What is Spinal Muscular Atrophy (SMA)?

Spinal Muscular Atrophy (SMA) is a group of genetic disorders that cause the damage and death of motor neurons in the spinal cord and the lower part of the brain. These cells are responsible for sending motor signals to the muscles of the arms, legs, face, chest, throat, and tongue. As these cells are lost, muscles weaken and atrophy (waste away), negatively impacting the patient's ability to breathe, swallow, and walk [1] [2].

Classification of SMA Types

Physicians classify the disease based on the age of onset and severity. Most cases result from a mutation in the SMN1 gene, which is responsible for producing the protein necessary for motor nerve health [2]:

• Type 0 and 1: Type 1 (Werdnig-Hoffmann disease) is the most common, with symptoms appearing before 6 months of age. Affected individuals suffer from severe weakness and difficulties swallowing and breathing. Without therapeutic intervention, many children with this type may not survive past the age of two [1].
• Type 2: Symptoms usually appear between 6 and 18 months of age. Children are often able to sit without support but cannot stand or walk independently, and they may suffer from respiratory issues [2].
• Type 3: Known as Kugelberg-Welander disease, symptoms appear after 18 months of age. Patients can walk independently but face difficulty climbing stairs or rising from a sitting position; they typically have a normal life expectancy with medical care [1].
• Type 4: This is a rare and mild type; symptoms usually appear after the age of 21, where the patient experiences progressive muscle weakness in the legs as they age [1].

Diagnosis and Early Intervention

Early diagnosis is crucial to ensuring the best outcomes for the patient. Physicians begin by evaluating the medical history and performing a physical examination, followed by genetic testing to detect mutations in the SMN1 gene, which identifies more than 95% of cases for types 1, 2, and 3 [2]. Specialists may also use electromyography (EMG) and nerve conduction studies to evaluate muscle and nerve activity [3]. For more specialized information, you can review the article Spinal Muscular Atrophy: Early Diagnosis and Comprehensive Care (Arabic).

Therapeutic Management Methods

Although there is no cure that completely eliminates Spinal Muscular Atrophy, available therapeutic options aim to boost levels of the missing protein and alleviate symptom severity. Available treatments include medications administered via the spinal canal or orally, as well as gene therapy for children under two years of age. The treatment plan is completed with physical and occupational therapy programs to maintain joint flexibility and muscle strength, along with the importance of balanced nutrition and the use of respiratory assistance devices when needed. This condition requires regular, meticulous medical follow-up by a multidisciplinary team to adapt to the patient's changing needs [1] [2].

Medical references

• Spinal Muscular Atrophy
• Spinal Muscular Atrophy
• Electromyography (EMG) and Nerve Conduction Studies