Lecture 05 Clinical Aspects of the Sensory and Motor Pathways

Question 1

What does destruction of the dorsal root result in? What happens with the sacral region specifically?

Answer 1

Diminished motor reflexes including muscle tonicity

Sacral region: atonic bladder and painless retention of urine

Question 2

What does complete unilateral lesions of the posterior columns result in?

Answer 2

an ipsilateral loss of proprioception, 2-pt tactile discrimination and vibratory sensations below the lvl of lesion

Question 3

What does a unilateral lesion of the fasiculus gracilis result in?

Answer 3

ipsilateral loss of proprioception, 2-pt tactile discrimination and vibratory sensations from the lower half of the body and lower extremity

Partial lesion: sensory dermatomal deficit corresponding to affected region

Question 4

What does a unilateral lesion of the fasciculus cuneatus result in?

Answer 4

ipsilateral loss of proprioception, 2-pt tactile discrimination and vibratory sensations from the upper half of the body and upper extremity

partial lesion: sensory dermatomal deficit corresponding to affected region

Question 5

What is found in the lateral funiculus?

Answer 5

Lateral corticospinal tract

Lateral reticulospinal tract

Question 6

What does the destruction of the LCSt and associated motor tracts in lateral funiculus result in?

Answer 6

spastic paralysis
hyperreflexia
hypertonia
Babinski sign
clonus
disuse atrophy

Question 7

What does transection of the spinal cord above S2 intterupt?

Answer 7

the LRST to the sacra autonomic nucleus

Question 8

What does LRST interruption result in?

Answer 8

pt unable to voluntarily void bladder = urinary retention

After spinal Shock, bladder reflex may return w/o voluntary control, automatic reflex voiding or reflex bladder

Question 9

What is found in the anterior funiculus?

Answer 9

Lateral spinothalamic tract
Anterior white commissure
LMN

Question 10

What does unilateral lesions of the lateral spinothalamic tract result in?

Answer 10

contralateral loss of pain and temp sensation 2 sensory dermatomal segments BELOW the lvl of lesion

Question 11

What does destruction of the anterior white commissure result in?

Answer 11

bilateral loss of pain and temp sensations to the upper extremities (yoke-like)

Question 12

What does Destruction of LMN or axons of one or more of the cranial or spinal motor nuclei result in?

Answer 12

LMN paralysis: flaccid paralysis, areflexia, attonia, atrophy, and fasiculations

Question 13

What are pts that are insensitive to pain missing. (congenital)

Answer 13

C type fibers

Question 14

What does Herpes Zoster compromise?

Answer 14

non-nociceptive A alpha/beta fibers

C fibers take over and open gate to pain

Question 15

What does unilateral lesions of the spinoreticular fibers result in?

Answer 15

no significatn sensory deficits

Bilateral may eliminate crude pain sensations

Question 16

What is done neurosurgically to treat intractable pain?

Answer 16

LSTT transected

Anterolateral quadrant of the cord is cut two segments above and on the opposite side of the area of pain

Question 17

What serves as a landmark between LSTT and corticospinal fibers during anterolateral cordotomy?

Answer 17

denticulate ligaments

Question 18

What does unilateral lesions of the spinal lemniscus result in?

Answer 18

contralateral hemianalgeisa and thermal hemianesthesia

Question 19

Syringomyelia results in the destruction of what?

Answer 19

anterior white commissure
lateral corticospinal tracts
anterior horns
posterior columns

Question 20

What does unilateral lesions of the medial lemniscus result in?

Answer 20

a loss of proprioception, 2-pt tactile discrimination and vibratory sensations on the opposite side of the body and limbs

Question 21

What are lightning pains or rheumatic pains from the lower limbs in pts with tabes dorsalis is probably due to what?

Answer 21

irritation of the type A pain fibers in the dorsal roots

Question 22

What are the symptoms of LMN paralysis

Answer 22

Flaccid paralysis 
Areflexia
Atonia
Atrophy 
Fasiculations

Question 23

What is flaccid paralysis?

Answer 23

muscle completely limp and there is no resistance to passive movement

Question 24

What is areflexia?

Answer 24

loss of efferent component of reflex arc to a muscle results in an absence of the associated muscle reflex

Question 25

What is Atonia?

Answer 25

Destruction of gamma motor neurons or their axons results in the absence of muscle tone

Question 26

What is atrophy?

Answer 26

tissue waste | - denervated muscle atrophies due to loss of stimulation from the motor neurons

Question 27

What are fasiculations?

Answer 27

twitchings of denervated muscle probably due to hypersensitivity of the motor end plate

Question 28

What does poliomyelitis involve?

Answer 28

the motor neurons of the anterior horns and the cranial nerve motor nuclei

Question 29

What are the symptoms of UMN paralysis ?

Answer 29

Varying degree of spastic paresis of axial and proximal limb m Some degree of spastic paralysis of distal limb m especial upper Hypertonia Hyperreflexia Babinski sign Clonus Disuse atrophy

Question 30

What is spasticity ?

Answer 30

abnormal, passive resistance to movement in one direction

Question 31

What is rigidity ?

Answer 31

abnormal passive resistance to movement in one direction

Question 32

What are the three phases of physical events following UMN lesion?

Answer 32

1. Spinal shock with areflexia, atonia, and flaccid paralysis 2. wks-months: return of basic spinal reflexes, some spastic paresis of axial and prox limb mm and spastic paralysis of distal limb 3. yrs: spasms of extensors, flexors or remain flaccid

Question 33

Clonus, clasp-knife spasticity, babinski reflex | UMN or LMN lesion?

Answer 33

UMN

Question 34

Hyperactive deep tendon reflexes | UMN or LMN lesion?

Answer 34

UMN

Question 35

Hypoactive or absent deep tendon reflexes | UMN or LMN lesion?

Answer 35

LMN

Question 36

Hypotonia | UMN or LMN lesion?

Answer 36

LMN

Question 37

The most common form of amyotrophic lateral sclerosis (ALS) involves the combination of what structures?

Answer 37

LMN: anterior horn cells, hypoglossal nucleus, nucleus ambiguus, facial motor nucleus UMN: chronic, progressive degeneration of the corticospinal tracts

Question 38

What does ALS lead to?

Answer 38

LMN paresis and atrophy of the intrinsic mm of the hand followed later by arms and shoulder musculature

Question 39

What does the involvement of the corticospinal tract with ALS lead to?

Answer 39

spastic paralysis, hyperreflexia and babinski sign NO SENSORY DEFICITS

Question 40

What are the 7 clinically important regions of the spinal cord?

Answer 40

``` Dorsal roots Posterior columns Lateral corticospinal tract (UMN) Lateral spinothalamic tract (pain/2pt) Anterior white commissure Anterior horn (alpha motor neurons, LMN) Lateral reticulospinal tract ```