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Myopathy: A Closer Look

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  1. Myopathy: A Closer Look Sofiya Prilik, MD Physical Medicine and Rehabilitation

  2. Myopathy • Definition neuromuscular disorders in which the primary symptom is muscle weakness due to dysfunction of muscle fiber.* * Definition by the National Institute of Neurological Disorders and Stroke

  3. Let’ Start With Basics!

  4. Muscle Anatomy: gross and microscopic


  6. Function of Muscle

  7. Motor Unit A motor unit is made up of a motor neuron and all the muscle cells it stimulates. Motor units vary in size. Small motor units are used for precise, small movements; large motor units are are used for gross movements. The number of cells within a motor unit determines the degree of movement when the motor unit is stimulated. Muscle tone is maintained by asynchronous stimulation of random motor units.

  8. Normal Muscle

  9. Abnormal Muscle

  10. Myopathy: symptoms • Muscle Weakness • Proximal Muscles>distal muscles • Fatigue • Difficulty rising from a chair, floor, tub • Difficulty with stairs • Difficulty with overhead tasks • Respiratory muscles • Bulbar weakness- speech, swallowing, oculomotor, facial

  11. Myopathy: symptoms • Pain • Mostly with inflammatory and metabolic • High serum CK level • Aching, dull, cramping • Patients will say: “sore”, “ache”, “spasm” • No numbness or paresthesias

  12. Physical Exam: • Full exam is important! • Observation – look for muscle atrophy, deformities • Strength testing – manual muscle test • ROM testing • Functional testing • Stand up from a chair • Walk • Step up on a low stool • Don’t forget REFLEXES and SENSATION

  13. Inflammatory Myopathies Polymyositis Dermatomyositis Inclusion body myositis Viral Muscular dystrophies X-linked Limb-girdle(ar/d) Congenital Fasioscapulohumeral (ad) Scapuloperoneal (ad) Distal (Welander) (ad/r) Myotonic Syndromes Myotonic dystrophy (ad) Inherited Schwarz-Jampel Drug-induced Congenital myopathies Central core disease Nemaline myopathy Myotubular Fiber-type disproportion Metabolic myopathies Glycogenoses Mitochondrial Periodic paralysis Endocrine myopathies Thyroid Parathyroid Adrenal/steroid Pituitary Drug-induced/toxic Myopathic Disorders

  14. Myopathy: types • Muscular dystrophies • Inherited • Abnormal muscle proteins • Progressive course and early onset • Congenital • Slowly progressive or non-progressive • Distinct finding on muscle biopsy

  15. Metabolic • Defect in intracellular energy production • Inflammatory • Acquired • Caused by immune or infectious process • Almost always are associated with elevated Creatinine Kinase level in serum. • Atrophic • Drug-induced (Colchicine, AZT, ETOH, Statins (1/10,000 per year) • Endocrine (steroid) • CK is most often normal

  16. Myotonic • Congenital or adult • Cardiopulmonary compromise

  17. Epidemiology • Worldwide incidence of all inheritable myopathies is about 14% • Overall incidence of muscular dystrophy is about 63 per 1 million. • Worldwide incidence of inflammatory myopathies is about 5–10 per 100,000 people. More common in women • Corticosteroid myopathy is the most common endocrine myopathy and endocrine disorders are more common in women • Overall incidence of metabolic myopathies is unknown.

  18. Diagnosis • Case: • 59 year-old male with history of smoking, who was diagnosed with severe COPD/emphysema 2.5 years ago. Since then, he had several hospitalizations due to worsening SOB and productive cough. He was treated with high doses of IV corticosteroids followed by very slow oral steroid tapers. After the last hospitalzation 4 months ago, he has been maintained on a Prednisone 5 mg daily. • Normally, the patient is independent with transfers, ambulation and ADL’s. His walking tolerance is about 1-2 blocks, limited by SOB. • 2 weeks ago, patient presented to his PMD c/o progressive functional decline in walking tolerance, and especial difficulty with transfers and stairs. • Exam revealed a thin male, with O2 saturation of 93% on RA. No apparent respiratory distress was noted. No cushinoid features were seen. Pertinent positives included visibly apparent atrophy in the proximal muscles groups of both UE and LE. Strength testing was within normal limits. Patient had difficulty standing up from a sitting position. He was unable to perform squats. • Labs – WBC 11.8, Glu 120, otherwise normal. CK - normal • NCS/EMG - normal

  19. DIAGNOSIS Steroid induced myopathy.

  20. STEROID INDUCED MYOPATHY • Insidious disease process • weakness of proximal muscles of the upper and lower limbs and neck flexors. • First described by Cushing in 1932 • An excess of either endogenous or exogenous corticosteroids is believed to cause the condition. • Chronic or acute (less common) • Catabolic effect on muscle – gluconeogenesis from aminoacids

  21. STEROID INDUCED MYOPATHY • Fluorinated steroids are implicated • Dexamethasone • Triamcinolone • Also seen with non-fluorinated ones • Prednisone • Inhaled steroids

  22. Pathophysiology • decreased protein synthesis • increased protein degradation • alterations in carbohydrate metabolism • mitochondrial alterations • electrolyte disturbances • decreased sarcolemmal excitability

