Spinal Muscular Atrophy Type 1

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SMA is a genetic disease, and like many genetic diseases, it has a tremendous spectrum of involvement. There are almost infinite, different variations of severity, the age of onset, and the ultimate prognosis of SMA children and young adults. But for the sake of convenience, we think in terms of categorization of Type 1, Type 2, Type 3, and Type 4 SMA.You may never have heard of spinal muscular atrophy before, however it’s important to realize that SMA is the number one genetic killer of children under the age of 2. What is SMA? Spinal Muscular Atrophy. SMA is a disease of the motor neuron, the cells which are located in our spinal cord, the deep structures of our brain called the brain stem, and these cells send out processes in the peripheral nerve to eventually make contact with the muscles in our arms, our legs, our chest, and our breathing muscles. If there is something wrong, if the anterior horn cells, the motor neurons become sick or die, then, the nerve no longer carries the trophic message, the life-giving message to the muscles and the muscle cells atrophy and die, thereby the term Spinal Muscular Atrophy.

In type 1 SMA, the most severe form of the disease, symptoms are present before the age of six months and these children never acquire the power, the strength, and the endurance to sit independently, to crawl, or to walk. The greatest threat to their life and limb are respiratory complications, which we’ll discuss in just a bit.

The typical presentation is the classical type 1 baby – the babies who were described over 100 years ago by Doctors Werdnig and Hoffman. These children may appear quite normal at birth, but before the age of 6 months it becomes apparent that there are problems with their motor control. Oftentimes head control is poor, there are difficulties with feedings, there are problems with breathing, a very unusual breathing pattern is apparent with the stomach pumping up and down with each breath, so-called “paradoxic respiration,” and this is due to weakness of the chest wall. Chest wall muscle weakness, difficulty breathing and difficulties with clearing secretions, constitute the greatest threat to the survival of these youngsters. This threat is compounded by the fact that there’s oftentimes bulbar weakness – weakness of the muscles of the lips, the tongue and the pharynx – which makes it very difficult for these children to handle secretions such as saliva. It oftentimes, makes them vulnerable to breathing food, formula, and breast milk. Instead of food going into the food pipe (the esophagus) there may be aspiration into the windpipe (the trachea) and clinical pneumonias may then result. These can prove extremely serious. They may prove lethal to these youngsters.

The care, the support of the child with SMA Type 1 is a heroic effort and we appreciate that this oftentimes dominates the lives of parents and caregivers. What do we need to do? How can we prepare a parent a caregiver for the Herculean task of caring for a child with SMA? Well firstly, you are not alone. There is a network of services available. There are other parents and caregivers who have faced the same obstacles and same challenge that you are facing right now. It becomes critical to find a healthcare resource which includes a multi-disciplinary team of clinicians and therapists. A child with SMA 1 needs the whole team, the whole village, to care adequately for his or her needs. The typical captain of that team is either a neurologist or a physical medicine and rehabilitation specialist, and it’s important that you, yourself, choose a team captain with whom you can establish an easy, on-going, and respectful relationship.

It takes a team, usually captained by the family, and implemented in a neuromuscular center to meet the needs to provide for the ultimate healthcare support for a Type 1 infant. The team will typically consist of a neurologist or physical medicine and rehabilitation specialist, a pulmonary medicine specialist and a respiratory therapist, a gastroenterologist or a nutrition specialist, physical and occupational therapists, a genetic counselor, and very importantly, a case worker or social worker must be present who can help parents navigate the almost interminable and complex rules and regulations of healthcare insurance to make sure that their child is provided with the very best care, therapy, orthotic devices, and durable medical equipment.

The constant and ever looming threat to children with SMA type 1 are breathing problems, respiratory insufficiency, the inability to take a deep enough breath, the difficulty with clearing secretions, because of the weakness of the chest wall making it very difficult for a child to cough up saliva, mucus during the onset of an otherwise quote on quote “benign” respiratory infection. These breathing problems make these children vulnerable to more serious episodes of pneumonia, and lung collapse. Most often, respiratory issues take the lives of these children. It’s very important for parents and healthcare givers to establish a relationship with the neuromuscular team so that they will have the optimal information needed to care for that child within the dictates of the conscience of the parents and family.

It takes a village, and it takes a village of mutual respect such that a game plan can be put in place for the routine care of this youngster. In the event of a quote on quote “sick day,” an acute intercurrent illness, what will the plan be? Will there be the continuation of basic healthcare support? Will there be the introduction of non-invasive ventilation – a mask placed over the child’s nose and mouth or nasal prongs put into the nostrils attached to a non-invasive breathing machine? In the event that the child not only has lung weakness but weakness of the lips and tongue the only way to support the breathing pattern in that child, may prove to be invasive ventilation – the performance of a tracheotomy, with a hole in the windpipe, and then ongoing oftentimes 24-7 mechanical ventilation. These are incredibly difficult decisions to make and must be made in the context of an informed family that in their heart of hearts knows what’s best for their child.

I don’t pretend to have all the answers. When I discuss this issue with family members, parents, and grandparents of SMA Type 1 children, I learn as much as I can and impart scientific and clinical knowledge. It becomes imperative that family members have as much information as possible at their disposal to make the best decisions for their child.

There are tremendous advances which have been made in our basic understanding of spinal muscular atrophy, its cause, and potential therapies. There are meetings which go on throughout the year, including a very important meeting sponsored by FightSMA held every April in Washington, DC. There are resources available through this webpage to help you understand the basic science, the hope through research, and the opportunity to post questions to ask of other families and healthcare experts, so that your decisions are the decisions which are right for you and your child. I hope you’ll take the time to visit other areas within this web page, I thank you very much for your attention. I know that you’re in for a difficult fight, but it’s one that we’d like to help you along with as best as we can.

Although the preceding classification of spinal muscular atrophy is useful to patients, families, and the medical team working with them, it must be emphasized that SMA Types I, II, and III (and in some cases SMA Type – IV) represent a continuum. Additional understanding of the gene defects will undoubtedly explain the tremendous clinical variation that children and young adults with SMA demonstrate.

The above was prepared for FightSMA by: Robert T. Leshner, M.D., Professor, Neurology and Pediatrics, Children’s National Medical Center. Special thanks to Metro Productions for the pro bono production of Dr. Leshner’s video.

More resources:

Diagnosis and Tests

Symptoms and Treatment