What is underweight? Nutrition

There are a number of reasons why children with muscle disease may be underweight:

It is a common misconception that all children with a muscle condition will be thin because of their reduced muscle bulk or as a result of loss of muscle or weakness. There are a wide variety of shapes and sizes in individuals with muscle conditions. While on one hand it is easier for the thin child to perform some movements and reduced weight makes transferring for parents/carers easier, it is also important to realise that maintaining good nutrition is fundamental to maintaining good health.

It is important to realise that, whatever the cause, there are often strategies that can be used to help lessen the problems associated with eating and it is important to discuss these with a specialist.

• Nocturnal hypoventilation: Some children who have nocturnal hypoventilation (not breathing well at nighttime) wake-up with a headache and do not feel well rested in the mornings and as a consequence may have a reduced appetite.
• Illness: When children with a muscle condition become unwell (eg, with a chest infection) they often lose weight. This is because they may lose their appetite and do not eat so much. At the same time, they need more calories and protein than usual to fight off an infection and help the body recover. Children can also have increased requirements for repair when they have had surgery and this is an important time to make sure they a receiving the right amount and kind of nutrition.
• Swallowing and Chewing: Children with a muscle condition sometimes have weakness of the muscles of the face and neck involved in chewing and swallowing. Weakness in these muscles can make chewing prolonged, particularly if the food is hard, chewy or textured. Additional problems that can be found in some children are teeth malposition, limited jaw opening, high arched palate or limited tongue movement. In order to overcome these difficulties often children take a long time to eat or eat only small amount of food. Some children who eat like this are labelled “fussy eaters” as they will often avoid certain textures and will opt for foods they find easy to chew.

In some cases the muscles involved in swallowing are not well co-ordinated and the child can be at risk of swallowing problems. When food or liquids go down the wrong way (aspiration) the child may cough and choke to try and stop it. If food goes down the wrong way and the child doesn’t cough (silent aspiration) the food or liquid passes into the lungs and could cause a chest infection.

• Gastro-oesophageal reflux: Reflux is the backflow of stomach contents from the stomach into the food pipe (oesophagus). Reflux may be due to poor muscle tone or scoliosis and can result in feeding problems. If an individual vomits or has frequent small regurgitation of stomach contents this can lead to pain and oesophagitis more commonly referred to as heartburn (irritation of the oesophagus). If the reflux is very frequent, the child will often associate eating as being a painful experience and not want to eat. This is known as “food aversion”. If regurgitated food comes back into the throat it could go down into the lungs and cause a chest infection or choking as described above.
• Getting full quickly: Sometimes poor muscle tone in the stomach can cause its contents to “empty out” slowly making a child feel full quickly or not feeling hungry. Again, this can result in small volumes of liquids and solids being taken.
• Reduced mobility: Reduced mobility can affect self-feeding abilities. A child may be unable to lift cutlery to their mouth or may be in an awkward position for feeding, or may get progressively more tired during the course of the meal. If the sitting position of a child is not good because of a curvature of the spine or neck, chewing and swallowing can become difficult. Because of these difficulties, mealtimes can last a long time or only small volumes are taken.
• Psychological/social factors: Some physical problems can lead to worries and fears about eating. If an individual is reluctant to eat or drink it may be because of a previous bad experience with choking. Long mealtimes can also result in a child feeling left out socially as their friends may finish their meals earlier and leave the table. Parental worries about poor weight gain and small volumes can lead to over enthusiastic approaches to eating such as lots of coaxing or force feeding. This approach may make a child reluctant to eat. Mealtimes are sometimes feared rather than being enjoyed. Assessment of feeding may help to identify difficulties and suggest various management options.

The specialist assessment team may consists of:

• Dietitian – will be involved in making an assessment of the types and amounts of food eaten via a food diary and assessments of growth chart measurements. This involves measuring weight and height and plotting these measurements on a growth chart. Height can be difficult to accurately obtain due to being wheelchair dependent or having limitations of joint range in the ankles or a curvature of the spine. There are other ways to estimate height eg by taking demi arm span measurements. Mid-arm circumference can also be a useful measurement if weightor height cannot be obtained. Repeated measurements over time are essential to look at change over time and assess growth. A diet history or food diary can give information about types, quantity and textures of food eaten. This also gives an indication of how balanced the diet is and which nutrients may be missing. Good growth is an indication of good nutrition. The dietitian is able to give advice on how to alter nutrients in the diet and also advise on alternative forms of feeding.
• Speech and Language Therapist – will take a feeding history and look at how the muscles of the tongue, lips and throat are working. In addition s/he will look at any other problems that may affect chewing eg, with teeth. The safety of swallowing and if there are any risks of food or drink going down the wrong way (aspiration) needs to be assessed to enable safe management. The doctors and speech therapist will evaluate if this needs to be assessed in more detail. A videofluoroscopy, which is an X-ray of swallowing, may be done to look closely at how food is chewed and swallowed.
• Doctors/Gastroenterologist - may investigate gastro-oesophageal reflux by doing a pH study or barium meal.
• Psychologist - may help with some of the social or emotional problems for the child and family that may result from eating and drinking difficulties.
• Occupational Therapist/Physiotherapist - may make suggestions on seating and positioning or any cutlery or equipment that may make eating easier.