B6.074 Prework: Endocrine Myopathies

Question 1

myopathy

Answer 1

any abnormal state of striated muscle

Question 2

source of muscle disorders associated with endocrine abnormalities

Answer 2

interactions between the force generating and metabolic functions of skeletal muscle

Question 3

endocrine abnormalities that can lead to myopathy

Answer 3

adrenal dysfunction - Cushing, steroid myopathy
thyroid dysfunction - myxedema coma or thyrotoxic myopathy
parathyroid dysfunction - MEN
pituitary dysfunction
Islands of Langerhans dysfunction - diabetic myopathy from ischemic infarction of the femoral muscles

Question 4

symptoms of myopathy

Answer 4

muscle weakness, pain, cramps, tenderness, and spasms of various degrees

Question 5

epidemiology of endocrine myopathies

Answer 5

increasingly recognized

corticosteroid myopathy is most common

Question 6

recognition of endocrine myopathies

Answer 6

patients frequently complain of fatigue and weakness
usually other multisystem signs and symptoms (myopathy rarely the presenting symptoms)
myopathy as sole manifestation may have delayed diagnosis

Question 7

diagnosis of endocrine myopathy

Answer 7

lack of histologic and electrophysiologic criteria

often muscle atrophy without degeneration

Question 8

components of the endocrine system

Answer 8

hypothalamus
pituitary
thyroid
parathyroid
thymus
adrenals
pancreas
ovaries

Question 9

hypothalamus

Answer 9

regulates hunger, thirst, sleep, and wakefulness plus most of involuntary mechanisms including temperature

Question 10

pituitary

Answer 10

controls all other endocrine glands

influences growth, metabolism, and regeneration

Question 11

thyroid

Answer 11

regulates energy and metabolism

Question 12

parathyroid

Answer 12

secretes hormones necessary for calcium absorption

Question 13

thymus

Answer 13

helps build resistance to disease

Question 14

adrenals

Answer 14

secrete hundreds of compounds including cortisone and adrenaline which helps you react to emergencies
regulates metabolic processes in the cells, water balance, BP, etc

Question 15

ovaries

Answer 15

influences how your blood circulates and determines your mental vigor and sex drive

Question 16

metabolism

Answer 16

conversion of nutrients into energy and building materials to meet your body’s needs

Question 17

etiologies of hypoadrenalism

Answer 17

infection
inflammatory disease
tumor
may follow pituitary failure

Question 18

findings associated with hypoadrenalism

Answer 18

neuro manifestations such as disturbances of behavior and mentation are prominent
myopathy is not likely to be a presenting finding

Question 19

factors contributing to myopathy in hypoadrenalism

Answer 19

circulatory insufficiency
fluid and electrolyte imbalance
impaired carb metabolism
starvation

Question 20

etiologies of hyperadrenalism

Answer 20

pituitary or ectopic overproduction of ACTH
adrenal tumors
exogenous steroid administration

Question 21

pituitary ACTH hypersecretion

Answer 21

Cushing disease

caused by corticotroph microadenoma in 90% of patients

Question 22

signs of a hormone secreting tumor on physical exam

Answer 22

neck flexor weakness
dysphagia
respiratory muscle weakness
muscle stretch reflexes are usually present (even in weak muscles) but may be depressed

Question 23

Addison disease

Answer 23

long term insufficient function of the adrenal cortex leading to underproduction of corticosteroids

Question 24

ACTH stimulation test

Answer 24

evaluation of cortisol after IV injection of ACTH
normal individual should have an increase in cortisol
patient with adrenal insufficiency will have no response or a limited one

Question 25

causes of Addison disease

Answer 25

US - autoimmune destruction of adrenal glands | worldwide - tuberculous adrenalitis

Question 26

primary adrenal deficiency

Answer 26

adrenal gland themselves are destroyed so the patient becomes deficient in cortisol and aldosterone uncommon

Question 27

secondary adrenal insufficiency

Answer 27

adrenal failure caused by a lack of ACTH stimulation from the pituitary caused by disease of the pituitary OR commonly by chronic exogenous admin of steroids, which suppress the H-P-A axis R-A-A system usually maintains aldosterone, so patient is only deficient in cortisol

Question 28

Cushing Syndrome

Answer 28

chronic endogenous hyper-cortisolism | chronic, autonomous and excessive secretion of cortisol from the adrenal glands

Question 29

most common cause of Cushing Syndrome

Answer 29

70% cause by pituitary tumor producing excess ACTH

Question 30

Cushing comorbidities

Answer 30

``` metabolic syndrome (systemic arterial hypertension, visceral obesity, impairment of glucose metabolism, and dyslipidemia) MSK disorders (myopathy, osteoporosis, fractures) neuropsychiatric disorders (impairment of cognitive function, depression, mania) impairment of repro and sexual function derm (acne, hirsutism, alopecia) ```

Question 31

symptoms of hypothyroidism

Answer 31

``` weight gain neuropathy fatigue dry skin cold intolerance bradycardia sleepiness emotional disturbances muscle stiffness, weakness, and pain (may be main or only presenting symptoms) ```

