Spinal muscular atrophy
(SMA) is a rare disease that affects the motor neuro cell in the spinal cord
and part of the brain that connects to the spinal cord, the brainstem. The loss
of this motor neurons leads to the loss of some abilities such as walk, eat,
and breath. It is one of the most dangerous and the number one genetic disease
that cause of death in infants. “Frequency of eight cases
per 100,000 live births with a high mortality during infancy and no known
treatment. Death is caused by severe and progressive restrictive lung disease”
(Iannaccone, Smith, & Simard,2004). It is also called muscular atrophy
because the primary effect is on the muscles since the muscles do not receive
signals from the nerve cell. Some patients affected by this disease do not have
any muscle tone, that is why they cannot walk, breath or swallow. The purpose
of this paper is the to explore and gather all the knowledge about Spinal
Muscular Atrophy because  we may use this
information in the future as Respiratory Therapist to help some of our patients,
families, and parents of patients that carry this terrible disease since some of
them need ventilator assistance.

“The term spinal
muscular atrophy (SMA) refers to a group of genetic disorders all characterized
by degeneration of anterior horn cells and resultant muscle atrophy and
weakness. The most common SMA, accounting for over 95% of cases, is an
autosomal recessive disorder that results from a homozygous deletion or
mutation in the 5q13 survival of motor neuron (SMN1) gene”(Kold &Kissel,2015).
The function of the SMN1 is to create protein that is a critical part of the
nerves that control our muscles, without this protein these nerves do not
function appropriate and will later die. This create muscle weakness and people
with this disease are not able to walk. The breathing and swallowing difficulties
that affects patients with SMA are associated to the weakness of the
intercostal muscles. The intercostal muscles support the chest wall leaving the
diaphragm as the primarily breathing muscle. This weakness creates a serious
health problem 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.  It
runs in the family, parents do not show any symptoms of the disease but do
carry the genes. This atrocious disease also affects the ability of breathing and
swallowing but does not affect the ability of think, learn, and have a
relationship with others. Some of the patients that have this disease has to be
assistance by a ventilator, invasive or noninvasive since they cannot breathe
by their own and also have to be feed with a tube because they cannot swallow.

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There are five main
types of spinal muscular atrophy and they are based on age, but the population
that this disease affects the most is babies. Spinal Muscular Atrophy type zero
or prenatal SMA is the most severe type of SMA. It’s usually characterize by a
decreased fetal movements in the utero between 30 to 36 weeks of pregnancy.
Neonates with this disease usually are affected between two to six months of
age, but respiratory failure is a symptom that we usually see at birth in these
patients. This babies do not develop any motor skills and they present a low
muscle tone, and severe muscle weakness. Patients with this disease usually die
before the age of six months. There is not cure or technique that can prolong
the life of babies with SMA type zero, the only thing we can do is bring
support to the parents of these babies.

SMA type one is
really severe too and it’s also called infantile onset or Werdnig-Hoffmann
disease. It affects the neonates from birth to six months of age. In most of
the cases, babies start to show signs around three months, but they can develop
the disorder before birth. In general, babies diagnosed with SMA type one have
low muscle tone and severe muscle weakness, usually described as floppy.
Because of the muscle weakness these patients are unable to lift or support
their head. May have weak cry and their weak breathing muscle cause difficulty
to breathing, this can increase the chance of respiratory infections which can
be life-threatening. This babies also have difficulty swallowing which make it
difficult to feed or gain weight. There is an increased risk of fluids of food
passing to the lungs, in other words aspiration which can cause chocking or in
some case pneumonia. Babies with this disease usually die by the age of two
years old. This patients are the ones that need the most from respiratory
therapist because most of them need mechanical ventilation and tracheostomy,
these techniques won’t cure these babies but will give them a longer life
expectancy. “SMA type 1 children can survive beyond 2 years of age when offered
tracheostomy or noninvasive respiratory support. The latter is associated with
fewer hospitalizations after age 5 years, freedom from daytime ventilator use,
and the ability to speak” (Bach, Baird, Plosky, Navado, & Weaver, 2002).
However, babies with a tracheostomy will never be able to speak. For the
proposed of this paper SMA type one is the spinal muscular atrophy that I will
focus the most.

