Spinal Muscular Atrophy (SMA)
Spinal Muscular Atrophy (SMA) is a neuromuscular disease characterized by degeneration of motor neurons, resulting in progressive muscular atrophy (wasting away) and weakness. The clinical spectrum ranges from early infant death to normal adult life with only mild weakness. These patients often require comprehensive medical care involving multiple disciplines, including pediatric pulmonology, pediatric neurology, pediatric orthopaedic surgery, pediatric critical care, and physical medicine and rehabilitation. It can also involve physical therapy, occupational therapy, respiratory therapy, and clinical nutrition.
In all of its forms, the primary feature of SMA is muscle weakness, accompanied by muscle atrophy . This is the result of denervation, or loss of the signal to connect, that is transmitted from the spinal cord. This is normally transmitted from motor neurons in the spinal cord to muscle via the motor neuron’s axon, but either the motor neuron with its axon, or the axon itself, is lost in all forms of SMA.
The features of SMA are strongly related to its severity and age of onset. SMA caused by mutation of the SMN, Survival Motor Neuron, gene has a wide range, from infancy to adult, fatal to trivial, with different affected individuals manifesting every shade of impairment between these two extremes. Many of the symptoms of SMA relate to secondary complications of muscle weakness.