroesophageal reflux. Constipation is a frequently reported problem and is likely multifactorial in origin (ie, abnormal gastrointestinal motility, reduced intake of dietary fiber, inadequate fluid intake, low muscle tone of the abdominal wall). Infrequent bowel movements can lead to abdominal distention and bloating. In children dependent on their abdominal muscles to assist with respiration, desaturation or respiratory distress in association with attempted bowel movements may occur.
Evaluation of Gastrointestinal Dysfunction
The symptoms of gastroesophageal reflux (emesis, regurgitation, gurgling after feeds) should be sought early. A routine upper gastrointestinal series is recommended for presurgical evaluation for gastrostomy tube placement to primarily rule out anatomic anomalies and secondarily to document reflux. In rare cases, esophageal stricture, foreign body, or other abnormality may contribute to swallowing difficulties or gastrointestinal dysmotility. Motility studies, including scintigraphy, can be helpful in documenting delayed gastric emptying, which may contribute to gastroesophageal reflux and early satiety. There are no data to support the routine diagnostic use of pH probe studies in documenting reflux.
Management of Gastroesophageal Reflux
Medical management of gastroesophageal reflux typically involves the use of acid neutralizers (eg, magnesium or calcium carbonate) and/or inhibitors of acid secretion. This latter category includes both histamine blockers and proton pump inhibitors (eg, famotidine, ranitidine, omeprazole). Short-term use of these agents is reasonable for symptomatic management. However, increasing evidence suggests that prolonged use of these agents may be associated with a greater risk for gastroenteritis and pneumonia. When delayed gastric emptying or diminished motility is present, prokinetic agents may be useful (eg, metaclopramide, erythromycin). Use of probiotics such as acidophilus or lactobacillus to help maintain a healthy gastrointestinal flora, particularly after antibiotic treatment or in the setting of prolonged use of acid inhibitors, is an area deserving further study.
Gastrostomy tube feeding does not ameliorate gastroesophageal reflux. This is of particular concern in nonsitters who are the least able to protect their airway via a triggered cough. Determining whether aspiration has occurred during swallow or as a result of gastroesophageal reflux is often difficult, and sometimes both may contribute. A laparoscopic antireflux procedure (eg, Nissen fundoplication) is commonly performed as a combined procedure during the same general anesthesia for gastrostomy tube insertion. Although some physicians support a proactive combined laparoscopic Nissen and gastrostomy tube procedure in those children with spinal muscular atrophy who are deemed at greatest risk for aspiration, there is as yet no published data nor consensus to support this strategy. However, in the spinal muscular atrophy patient with medically refractory gastroesophageal reflux, and in whom the benefit is deemed to outweigh the associated surgical and anesthetic risks, laparoscopic Nissen fundoplication during gastrostomy tube placement is supported as an appropriate intervention.
Growth and Undernutrition/Overnutrition Problems
From Consensus Statement for Standard of Care in Spinal Muscular Atrophy
Children with spinal muscular atrophy are at risk for growth failure or excessive weight gain. Growth failure is commonly seen in nonsitters and some sitters, whereas obesity is a problem of the stronger sitters and walkers. There are no articles in the literature that specifically address body composition and growth expectations or typical anthropometric measures in children with spinal muscular atrophy. However, data can be extrapolated from literature on patients with spinal cord injury. Individuals with spinal cord injury have been shown to have lower lean tissue and higher percentage body fat than controls. Body mass index significantly underestimates body fat in these patients. Children with spinal muscular atrophy may have acceptable fat mass but may plot as underweight based on weight/height criteria due to the decrease in lean body mass. Hence, normal body mass indexes may not represent the ideal weights for children with spinal muscular atrophy. Decreased activity and lean body mass will lead to reduced resting energy expenditure and increased risk of obesity.
