Spinal muscular atrophy (SMA) is characterized by a progressive loss of muscle control, muscle movement, and increasing muscular weakness. Most people with SMA start showing the first symptoms early in life (as early as birth), and the disease becomes more severe over time.
As a genetic neuromuscular disease, SMA affects the proximal muscles, or those closer to the center of the body, more severely than more distant muscles, such as those in the hands and feet (called distal muscles).
People with SMA may never acquire or may gradually lose the ability to walk, sit, or move. In addition, normal growth and development can also place additional stress on muscles that are already weakened.
People with SMA do not have intellectual difficulties as a result of the disease, and their intelligence is normal.1
SMA and breathing difficulties
The breathing, sucking, and swallowing difficulties that arise in people with SMA are related to the weakness of the intercostal muscles (muscles supporting the chest wall) leaving the diaphragm as the primarily breathing muscle.2 This weakness creates a serious health danger, because people with SMA often develop respiratory complications, including those due to lung underdevelopment and weak cough, and are vulnerable to respiratory tract infections, to the aspiration of food and fluids, and to sleep problems with hypoventilation.3, 4
Children with SMA, as mentioned, rely on their diaphragm to breathe. At night as they lay in bed, abdominal contents push up against the diaphragm and gravity is eliminated, making it harder for them to take deep breaths. This can lead to a shortness of oxygen and a carbon dioxide build up, resulting in hypoventilation. Hypoventilation means that breathing is too shallow or too slow.4 As a result, these children may experience daytime sleepiness or headaches.2 When situations like these arise, they can be managed by assisted ventilation or by the clearance of secretions.
Each child with SMA type 1 is unique and has different challenges regarding their chest muscle weakness, making it difficult to predict individual needs. There is a range of non-invasive breathing supports available for these children, such as a ventilator with a nasal mask or a BiPAP (a machine that can sense a child’s normal breathing cycle and synchronize it. The machine will also give breaths when the child is in deep sleep and is not breathing adequately). Also, when needed, invasive respiratory care with intubation (tracheostomy) is a solution.4 During colds, most children with SMA type 1 will need extra breathing support, including a breathing machine for 24 hours a day, until full recovery.
Children with SMA type 2 rarely need a tracheostomy. These children are stronger and can be managed with non-invasive breathing supports on a day-to-day basis. Some children with SMA type 2 do not need any breathing support during sleep.4
People with SMA type 3 generally have good respiratory function. In times of illness (colds, flu, infection), they may need non-invasive breathing support with manual cough assistance. Non-invasive breathing support, combined with airway clearance techniques, will reduce the need for intubation. Tracheostomies are not appropriate for these patients.
In some cases, children and adults with SMA type 3 can have breathing trouble that goes unrecognized, including obstructive sleep apnea and hypoventilation.4
SMA News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.