Exam 1 Flashcards
What makes up the PNS?
- CN 3-12
- spinal roots
- peripheral nerves
- the ANS
- and muscles
What is a myopathy?
Disorder of muscles
What is the hallmark sign of myopathies?
Proximal muscle weakness
What are signs and symptoms of myopathy
- symptoms often vague
- weakness = #1 sign
- fatigue
- muscle pain (myalgia)
- cramps
- urine discoloration secondary to myoglobin break down
What lab values are associated with muscles being destroyed?
- elevated CK levels
Muscle fiber necrosis mean?
-the muscle fiber is destroyed but the support structure is intact
Fiber disfiguration means
the structure or morphology is altered
Gross abnormality mean
entire structure is changed. change in fiber type or type of connective tissue, etc.
Electromyography (EMG)
using a needle to test the muscles.
Muscular dystrophy (what is it, characteristics)
- genetic disorder
- characterized by progressive muscle weakness
- – get degeneration and necrosis of skeletal muscle
- – eventually replacement with adipose and fibrous tissue (calves pseudo hypertrophy)
- DMD, Becker’s, Limb-girdle, and facioscapulohumeral
Duchenne MD
- absent dystrophin (out of frame transcription)
- most severe
- X linked recessive (1 in 3500 males)
- onset = early childhood
- Rapid progression (3-6 yrs = gower’s sign, pseudo hypertrophy of calf; inc lordosis, mm imbalances, contractors. 12 yrs = w/c; teens-20 yrs = resp and cardiomyopathy. - > early death.
Becker’s MD
- reduced amount of dystrophin (in-frame transcription)
- x linked recessive
- milder and slower progression
- onset = variable (usually 5-25 years)
- **pelvic girdle weakness with waddling gait
- normal life span unless cardiomyopathy
Dystrophin
-a structural protein supporting sarcolemma needed for proper muscle structure.
Damage to the muscles lead to necrosis due to exceeding rate of repair. Collagen and adipose tissue take over muscle structure.
Gower’s sign
getting up from the floor and needing to use arms.
Limb-girdle MD
- Autosomal dominant or recessive
- autosomal recessive = most common
- onset = 2 yrs-adult (male and females equal)
**Presentation: limb-girdle atrophy and weakness. Gluteals hip abd weakness. Can by highly variable progression.
**Pathology = loss of sarcoglycans.
Sarcoglycans
- linked to dystrophin and help with structure/integrity of muscle.
- loss of these results in limb-girdle MD.
Facioscapulohumeral
- most common dominantly inherited dystrophy
- 3rd most common inherited dystrophy
- Pathology: something to do with chromosome 4
Signs: weakness of facial, shoulder girdle, prox arm muscles ( serrates, delts, traps, rhomboids)
- normal lifespan
- onset = variable (3-4th decade)
How can you treat dystrophies?
- genetic counseling
- potential new rx and research (stem cell, etc.)
- pharmocological (cortisone, deflazacort, gentamyacin)
What is a myotonia?
- difficulty relaxing muscles, can be perceived as cramping
- abnormality in ion channels and permeabilities of mm cell membranes -> excessive firing of action potentials -> hypertrophy
-repeated mm warming up gives some relief to stiffness
***affects distal muscles.
Myotonic dystrophy
- pathophys: myopathy is caused by mutation in gene for myotonic dystrophy protein kinase (DMPK)
- genetic autosomal dominant
-affects multiple systems (cardiac conduction, gastric immobility, cognitive delays.)
What is the presentation of myotonic dystrophy?
slow progressive weakness of eyelids, face and neck mm as well as distal mm
- starts early teens with noticeable weakness of the hands and often foot drop.
- neck muscles involved and SCM mms are often atrophic and poorly defined
-middle age = repeated falls. more mm involved. myotonia may diminish. facial weakness = swallowing difficulty and dislocation of the jaw
- daytime somnolence and altered sleep patterns
- ventilatory difficulties
- cataracts common
- endocrine abnormalities
- cholecystitis
characteristics of myotonic dystrophy
- long face: master and temporals atrophy
- fully developed = eyes are hooded and mouth slacks. Muscle weakness is not limited to distal mm. Shoulder, hip, and leg weakness may be very prominent.
*ptosis
Cushings syndrome
adrenal gland produces too much glucosteroids.
Addison’s disease
adrenal insufficiency. Electrolyte problem. general feeling of weakness and easily fatigued. BUT no objective mm weakness. impaired mm carbohydrate metabolism
Graves’ disease
thyroid dysfunction. autoimmune. hyperthyroidism. Untreated 80% develop moderate mm weakness and atrophy especially shoulder girdle. prox UE, hip flexors, and pelvis
Acromegaly
pituitary dysfunction. Initial hypertroph and inc strength. later myopathy -> prox weakness and mm atrophy.