Question 32

physical exam findings of hypothyroidism

Answer 32

motor movements have reduced velocity delayed relaxation of muscle stretch reflexes median neuropathy at wrist (carpal tunnel) myoedema or muscle enlargement rarely occur

Question 33

severe muscular association with hypothyroidism

Answer 33

rhabdomyolysis | weakness, myalgia, markedly elevated CK and myoglobinuria

Question 34

thyrotoxic myopathy

Answer 34

disturbance in the function of muscle fibers from increased mitochondrial activity, accelerated protein degradation and lipid oxidation, and enhanced B adrenergic sensitivity due to excess thyroid hormone

Question 35

symptoms of hyperthyroidism

Answer 35

``` weight loss sweating tremor muscle wasting painless weakness ocular symptoms myalgia cramps ```

Question 36

pathophysiology of hypoparathyroidism

Answer 36

deficiency of PTH or inability of hormone to have effect at end receptors

Question 37

symptoms of hypoparathyroidism

Answer 37

``` tetany, with or without carpopedal spasm muscle pain cramps mild weakness short stature rounded face bony abnormalities neuro symptoms ```

Question 38

physical exam findings with hypoparathyroidism

Answer 38

tetany is common cataracts may be present increased intracranial pressure, not constant but possible

Question 39

pathophysiology of hyperparathyroidism

Answer 39

over secretion of PTH, frequently from parathyroid adenoma | myopathy results from altered TH level and impaired action of vit D

Question 40

symptoms of hyperparathyroidism

Answer 40

painful bones renal stones GI groans pscyh moans (depression, mentation defects, memory loss, mood changes)

Question 41

physical exam findings in hyperparathyroidism

Answer 41

myopathy is prominent | symmetric weakness of the proximal limbs and atrophy

Question 42

myopathy due to pituitary disease

Answer 42

may be a result of secondary adrenal dysfunction and/or other endocrine disturbances such as thyroid dysfunction

Question 43

symptoms of hypopituitarism

Answer 43

``` amenorrhea loss of libido alabaster skin lethargy constipation cold intolerance ```

Question 44

symptoms of hyperpituitarism

Answer 44

infertility impotence headaches mass effects of the tumor

Question 45

etiology of polymyalgia rheumatics and temporal arteritis

Answer 45

age related changes in the neuroendocrine system could represent a pathogenic factor in genetically disposed individuals

Question 46

hyper parathyroid myopathy sex

Answer 46

female to male ratio 2:1

Question 47

hyperthyroid myopathy sex

Answer 47

female to male ratio 1:1

Question 48

Iatrogenic steroid myopathy sex

Answer 48

female to male ratio 2:1

Question 49

hypothyroid myopathy sex

Answer 49

female to male ratio 5:1

Question 50

Cushing myopathy sex

Answer 50

female to male ratio 3:1 | though depends on etiology

Question 51

hyper parathyroid myopathy age

Answer 51

40-60

Question 52

hyperthyroid myopathy age

Answer 52

20-60

Question 53

hypothyroid myopathy age

Answer 53

incidence increases after 40

Question 54

Cushing myopathy age

Answer 54

20-40

Question 55

history of endocrine myopathy in general

Answer 55

proximal > distal with or without pain, cramps, spasms symmetric atrophy may or may not be present

Question 56

CK levels in endocrine myopathy

Answer 56

may be normal or elevated hypothyroidism: usually elevated hyperthyroidism: usually normal

Question 57

screening for hypothyroidism

Answer 57

``` serum TSH (elevated) free T3, T4 (low) ```

Question 58

EMG findings in endocrine myopathy

Answer 58

may reveal myopathy, but a normal exam does not rule out EMG preferentially studies type I units, so disease processes that involving type II units may reveal no abnormalities on EMG (steroid myopathy)

Question 59

EMG findings with myopathic process

Answer 59

polyphasic motor unit potentials shortened duration of motor unit potentials decreased amplitude of motor unit potentials

Question 60

EMG in hypothyroidism

Answer 60

differentiated delayed muscle relaxation from myotonia

Question 61

EMG in hyperthyroidism

Answer 61

abnormalities more proximal | myopathic type

Question 62

EMG in hyperparathyroidism

Answer 62

myopathic motor unit potentials and increased polyphasic potentials without spontaneous activity if severe, may have fasciculations and a reduced recruitment pattern with normal nerve conduction velocities

Question 63

muscle biopsy in endocrine myopathy

Answer 63

considered mainly to exclude other treatable or congenital muscle diseases variable findings, rarely specific

Question 64

diagnostic histo features of myopathies

Answer 64

absence of neurogenic abnormalities necrotic muscle fibers basophilic (regenerating myofibers) fibrosis of the endomysium

Question 65

treatment of endocrine myopathy

Answer 65

correction of underlying endocrine dysfunction (surg or med) | B clockers may improve muscle strength, esp in resp muscles

Question 66

prognosis of endocrine myopathy

Answer 66

depends on underlying disease process often abates with correction of underlying disease prolonged weakness and partial recovery are common especially in severe cases and in patients with delayed or suboptimal treatment