Myopathy: A Closer Look

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Myopathy A Closer Look

• Dr shabeel pn

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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

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Let Start With Basics!
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Muscle Anatomy gross and microscopic
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MUSCLE FIBER
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Function of Muscle
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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.
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Normal Muscle
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Characteristics of the Three Muscle Fiber Types Characteristics of the Three Muscle Fiber Types Characteristics of the Three Muscle Fiber Types Characteristics of the Three Muscle Fiber Types
Fiber Type Slow Twitch Type I Fast Twitch A Type IIA Fast Twitch B Type IIB
Contraction time Slow Fast Very fast
Size of motor neuron Small Large Very large
Resistance to fatigue High Intermediate Low
Activity used for Aerobic Long term anaerobic Short term anaerobic
Force production Low High Very high
Mitochondrial density High High Low
Capillary density High Intermediate Low
Oxidative capacity High High Low
Glycolytic capacity Low High High
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Abnormal Muscle
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Myopathy symptoms

• Muscle Weakness
• Proximal Musclesgtdistal muscles
• Fatigue
• Difficulty rising from a chair, floor, tub
• Difficulty with stairs
• Difficulty with overhead tasks
• Respiratory muscles
• Bulbar weakness- speech, swallowing, oculomotor,
  facial

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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

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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
• Dont forget REFLEXES and SENSATION

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Myopathic Disorders

• 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

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Myopathy types

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

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• 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

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• Myotonic
• Congenital or adult
• Cardiopulmonary compromise

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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 510 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.

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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 ADLs. 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

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DIAGNOSIS

• Steroid induced myopathy.

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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

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STEROID INDUCED MYOPATHY

• Fluorinated steroids are implicated
• Dexamethasone
• Triamcinolone
• Also seen with non-fluorinated ones
• Prednisone
• Inhaled steroids

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Pathophysiology

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

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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

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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

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DIAGNOSTIC STUDIES

• Electrodiagnostic studies
• Normal nerve conduction studies (NCS)
• Electromyography can be normal
• (EMG tests type I fibers, while SM mostly affects
  IIB)
• DONT FORGET
• A chronically or critically ill patient, can have
  other co-morbid conditions, that may impact NCS
  or EMG

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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

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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

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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
• Parkinsons

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QUESTIONS?
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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

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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)

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PPS vs. CMS 60 Rule

• 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
  comorbs that qualify cases in the ruling
• No impact on reimbursement
• Compliance maintains facilitys status as an IRF

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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

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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 patients 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

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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

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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

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Contact your PPS Coordinators anytime with
Questions ?

• Meryl Eisdorfer, R.N.,B.S.N.
• x 33754, In-house pager 1910
• meryl.eisdorfer_at_nyumc.org
• Randi Farkas, M.A.,CCC-SLP
• x 33744, In-house pager 2522,
• Cell 917-589-9386
• randi.farkas_at_nyumc.org