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spinal muscular atrophy sma by allelieh


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spinal muscular atrophy sma by allelieh

  1. 1. Spinal Muscular Atrophy Allelieh Javier Capistrano, RT Pediatric Respiratory Therapist Section of Pulmonary MedicinePhilippine Children’s Medical Center
  2. 2. What is SMA? Spinal muscular atrophy (SMA) is a group of inherited neuromuscular diseases that attack motor neurons, which control the movement of voluntary muscles. This disease causes anterior horn cells (lower motor neurons) in the base of the brain and spinal cord to gradually disintegrate. The disorder causes weakness and wasting of the voluntary muscles. Weakness is often more severe in the legs than in the arms.
  3. 3. What is SMA? Loss of function of spinal motor neurons causing progressive weakness of muscles Muscles include extremities, respiratory muscles Sensation is normal Brain function is normal
  4. 4. What is the lower motor neuron?
  5. 5. Types of SMA Infantile progressive spinal muscular atrophy (SMA Type 1) Intermediate SMA (SMA Type 2) Juvenile SMA (SMA Type 3) Adult SMA (SMA Type 4) SMARD1 Congenital SMA with arthrogryposis
  6. 6. SMA Type 1 Also known as, Werdnig-Hoffmann acute infantile, non-sitters, occur birth up to 6 months (95% by 3 months) Severe, progressive muscle weakness and flaccid or reduced muscle tone (hypotonia). Bulbar dysfunction includes poor suck ability, reduced swallowing, and respiratory failure. Patients have no involvement of the extraocular muscles, and facial weakness is often minimal or absent. They have no evidence of cerebral involvement, and infants appear alert.
  7. 7. SMA Type 1 Impaired fetal movements are observed in 30% of cases 60% of infants with SMA type I are floppy babies at birth. Prolonged cyanosis may be noted at delivery. In some instances, the disease can cause fulminant weakness in the first few days of life. Such severe weakness and early bulbar dysfunction which has a mean survival of 5.9 months. Affected children never sit or stand. In 95% of cases, infants die from complications of the disease by 18 months.
  8. 8. SMA Type 2 SMA type II (intermediate SMA, sitters) usually begin between 6 - 18 months. Most common form of SMA Most common manifestation is developmental motor delay. Infants with SMA type II often have difficulties with sitting independently or failure to stand by 1 year of age. These children may learn to sit but will never be able to stand or walk.
  9. 9. SMA type 2 An unusual feature of the disease is a postural tremor affecting the fingers. This is thought to be related to fasciculations in the skeletal muscles Pseudohypertrophy of the gastrocnemius muscle, musculoskeletal deformities, and respiratory failure can occur. The lifespan of patients with SMA type II varies from 2 years to the third decade of life. Respiratory infections account for most deaths.
  10. 10. SMA Type 3 SMA type III (Kugelberg-Welander, chronic juvenile, walkers) appear 18 months – adult. Slowly progressive proximal weakness. Most can stand and walk but have trouble with motor skills, such as going up and down stairs. Bulbar dysfunction occurs late in the disease.
  11. 11. SMA Type 3 Patients may show evidence of pseudohypertrophy. The disease progresses slowly, and the overall course is mild. Many patients have normal life expectancies.
  12. 12. SMA Type 4 is the adult form of the disorder. Most people affected by this type start having symptoms after age 35, and these symptoms slowly get worse over time. Because it develops slowly, many people with type IV SMA dont know that they have it until years after symptoms begin.
  13. 13. Spinal Muscular Atrophy with Respiratory Distress Type 1 (SMARD1) In SMARD1, the predominating symptom is a severe respiratory distress due to a paralysis of the diaphragm. Most patients present show symptoms at the age of 1 to 6 months with respiratory failure and progressive muscle weakness with predominantly distal lower limb muscle involvement.
