Type 2

This information sheet briefly explains the cause, effects, and management of Spinal Muscular Atrophy (SMA) Type 2. It includes sources of further information and support. It is for the families of children diagnosed with SMA Type 2. It may also be useful for healthcare and other professionals.

SMA Type 2 is a complex condition; there is a lot of information to take in, and every child with SMA is different. Your child’s medical team will always be happy to go over any of this with you.

What is SMA Type 2?

SMA Type 2 is sometimes called intermediate SMA or chronic infantile SMA. The symptoms of muscle weakness and floppiness (low tone / hypotonia) usually appear between 7 and 18 months of age.

Each child with SMA Type 2 is different.  Some children will sit independently whilst others will require some support. Usually children with SMA Type 2 will need supportive aids for standing and a wheelchair to get around.

Sometimes doctors try to indicate the degree of severity within SMA Type 2 by using a decimal classification3, for example, 2.1, 2.2, 2.5, 2.9. If you have any queries regarding this please speak to your child’s medical team.

Though this is a serious inherited neuromuscular condition that may shorten life expectancy, improvements in care standards mean that the majority of people can live long, fulfilling and productive lives.

How is SMA Type 2 diagnosed?

A doctor will diagnose SMA Type 2 after taking a medical history, physically examining your child, and by taking a blood sample for DNA testing. The blood sample is tested for a deletion mutation in the survival motor neurone 1 (SMN1) gene on chromosome 5. The result of this test is usually available within 2 – 4 weeks.

If there is any uncertainty about the diagnosis, further muscle tests such as an electromyogram (EMG) or a muscle biopsy may be discussed, but these are not usually needed to confirm SMA.

Is there a treatment or cure for SMA Type 2?

There is currently 1 approved treatment for SMA, Spinraza™, available in certain countries in Europe. If Spinraza™ is not available, symptoms can be managed so that your child can achieve their maximum mobility, independence, and quality of life.

What are the effects of SMA Type 2?

This section describes the effects of SMA Type 2 in general terms. But, it’s important to remember that each child with SMA Type 2 is affected differently and the severity of the condition varies from child to child.

Children’s muscle weakness is usually the same on both sides of their body (symmetrical). The muscles closest to the centre of their body (proximal muscles) are usually more severely affected than the muscles furthest from the centre of their body (distal muscles). This can make it difficult for children with SMA Type 2 to lift their arms and legs but they will still be able to use their hands and fingers.  Generally, children with SMA Type 2 find that their legs are weaker than their arms.

As your child grows it may be difficult for their muscles to keep up with their daily activities. If your child has been able to, for example, crawl or roll, they may lose this ability as they get older. They may also become weaker after infections and at times of major growth spurts such as puberty. SMA doesn’t affect a child’s sexual or intellectual4 development.

Because a child with SMA Type 2 has weak respiratory muscles it can be difficult for them to cough effectively. This can make them more vulnerable to respiratory (chest) infections.

In SMA Type 2 the muscles supporting the spinal column are weakened. This means that most children will develop a sideways curvature of their spine5 (scoliosis). Also, because the condition reduces children’s ability to move, some joints may become tight (contracture) restricting their range of movement.

SMA Type 2 can weaken children’s chewing and swallowing muscles (bulbar muscles). Some children find that their tongue or shoulder muscles twitch (fasciculation) and they may have a slight tremor in their hands6. SMA Type 2 doesn’t affect bladder and bowel control but children will need help, for example, with transferring from their wheelchair to the toilet, dressing, and undressing.

What healthcare and support is needed for SMA Type 2?

Your child should receive care from a multidisciplinary healthcare team, which can feel like an overwhelming number of people but they all have an important role to play. You will have contact with specialists in neuromuscular conditions, respiratory medicine, orthopaedics, physiotherapy, occupational therapy, speech and language therapy, dietetics, and a hospital or community consultant paediatrician. If possible one of the team should be your keyworker whose job it is to help co-ordinate services for your family.

