Spinal muscular atrophy was first reported by Guido
Werdnig in 1891, when he described “Two hereditary
cases of progressive muscular atrophy appearing as dystrophy, but on a neurotic basis.” A year later, Professor Johann Hoffmann of the University of Heidelberg used the term “spinale muskelatrophie.” These initial descriptions were the first
to correlate the clinical findings of these patients with the histological analysis that demonstrated a lack of anterior horn cells with the normal number of motor neurons. Although classification systems such as the one described by Byers and Banker have been developed to aid physicians in making a prognosis for these patients, spinal muscular atrophy is an extremely heterogeneous condition in which clinical manifestations as well as life span vary widely. The classification system of Byers and Banker is the one that is most often used; however, neurologists have used a slightly different nomenclature that is based primarily on the age of the patient at the time of onset of symptoms.