Management of Growth and Undernutrition or Overnutrition Problems
Routine history, physical examination, and monitoring of growth velocity measures (growth charts) form the evaluation process to detect signs and symptoms of growth failure or excess. This will influence decisions regarding when and how to intervene. The goal is to maintain each child on his or her own growth velocity. Growth velocity curves (weight, height/length, weight/height) followed over a period of time are, for the most part, the most accurate indicator of nutritional status. Difficulty in obtaining accurate standing height measurements due to contractures or inability to stand may complicate growth monitoring in these children. Recumbent length, segmental measurements, or arm span may be useful surrogate markers for linear growth in these children. Other methods for monitoring body composition include skinfold measurements, muscle circumference, or bioelectric impedance analysis. Assessment of nutritional intake by a dietitian or other health care provider proficient in nutrition is recommended at each visit. A 3-day dietary record is a simple and accurate tool that can help assess whether nutritional intake is adequate. A 24-hour food recall is a practical method to highlight major nutritional concerns and to obtain information regarding use of any special supplements. Analysis should target adequacy of macronutrient (including fiber intake) as well as micronutrient intake. Currently, there is no indication for increasing or decreasing specific nutrients (ie, protein, fat, or selected vitamins or minerals). Until more specific data are available, nutrient intake should meet the daily recommended intakes for age. Supplements to provide more than the dietary recommended intake for vitamin, mineral, protein, or fat should be discouraged. Although anecdotal benefit with the use of elemental or semi-elemental formulas has been reported by some families and care providers (satisfactory growth and decreased secretions), there is currently insufficient data to make specific recommendations regarding their use. If an elemental formula is used, a dietitian should be involved to help ensure the child does not receive insufficient or excessive amounts of nutrients, to perform laboratory assessments as needed, and to monitor adequate growth. As previously mentioned, with a reduction in lean body mass, calculated body mass index will significantly underestimate body fat. Children with spinal muscular atrophy may have acceptable fat mass but may be perceived as underweight based on weight/height criteria because of their decreased lean body mass. This will result in inappropriate dietary recommendations that could lead to relative obesity. The spinal muscular atrophy patients at risk for obesity should have growth parameters in the lower percentiles for weight/height and body mass index. In any case, each child should be evaluated individually on a routine basis, with the goal of following their established growth curves and avoiding inadequate or excessive intake. There is some evidence that decreased bone mineral density may occur in nonsitters and sitters, resulting in recurrent fractures in a subset of patients. There is preliminary evidence that dual energy x-ray absorptiometry could be a useful technique for estimating lean versus fat mass in spinal muscular atrophy patients. However, insufficient data are available at this time to recommend the routine use of dual energy x-ray absorptiometry scans for monitoring bone mineral density or body composition. Instead, the importance of documenting appropriate intake of calcium and vitamin D was emphasized. There is no consensus regarding performing biochemical tests to monitor nutritional status for patients with spinal muscular atrophy. However, consideration should be given to checking prealbumin levels to help assess adequate protein status.
Management of Nutrition in the Acutely Sick Spinal Muscular Atrophy Patient
From Consensus Statement for Standard of Care in Spinal Muscular Atrophy
Spinal muscular atrophy patients are particularly vulnerable to catabolic and fasting states. Patients with severe muscle wasting from any disorder, including spinal muscular atrophy, are more likely to develop hypoglycemia in the setting of fasting. A number of case series and individual case reports have documented secondary mitochondrial dysfunction and abnormalities of mitochondrial fatty acid oxidation in spinal muscular atrophy patients. Significant abnormalities are most likely in nonsitters and sitters, increasing their vulnerability for metabolic decompensation in the setting of a catabolic state. Thus, it is necessary to avoid prolonged fasting, particularly in the setting of acute illness, in all spinal muscular atrophy patients. Nutritional intake should be optimized to meet full caloric needs within 4 to 6 hours after an admission for acute illness, via enteral feeding, parenteral feeding, or a combined approach as necessary. Prompt postoperative caloric supplementation is recommended to avoid muscle catabolism, particularly in a child with reduced fat store. If enteral intake is not imminent, then intravenous caloric feeding should be considered.
Conclusion
From Consensus Statement for Standard of Care in Spinal Muscular Atrophy
Because nutritional problems associated with spinal muscular atrophy influence the patient’s pulmonary status and general well-being, optimal management of these problems by a multidisciplinary or interdisciplinary team of physicians, speech therapists or occupational therapists, dietitians, and pediatric surgeons should greatly improve survival and quality of life.