Spinal Muscular Atrophy Diagnosis and Tests Clinical Diagnosis
and Classification of Spinal Muscular Atrophy Physicians
encountering children with hypotonia and weakness should
maintain a high index of suspicion for the diagnosis of spinal
muscular atrophy. Certain physical characteristics are readily
identifiable. The weakness is usually symmetrical and more
proximal than distal. Sensation is preserved. Tendon reflexes
are absent or diminished. Weakness in the legs is greater than
in the arms. The severity of weakness generally correlates with
the age of onset. The most severe type presents in infancy. The
infant may appear normal at birth. Weakness evolves within the
first few months of life. Occasionally, decreased intrauterine
movements suggest prenatal onset of the disease and present with
severe weakness and joint contractures at birth. Milder types of
spinal muscular atrophy present with later onset, and the course
is more insidious. Some children sit but never walk, whereas
others show delayed walking