Long-term natural course of spinal deformity in a patient with type 1 spinal muscular atrophy: A case report

Background

Spinal muscular atrophy (SMA) is a neuromuscular disease characterized by muscle atrophy and weakness. Patients with type 1 SMA become symptomatic within the first 6 months of their lives. As most patients die before the age of 2, spinal deformity has not been a clinical problem; however, with the emergence of disease-modified therapies (DMT), longer survival is expected. Nonetheless, little is known about the natural long-term course of spinal deformities in patients with type 1 SMA. Case presentation: We report a case of type 1 SMA treated with supportive care without DMT until the age of 22. Radiography revealed a bell-shaped chest at 9 months of age. Thoracic scoliosis was first observed at age 3, progressed to a Cobb angle of 68° at age 13, and remained stable until the age of 26 years. Computed tomography (CT) images obtained after skeletal maturity revealed thoracic lordosis and spontaneous fusion of the lumbar laminae.

Discussion

Respiratory failure is the leading cause of death with type 1 SMA, and chest wall deformities can result in reduced breathing capacity and tracheal obstruction. In this case, the slow progression of the deformities may have contributed to the stable ventilation. Thoracic lordosis was also observed. This finding contrasts with the previously reported thoracic kyphosis in patients with type 2 SMA. Three-dimensional computerised tomography (3DCT) images demonstrated laminar fusion, which contributed to spinal stability.