Trans 054 Approach to Myopathy Flashcards
refers to a clinical disorder of the skeletal muscles. Abnormalities of muscle cell structure and metabolism lead to various patterns of weakness and dysfunction. In some cases, the pathology extends to involve cardiac muscle fibers, resulting in a hypertrophic or dilated cardiomyopathy.
Myopathy
The first goal in approaching a patient with a suspected muscle disease is to determine____________
The second goal is to determine the __________
site of the lesion/ pattern of weakness.
cause of the myopathy.
in evaluation of myopathy,
The third goal is to determine ___________.
whether a specific treatment is available and if not, to optimally manage the patient’s symptoms to maximize his or her functional abilities and enhance quality of life.
In adulthood presentation, what are under muscular dystrophy?
o Limb-girdle
o Facioscapulohumeral
o Becker
o Emery-Dreifuss
In adulthood presentation what are under Inflammatory myopathies ?
o Polymyositis
o Dermatomyositis
o Inclusion body myositis
o Viral [HIV]
In adulthood presentation what are under, metabolic myopathies?
o Acid maltase deficiency o Lipid storage diseases o Debrancher deficiency o Phosphorylase b kinase deficiency o Mitochondrial myopathies
In adulthood presentation what are under Endocrine myopathies?
o Thyroid
o Parathyroid
o Adrenal
o Pituitary disorders
In adulthood presentation what are under Toxic myopathies?
o Alcohol o Corticosteroids o Local injection of narcotics o Colchicine o Chloroquine o Statins
what does this presentation suggests regarding the pattern of weakness?
Difficulty climbing stairs, arising from a low chair or toilet, or getting up from a squatted position.
Proximal lower extremities:
what does this presentation suggests regarding the pattern of weakness?
trouble lifting objects over their head and brushing their hair.
Proximal upper extremities:
what does this presentation suggests regarding the pattern of weakness?
difficulty opening jars, inability to turn a key in the ignition.
Distal upper extremities:
what does this presentation suggests regarding the pattern of weakness?
Tripping due to foortdrop
Distal lower extremities:
if there is constant weakness, what are some diff diagnosis?
acute
chronic c slow progresssion
non progressive weakness
inflammatory myopathies (dermatomyositis and polymyositis).
o most muscular dystrophies
o Inclusion Body Myositis (IBM1)
o congenital myopathies
can occasionally have an acute monophasic course with complete resolution of strength within weeks or months.
• Patients with periodic paralysis or metabolic myopathies can have recurrent attacks of weakness over many years,
polymyositis
Periodic paralysis is characteristically provoked by
exercise or ingestion of a carbohydrate meal followed by a period of rest.
Patients with para-myotonia congenita frequently report that _________ may precipitate their symptoms of muscle stiffness
cold exposure
what are X linked myopathies?
o Duchenne
o Becker
o Emery-Dreifuss
Autosomal Dominant myopathies
o Facioscapulohumeral o Limb-girdle o Oculopharyngeal muscular dystrophy o Myotonic dystrophy o Periodic paralysis o Para-myotonia congenita o Thomsen disease o Central core myopathy
Autosomal Recessive myopathies?
o Limb-girdle
o Metabolic myopathies
o Becker myotonia
Maternal Transmission myopathy?
Mitochondrial Myopathy
Selective atrophy of the quadriceps and forearm flexor muscles is highly suggestive of
inclusion body myositis
may have profound atrophy of the anterior or posterior lower extremity compartments
Distal myopathies
what can cause hypertrophy
o LGMD2C-2F, LGMD2I, (LGMD 2G in 50% of pt)
o Myotonia congenita
o Amyloidosis o Sarcoidosis, and
o Hypothyroid myopathy
wha can cause Pseudohypertrophy
Duchenne and Beckers MD
muscular enlargement through deposition of fat rather than muscle fibre
Pseudohypertrophy
what can cause scapular winging
o Facioscapulohumeral muscular dystrophy (FSHD3) o LGMD1B (laminopathy), LGMD2A (calpainopathy), LGMD2c-2f (sarcoglycanopathies)
The most common pattern of muscle weakness in myopathies
Pattern 1 proximal limb girdle weakness
This pattern of weakness is seen in most hereditary and acquired myopathies and therefore is the least specific in arriving at a particular diagnosis
proximal limb girdle weakness
The involvement is usually, although not invariably, symmetrical.
• more commonly a feature of neuropathies
Distal Weakness
This pattern of weakness affects the periscapular muscles of the proximal arm and the anterior compartment muscles of the distal lower extremity (scapuloperoneal distribution)
• The scapular muscle weakness is usually characterized by scapular winging.
• Weakness can be very asymmetrical.
PROXIMAL ARM/DISTAL LEG WEAKNESS
- The facial muscles are usually spared.
- Involvement of other muscles is extremely variable.
- The weakness is often asymmetrical between the two sides, which is uncommon in most myopathies.
DISTAL ARM/PROXIMAL LEG WEAKNESS
• This pattern is essentially pathognomonic for inclusion body myositis (IBM).
