Ch 3: Clinical Correlates pg 74-76

Question 1

absence of voluntary or reflex contractions of denervated muscles

Answer 1

flaccid paralysis, LMN lesion

Question 2

absence of or suppressed muscle stretch reflex (hypo- or areflexia, hypotonicity)

Answer 2

flaccid paralysis, LMN lesion

Question 3

fasiculations, random twitches of denervated motor units visible beneath the skin

Answer 3

flaccid paralysis, LMN lesion

Question 4

atrophy or wasting of denervated muscles

Answer 4

flaccid paralysis, LMN lesion

Question 5

fibrillations (invisible 1-5 ms potentials) detected with electromyography

Answer 5

flaccid paralysis, LMN lesion

Question 6

flaccid paralysis: lesion site, side, level?

Answer 6

LMN lesion, ipsilateral, at level of

Question 7

polismyelitis: cause and symptoms

Answer 7

loss of LMNs in ventral horn cause by poliovirus

–>flaccid paralysis (accompanying hyporeflexia, fasciculations, atrophy)

Question 8

Werdnig-Hoffman disease/infantile spinal muscular atrophies: cause and symptoms

Answer 8

destruction of LMNs in infants/young children

–>difficulty sucking, swallowing, breathing, weakness in limbs; “floppy” babies

Question 9

elevated or hyperactive muscle stretch reflexes (hyperreflexia or hypertonicity)

Answer 9

UMN lesion

*UMN has net overall inhibitory effect on muscle stretch/inverse muscle stretch reflexes (ex. loss of inhibition of gamma motor neurons by reticulospinal medullary UMNs)

Question 10

clonus

Answer 10

UMN lesion

*rapid successive reflex contractions and relaxations of agonists and antagonists (usually observed at knee and ankle joints)

Question 11

clasp knee reaction

Answer 11

UMN lesion

*loss of inhibition of inverse muscle stretch reflex

Question 12

altered cutaneous reflexes

Answer 12

UMN lesion

Question 13

Babinski sign

Answer 13

UMN lesion

• toes extend and fan in response to plantar cutaneous stimulus
• normal in infants until UMN tracts are fully myelinated

Question 14

abdominal reflex

Answer 14

ABSENT in UMN lesion

• T8-T12
• stroke abdomen–>contraction with umbilicus toward stimulus

Question 15

cremasteric reflex

Answer 15

ABSENT in UMN lesion

• L1
• stroke medial thigh–>contraction of cremaster muscle and elevation of testis

Question 16

atrophy of weakened muscle

Answer 16

UMN lesion

**ONLY because of disuse (can be made to contract by stimulating muscle stretch reflexes… UNLIKE LMN lesions)

Question 17

spastic paresis: lesion site, side, level

Answer 17

UMN lesion
always below

• if in spinal cord–>ipsilateral
• if b/w cerebral cortex and medulla above decussation of pyramids–>contralateral

Question 18

decorticate posturing

Answer 18

UMN lesion above the red nucleus in the midbrain

• contractions of muscles that act to flex joints of the upper limb and contractions of muscles that act to extend joints of lower limb

Question 19

decerebrate posturing

Answer 19

UMN lesion below the red nucleus in the midbrain

• postural extension at joint of both the upper and lower limbs

Question 20

amytrophic lateral sclerosis (ALS) affects….

Answer 20

BOTH UMNs and LMNs

*Lou Gehrig’s disease

Question 21

where are the common sites of ALS?

Answer 21

• lower cervical segments that supply upper limbs (40%)
• lumbrosacral segments that supply lower limbs (40%)
• LMNs in cranial nerves (20%)

Question 22

what are common symp of ALS?

Answer 22

• at lower cervical levels: bilateral flaccid weakness at level of lesion in upper limbs and bilateral spastic weakness below the lesion in muscles of lower limbs
• if progresses above cervical levels: LMNs of phrenic nerve can be affected, compromising respiration
• if at caudal brainstem: difficulty swallowing and speaking (weakness of pharyngeal or tongue muscles innervated by CN X and XII)