FACT SHEET SPINAL MUSCULAR ATROPHY Spinal Muscular Atrophy (SMA) is a Motor Neuron Disease. It is caused by the mutation of the Survival of SYMPTOMS IN INFANTS • Muscle weakness. Motor Neuron (SMN) gene. It occurs due to the loss of • Muscle atrophy (wasting). motor neurons within the spinal cord and brain. It results • Poor muscle tone. in the progressive wasting away of muscles (atrophy) and • Areflexia (delayed reflexes). muscle weakness. SMA can affect people of all ages, races • Weak cry. or genders; however, the majority of cases occur in infancy • Difficulty sucking or swallowing. or childhood. There are four types of SMA. • Feeding difficulties. FORMS OF SMA • Weak cough. • Lack of developmental milestones (inability to lift head TYPE I (ACUTE INFANTILE) or sit up). • Also called Wernig-Hoffman Disease. • Limpness or a tendency to flop. • Most severe form of SMA. • Accumulations of secretions in the lungs or throat. • Usually diagnosed before six months of age. • Those affected cannot sit without support, lungs may SYMPTOMS IN ADULTS not fully develop, swallowing and breathing may be • Muscle weakness. difficult and there is weakness of the intercostal muscles • Muscle atrophy (wasting). (muscles between the ribs). • Weak tongue. • 95 per cent fatal by 18 • Stiffness. • Cramps. TYPE II (CHRONIC INFANTILE) • Fasciculation (twitching). • Usually diagnosed before the age of two, with the • Clumsiness. majority of cases diagnosed by 15 months. • Dyspnea (shortness of breath). • May be able to sit without assistance or even stand with support. DIAGNOSIS • Increased risk for complications from respiratory • A diagnosis can be made by an SMN gene test which infections. determines whether there are any traces of the SMN1 • Usually do not live past 30 years of age. gene. TYPE III (CHRONIC JUVENILE) • When the SMN gene test is not possible or shows no abnormality, an electromyography (EMG) or muscle • Also known as Kugelberg-Welander or Juvenile Spinal biopsy can be done. Muscular Atrophy. • Usually diagnosed before the age of three but can strike TREATMENT as late as adolescence. • Physical and occupational therapy. • Able to walk but experience noticeable weakness. • Ventilation is crucial, as many infants with severe forms • Most patients eventually need to use a wheelchair. of SMA succumb to respiratory disease due to weakness of • Usually survive well into adulthood with normal life breathing muscles. expectancy. • Assistive devices, such as ventilators and power wheel- chairs, help those living with SMA live longer and fuller TYPE IV (ADULT ONSET) • Much less common than the other forms. OTHER FACTS • Symptoms tend to surface after the age 35 but sometimes earlier. • Lifespan depends on the severity of SMA in the patient. • The bulbar muscles – used for swallowing and • Intellectual ability is unaffected. respiratory function – are rarely affected. • Sexual response and reproductive functions are also • Progression is slow and those affected have a normal life unaffected. expectancy. PROVINCIAL OFFICE ALS SOCIETY OF ALBERTA EDMONTON OFFICE 7874 10 STREET NE WWW.ALSAB.CA 5418 97 STREET NW CALGARY, AB T2E 8W1 1-888-309-1111 EDMONTON, AB T6E 5C1.