Diseases of the Muscle, NMJ, Myotonia Flashcards
Mechanoreceptor for sensation of deep pressure-pain
Free nerve endings
Are tension receptors that participate in the maintenance of muscle tone and reflex activity
(2)
Golgi tendon organs
and Muscle Spindles
p. 1406
These are specialized groups of small muscle fibers that regulate muscle contraction and relaxation
Muscle spindles
Sheets of collagen that binds together individual muscle fibers into fascicles
Perimysium
a fully formed myofiber has its nuclei located:
A. Centrally
B. Peripherally
B. peripherally
Counting up to 20 equates with a vital capacity of approximately?
20 liters
page 1413
Defining histopathological feature of Inclusion body myositis
intracytoplasmic, subsarcolemmal vacuoles and eosinophilic inclusions in both the cytoplasm and nuclei of degenerating muscle fibers
The following statements are true of inclusion body myositis, EXCEPT:
a. it is common in patients older than 50 years old
b. common in males more than females
c. presents as painless distal weakness in the arms and both proximal and distal weakness in the legs
d. it is responsive to steroids and other immunosuppressive agents
d.
it is not responsive to corticosteroids and immunosuppressive agents.
no benefit of IVIG
plasma exchange and leukocytapheresis - poor results.
page 1423
Main source of energy during exercise (1) ______
later, with exhaustion of glycogen stores, energy is provided by oxidation of (2) ______
1 Glucose
2 fatty acids
difference of myasthenia gravis and botulism
PUPILS
botulism = pupils are usually large and unreactive
eye signs are followed in rapid succession by involvement of the bulbar, trunk and limb muscles
Cancer most often associated with Lambert-Eaton Myasthenic Syndrome
Small cell lung Ca
Gene mutation associated with Central Core Disease?
a. ACTA1 mutation
b. ryanodine receptor 1 gene (RYR1)
c. MTM1
d. Dynamin (DNM2) gene
b. ryanodine receptor 1 gene (RYR1)
IDENTIFY
Gene mutation associated with Nemaline Myopathy
ACTA1 mutation
Nebulin
2 are most common
Pathological finding in nemaline myopathy
red stained rods in the peripheral clusters on Modified Gomori Trichrome stain
Match the following with the enzyme deficiency
- Pompe
- McArdle
- Tarui
- Cori
- Andersen
a. Debranching enzyme
b. Branching enzyme
c. phosphofructokinase
d. alpha-glucosidase
e. myophosphorylase
- Pompe - D. Alpha-glucosidase
- McArdle - E. Myophosphorylase
- Tarui C. Phosphofructokinase
- Cori - A. Debranching enzyme
- Andersen - B. Branching Enzyme
Gene involved in Duchenne Muscular Dystrophy (1)
Codes for this protein (2)
DMD gene
Dystrophin
Autosomal dominant disease presenting as asymmetric weakness of the facial, shoulder and upper arm muscles with sparing of the deltoids
Fascioscapulohumeral dystrophy
childhood/adolescent with classic triad of
- weakness of biceps, triceps, deltoids and typically distal more than proximal legs
- elbow and or ankle contractures
- cardiac conduction defects
Emery Dreifuss muscular dystrophy
Most common adult muscular dystrophy
Myotonic dystrophy Type 1
Which of the following would be a pathological finding in Myotubular myopathy?
A. peripherally placed masses and circular bundles of myofibrils (ringbiden fibers)
B. centrally located nuclei with perinuclear sarcoplasmic reticulum extending radially in a halo formation
C. rod or thread like eospinophilic structures on Gomori Trichrome stain
D. lucent central cores on NADH stain with variably sized fibers with internalized nuclei
Answer: B.
A. peripherally placed masses and circular bundles of myofibrils (ringbiden fibers) - MYOTONIC DYSTROPHY
B. centrally located nuclei with perinuclear sarcoplasmic reticulum extending radially in a halo formation - MYOTUBULAR DYSTROPHY
C. rod or thread like eospinophilic structures on Gomori Trichrome stain - NEMALINE MYOPATHY
D. lucent central cores on NADH stain with variably sized fibers with internalized nuclei - CENTRAL CORE MYOPATHY
Which of the following is NOT a characteristic of Limb Girdle Muscular Dystrophy?
a. patient will not have hypertrophy of calf muscles
b. cardiac involvement is infrequent
c. may have facial muscle involvement
d. mentation is usually normal
c. may have facial muscle involvement
- facial muscles are spared.