Children with SMA Type 2 should be seen by their medical team regularly to measure any change in their health and to offer advice and interventions at the right time. The aim is to enable your child to remain healthy and enjoy a good quality of life.

At every appointment with your child’s medical team you should be given time to ask questions and then jointly decide what support is best for your child.

Children with SMA Type 2 can have breathing problems such as hypoventilation and their muscle weakness can lead to an increased risk of respiratory (chest) infections. Some may need help with their breathing and coughing. Your child’s medical team will advise you on what is best for your child.

You can read an overview of what good respiratory management involves in the booklet ‘Standards of Care for Spinal MuscularAtrophy – the family guide’ 7. As each child is affected differently it’s important to discuss any queries you have with your child’s medical team.

Children with SMA Type 2 sometimes have difficulty with their chewing, swallowing, and nutrition.

Your child’s health visitor, consultant, speech and language therapist, or dietitian will be able to provide advice and support on eating and nutrition. Occupational therapists and physiotherapists may also advise on positioning, seating, or arm supports to help your child to eat independently.

Your child may have problems putting on weight if eating becomes tiring for them or if they have illnesses or infections. Equally, your child may become overweight due to their reduced mobility. If this happens the extra weight can increase the stress on muscles, bones and joints, making physical activity even more difficult. A dietitian will be able to advise on a healthy diet that will suit your child.

If your child has difficulty swallowing there is a risk that they may inhale liquids or food into their lungs (aspirate) which can cause chest infections. If this is happening, or your child is not putting on weight, your child’s medical team may suggest alternative ways for them to take in food. This may involve your child’s food going through a tube directly into their stomach (gastrostomy (G) tube).

Children with SMA Type 2 can become constipated which may cause discomfort and can make breathing more difficult. You can discuss how to manage this with your child’s medical team.

Muscle weakness may make it difficult for your child to open their mouth widely. This can cause problems with eating, teeth cleaning, and dental care. Regular dental check-ups and getting help with these sorts of problems early may help to prevent complications such as aspiration8, when food gets into the lungs.

SMA Type 2 will mean that your child will have difficulties with their posture, movement, and mobility. They will need their own exercise routines designed by their physiotherapist to help with this. Routines may include exercises to help maintain their range of motion, reduce any discomfort, stretch any tight muscles, and prevent contractures. Regular gentle stretching of their tight joints can help to reduce the pain that contractures can cause. If your child does have any pain, do talk to their doctor and physiotherapist. Your child might enjoy doing these exercises in the bath, or a swimming or hydrotherapy pool as the warm water aids buoyancy.

Regular moderate exercise will also help your child to maintain their fitness and stamina and activities such as swimming and horse riding can be adapted to match their physical ability.

Although your child will lose muscle strength over time, it is important that they maintain activities like supported standing for as long as possible. Standing is good for breathing, blood circulation, bladder, bowels, bones and joints.

As your child’s physical abilities change, an occupational therapist will advise what sort of seating will give them the best, most comfortable support. This will make it easier for them to play with toys, eat independently, and join in at home and at school.

A physiotherapist will assess your child and provide appropriate equipment to support their standing and positioning. Some children benefit from having splints (sometimes called orthoses) for support. Types of orthoses include ankle foot orthoses (AFOs) and knee, ankle, foot orthoses (KAFOs). These will be made specifically for your child by an orthotist who will explain how they will help.

Your child’s physiotherapist and occupational therapist will be able to advise you about powered wheelchairs. This should be at around the time that your child would have been learning to walk. This equipment will mean that they will be able to explore and join in much more easily and this will help with their physical, emotional, social, and educational development9.

As already mentioned, most children with SMA Type 2 develop a sideways curvature of their spine (scoliosis). It is important that the medical team monitors your child regularly so that any increase in curvature is noticed early. The degree of the curvature and your child’s age will be factors in deciding how to manage this. Initially this may be with a spinal brace or jacket but surgery to correct scoliosismay be recommended if the scoliosis is contributing to breathing difficulties, is preventing comfortable sitting, or if the curvature has progressed beyond a certain point.