  23. Epidimiology • For a given dose of steroid, women appear to be twice as likely as men to develop muscle weakness • Worldwide incidence or prevalance is unknown

  24. Diagnostic studies • Labs • Routine Labs • Special labs • Creatinine Kinase – normal • Urine Creatinine – increased • No myoglobinuria or rhabdomyalysis • Muscle biopsy • type IIB fibers are mostly affected • No inflammation, necrosis or regeneration

  25. DIAGNOSTIC STUDIES • Electrodiagnostic studies • Normal nerve conduction studies (NCS) • Electromyography can be normal • (EMG tests type I fibers, while SM mostly affects IIB) • DON’T FORGET: • A chronically or critically ill patient, can have other co-morbid conditions, that may impact NCS or EMG

  26. TREATMENT • Steroid treatment modification • Pain control • Prevention of contractures • Avoid exercise to the point of exhaustion • Aerobic exercise • ROM • Moderate resistance exercise • Assistive devices • Other: ventilation, percutaneous enteric feed

  27. MYOPATHY RELATED TO CRITICAL ILLNESS • Common in patients even after a brief period in the intensive care unit. Estimated to be about 25%. • Gained recognition in the last decade • Often misdiagnosed or missed • Can occur in conjunction with polyneuropathy • Associated with prolonged ventilation and difficult weaning

  28. Differential Diagnosis • Motor neuron disease • ALS • Late onset spinal muscular atrophy • Post-polio syndrome • Neuromuscular junction disorders • Myasthenia Gravis • Lambert-Eaton myasthenic syndrome • Motor neuropathy • Myelopathy/ spinal stenosis • Parkinson’s


  30. What is PPS? • Initiated January 1, 2002 • Inpatient Rehab Facility Prospective Payment System (IRF-PPS) is the reimbursement program for Medicare Part-A patients based on their specific impairment + level of functioning upon admission • 21 general Rehab Impairment Categories (RIC), 85 specific Impairment Group Codes (IGC), Admission FIM scores and sometimes Age, determine the Case Mix Group (CMG) • The CMG determines the one-time fixed reimbursement amount per patient per stay at an IRF and generates an Average Length of Stay (ALOS) based on national norms • ~ 70% Rusk population are MCR Part-A recipients

  31. What is the 60% Rule? To qualify as an IRF, a provider must deliver intensive rehabilitation services to a population of inpatients, currently 60% of whom, fall into one or more of 13 specific impairment categories, (the “CMS 13”), from the total 21 Rehab Impairment Categories (RICs)

  32. PPS: 21 IGCs Specific ICD-9-CM codes for comorbs that provide additional reimbursement 3 Tiers (B,C,D) – High to low levels of additional reimbursement 60% Rule: 13 Qualifying IGCs Specific ICD-9-CM codes for etiologies and comorbsthat qualify cases in the ruling No impact on reimbursement Compliance maintains facility’sstatus as an IRF PPS vs. CMS 60% Rule

  33. Active Comorbidities “Conditions resulting in functional deficits that will be addressed or monitored during the inpatient rehab stay”: • Medical conditions requiring consults, testing and/or medications • Conditions affecting ADLs • Conditions or complications that affect rehab treatment course or plan of care

  34. How Can Health Care Providers Contribute? • Familiarize yourselves with commonly seen comorbid conditions, including, but not limited to, qualifiers in the 60% rule and PPS reimbursable comorbidities • Identify patients who have deficits indicative of myopathy and discuss deficits with the rehab physicians • Clearly document the current deficits, assign accurate motor and cognitive FIM scores to represent the patient’s true functional levels of assistance and burden of care while in rehab • Clearly document any residual deficits from previous illnesses/events that are still being addressed in therapy sessions, including “resolving” conditions

  35. Specificity in Documentation – Importance of Communication between Therapists and MDs • Rehab-designated Medical Records Coders can only assign ICD-9-CM Codes for conditions included in physician documentation • If therapies or nursing alone provide documentation - conditions will not be coded • Accurate coding contributes to both qualifying cases in the 60% Rule and additional reimbursement for PPS

  36. 60% rule Qualifying ICD-9-CM Codes and Verbiage for Myopathy • 359.0 - Congenital Hereditary Muscular Dystrophy • 359.1 - Hereditary Progressive Muscular Dystrophy • 359.2 - Myotonic Disorders • 359.3 - Familial Periodic Paralysis • 359.4 - Toxic Myopathy • 359.5 - Myopathy in Endocrine Diseases Classified Elsewhere • 359.6 - Symptomatic Inflammatory Myopathy in Diseases Classified Elsewhere • 359.81 - Critical Illness Myopathy • 359.89 - Other Myopathies • 710.3 - Dermatomyositis • 710.4 - Polymyositis

  37. Contact your PPS Coordinators anytime with Questions  • Meryl Eisdorfer, R.N.,B.S.N. x 33754, In-house pager: 1910 • Randi Farkas, M.A.,CCC-SLP x 33744, In-house pager: 2522, Cell: 917-589-9386