SMA Type 1 (Infantile) — Werdnig–Hoffmann disease (0–6 months onset): The severe form manifests in the first months of life, usually with a quick and unexpected onset (“floppy baby syndrome”). Rapid motor neuron death causes inefficiency of the major bodily organs – especially of the respiratory system – and pneumonia-induced respiratory failure is the most frequent cause of death. Babies diagnosed with SMA type 1 do not generally live past two years of age, with death occurring as early as within weeks in the most severe cases (sometimes termed SMA type 0). With proper respiratory support, those with milder SMA type I phenotypes, which account for around 10% of SMA1 cases, are known to live into adolescence and adulthood.

Usually doctors diagnose SMA1 within the first 6 months of life – and often before the age of 3 months. SMA1 is the most severe form of all the Spinal Muscular atrophies with a high mortality rate. Developing care options however, now can be used to prolong and assist in the quality of life for Type 1 SMA babies. This includes the possibility of using Cough Assist and or Bi-Pap machines.

In the early stages of diagnosis some mothers have reported noticing reduced foetal movement during the last trimester. All SMA children appear normal at birth before the deterioration and loss of movement in their limbs is noticed. Most symptoms appear before six months of age.

Key features include:

  • Poor head control or loss of head control since birth.

  • Weak cry and cough.

  • Difficulties swallowing and chewing.

  • Poor or lack of tendon reflexes.

  • Weakness of muscles of the chest wall.

  • Difficulties/inability to cough or breathe deeply.

  • Weakness of muscles of the arms and legs resulting in an inability to roll or sit.

  • A bell shaped stomach or belly breathing which results from using muscles and collapse of the chest wall.

  • Trembling (fasciculation) or shrinking (atrophy) of the tongue; clinical signs unique to children with SMA.

Intelligence is unaffected and like all small babies they are sponges and what they lack in the ability to move, they make up for with their brain power.

Keeping their rapidly growing mind stimulated can prove challenging with their physical ailments. A notable trait for these babies are their knowing eyes that watch, absorb and communicate in an astounding way.

Children with type 1 SMA and their caregivers face a difficult battle for survival. At constant risk of respiratory infection and pneumonia, and issues with feeding, constipation, airway maintenance and ensuring healthy bodily function presents real emotional, physical and financial challenges for parents.

First and foremost, treating the symptoms of the child is paramount for the child’s quality of life. Developing a care plan in the early stages of diagnosis will assist you in making some tough decisions later on. This coupled with being pro-active rather than reactive, will make your journey through SMA1 more bearable. There are a few options that you may like to consider, they are listed below.

OPTION 1 – No treatment / Palliative care

This option is for those families who do not want to intervene with the progression of the disease and believe their child’s quality of life would be poor or wish to choose comfort care as priority. As with all life limiting conditions, palliative care is an option here. Opinions may differ considerably between families and clinicians, be influenced by personal values, or conflicting goals about perceptions of quality versus quantity of life, or whether one should prolong life or whether the priority is relief of the condition but as with all, at the end of the day these are your choices and you need to choose what is right for your family. Palliative care does not have to mean the end, it can be approached in a number of ways.

OPTION 2 – Non-invasive treatment

With the advancement of care options for SMA there is fast becoming a new normal in the treatment of the disease. These interventions can assist in improving quality of life and prolonging it. Proper respiratory care and support help to sustain lung function and breathing, as well as making recovery from or preventing an illness possible. A bi-pap machine is vital to allow this to happen. The use of a Cough Assist machine will also greatly reduce the chances of severe illness, aid in recovery time if illness presents and assist with better quality of life. Speech, occupational and physical therapy should be introduced as soon as possible into the diagnosis to help assist patients and families throughout their journey.

Without interventions babies/children with SMA1 rarely live beyond 2, but they are there for families as a choice in the treatment of SMA. With the advancement of clinical trials for gene therapy research, many families have been given a life of hope ahead of them instead of a bleak outlook, and this is the most refreshing news about the treatment of SMA1 in the lifetime of the disease. These therapies are set to revolutionize the way the disease is treated in the future. A proactive approach in the early stages of diagnosis for the pre-empting of feeding issues, (with the possibility of getting a PEG (Percutoneous Endoscopic Gastrostomy placement) inserted in the stomach may be required. This could save on many feeding issues later on down the track. The use of bi-pap and cough assist can drastically change the outcome for an SMA1 patient. Chest physio and postural drainage (a position where the child is put at a sloping incline with their head and chest lower than the buttocks) also playing a vital part in keeping the patient healthy.

OPTION 3 – Invasive Treatment

Invasive treatment involves the insertion of a tracheostomy (A tracheostomy is a surgical procedure to cut an opening into the trachea (windpipe) so that a tube can be inserted into the opening to assist breathing. A tracheostomy may be temporary or permanent, depending on the reason for its use.[1]) A tracheostomy provides a stable airway and respiratory support when other interventions fail. It is a widely used practice in America, but here in Australia many doctors frown upon this avenue of treatment. There are many associated issues with having a tracheostomy placed, and this procedure is not taken lightly. Families consider this option when they feel they can provide their child with good quality of life now and in the future. Quality of life issues are debated on this subject and again this is a personal choice, and must be discussed thoroughly with your support team and associated medical professionals.

