Spinal Muscular atrophy(SMA) is a neuromuscular disorder in which nerve cells (neurons), degenerate leading to lose of muscle tone ,progressive weakness of the muscles and atrophy. It is a major cause of infant mortality and the second most common neuromuscular disease among children. It is an x-linked genetic disorder that is inherited. Patients with Spinal Muscular atrophy are known to have abnormalities in the spinal cord neurons due to mutations or deletion of certain genes. There is currently no cure for Spinal Muscular atrophy.
The course of Spinal Muscular atrophy varies based on the age at time of onset, clinical presentation and the functional capabilities of the patients. SMA is classified into _ broad types.
- Wednig -Hoffmann Disease (Type I Spinal Muscular atrophy) which develops from birth to about 6 months of age. It is the most severe form
- Type II SMA (intermediate Spinal Muscular atrophy)_develops between 6-18 months
- Kugelberg -Welander disease (Type III Spinal Muscular atrophy) whose time of onset is about 18 months.
- Adult onset SMA (Type IV Spinal Muscular atrophy )
The clinical manifestations range from mild muscle weakness to total paralysis. Prognosis of Spinal Muscular atrophy varies according to type of SMA, age of onset, and the functional abilities achieved by the patient.
Muscle weakness in Spinal Muscular atrophy is progressive and mostly symmetrical and starts from the proximal areas and moves to the distal muscles. Other symptoms include:
- Loss of deep tendon reflexes.
- Hand tremors
- Involuntary tongue movements
Spinal Muscular atrophy Type II Symptoms
Children suffering from Type II SMA may be able to stand on their own but fail to walk without support. Assistive devices such as braces may be required to aid their movement.
Muscle weakness is observed but is of a less severe degree than in type I Spinal Muscular atrophy and may start later in life. It then progresses with age.
Delayed motor skills are a common symptom, with many of the children being able to sit at about 12 months of age.
Spinal Muscular atrophy Diagnosis
A clinician may suspect Spinal Muscular atrophy on the bases of clinical presentation, muscle biopsy and electromyography. Genetic testing is the surest way of testing for Spinal Muscular atrophy.
Spinal Muscular atrophy Complications
Complications of muscle atrophy include impaired motor functioning, restrictive lung conditions and orthopedic deformities. In later stages of the disease, development of contractures including scoliosis is common. Due to the loss of ability to perform normal duties, patients with SMA may suffer from psychosocial problems.
Spinal Muscular atrophy Management
There is currently no specific therapy for treatment of SMA. Management depends on the requirements of the patient. A multidisciplinary approach is usually taken up when managing SMA patients. This includes physical therapy, nutritional support, orthopedic management, occupational therapy and in some cases surgical interventions.
Achieving the maximum possible independence and mobility in patients is the main aim of treatment. Prevention of complications is also an important goal.
Another aspect of management that should not be ignored is the family education and the patient/family oriented care. Information given to the family should include the disease process, any associated complications, functional limitations, therapy and prognosis of the patient.
Iannacccone ,S.(1998).Spinal Muscular Atrophy.Seminars in Neurology, Vol. 18,pp 19-26.
Yasser Salem (2012). Spinal Muscular Atrophy, Neuromuscular Disorders, Dr. Ashraf Zaher (Ed.), ISBN: 978-953-51-0696-8, InTech, DOI: 10.5772/47952. Available from: http://www.intechopen.com/books/neuromuscular-disorders/spinal-muscular-atrophy
Kroksmark,A.,Beckung,E.,& Tulinius, M. (2001).Muscle strength and motor function in children and adolescents with spinal muscular atrophy II and III.European Journal of Paediatric Neurology,Vol.5, pp 191-198