Path - NMJ and Skeletal Muscle

Question 1

what lab result is a muscle damage marker

Answer 1

creatinine kinase

Question 2

what finding on histologic staining indicates muscle damage

Answer 2

basophilic (blue) staining, enlarged nuclei, prominent nucleoli

Question 3

adaptation of muscle fibers to exercise or chronic myopathic conditions manifests as what

Answer 3

myofiber hypertrophy

Question 4

purple discoloration of the upper eyelids with periorbital edema is associated with what skeletal muscle dz

Answer 4

dermatomyositis

Question 5

grotton lesions are associated with what skeletal muscle dz

Answer 5

dermatomyositis

Question 6

“cant comb my hair, can’t climb the stairs” is indicative of what skeletal muscle dz

Answer 6

dermatomyositis

• from PROXIMAL muscle weakness

Question 7

10% of dermatomyositis pts have what other dz

Answer 7

interstitial lung dz

Question 8

histological hallmark of dermatomyositis

Answer 8

perifascicular atrophy

inflammation and atophy in the perimysial connective tissue at the periphery of fascicles

Question 9

pathogenesis of polymyositis

Answer 9

inflammation (CD8 T cells) of the endomysium (center of the fascicles)

Question 10

what gene and locus is affected in x-linked muscular dystrophy

Answer 10

Xp21

dystrophin

Question 11

compare clinical presentaiton of duchene MD and becker MD

Answer 11

duchene: symptoms before 5 y/o, wheelchair by 10-12 y/o
becker: sx in late childhood/adolescence, nearly normal lifespan with some risk for cardiac dz

Question 12

describe pseudohypertrophy in muscular dystrophy

Answer 12

enlargement of the muscles of the lower leg occurs with normal development, but in DMD the muscle is converted to adipose tissue in DMD, so it appears as if the legs are becoming larger because of muscle but it is actually because of fat

Question 13

describe clinical sx of limb-girdle muscular dystrophy

what is the age of onset

Answer 13

muscle weakness that preferentially involves proximal muscle groups

age of onset and severity vary greatly

Question 14

what is mcardle dz

Answer 14

deficiency of myophosphorylase

glycogen storage dz

Question 15

what is “floppy infant” syndrome?

Answer 15

infants with neurologic or neuromuscular dz presenting with generalized hypotonia

Question 16

what is the pathogenesis of spinal musclar atrophy

Answer 16

SMN1 gene mutation –> insufficient levels of SMN protein –> destruction of anterior horn cells in the spinal cord –> skeletal muscle atrophy

Question 17

mutations in SMN1 are associated with what dz process

Answer 17

spinal muscular atrophy

Question 18

what is wernig-hoffman and what are the clinical sx

Answer 18

spinal muscular atrophy type 1

onset is at birth with floppy baby, death before 3 y/o

initially muscle weakness of trunk and extremities, followed by chewing, swallowing, and breathing difficulties

Question 19

what are the symptoms of ion channel myopathies (channelopathies)

Answer 19

epilepsy, migraines, movement disorders, muscle dz, peripheral nerve dz

Question 20

RYR1 mutation is associated with

Answer 20

central core-disease (causes malignant hyperthermia)

Question 21

sx of malignant hyperthermia

Answer 21

tachycardia, tachypnea, muscle spasms, hyperpyrexia