SMA Type 2 (Intermediate or Chronic Childhood SMA)) — Dubowitz disease (6–18 months onset): The intermediate form affects children who are never able to stand and walk but who are able to maintain a sitting position at least some time in their life. The onset of weakness is usually noticed some time between 6 and 18 months. The progress is known to vary greatly, some patients gradually grow weaker over time while others through careful maintenance avoid any progression. Scoliosis may be present in these children, and correction with a brace may help improve respiration. Body muscles are weakened, and the respiratory system is a major concern. Life expectancy is somewhat reduced but most SMA2 patients live well into adulthood.


The onset of the symptoms of SMA type 2 is usually between the ages of seven and 18 months. Parents often notice that milestones such as sitting are delayed. These children do eventually develop the ability to sit unsupported but they may need some help to get into a sitting position. Some children with SMA type 2 are able to crawl or stand with assistance or bracing, but they usually never walk.

Weakness of the spinal muscles results in scoliosis (curvature of the spine) which may require bracing and eventually surgery. Shortening of the muscle (contractures) can restrict movement especially around the hip, knee and ankle joints. Usually the muscles used in chewing and swallowing are not significantly affected early on. The muscles of the chest wall are affected, causing poor breathing function and susceptibility to respiratory infections and complications.

Sometimes muscle weakness can seem to be non-progressive, but in most cases weakness and disability will slowly increase. Severe illness with prolonged periods of relative immobility, putting on excessive weight or growth spurts may contribute to deterioration in function.

Parents initially notice floppy or limb limbs (hypotonia), and while type 2 children may be able to stand with assistance or bracing, they usually never walk. Those who experience swallowing difficulty may also have difficulty maintaining or gaining weight, therefore assisted feeding with a nasogastric tube or a PEG may be required. Weakness of the spinal muscles may result in scoliosis (curvature of the spine), especially for those that are wheelchair bound. Muscle wasting in the limbs can result in stiffness (contractures). Physical therapy and orthopedic intervention to reinforce the spine may be appropriate.

As with all forms of SMA, weakness increases over time though physical growth continues at a normal pace. There is a wide variation in symptoms. Severity and prognosis depends on the age of diagnosis and while some with type 2 die prematurely, but with the advancement of treatments ( like a cough assist machine) many type 2 children live well into adult hood, hold jobs, have relationships and live happy lives.

Keeping the airways clear with the use of a cough assist machine at times of illness can greatly reduce respiratory illness recovery times. BiPAP may also be an option for families wanting breathing support.

Always remember SMA is a physical disability only, their intelligence in not affected. Children with SMA type 2 are bright and alert and it is important that they receive all the available opportunities to develop their intellectual capacities to their fullest extent. They can attend a main stream school and it is often reported that children with SMA have an above average intelligence.

The symptoms of SMA type 2 include:

  • Muscle weakness and poor muscle tone

  • The legs tend to be weaker than the arms

  • Some children have swallowing and feeding difficulties

  • Increased susceptibility to respiratory tract infections

  • Scoliosis (curvature of the spine)

  • Deformities of the hands, feet and chest may develop in childhood

  • Joints may be affected by tendon contractures which reduce movement of the limbs

SMA Type 3 (Juvenile) — Kugelberg–Welander disease (>12 months onset): The juvenile form usually manifests after 12 months of age and describes patients who are able to walk without support at some time, although many later lose this ability. Respiratory involvement is less noticeable, and life expectancy is normal or near normal.

Type 3 SMA varies in severity according to the age first diagnosed, though children tend to be diagnosed anywhere between 18 months of age and early adolescence. Most are diagnosed before the age of three.

Most children with SMA III can stand and walk but have trouble with motor skills, such as going up and down stairs; their varying degrees of muscle weakness may be so mild that medical attention is not sought for years. Early milestones are usually reached. Most will show difficulty walking at some stage, though toddlers and children will fall frequently, have difficulty getting up from a sitting position, or be unable to run, whereas others may be diagnosed in late adolescence or early adulthood. The lower extremities are often more severely affected than the upper extremities

Feeding and swallowing difficulties in this type of SMA are less common than type 2, though may occur. Muscle aches and symptoms of joint overuse are common. The disease progresses slowly, and the overall course is mild. Many patients have normal life expectancy.

SMA Type 4 (Adult-onset): The adult-onset form (sometimes classified as a late-onset SMA type 3) usually manifests after the third decade of life with gradual weakening of muscles – mainly affects proximal muscles of the extremities – frequently requiring the patient to use a wheelchair for mobility. Other complications are rare, and life expectancy is unaffected.

Symptoms of type 4 are usually not noticed until early to late adulthood (mid 30’s ).

Symptoms include generalized weakness and muscle wasting with muscle twitches common, atrophy of distal leg muscles, thigh muscle weakness, distal arm muscle weakness, impaired vibratory sense, variable diminished leg deep tendon reflexes, no cortical spinal tract dysfunction. The bulbar muscles used for swallowing and respiratory function are rarely affected in SMA4.

In many ways, the disease mimics the symptoms of type III, with the progression of muscle weakness getting worse over time.

Loss or reduced function in the limbs is usually mild and respiratory or gastrointestinal problems are rare. People with type 4 have a normal lifespan, and only a small proportion of people will need wheelchair assistance.