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FRANCAIS    

Spinal Muscular Atrophy Type 1
Werdnig-Hoffman Disease

The diagnoses of type 1 SMA is usually made when the child is between 3 – 6 months of age.  This is the most severe form of SMA.   Some mothers even notice a decreased movement in the final months of her pregnancy. A child with type 1 is typically never able to lift his/her head or accomplish the normal gross and fine motor skills expected early on in infancy.  They generally have poor head control, and may not kick their legs as vigorously as they should.  They typically never bear weight on their legs or sit unsupported.  Swallowing and feeding may be difficult and are usually affected at some point, and the child may show some difficulties managing their own secretions.   Tremors can be seen on the tongue.  There is weakness of the intercostal muscles (the muscles between the ribs) that help expand the chest when breathing.  The chest is often smaller than usual, giving the trunk a bell shape.  The child with SMA type 1 generally uses the diaphragm to breath, giving them the appearance to breathe with their stomach.  Due to this type of breathing, the lungs never fully develop, the child has a weak cough.   They may have a difficult time taking a deep breath while sleeping, affecting their ability to maintain normal oxygen and carbon dioxide levels.

Caring for a type 1 child

While most children diagnosed with Type I are still infants there are a myriad of things that can be done to assist in the cognitive, physical and emotional health of your child. Using balloons and feathers as toys makes for wonderful stimulation and allows them a feeling of independence and accomplishment. Reaching games are a form of physical or occupational therapy that can be very helpful. Instructions in range of motion and other physical/occupational therapy ideas by a licensed therapist are important no matter how young the child. Your physical/occupational therapist can also suggest ideal seating systems that will be most helpful in the comfort and maximum mobility of your child.

Water therapy can be very helpful as the buoyancy of the water allows movement of the arms and legs that may otherwise not be there. Be sure that the water temperature is at least 90˚F and that the child’s head does not go under the water or into the water. You must watch so that the child has no possibility of aspirating (getting fluid into their lungs).

Children with SMA who have difficulty swallowing are at risk for aspirating when eating. Sometimes the child may aspirate his/her own secretions. The child may choke while eating and may also experience weight loss as swallowing becomes more difficult. Assistive feeding may be necessary. Two possible options are:

Nasogatric Tube (NG-Tube): a surgically placed tube through the nose that goes directly into the stomach. Gastrostomy Tube (G-Tube): a surgically placed tube through the skin that goes directly into the stomach. Because a child with SMA Type I has difficulty coughing, contacting a respiratory therapist is very important so you can be instructed in chest physiotherapy (CPT). CPT is a method of clearing the lungs of accumulated mucus by using positioning and clapping on the chest to assist in loosening secretions. Saliva can settle in the nasopharynx causing a faint gurgling sound. Often the secretions or mucus need to be removed by the use of a suction machine. Blowing raspberries and bubbles encourages respiratory strength.

Individuals with SMA can also benefit from the use of a cough assist machine. The CoughAssist™ achieves this by applying a positive pressure to the airways to inflate the lungs, and then rapidly shifts to negative pressure to pull the air out of the lungs. The rapid shift in pressure produces a high expiratory flow from the lungs, simulating a cough. This technique, referred to as “mechanical insufflation-exsufflation,” avoids airway damage while clearing the lungs of secretions. The device offers patients greater comfort and quality of life without the use of invasive procedures and equipment. Patients as young as 4 months have been able to use the CoughAssist™ successfully.

Respiratory distress can be monitored by measuring the level of oxygen saturation in the blood using a tool called a pulse oximeter. A small clip or tape with a red light and a sensor is placed on the patient’s finger or toe to determine the oxygen saturation. Children with SMA Type I usually require breathing support while sleeping. Some children require more breathing support, especially with colds. There are several options to consider.

Type 1 using Bi-PAPBiPAP (Bilevel Positive Airway Pressure) uses a nasal mask with a cap, which fits over the head to hold it in place over the nose. BiPAP provides a higher volume of air into the lungs during inhalation and inflates the lung greater than what the person can do on their own. During exhalation, the BiPAP pressure drops so that air can passively leave the lungs. The BiPAP machine can sense when the person is taking a breath and give the breath in synchrony with the individual. A respiratory rate is also set so that the BiPAP gives a minimum number of breaths per minute. The person can breathe above that rate and the BiPAP will deliver more breaths. CPAP (continuous positive air pressure) should never be used in patients with SMA.

Negative Pressure Ventilation refers to providing breaths into the lungs using a large chamber or tank that encircles the chest similar to the old Iron Lung. The chamber is connected to a vacuum pump that takes the air out of the chamber and, as a result, the chest wall expands to bring air into the lungs. A Port-A-Lung is an example of a negative pressure ventilator. It can be set to deliver a specific number of breaths per minute and a vacuum pressure.

Mechanical ventilators or respirators come in a variety of models. Mechanical ventilators are more complex, but also allow for control of more variables. The ventilator can be set to deliver a specific size breath at a set number of breaths per minute. Mechanical ventilation can be delivered with a nose mask, mouthpiece while awake, or through a tracheostomy tube. A tracheotomy is placement of a surgical hole in the neck to the large airway (trachea) that a tube can be inserted. A tracheostomy tube bypasses the mouth and vocal cords and goes directly from the skin to the trachea (wind-pipe). A respirator or ventilator is connected to the endotracheal tube or tracheostomy tube. Consult your physicians and respiratory therapists or contact Families of SMA Canada for literature.

It is important to understand your rights when it comes to making life-sustaining decisions for your child. Be sure that both parents discuss their feelings about this very delicate topic. It is a decision that cannot be made lightly and all options should be covered. Talking to a counselor in the department of social services at your hospital may be helpful. Once your decision has been reached be sure that you put it in writing, and that all necessary medical personal and family members are aware of your wishes. This is your decision, one you have reached with great care and anguish, and under no circumstances should you allow others to judge you or place their values upon you. You are never alone. Families of SMA Canada is always just a phone call or email away.

Prognosis

Researchers have identified the SMN1 gene as the primary manufacturer of the SMN Protein. It is the absence/defect of this SMN1 gene that causes Spinal Muscular Atrophy. However, there is another form of this gene called SMN2. The SMN2 gene is similar to SMN1, but does not produce as much protein, or the right kind of protein, as the SMN1 gene. One determination of prognosis is the number of copies of the SMN2 gene. The greater the number of SMN2 copies, the more SMN protein is produced and the greater likelihood that more motor neurons remain healthy and productive. Individuals with only 1 or 2 copies of the SMN2 gene will typically have the most severe expressions of SMA. Three or more copies of the SMN2 gene will typically mean a less severe expression.

Each type of SMA has variability among individual patients. Please keep this in mind when considering an individual’s care.

Raising a child with SMA should be no different than raising a child who is not affected. Do as many things as possible that are age appropriate. Many times this means making adaptations. It is very important that children with SMA are assisted in reaching their utmost potential.

It is important to understand that parents and patients have rights and that you are not alone. Most hospitals have social service departments that can give you a shoulder to lean on. Don’t be afraid to say NO if something doesn’t seem right. Don’t be intimidated or afraid to ask questions. If you forget to ask something, call your doctor or contact Families of SMA for suggestions. In this context, it is also important that your child be followed by a physician who is familiar with SMA and its complications.