22: Somatosensory Tracts: ALS

Question 1

ALS: anterolateral system

Answer 1

Fibers that relay pain, temp, and non-discriminate touch via five different tracts

Question 2

Five tracts of the ALS

Answer 2

1. Spinothalamic
2. Spinoreticular
3. Spinomesencephalic
4. Spinobulbar
5. Spinohypothalamic

Question 3

Largest tract of the ALS

Answer 3

Spinothalamic

Question 4

Where are the free nerve endings of the ALS?

Answer 4

Skin, muscles, joints, vessels, viscera

Question 5

How do ALS afferent fibers enter the SC?

Answer 5

Posterior root

Question 6

When afferent fibers of the ALS enter the SC, what do they first do?

Answer 6

Ascend/descend 1-2 levels in Lissauer tract (posterolateral tract)

Question 7

Where are second order neurons located for all ALS tracts?

Answer 7

Superficial lamina I and II, nucleus proprius (laminae III and IV)

Question 8

Somatotopic nature of ALS

Answer 8

Opposite of posterior columns - lower levels are found more posterolaterally, rostral levels are added anteromedial lay

Question 9

Origin of BS to ALS

Answer 9

Arterial vasocorona + sulcus branches of ASpA

Question 10

Occlusion of blood supply to ALS

Answer 10

Patchy loss of nociceptive, thermal, and touch over contralateral side of body, beginning about two spinal segments below lesion

Question 11

Lateral medullary syndrome: cause

Answer 11

Medullary lesion of ALS

Question 12

Two other names for lateral medullary syndrome

Answer 12

PICA syndrome, Wallenberg syndrome

Question 13

Deficits seen in Lateral Medullary Syndrome

Answer 13

1. Contralateral loss of pain and thermal sensation
2. Ipsilateral loss of pain/thermal sensation due to trigeminal tract damage
3. Other sx: dysphagia, soft palate paralysis, nystagmus, Horner syndrome, nausea, diplopia, vertigo, ataxia

Question 14

Major vascular supply related to Lateral Medullary Syndrome

Answer 14

PICA

Question 15

Lateral pontine syndrome cause

Answer 15

Lateral pontine lesion of ALS

Question 16

Deficits in lateral pontine syndrome

Answer 16

Contralateral loss of pain and thermal sensation of the body

Question 17

What three structures are involved in lateral pontine syndrome

Answer 17

1. ALS
2. Trigeminal nucleus
3. Facial motor nucleus

Question 18

Vascular territory involved in lateral pontine syndrome

Answer 18

Circumferential branches of basilar A, AICA or SCA

Question 19

Sx of complete SCI (spinal cord injury)

Answer 19

Bilateral total loss of motor and sensory function at/below level of injury

Question 20

Four examples of incomplete SCI

Answer 20

Anterior, central, and posterior cord syndrome + spinal contusions

Question 21

Anterior cord syndrome

Answer 21

Injury to motor pain and temp pathways in anterior SC

Question 22

Central cord syndrome

Answer 22

Loss of pain/temp

Question 23

Sx of spinal contusion

Answer 23

Numbness, tingling, electric shock-like sensations, burning in extremities

Question 24

Brown-Sequard Syndrome: three parts damaged

Answer 24

ALS, PCML, CST pathways

Question 25

Deficits in Brown-Sequard Syndrome

Answer 25

Contralateral: loss of nociception, thermal sensation (two levels below lesion) (ALS)
Ipsilateral: loss of discrim touch, vibratory, and positional sense (at/below level of lesion) (PCML)
Paralysis of trunk and extremity depending on level of lesion (CST)

Question 26

Syringomyelia

Answer 26

A type of central cord syndrome with cystic cavitation of central SC

Question 27

Level of spinal cord syringomyelia typically occurs at

Answer 27

C3-T2

Question 28

Initial path affected in syringomyelia

Answer 28

ALS fibers in AWC

Question 29

Deficits in syringomyelia

Answer 29

Deficits in a cape-like pattern over arms and shoulders - loss of pain and temp bilaterally + weakness, atrophy, fasciulations of hand muscles