Myopathy Flashcards
(45 cards)
What are the three major groups of myopathies?
- Muscular dystrophies (dystrophic: fiber splitting + ^ CT)
- Inflammatory myopathies
- Metabolic myopathies
Duchenne Muscular Dystrophy:
- Inheritance
- Chromosome
- Onset
- Initial Weakness
- Rate of progression
- CK
- EKG
- Muscle biopsy?
- XR; 1/3 spontaneous
- Xp21, large deletion
- Onset 5 yoa
- Pelvic weakness first; (+) Gower’s sign
- Rapidly progressive
- ^^^CK
- Abnormal EKG
- Muscle biopsy shows MQ invasion, necrotic fibers
Becker Muscular Dystrophy:
- Inheritance
- Chromosome
- Onset
- Initial Weakness
- Rate of progression
- CK
- EKG
- XR; Xp21
- Onset 10 yoa
- Pelvic weakness first
- Slower progression
- ^^CK (more moderate)
- Abnormal EKG
Face-Scapulo-Humoral
- Inheritance
- Chromosome
- Onset
- Initial Weakness
- Rate of progression
- CK
- EKG
- AD; chromosome 4
- Onset 10-20 yoa
- Initial shoulder weakness w/ early facial weakness
- Slow progression
- Normal CK and EKG
Myotonic Muscular Dystrophy
- Inheritance
- Chromosome
- Onset
- Initial Weakness
- Rate of progression
- CK
- EKG
- AD; chromosome 19
- Onset 15-30 yoa
- DISTAL weakness first** w/ early facial weakness
- Slow progression
- Normal CK w/ abnormal EKG
Limb Girdle Muscular Dystrophy
- Inheritance
- Chromosome
- Onset
- Initial Weakness
- Rate of progression
- CK
- EKG
- AR or AD; mult. chroms
- Onset 10-30 yoa
- Pelvic- shoulder weakness first; spares the face
- Slowly progressive
- ^ CK
- Occasionally abnormal EKG
Compare the pathophys of Duchenne and Becker’s musculodystrophy: which mutations are in frame vs. out of frame?
- Duchenne is out of frame
- Beckers is in frame
Both result in deficient dystrophin, weak sarcolemma, and muscle necrosis
What are the clinical features of Duchenne’s Muscular Dystrophy?
- Waddling gait, pseudo hypertrophy of calves, lumbar lordosis, weak neck flexors
- Wheel chair at 13 yoa
- Cognitive impairment
- GI pseudoobstruction
- Cardiomyopathy and death by 20yoa form cardio/resp failure
How do we treat Duchennes?
Steroids; delazacort at 4yoa
What are the clinical features of a DMD carrier; how many carriers demonstrate sx?
- 8% have sx
- Asstd with X inactivation: patients have mild myalgia, CVD, Cognitive, bx issues
- ^ CK, ^ aldolase
Describe how Beckers differed from DMD:
- Onset 12 yoa; ambulatory into adulthood; live beyond 30 yoa
- Less likely cognitive, CVD, contractors, scoliosis, GI issues
Facioscapulomumoral MD:
What are the clinical features?
Slowly progressive wasting of facial, scapular, humeral, and perineal muscles (winged scapula)
No reduction in life expectancy
List some features of Myotonic Dystrophy 1 that differentiate it from Myotonic dystrophy 2: (4)
MD1:
- Distal weakness
- Congenital; DMPK gene; anticipation
- Cataracts, Cardio problems
- MR, avoidant personality
What differentiates Myotonic Dystrophy 2 from Myotonic dystrophy 1?
MD2:
- Proximal weakness
- Rare; zinc finger protein 9 gene mutation
Limb Girdle MD:
- What are the general features of this disease
- Two common comorbidities
- Pace of the typical course
- Which is dominant and which is recessive?
Slowly progressive hip and shoulder weakness
Commonly comorbid with cardiorespiratory problems
Slowly progressive, symmetric, proximal
Type 1 is dominant; type 2 is recessive
Emmy Dreifuss MD, Type 1 vs Type 2:
- What are the mutant proteins
- What is the inheritance pattern
- Which has contractures?
- What is a common comorbidity associated with both?
- 1 = Emerin; 2 = Lamin A/C
- Type 1 always XR; type 2 may be dominant or recessive
- Type 1 has contractures before weakness
- Both have cardiac comorbitities; type 1 specifically conduction abnormalities
Oculopharyngeal Muscular Dystrophy:
- Inheritance pattern
- Age of onset
- Clinical features
- Treatment
- AD; onset in middle age
- Ptosis, EOM and limb weakness, dysphagia
- Treat with oculoplasty and PEG
Dermatomyositis:
- Rash?
- Location of weakness?
- Age of onset? Population?
- Asstd w cancer?
- Response to steroids?
- CK?
- EMG
- Muscle biopsy findings
- Rash present
- Proximal weakness
- Bimodal onset: kids, 40+
- Asstd w breast cancer; Women»>
- Good response to steroids
- ^ CK
- Myopathic EMG
- Muscle biopsy = perifasicular atrophy
Polymyositis:
- Rash?
- Location of weakness?
- Age of onset? Population?
- Asstd w cancer?
- Response to steroids?
- CK?
- EMG
- Muscle biopsy findings
- NO RASH
- Proximal weakness
- Adult onset; Women»>
- Asstd w cancer
- Variable response to steroids
- ^ CK
- Myopathic EMG
- Endopysial Inflammation
Inclusion Body Myositis:
- Rash?
- Location of weakness?
- Agoe of onset? Population
- Asstd w cancer?
- Response to steroids?
- EMG
- Muscle biopsy findings
- NO RASH
- DISTAL–> Proximal weakness; asymmetric
- Onset 50+ yoa; Men»>
- NO assn w cancer
- Myopathic + neuropathic EMG findings
- Amyloid Inclusion bodies + rimmed vacuoles on biopsy
Which of the inflammatory myopathies can not be treated with immunosuppression?
Inclusion body; does not respond well
List the three glycogenoses myopathies:
- McArgles (myophosphorylase)
- Pompe’s (acid maltase)
- PFK deficiency
List the 2 lipidoses myopathies:
- Carnitine Deficiency
- Carnitines Palmityl Transferase Deficiency
What are the two channelopathies that cause myopathy?
What are the channels that they compromise?
What are the triggers for sx?
- Hyperkalemic periodic paralysis (SCN4A channels)–triggered by rest after fasting or exercise; better w/ fasting and exercise
- Hypokalemic periodic paralysis (L type Ca channels):
Weakness lasting hrs or days w carboloading or exercise
