Other types of SMA

Spinal Muscular Atrophy Type 2

SMA Type 2, otherwise known as Intermediate Spinal Muscular Atrophy, is usually diagnosed before the age of 2. Every child is different and so lifespan can vary greatly from early childhood through to adulthood dependant of severity, but weakness does increase over time. There is a generalised weakness of muscles with the proximal muscles (those closest to the body) usually being more affected. The legs tend to be more impaired than the arms. Children with SMA Type 2 can sit unsupported and some are able to crawl and stand, but as the child grows these abilities can reduce over time as the weakness to the muscles in the legs and trunk become more apparent. However, some children who have been on Spinraza are appearing to regain muscle tone. For more information on Spinraza please visit the SMA Trust's Website.

The muscles of the chest wall can be affected causing poor breathing function and susceptibility to respiratory infections. Although feeding and swallowing problems are not common they are possible later on. Tongue fasciculations are less often found in Type 2 children, but a fine tremor may be seen in outstretched fingers.

SMA Type 2 does not affect congnitive abilities. Type 2 children are often very bright, alert and intelligent and should be encouraged to reach their upmost potential. Their physical growth develops at a normal pace though scoliosis (curvature of the spine) can become a big problem, especially when wheelchair bound. This is caused by a weakness in the muscles supporting the bones of the spinal column. As this becomes worse it can cause problems with breathing and may be uncomfortable. Spinal fusion surgery may need to be considered. As well as scoliosis some children suffer from deformities to their hands and feet. Where joints are affected this can result in reduced movement of the limbs. Motorised wheelchairs can be considered as early as the age of 2, until then an appropriate buggy should be used.

Physiotherapy is very important to improve good posture, this will enable the child to breathe much easier and exercises will also help to maintain muscle strength. Respiratory exercises and breathing techniques may help to reduce the effects of chest infections. Swimming is a very good form of exercise that enables the child to move all limbs with ease.

Spinal Muscular Atrophy Type 3

SMA Type 3, also known as Mild Spinal Muscular Atrophy and Kugelberg-Welander Disease, is usually diagnosed between 18 months and early adolescence. This is the mildest form of child onset SMA and prognosis is very good with people living a typically normal life span, however, weakness gets progressively worse over time. Balance and climbing stairs can both be problems, and getting from sitting to standing may prove difficult. It is possible those affected are wheelchair bound in time.

Tongue fasciculations are rarely seen in SMA Type 3 patients but a fine tremor may be seen in outstretched fingers. Respiratory complications and problems with swallowing are also rare.

Scoliosis (curvature of the spine) occurs in some children, this is due to a weakness in the muscles supporting the bones of the spinal column. An operation can be done to straighten the spine and prevent further deterioration. They should be regularly monitored so problems can be picked up and dealt with early on.

Respiratory infections should be dealt with quickly. SMA Type 3 patients may tire very easily and excess weight will add to their problems. A dietician can help give advice and support as a sensible diet is very important as unnecessary weight puts strain on the muscles, which makes moving more difficult. Physiotherapy is very important as regular exercise helps to maintain muscle strength. There are some neuromuscular centres across the UK that have specially trained physiotherapists and occupational therapists.

Spinal Muscular Atrophy Type 4

SMA Type 4, also known as Adult Onset Spinal Muscular Atrophy is not life threatening. Typically symptoms begin after the age of 35 and can have a very slow progression with muscle weakness getting worse over time.

The effects of Adult Onset SMA depends on the muscles affected. The muscles used for respiratory functions and swallowing are very rarely affected. In most cases weakness only shows on one side at onset, but may progress over time to both sides of the body. There is often no pain but tired aching muscles, along with the feeling of heaviness, numbness, tingling and cramp are possible. Fatigue is very common.

As with the other types of SMA physiotherapy and regular exercise are very important to maintain mobility, and there are some neuromuscular centres across the UK that have specially trained physiotherapists and occupational therapists.

Spinal Muscular Atrophy with Respiratory Distress

SMARD (Spinal Muscular Atrophy with Respiratory Distress) is a neuromuscular disease which causes progressive weakness of the muscles and severe respiratory distress, due to paralysis of the diaphragm, which tends to be the first noticeable symptom. This is caused by a breakdown of the link between the brain and the muscles due to affected nerve cells.

Some signs may be present before birth, with the mother noticing less fetal movement than that of a healthy baby. Most SMARD patients will experience respiratory failure within their first six months of life, and go on to require artificial ventilation. Symptoms seem to appear in reverse order to that of SMA Type 1, with respiratory problems coming first, followed by severe muscle weakness, especially in the lower limbs.

Health typically deteriorates very quickly by the age of 2, but there is such a range of severity that different cases are picked up at different ages and progression can vary greatly

For a child to be affected by SMARD both parents must be a carrier of the faulty gene which is caused due to mutations in the IGHMBP2 gene on chromosome 11q13.

It is believed that approximately 1 in 50,000 people are a carrier of this faulty gene, making it very rare with very few known cases in the UK at present. If both parents are a carrier they have a one in four chance of their child being affected by SMARD, a two in four chance of their child being a carrier and a one in four chance of them being completely unaffected,

SMARD is diagnosed through a simple blood test, though further testing such as EMG (electromyogram) or a muscle biopsy may be considered in cases where the diagnosis is uncertain.

Every case is different but typical symptoms of SMARD include;

Less fetal movement towards the end of pregnancy

Paralysis of the diaphragm

Slow weight gain

Weak cry/cough

Deformities of the hands/feet

Sweating

Severe muscle weakness

There is currently no known cure for SMARD. Palliative care services will be put in place and there is the option of medical intervention, if both the parents and medical team involved believe it to be in the best interests of the child. Children with SMARD require mechanical ventilation to survive and many go on to have a tracheostomy, followed by ventilation. However, this ventilation would likely be in place for the rest of their life.