  14. 14. Spinal Muscular Atrophy with Respiratory Distress Type 1 (SMARD1) In SMARD1, the predominating symptom is a severe respiratory distress due to a paralysis of the diaphragm. Most patients present show symptoms at the age of 1 to 6 months with respiratory failure and progressive muscle weakness with predominantly distal lower limb muscle involvement.
  15. 15. Congenital SMA with arthrogryposis Congenital SMA with arthrogryposis (persistent contracture of joints with fixed abnormal posture of the limb) is a rare disorder. Manifestations include severe contractures, curvature of the spine, chest deformity, respiratory problems, an unusually small jaw, and drooping upper eyelids.
  16. 16. Congenital SMA with arthrogryposis
  17. 17. A Genetic Cause SMA is usually inherited. This means that both parents must have an altered (mutated) or missing copy of the gene involved in the disorder for a child to develop it.
  18. 18. A Genetic Cause Most cases of SMA are caused by a deficiency of a special protein called SMN ("survival of motor neurons"). Motor neurons need this protein to function. The gene that carries this protein is called SMN1. When each parent passes onto their child a chromosome with a mutated or missing SMN1 gene, the protein is not produced and motor neurons die, leading to SMA.
  19. 19. A Genetic Cause The genetic defects associated with SMA types I-III are localized on chromosome 5q11.2-13.3. Mutations in the SMN gene result in a loss of function of the SMN protein.
  20. 20. Clinical Features (general for all types of SMA) Progressive degeneration and loss of the lower motor neurons (anterior horn cells) in the spinal cord and sometimes in the brainstem nuclei.  Results in muscle weakness and atrophy  The onset varies from before birth until adulthood  The weakness is symmetric and progressive Contractures, usually mild Anterior horn cell involvement, apparent due to tongue fasciculations and absent deep tendon reflexes Respiratory failure Variable cranial nerve involvement: opthalmoplegia, facial diplegia
  21. 21. Diagnosis
  22. 22. Diagnosis A diagnosis usually comes only after the child undergoes several tests that rule out other diseases that cause similar symptoms. These tests usually include:  nerve conduction tests, such as an electromyogram (EMG)  computed tomography (CT) scan  magnetic resonance imaging (MRI)  muscle tissue biopsy
  23. 23. Diagnosis To confirm an SMA diagnosis, the doctor will usually recommend a blood test to look at the childs genes. If the SMN1 gene is missing or imperfect, it will confirm the diagnosis of SMA. The doctor might also recommend that parents and other members be screened for the disorder, even if theyve never had any symptoms.
  24. 24. Treatment Unfortunately, there is no cure for SMA. The treatment that children receive for SMA varies, depending on their age and the severity of symptoms. The goal of treatment is to relieve specific symptoms, maintain function and enhance a childs mobility for as long as possible, and maximize the childs independence and quality of life.
  25. 25. Prevention and Maintenance Today, much can be done for SMA patients in terms of medical and in particular respiratory, nutritional and rehabilitation care. Physical therapy and occupational therapy to promote and maintain motor skills. Monitoring of respiratory function, ventilatory support.
  26. 26. Respiratory Support Children with SMA commonly need help breathing when muscle weakness begins to affect the respiratory muscles. Different therapies can help a child breathe.  Oxygen therapy  Non-invasive positive pressure ventilation (NIPPV)  BiPAP  tracheostomy
  27. 27. Respiratory Support A critical factor in respiratory care is preventing infection, especially pneumonia. Pneumonia is common in children with SMA and is life threatening.
  28. 28. Respiratory Aids Cough Assist Chest physiotherapy Home suction Pulse oximeter Ambubag Nebulizer  Bronchodilator, mucolytics, anticholinergics
  29. 29. Conventional Respiratory therapy 1. Oxygen administrated arbitrarily in concentrations that maintain SaO2 well above 95%. 2. Frequent airway suctioning via the tube. 3. Supplemental oxygen increased when desaturations occur. 4. Ventilator weaning attempted at the expense of hypercapnia. 5. Extubation not attempted unless the patient appears to be ventilator weaned.