You may be provided with a sleep system which will support your child’s back, arms, and legs, and make sleeping more comfortable. Your occupational therapist can advise you about sleep systems.

Occupational therapists can also give you advice about other adaptations and equipment that will help with your child’s everyday activities such as writing, playing, washing, dressing, cooking and eating, both at home and at school. With appropriate encouragement, adaptations, and support, your child will be able to lead as fulfilling a life as their friends.

Your child’s medical team may work with you to develop an emergency health plan.  This records the treatment you wish your child to receive if there is an emergency or if their health deteriorates.  You should have your own copy so that you can give it to hospital services if you are away from your home area. The plan can be reviewed and you can change your mind about its contents at any time.

What other help is available?

A diagnosis of SMA Type 2 with all its complexity has an enormous impact on families. It’s important for you and your child to have emotional support and plenty of time to talk and ask questions. This can be with members of your child’s medical team, your local G.P., health visitor, social worker, psychologist or a counsellor.

To enable your child to fully participate in activities at home, school, and in their community, you will need information, advice and support on mobility, education, equipment and sources of funding that will aid their inclusion. You can find out more by talking to your child’s healthcare team or your national SMA patient organisation.

As a parent with a child with SMA you should be offered a referral for genetic counselling to help you understand how SMA is passed on and what the chances are of other people in your family being affected. Genetic counselling also provides you with the opportunity to discuss your choices for any future pregnancies.

As your child and any siblings grow up they can also ask for genetic counselling, particularly if they are considering having children.


  1. Lunn, M.R. and Wang, C.H. (2008) ‘Spinal muscular atrophy’,The Lancet, 371(9630), pp. 2120-2133.
  2. Lefebvre, S., Bürglen, L., Reboullet, S., Clermont, O., Burlet, P., Viollet, L., Benichou, B., Cruaud, C., Millasseau, P., Zeviani, M., Le Paslier, D., Frézal, J., Cohen, D., Weissenbach, J., Munnich, A. and Melki, J. (1995) ‘Identification and characterization of aspinal muscular atrophy-determining gene’, Cell, 80(1), pp. 155-165.
  3. Dubowitz, V. (1999) ‘Very severe spinal muscular atrophy (SMA Type 0): an expanding clinical phenotype’, European Journal Paediatric Neurology, 3(2), pp. 49-51.
  4. Montes, J., Gordon, A.M., Pandya, S., De Vivo, D.C. and Kaufmann, P. (2009) ‘Clinical outcome measures in spinalmuscular atrophy’, Journal of Child Neurology, 24(8), pp. 968-978.
  5. Mercuri, E., Bertinie, E. and Iannacconne, S. (2012) ‘Childhoodspinal muscular atrophy: controversies and challenges’ The Lancet Neurology, 11(5), pp. 443-452.
  6. Tsirikos, A.I. and Baker, A.D.L. (2006) ‘Spinal muscular atrophy: classification, aetiology, and treatment of spinal deformity in children and adolescents’, Current Orthopaedics, 20(6), pp. 430-445.
  7. TREAT-NMD Neuromuscular Network (2008) Standards of Care for Spinal Muscular Atrophy. Available here.
  8. van Bruggen, H.W., van den Engel-Hoek, L., van der Pol, W.L., de Wijer, A., de Groot, I.J.M. and Steenks, M.H. (2011) ‘Impaired mandibular Function in Spinal Muscular Atrophy Type II: Need for Early Recognition’, Journal of Child Neurology, 26(11), pp. 1392-1396.
  9. Dunaway, S., Montes, J., O’Hagen, J., Sproule, D., de Vivo, D. and Kaufmann, P. (2013) ‘Independent Mobility After Early Introduction of a Power Wheelchair in Spinal Muscular Atrophy’,Journal of Child Neurology, 28(5), pp. 576-582.
  10. Commission of the European Communities (2008)Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee to the Regions on Rare Diseases: Europe’s challenges. Available here.