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Similar to Spinal Muscular Atrophy: Diagnosis and Global Management Considerations by Dr. Robert Rinaldi, Associate Professor of Pediatrics, Co-Director, Nerve and Muscle Program, Division of Pediatric Rehabilitation Medicine, Children's Mercy Kansas City
Similar to Spinal Muscular Atrophy: Diagnosis and Global Management Considerations by Dr. Robert Rinaldi, Associate Professor of Pediatrics, Co-Director, Nerve and Muscle Program, Division of Pediatric Rehabilitation Medicine, Children's Mercy Kansas City (20)
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Spinal Muscular Atrophy: Diagnosis and Global Management Considerations by Dr. Robert Rinaldi, Associate Professor of Pediatrics, Co-Director, Nerve and Muscle Program, Division of Pediatric Rehabilitation Medicine, Children's Mercy Kansas City
- 1. Spinal Muscular Atrophy: Diagnosis and Global Management Considerations Robert Rinaldi, MD FAAPMR Co-Director, Nerve and Muscle Program Associate Professor of Pediatrics Division of Pediatric Rehabilitation Medicine The Children’s Mercy Hospital and Clinics
- 2. Disclosures *I have no financial disclosures to make *I am not a pulmonologist *I am not using the official CMH slide template
- 3. What is SMA? • Spinal Muscular Atrophy • A neuromuscular disease of infancy, childhood, and adulthood, that effects the survival and function of the anterior horn cells of the spinal cord. • It is characterized by progressive, predominantly proximal and symmetric muscle weakness • Sensation and cognition are preserved • Broad clinical heterogeneity across phenotypes
- 4. Epidemiology • Autosomal Recessive • Incidence – 1:100,000 live births • 95% - homozygous deletion or mutations in Chromosome 5q, SMN1 gene • SMA type 1-3 • 5% - various other deletions associated with AHC involvement • Distal SMA syndromes • Kennedy Disease (X linked, SMAX1) • SMA with respiratory distress/SMARD (11q, IGHMBP2)
- 5. Pathology • Genetic – 2 genes, SMN1 and SMN2 • Homozygous deletion or mutations in SMN1 gene • SMN2 – production of alternative SMN protein • Unstable • Rapidly degrades • SMN2 copy # to clinical severity ratio • Deficiency of SMN1 leads to selective motor neuron degeneration • ? Motor neurons only • ? Role of SMN1 • ? Possible role in other organ systems
- 6. Anatomic Correlates - SMA en.wikipedia.org
- 7. Diagnostic Evaluation • Clinical presentation/Physical examination • Electrodiagnostic studies • Motor nerve conduction study – abnormal ( amplitudes, nml CV) • Sensory nerve conduction study – normal • EMG – denervation potentials • Targeted mutation analysis • deletions of exon 7 and 8, SMN1 gene (95-98%) • SMN2 copy count • Biopsy – grouped atrophy (motor unit loss) • not necessary anymore
- 8. Muscle Biopsy – group atrophy
- 9. Phenotypic Variants SMA Type Age of onset Highest Function Natural Age of Death Type 1 (severe) 0 – 6 months Never sits independently <2 y Type 2 (intermediate) 7-18 months Never stands independently >2 y Type 3 (mild) >18 months Stands and walks Adulthood Type 4 (adult) 2nd – 3rd decade Walks during adult years Adulthood
- 10. Phenotypic Variants • SMA 1 • Classic “floppy baby” • Profound hypotonia • Absent reflexes • Muscle fasiculations • Marked proximal-general weakness • Intercostal weakness plus spared diaphragm • Paradoxical breathing pattern • Bell shaped chest • Bulbar dysfunction Ehealthwall.com
- 11. Phenotypic Variants • SMA 2 • Delayed motor milestones • Inability to maintain independent sitting • Lower extremities affected more than upper extremities • +/- bulbar weakness and swallowing difficulties • Decreased cough and tracheal clearance • Risk: • Kyphoscoliosis • Evolving joint contractures – LE >> UE
- 12. Phenotypic Variants • SMA 3 • Subtypes: • A – onset before 3 y • B – onset after 3y • Late and variable onset • Independent walking achieved • May decline with age • +/- bulbar weakness - mild • +/- cough and nocturnal hypoventilation • Risk: • Scoliosis • Joint contractures