Which of the following is true of Myotonic Dystrophy type 1?
a. it is a milder form of myotonic dystrophy
b. it is inherited as a autosomal recessive form
c. caused by an expanded triplet repeat in CNBP gene on Chromosome 3
d. a critical element in pathogenesis of this disease is intranuclear accumulation of the expanded RNA sequences
D. a critical element in pathogenesis of this disease is intranuclear accumulation of the expanded RNA sequences - SEEN in both TYPE 1 AND 2
A, B and C are characteristics of Myotonic Dystrophy Type 2
Gene mutation associated with Malignant hyperthermia
RYR1 gene
ryanodine receptor 1 gene
Which is NOT TRUE of paramyotonia congenita?
a. it is associated with gene mutationin CACNA1
b. it is inherited as autosomal dominant pattern
c. it is characterized by attacks of periodic paralysis associated with myotonia during exercise and worsening as exercise continues
d. it is induced by cold
a.
gene mutation ; SCN4A
Which of the following is disease involving the calcium channel?
a. Myotonia Congenita
b. Hyperkalemic periodic paralysis
c. Andersen Tawil Disease
d. Hypokalemic Periodic Paralysis
D. Hypokalemic periodic paralysis
a. Myotonia Congenita - CHLORIDE CHANNEL
b. Hyperkalemic periodic paralysis - SODIUM CHANNEL
c. Andersen Tawil Disease - POTASSIUM CHANNEL
d. Hypokalemic Periodic Paralysis - CALCIUM CHANNEL
Which of the following is a Na channel disease?
a. Hypokalemic periodic paralysis
b. Normokalemic periodic paralysis
c. Malignant Hyperthermia
d. Myotonia Congenita
B. Normokalemic periodic paralysis
a. Hypokalemic periodic paralysis - CALCIUM
b. Normokalemic periodic paralysis - SODIUM
c. Malignant Hyperthermia - CALCIUM
d. Myotonia Congenita - CHLORIDE
Gene mutation responsible for hypokalemic periodic paralysis
CACNA1S
A potassium channel disease with the triad
(1) periodic potassium sensitive weakness
(2) ventricular dysrrhythmias with long QT syndrome
(3) dysmorphic features - (micrognathia, short stature, scaphocephaly, hypertelorism, broad nose, low set ears and short index fingers)
what is the gene mutation
Andersen Tawil
dominant negative mutation in the gene KCNJ2
Tonic spasm of muscle after forceful voluntary contraction
Myotonia
Gene mutation in Myotonia Congenita
CLCN1
voltage dependent chloride channel gene
In older adults, the most common cause of isolated quadriceps femoris weakness?*
Inclusion body myositis
May be associated with congenital absence of muscle such as pectoralis and biceps?*
a. Duchenne
b. Becker
c. Emery Dreifuss
d. Limb Girdle muscular dystrophy
e. Fascioscapulohumeral muscular dystrophy
???
About 2/3 of cases of Stiff man syndrome are associated with antibodies that are reactive to this enzyme
glutamic acid decarboxylase
Match the myopathic syndrome with the corresponding cause
- Prednisone
- Colchicine
- Zidovudine
a. vacuolar myopathy
b. type II fiber atrophy
c. mitochondrial myopathy with ragged red fibers
- prednisone - Type II fiber myopathy
- colchicine - Vacuolar Myopathy
- zidovudine - Mitochondrial myopathy with ragged red fibers
Colchicine - rimmed vacuoles on gomori trichrome stain, central
the trident tongue is characteristically seen in
anti MUSK (+) MG
for MG, match the drug with the dose
- Azathioprine
- Cyclosporine
- Mycophenolate
A. 50mg/tab 1 tab BID
B. 6mg/kg/day in 2 doses
C. 500 mg TID
- Azathioprine A. 50mg/tab 1 tab BID
- Cyclosporine B. 6mg/kg/day in 2 doses
- Mycophenolate C. 500 mg TID
These drugs affect both pre and post synaptic neuromuscular transmission activity and hazardous when given to patients with MG
a. aminoglycosides
b. tetracyclines
c. floroquinolones
c. floroquinolones
