SPINAL MUSCLE ATROPHY TYPE 1: CASE REPORT

Resumo

Introduction: Spinal muscular atrophy (AME) is a progressive recessive
neuromuscular disorder caused by biallelic mutations in the SMN1 gene located on
chromosome 5q. It leads to degeneration and loss of alpha motor neurons, which
leads to progressive muscle weakness and respiratory failure and death in severe
cases. The prevalence is approximately 1-2 per 100,000 people and incidence
around 1 in 10,000 live births. The clinical phenotype of AME is heterogeneous,
ranging from severe to mild. Recently, a drug has been approved by the Food and
Drug Administration to treat AME, proving to be safe and well tolerated. Neonatal
screening measures are being proposed for early diagnosis and improvement of the
final prognosis. Description: M.A.M., 10 months, female,born by cesarean section,
with gestational age of 40 weeks, birth weight: 3,650 kg, Apgar 9/10, without
intercurrences in the prenatal and postpartum period. She was admitted to the 7-
month-old HRMS for pneumonia. Treatment, as well as initiation of investigation for
hypotonia and delayed neuropsychomotor development were performed. No
previous history of hospitalizations. In the first months of life, mother suspected the
absence of movement and control of the neck. During hospitalization,
electromyography was performed, with a result suggesting SMA. DNA analysis was
performed at the age of nine months, in which it was found absence of copies of the
SMN1 gene, confirming the diagnosis of the disease. Patient remained hospitalized
for three months, evolving with respiratory insufficiency and need for tracheostomy
and gastrostomy, being discharged for follow-up with home care and a
multidisciplinary team medical support. Discussion: AME is classified based on the
age of onset, motor milestones acquisition and disease progression, in three types:
type I, II and III. Type I (Werdnig-Hoffmann's disease) is the most common form,
accounting for about 60% of all cases. Newborns are normal at birth, developing
soon after hypotonia, weakness and food intake difficulty, followed by respiratory
failure. The diagnosis is based on the clinical picture and specific genetic alteration.
Recently the first medical treatment for SMA in the US (2016) and a reinforcement
in its recommendation in Europe (2017) were approved. The rapid and irreversible
loss of motor neurons begins in the first 3 months of life and 95% of these are lost
before 6 months (type I), reinforcing the need for early diagnosis for better
therapeutic results.