- 13. Treatment and Management • A systems and functional based approach • Medical management – improve health • Functional management – improve function, independence, and QOL • Primary considerations: • Developmental delay • Gastroeneterologic • Orthopedic / musculoskeletal • Craniofacial • Pulmonary • Mobility • Functional disabilities
- 14. Developmental • Intelligence– normal to above normal • Verbal IQ – above average • Gross motor milestones • SMA1 – no significant milestones achieved • SMA2 and 3 – may lose mobility as they age • ? etiology • Fine motor skills • Variable – based on upper extremity involvement • School modifications to accommodate physical disabilities • PT/OT – functional skills
- 15. Gastroenterologic • Considerations: • failure to thrive (35%) • Dysphagia – poor coordination of swallow and airway closure • Chewing difficulties – masticatory and facial weakness • Fatigue – decreased efficiency of pre-oral, oral and pharyngeal phases • Gastroesophageal reflux • Increased risk of aspiration • Management: • Formal swallow evaluation (OPM) • G-tube placement • Dietary modifications • Medication management for reflux
- 16. Orthopedic • Considerations: • Scoliosis • SMA2 > SMA3 > SMA1 • Early onset: 4-9 y • Bracing may slow progression, but wont stop it • Bracing may decrease tidal breathing if not fit correctly • Abdominal cut-out • Restrictive lung disease • Surgical correction • Curves >50 dgrees • Slows rate of respiratory deterioration
- 17. Orthopedic • Consideration: • Contractures • SMA 2 and 3 • Large joints – LE >>> UE • Hamstrings/knees; hip flexors • Can affect laying and sitting posture, mobility, comfort • Management • Stretching • Night time splinting • Surgical – soft tissue/tendon lengthenings and releases
- 18. Craniofacial • Considerations: • Deformities • Malocclusion • Jaw/mandibular deformity • Air leaks with non-invasive ventilation face masks • Poor dental hygiene • Open mouth posture due to facial weakness
- 19. Pulmonary • Major cause of morbidity and mortality in SMA 1 and 2 • Factors: • Weak inspiratory and expiratory muscles • Scoliosis – older SMA 2 and 3 • Progressive restrictive lung disease • Swallowing dysfunction and reflux • Recurrent infections • Progression to respiratory failure via recurrent infection/nocturnal desaturation and hypoventilation/daytime hypercarbia • Pulmonary evaluations every 6 months
- 21. Pulmonary • Considerations: • Weak Cough • Poor airway clearance • Decreased PCF, FVC • Risk: atelectasis, pneumonia • Management: • Adequate hydration • Assisted cough • MI/E devices – use 2x/d for maintenance, increase to 4x/d when ill • Pressures: children tolerate 40cm/-40cm well; adjust accordingly to age/size • Manual secretion mobilization • Chest percussion, etc….
- 22. Pulmonary • Considerations: • Recurrent infections • Aggressive secretion mobilization • Hydration • Monitoring for hypercapnia/inadequate ventilation • Non-invasive ventilation assistance if needed • Sleep-disordered breathing • Routine, semiannual monitoring of CO2, and PFTs • Polysomnograpghy • Management: nocturnal BIPAP
- 23. Functional Disabilities • The goal of rehabilitation medicine is to minimize the health impact of physical and cognitive impairments on an individual, while maximizing their functional capacity and quality of life…..regardless of diagnosis • Typical domains addressed • Cognition • Self care and activities of daily living skills • Fine motor skills • Gross motor skills / mobility • Communication
- 24. Functional Disabilities • Self care skills and ADLs • SMA1 – fully dependent • SMA2 – partially dependent • SMA3 – independent • Mobility • SMA1 – fully dependent • SMA2 – partially dependent • SMA3 – independent • Communication • SMA1 – dependent • SMA2 and 3 – independent • Goal: INCREASE AND MAXIMIZE FUNCTIONAL INDEPENDENCE
- 25. Self care skills and ADLs • Adaptive modifications