Muscle Flashcards
What is the clinical picture of Trichinosis?
Puffy face with tender muscles. There is ocular muscle weakness, tongue weakness, masseter and pharyngeal muscle weakness
What is the most realiable confirmatory test for a diagnosis of Trichinosis?
Biopsy of about 500mg of muscle demonstrating, encysted larvae, eosinophilia and inflammatory myopathy
What is the treatment for Trichinosis?
Albendazole/Thiabendazole + Prednisone
What parasite causes the pseudohypertrophy of thigh and calf muscles?
Cysticercosis
What is the main differential for HIV myopathy and how to distinguish between the 2?
Zidovudine induced myopathy showing ragged red fibers on biopsy. HIV myopathy is also associated with severe generalized muscle weakness that characterizes advanced cachectic AIDS
T or F. HIV myopathy has NORMAL CK enzymes
T
What factors favor IBM over polymyositis?
- Onset more than 50
- Normal CK
- Aberrant pattern: early wrist, finger flexor, quad, ankle dorsiflexion involvement
In polymyositis what percentage of patients have sparing of facial and distal muscles?
75%
What are the skin changes that precede muscle weakness in Dermatomyositis?
Erythema, maculopapular eruption, scaling eczematoid dermatitis, exfoliative dermatitis
Where the the ff manifestations of DM located?
- V sign
- Heliotrope rash
- Gottron papules
- Shawl sign
- neck and upper shoulders
- eyelids, bridge of nose, cheeks, forehead
- papules on elboes, knuckles, IP joints
- shoulders and upper arms
What tumors are most associated with PM and DM?
Men: Lung and colon
Women: Breast and ovarian
What treatment for RA increases the incidence of or precipitates a myositis?
d-penicillamine
20 percent of PM and DM have concomittant: arthritis, Raynaud syndrome, mechanic’s hands– what is the antibody associated with these synthetase syndrome
anti Jo1
What are the typical myopathic findings in EMG?
- brief action potentials of low voltage
- fibs
- polyphasic units
- trains of positive sharp waves
- myotonic activity
How to differentiate between the pathologic findings in DM vs PM
DM is characterized by perifascicular atrophy in contrast to evident necrosis of single fibers of PM
DM microvascular changes are also seen
PM inflammatory infiltrates by mononuclear cells are found scattered throughout the muscle unlike DM perimysial connective tissure only
Which one PM or DM is mediated by humoral response? cytotoxic response?
PM Cytotoxic
DM Humoral
What is thetreatment for DM and PM?
1st line
2nd line
Acute and severe cases
1st line: 1g per kg of prednisone. Taper when Cks are normal and weakness has subsided
2nd line: Methotrexate and Azathioprine
Acute and severe: MPPT and IVIG
What is the most common inflammatory myopathy in patients older than 50 years old?
Inclusion body myositis
NOT INCLUSION BODY MYOPATHY!!!!
What is the pattern of weakness in inclusion body myositis?
Distal in the arms, proximal and distal in the legs
MORE FOCAL compared to DM/PM
Selective weakness of the flexor pollicis longus
Which has depressed reflexes at the onset? PM/DM/IBM
IBM
What is the characteristic histopathologic findings in inclusion body myositis?
Intracytoplasmic, subsarcolemmal vacuoles and eosinophilic inclusions in both the cytoplasm and nuclei of degenerating muscle fibers
Save from this the muscle looks like less severe PM with CD8 T cells
T or F CKs can be high in muscular dystrophy
T! In some…
How to differentiate polymyalgia rheumatica with PM DM?
NORMAL CK and biopsy
Rapid response to prednisone WITHIN 48 HOURS!
HIGH sedimentation rate more than 65
Related to temporal arteritis
Which among these are characteristic of Duchenne/Becker OR Emery Dreifuss OR both
- Onset at the 1st decade
- X linked RECESSIVE
- Proximal muscles
- Cardiac arrhythmias
- Greated CK elevation
- DB
- BOTH
- BOTH
- ED>DB
- DB
What muscular dystrophy has its onset on the 2nd to 3rd decade, with a dysferlin pathology and begins in the DISTAL MUSCLES
Miyoshi myopathy
What percentage of Duchenne muscular dystrophy HAVE NO HISTORY OF THE DISEASE?
30%
In duchenne what is affected first? Pelvicrural OR pectoral girdle OR bulbar?
Pelvicrural then pectoral girdle
The ocular facial and bulbar muscles are spared
Becker muscular dystrophy patients have normal mentation and may walk into adulthood. T or F?
T
What is the histopathologic picture of duchenne and becker?
