SPINAL MUSCULAR ATROPHY CLINICAL FEATURES, CLASSIFICATION, NATURAL HISTORY, GENETICS, DIAGNOSIS, COMPLICATIONS AND TREATMENT OF THE DISEASE

Introduction: Spinal muscular atrophy (SMA) is a complex neuromuscular disorder, it is the most usual autosomal recessively inherited lethal neuromuscular disease in pediatrics, it presents a defective alteration in the survival motor neuron 1 (SMN1) gene. Spinal muscular atrophy clinically shows progressive weakness of skeletal and respiratory muscles. In recent years, drugs with encouraging results from phase II and III clinical trials have been presented. Objective: to detail current information related to spinal muscular atrophy, clinical features, classification, natural history, genetics, diagnosis, complications and treatment of the disease. Methodology: a total of 40 articles were analyzed in this review, including review and original articles, as well as clinical cases, of which 31 bibliographies were used because the other articles were not relevant to this study. The sources of information were PubMed, Google Scholar and Cochrane; the terms used to search for information in Spanish, Portuguese and English were: spinal muscular atrophy, Spinal Muscular Atrophy, spinal muscular atrophy and spinal muscular atrophy. Results: About 95 % of the occurrences of spinal muscular atrophy are generated by homozygous deletions. Individuals with 5q mutation make up 95% of cases of spinal muscular atrophy and the remaining 5% are generated by mutations in 5q1-5. Targeted treatments may prevent or delay the progression of some symptoms of spinal muscular atrophy. Conclusions: Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease characterized by muscle atrophy and weakness resulting from irreversible loss and progressive degeneration of the brainstem nuclei and anterior horn cells in the spinal cord (lower motor neurons). Clinically it presents with symmetrical proximal limb weakness that also impacts the axial muscles, intercostal and bulbar musculature and is progressive, and the classification protocol is important in genetics, as well as providing prognostic and clinical information. The natural history of the disease is variable and complicated. It is made by demonstrating a history of proximal muscle weakness, motor difficulties or regression, diminished or absent deep tendon reflexes. Among the most frequent complications in unsupported individuals are those previously mentioned such as poor weight gain with growth retardation, scoliosis, restrictive lung disease, joint contractures and sleep difficulties. In terms of treatment, several different compounds have been investigated in recent years, focused on increasing muscle strength and function. Proactive supportive treatment involving a multidisciplinary team is paramount to decrease the severity of symptoms. KEY WORDS: muscle atrophy, spine, spinal, spinal cord, motor neuron.