DISTAL ARM/PROXIMAL LEG WEAKNESS
The combination of ptosis, ophthalmoplegia (without diplopia), and dysphagia should suggest the diagnosis of
oculopharyngeal dystrophy
Ptosis and ophthalmoplegia without prominent pharyngeal involvement is a hallmark of
many of the mitochondrial myopathies.
Ptosis and facial weakness without ophthalmoplegia is a common feature of
myotonic dystrophy
Identify is this is a Ptosis s Ophthalmoplegia or Ptosis C Ophthalmoplegia?
Myotonic dystrophy
without
Identify is this is a Ptosis s Ophthalmoplegia or Ptosis C Ophthalmoplegia?
• Congenital myopathies
o Centronuclear myopathy
o Nemaline myopathy
o Central core myopathy
without
Identify is this is a Ptosis s Ophthalmoplegia or Ptosis C Ophthalmoplegia?
• Oculopharyngodistal myopathy
with
Identify is this is a Ptosis s Ophthalmoplegia or Ptosis C Ophthalmoplegia?
• Neuromuscular junction disease (myasthenia gravis, Lambert-Eaton, botulism)
with
Identify is this is a Ptosis s Ophthalmoplegia or Ptosis C Ophthalmoplegia?
Desmin (myofibrillary) myopathy
without
what pattern of weakness?
- ‘‘dropped head syndrome’’
- Involvement of the neck flexors is variable.
- Isolated neck extension weakness represents a distinct muscle disorder called isolated neck extensor myopathy.
- Prominent neck extensor weakness:
- amyotrophic lateral sclerosis and
- myasthenia gravis.
prominent neck extensor weakness
what are myopathies with prominent neck extensor weakness?
- Isolated neck extensor myopathy”
- Polymyositis “
- Dermatomyositis “
- Inclusion body myositis “
- Carnitine deficiency “
- Facioscapulohumeral dystrophy “
- Myotonic dystrophy “
- Congenital myopathy “
- Hyperparathyroidism
elevated in the majority of myopathies but may be normal in slowly progressive myopathies.
Creatine kinase
the CK level is invariably at least 10 times (and often up to 100 times) normal.
Duchenne Dystrophy
The CK level may not be elevated in
o corticosteroid administration, o collagen diseases, o alcoholism o hyperthyroidism o profound muscle wasting
If there are no muscles, the CK would not be elevated because there no muscles to be destroyed. This is why in late stages of Duchenne dystrophy, CK levels would be normal.
- Confirm localization
- Can be a guide as to which muscle to biopsy.
- rule/out neuropathy, NMG disease, MND.
electrophysiological studies
are typically normal in patients with myopathy.
Nerve Conduction Studies (NCS)
But abnormal in patients with neuropathy
o Brief duration,
o small-amplitude
o Early recruitment
Will show abnormality in patients with myopathy
Needle EMG examination: motor units
Muscles that are severely weak (MRC grade 3 or less) should [not be/ be] biopsied, since the results are likely to show only evidence of end stage muscle disease
not be
muscles that have recently been studied by needle EMG should be avoided because of the possibility of artifacts created by needle insertion. T or F?
True
Biopsies should generally be taken from muscles that demonstrate MRC grade ______ strength
grade 4
muscle of choice in mm biopsy?
biceps, vastus lateralis
why should the gastrocnemius be avoided in muscle biopsy?
The gastrocnemius should be avoided since its tendon insertion extends throughout the muscle and inadvertent sampling of a myotendinous junction may cause difficulty with interpretation.
histopathology of myopathies?
Typical myopathic abnormalities include:
o central nuclei,
o both small and large hypertrophic round fibers,
o split fibers, and
o degenerating and regenerating fibers.
o Chronic myopathies frequently show evidence of increased connective tissue and fat.
• characterized by: o the presence of mononuclear inflammatory cells in the endomysial and perimysial connective tissue between fibers and occasionally around blood vessels (perivascular)
inflammatory myopathies
- In addition, perifascicular atrophy, characterized by atrophy of fibers located on the periphery of a muscle fascicle, is a common finding.
- Inflammatory cell invasion of nonnecrotic fibers is not prominent.
- Deposition of the C5b-9 or membrane attack complex on or around small blood vessels
dermatomyositis
- Variability in fiber size,
- Scattered necrotic and regenerating fibers,
- Endomysial inflammation with invasion of non-necrotic muscle fibers
polymyositis
• Endomysial inflammation with invasion of non-necrotic muscle fibers • small groups of atrophic fibers, • eosinophilic cytoplasmic inclusions, and muscle fibers with one or more rimmed vacuoles lined with granular material • Amyloid deposition is evident on Congo red staining. • TDP-43 positive • Ubiquitin positive • Electron microscopy demonstrates 15-nm to 21-nm cytoplasmic and intranuclear tubulofilaments
inclusion body myositis?
- The typical muscle histopathology is “ragged red’’ fibers
- Subsarcolemmal accumulation of abnormal mitochondria stains red.
- Best seen with modified– Gomori trichrome stain
mitochondrial disorder