  30. 30. Conventional Respiratory therapy  6. Extubation to CPAP or low span bi-level positive airway pressure and continued oxygen therapy.  7. Deep airway suctioning by catheterizing the upper airway along with postural drainage and chest physical therapy.  8. With increasing CO2 retention or hypoxia supplemental oxygen is increased and ultimately the patient is reintubated.  9. Following re-intubation tracheostomy is thought to be the only long-term option or following successful extubation bronchodilators and ongoing routine chest physical therapy are used.  10. Eventually discharged home with a tracheostomy, often following a rehabilitation stay for family training.  
  31. 31. Protocol for SMA 1. Oxygen administration limited only to approach 95% SaO2. 2. Mechanical insufflation-exsufflation used via the tube at 25 to 40 cm H2O to -25 to -40 cm H2O pressures up to every 10 minutes as needed to reverse oxyhemoglobin desaturations due to airway mucus accumulation and when there is auscultatory evidence of secretion accumulation. Abdominal thrusts are applied during exsufflation. Tube and upper airway are suctioned following use of expiratory aids as needed. 3. Expiratory aids used when desaturations occur. 4. Ventilator weaning attempted without permitting hypercapnia.
  32. 32. Protocol for SMA 5. Extubation attempted whether or not the patient is ventilator weaned when meeting the following:  A. Afebrile  B. No supplemental oxygen requirement to maintain SaO2 >94%  C. Chest radiograph abnormalities cleared or clearing  D. Any respiratory depressants discontinued  E. Airway suctioning required less than 1-2x/eight hours
  33. 33. Nutritional Support SMA can affect the muscles used for chewing, sucking, and swallowing. This can cause a child to become malnourished or develop pneumonia if the child inhales food or liquids while eating. Some children do better by eating small, frequent meals throughout the day instead of having three large meals. Some children with SMA are at risk for obesity if they consume too many calories for their activity levels and they cant exercise to effectively burn the calories. Ongoing consultation with a nutritionist is necessary to ensure adequate nutrition that doesnt overload a child with unnecessary calories.
  34. 34. Nutritional Support Children who cant swallow or suck must be fed in another way to ensure that theyre receiving enough nutrition. Sometimes, they have a tube inserted into the stomach to help them eat. Through this tube, called a gastrostomy tube, they can receive a nutritionally sound liquid diet.
  35. 35. Function and Mobility
  36. 36. Function and Mobility Many children with SMA benefit greatly from physical and occupational therapies, which help to maintain function and mobility and enhance quality of life for as long as possible. In some cases, tools can help make these tasks easier, such as:  leg braces, standing frames, canes, and walkers, which provide stability and improve mobility  electric wheelchairs with customized controls  specialized seats to use in school  tools for using computers and phones and controlling other home electronics, such as the TVs and lights  tools to aid educational activities, such as writing and drawing
  37. 37. Spinal Deformity Children who develop spinal deformities need to wear a splint, brace, or corset to straighten their backs as toddlers or adolescents. Sometimes, surgery (called a spinal fusion) is done to correct the spinal deformity in children who are done growing and whose respiratory systems can tolerate sedation with anesthesia.
  38. 38. Outlook Scientists who are researching SMA have made dramatic breakthroughs in the past few years, including identifying the genes and the protein associated with the disorder. Research is now focused on finding drugs and other therapies that can help to keep motor neurons functioning as long as possible, enhance muscle tone and function, and even modify gene function. Many scientists are optimistic that ongoing research will lead to better treatment of SMA.
  39. 39. My ReferencesWeb references1. motor_synapses_lost_in_SMA.htm2. muscular-atrophy5. )Guidelines/books1. Guide to the Evaluation and Management of Patients with Neuromuscular Disease by Dr John Bach (2004)2. Facts about Spinal Muscular Atrophy. Muscular Dystrophy Association3. Handbook of Genetic Counseling
  40. 40. Thank you!!