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Spinal Muscular Atrophy (SMA) is a neuromuscular disease characterized by degeneration of motor neurons,[1][2] resulting in progressive muscular atrophy (wasting away) and weakness. The clinical spectrum of SMA 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; and physical therapy, occupational therapy, respiratory therapy, and clinical nutrition. Genetic counseling is also helpful for the parents and family members.
The term "juvenile spinal muscular atrophy" refers to Kugelberg-Welander syndrome.[3]
In all of its forms, the primary feature of SMA is muscle weakness, accompanied by atrophy of muscle. This is the result of denervation, or loss of the signal to contract, 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 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, and as such can be at least partially remediated by prospective therapy.
Infantile SMA is the most severe form. Some of the symptoms include:
• muscle weakness
• poor muscle tone
• weak cry
• weak cough
• limpness or a tendency to flop
• difficulty sucking or swallowing
• accumulation of secretions in the lungs or throat
• bell shaped torso, caused by breathing using muscles around the tummy area
• clenched fists with sweaty hands
• flickering/vibrating of the tongue
• head often tilted to one side, even when lying down
• legs that tend to be weaker than the arms
• legs lying in the "frogs leg" position
• hypotonia, areflexia, and multiple congenital contractures (arthrogryposis) associated with loss of anterior horn cells
• feeding difficulties
• increased susceptibility to respiratory tract infections
• bowel/bladder weakness
• lower-than-normal weight
• developmental milestones, such as lifting the head or sitting up, can't be reached
Related Information:
Diabetes Muscular dystrophy Spinal Muscular Atrophy Batten disease Ataxia Amyotrophic lateral sclerosis Dementia Multiple system atrophy Parkinson's disease Neuromuscular disease Stroke Multiple sclerosis Brain Injuries Spinal cord disorders Optic neuritis Huntington's disease Schizophrenia disease Major depressive disorder Spasm and convulsions Thyrotoxic Myopathy Polymyositis disease HMSN disease Toxic encephalopathy Autism disease Mental retardation Pachygyria disease SAH Idiopathic intracranial hypertension Mitochondrial myopathies Mitochondrial diseases
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