 Type two, it is also called chronic infantile
SMA and affects the children between six to eighteen months old. Type two is
less severe than type one but it can be moderate to more severe. Type two SMA usually
vary among patients but as type one we see generally muscle weakness and poor
muscle tone, with the legs being weaker than the arms. Some of this child may
experience difficulty in swallowing which can may them susceptible to
respiratory tract infections. Scoliosis, deformities of the hands, feet, and
chest are the most commons symptoms in patients with SMA type two. Some
children are able to stand with assistance or bracing, but most likely will
never be able to walk. Patients with type two SMA are bright and alert in most
of the cases so it’s important for these patients to develop their capacities
to fullest.

Type three, also known
as Kugelberg-Welander or juvenile type. Typically develop between early
childhood and adolescence. This type is less severe than the first two as some
of the patients with this type at least can stand and walk a few steps, but
walking normally and climbing stairs its not possible for people with type
three SMA. As type two the legs are the most severely muscle affected of the
body and also, we can see a develop of scoliosis in these patients. People with
type 3 usually do not have many respiratory problems until later in life. These
patients will require wheelchair assistance later in life.  

Type four is the rarest
of the SMA, also called adult-onset spinal muscular atrophy and the less severe
of all main four types. It is usually diagnosed in the second or third decade
of life, usually after 30 years old. Affected individuals by type four spinal
muscular atrophy usually experience milk muscle weakness, scoliosis, tremor, twitching,
or mild breathing problems.  Complication
for patients with SMA type four include joint contractures, pneumonia, and
metabolic abnormalities such as severe metabolic acidosis. The good thing in
type four SMA is that life expectancy is normal, and breathing and swallowing
functions are rarely affected.

Neonates with SMA type one has different challenges
regarding their chest muscle weakness, making it difficult to predict individual
needs. Some of the respiratory support that we can offer to this patients are
invasive mechanical ventilation, tracheostomy, and noninvasive mechanical
ventilation. There are different of noninvasive breathing supports available
for these children which give them comfort, such as a ventilator with a nasal
mask or a BiPAP. “Without ventilatory support, premature death from respiratory
insufficiency is universal in children with spinal muscular atrophy type 1
(SMA1). With mechanical ventilation, however, long-term survival in SMA1 has
been reported from numerous international centers”(Monique,2008).

The benefits of initiating mechanical ventilation for
children with SMA type one include the potential of life expectancy without a
surgical intervention. This technique may
facilitate discharge to home and may allow families to care for their child at
home for longer period of time. Implementation of mechanical ventilation may
also decrease respiratory symptoms, improve quality of life and comfort by
avoiding hospital stays, tracheotomy, and provide psychological, social, and
spiritual support for the family and individual with SMA. Tracheotomy is
another technique that can be vital for some patients with SMA type one. Children’s
with SMA type one that require full-time noninvasive ventilation, have airway
instability when they are well, and frequent episodes of respiratory
instability when off noninvasive ventilation and may benefit from tracheostomy
and mechanical ventilation. For some babies with SMA type one, without
tracheostomy tube placement and mechanical ventilation, they would not survive.
“Both non-invasive aids and tracheostomy can prolong survival for SMA 1
patients, and it should be left up to the family to decide which, if either,
they would like to use”(Bach,2008).

In conclusion, as I said in the introduction the main
purposed of this paper was to learn and gain all the information I could about
this rare and atrocious disease that can affect some many babies because as a
health care worker I need to be prepare and ready to help patients affected by
SMA. As a Respiratory Therapist is always so important to have knowledge of the
diseases that affect our patients because we can educate, give information, and
support to the families and parents of this babies. Also, have a knowledge
about the techniques that we can use especially in babies with Spinal Muscular
Atrophy type one is really important because we can give advice and information
to parents or families of this babies about how important this techniques can
be for their babies. It’s really hard for parents to see their baby with a tracheostomy,
not ones like to have a whole in their throat, but if we tell them the benefits
this technique can give their baby such as longer life expectancy, they will
accept it better. Finally, this paper also help me to understand that when we
are taking care of babies with SMA we need to be ready for the worst since a
lot of this patients do not make it out of the hospitals and we need to be
ready to bring support and comfort to the parents and the families of these
patients.