Segmental degeneration and phagocytosis of single muscle fibers and evidence of regenerative activity –> advanced; loss of muscle fibers, residual fibers of larger and smaller size, fibrosis and increase in lipocytes
T or F dystrophin is absent in patients with becker and duchenne
F. Present to some extent in Becker
What is dystrophin attached to inside and outside?
Attached to F actin of cytoskeleton inside and outside attached to dystrophin associated proteins and glycoproteins that link the sarcolemmal membrane to the extracellular matrix
What protein is deficient in emery dreifuss and what is its function?
Emerin– part of the nuclear membrane
Which of the ff are true of the Landouzy Dejerin Muscular Dystrophy?
- May be associated with congenital muscle absence
- Frequent cardiac involvement
- Caused by deletions at the tip of chromosome 6p interfering with chromatin structure
- Popeye arms
- T
- F
- F. gene 4q
- T
AKA Fascioscapulohumeral dystrophy
In Kearns-Sayre syndrome what is the first muscle to be affected
AKA as progressive external ophthalmoplegia
The eyelid levators are the first to be affected causing ptosis followed by EOM paralysis
Other features of KS syndrome include pigmentary retinopathy– less commonly, bilateral sensorineural deafness, heart involvement (cardiomyopathy, cardiac conduction defect), central nervous system involvement (cerebellar ataxia, dysarthria, bilateral facial weakness, intellectual deficit), skeletal muscle myopathy, intestinal disorders, endocrine disorders (delayed puberty, hypoparathyroidism, diabetes), and renal failure.
In the Kearns Sayre syndrome hutchinsonian facies seen because of?
In an attempt to raise the eyelids, the forehead is wrinkled and the head is thrown back
What genes are involved int he developement of the Kearns Sayre syndrome?
POLG
ANT1
Twinkle
At what age do the ff present?
- Oculopharyngeal dystrophy
- Progressive extrenal ophthalmoplegia
- Fascioscapulohumeral MD
- Emery dreifuss
- Becker MD
- Duchenne MD
- 6th to 7th decade
- Usually in adolescence
- 6-20 years old
- VARIES: Childhood, late adol, adulthood
- usually at 12 years old
- 3-6 years old
What is the trinucleotide repeat sequence at chromosome 19q causes myotonic dytrophy?
CTG in the DMPK gene chromosome 19q– intron therefore not coding for proteins
Normal: 5-30 CTG repeats
MD: 50-20,000
What are the first muscles affected in the myotonic dystrophy type 1?
The small muscles of the hands along with extensor muscles of the hands along with the extensor muscles of the forearms
BUT in some ptosis of the eyelids and thinness and slackness of the facial muscles may be the earliest signs
RECALL THAT IBM ALSO PRESENTS WITH INITIAL ATROPHY OF HAND MUSCLES–both conditions present with distal weakness that is “atypical” of myopathies.
What non muscular tissues are affected in myotonic dystrophy type 1?
Lens of the eye– 90% OF PATIENTS WILL HAVE LENTICULAR OPACITIES
brain–mild to moderate degrees of developmental cognitive delay
testicle atrophy
frontal alopecia
esophagus
heart
skin
Define myotonia
Prolonged idiomuscular contraction following brief percussion or electrical stimulation and in the delay of relaxation after strong voluntary contraction
What muscles show myotonia at best in MD1?
Tongue and flexors of fingers
What are the pathologic features of MD1?
- Hypertrophy of type 1 fibers
- Peripherally placed sarcoplasmic masses and circular bundles of myofibrils (ringbiden)
- Central nuclei much like myotubular myopathy
What protein is missing in miyoshi dystrophy?
Dysferlin responsible for calcium mediated membrane repair
What is the pattern of miyoshi myopathy?
Distal myopathy
Polymyositis can be distinguished from dystrophy on the basis of CK elevation except in which dystrophies that also present with elevated CKs
Duchenne and Miyoshi
T or F Prednisone trial for 6 months can distinguish between polymyositis and dystrophy
T. If it improves then PM!
How to distinguish between SMA and myositis?
EMG
What is the dose of prednisone for muscular dystrophy?
0.75mg per kg
What drug has been shown to reduce myotonia?
Mexiletine
ALL THE GLYCOGENOSES ARE INHERITED AS AUTOSOMAL RECESSIVE TRAITS EXCEPT FOR?
X linked phosphoglycerate kinase deficiency
What is the enzyome missing in patients with
- Pompe disease
- McArdle Disease
- Tarui
- Cori forbes
- Andersen disease
- Acid maltase
- Myophosphorylase
- Phosphofructokinase
- Debranching enzyme
- Branching enzyme