Ch 3: Clinical Correlates pg 76-89

Question 1

a lesion of the descending hypothalamic axons between the hypothalamus and the preganglionic sympathetic neurons in T1 spinal segment may result in… and to what side?

Answer 1

Horner’s syndrome and orthostatic hypotension

ipsilateral

Question 2

lesion in axons of pontine UMNs and neurons in anterior hypothalamus above sacral S2-S4 levels may result in…

Answer 2

spastic bladder

*sacral parasym neurons that innervate bladder not inhibited effectively when bladder is stretched during filling so will involuntarily empty with minimum stretch

Question 3

dorsal column/medial lemniscal system primary neuron synapse on what nuclei? and where do second neurons cross?

Answer 3

nucleus gracilis and nucleus cuneatus in caudal medulla

second neurons cross midline in vicinity of cell bodies–>form medial lemniscus

Question 4

lesion of dorsal column results in…. and on what side?

Answer 4

loss of epicritic sensations- discriminative touch, joint position sensation, vibration/pressure sensations

ipsilateral and below lesion

Question 5

dorsal column axons are sensitive to what types of diseases?

Answer 5

degenerative or demyelinating

*because use large-diameter, myelinated class Ia, Ib, II, and A-beta dorsal root fibers

Question 6

neurosyphilis can result in what condition?

Answer 6

Tabes dorsalis= bilateral degeneration of the large-diameter dorsal root fibers, neuron cell bodies, and dorsal column axons (most commonly fasciculi gracilis)

Question 7

what are the 3 “Ps” of Tabes dorsalis?

Answer 7

parethesias, pain, and polyuria

• parethesias: impaired vibration and position sense in lower limbs (carried by fasiculus gracilis)
• pain: hypersensitivity of small-diameter A-delta and class C pain and temp dorsal root fibers
• polyuria: loss of large-diameter sensory neurons that mediate bladder fullness–>frequent emptying; urine retention may also be present

**OTHER SYMP: muscle stretch reflex suppressed (degeneration of Ia dorsal root fibers) and Argyll Robertson pupils (accomodate but do not react to light)

Question 8

how do you distinguish between dorsal column lesion (sensory ataxia) and lesion in midline of cerebellum (motor ataxia)?

Answer 8

ROMBERG TEST

• if positive (sways with eyes closed, but not when eyes open)–>sensory ataxia
• versus cerebellar lesion will sway even with eyes open and have balance problems

Question 9

anterolateral system primary neurons synapse where? and where do second neurons cross?

Answer 9

collaterals ascend/descend 1-2 cord segments in dorsolateral tract of Lissauer before entering dorsal horn

second neurons cross in vicinity of cell bodies at all spinal cord levels–>spinothalamic tract

Question 10

in the skin, tissue damage results in the release of what, which activates pain and temp sensitive free nerve endings?

Answer 10

prostaglandin and bradykinin

Question 11

how do aspirin and nonsteroidal analgesics work as pain suppressants?

Answer 11

block enzyme used in synthesis of prostaglandins

Question 12

unilateral lesion of axons in the spinothalamic tract in the spinal cord or brainstem results in… and where/on what side?

Answer 12

loss of pain and temp
contralateral
if in spinal cord: 1-2 segments below lesion
if in brainsteam: below lesion

Question 13

if dorsal roots of anterolateral system are lesioned, this result in… and where/on what side?

Answer 13

loss of pain and temp
ipsilateral
limited to dermatomal distribution at the level of the lesion

Question 14

syringomyelia is caused by…. and results in….

Answer 14

• cavitation/syrinx of the central canal of the spinal cord (commonly cervical segments)
• bilateral loss of pain and temp initially at or just below level of cavitation (*spinothalmic axons cross in ventral white commissure just below central canal)
• then as expands, LMN may be compressed–>flaccid paralysis of upper limb muscles
• unilateral or bilateral Horner’s may be late manifestation (compression of descending hypothalamic axons near ventral horns)

Question 15

infants with Arnold-Chiani malformation can have…

Answer 15

synringomyelia

Question 16

dorsal spinocerebellar tract carry what information, arise what nucleus and cross where?

Answer 16

proprioceptive input from muscle spindles/GTOs of lower limbs and trunk
Clarke’s nucleus (T1-L2)
DO NOT CROSS (ipsilateral)

Question 17

cuneocerebellar tract carry what information, arise what nucleus and cross where?

Answer 17

proprioceptive input from muscle spindles/GTOs of upper limbs and trunk
external cuneate nucleus
DO NOT CROSS (ipslateral)

Question 18

Friderich’s ataxia is caused by what? and results in what?

Answer 18

• degeneration of SPINOCEREBELLAR tracts, also dorsal columns and corticospinal tracts
• sensory ataxia (pos Romberg) initially, then hyporeflexia and altered vibratory sensations

Question 19

• 2 ipsilateral long tract signs (UMN, dorsal column) and 1 contralateral long tract sign (spinothalamic)
• if at cervical spinal cord levels may have ipsilateral Horner’s
• if above S2, may have spastic bladder (likely will resolve because bilateral innervation)
• at level of lesion, incoming dorsal roots and outgoing ventral roots may be lesioned–>ipsilateral loss of all sensation (touch/pain/temp) and ipsilateral flaccid paralysis supplied by segments affected

what syndrome is this?

Answer 19

Brown-Sequard syndrome

Question 20

spastic paresis ipsilateral to and below level of lesion of spinal cord

Answer 20

lesion of axons of UMN including corticospinal tract

Question 21

loss of joint position sense, tactile discrimination and vibratory and pressure sensation ipsilateral to and below lesion of spinal cord

Answer 21

lesion to fasciculus gracilis or cuneatus

Question 22

loss of pain and temp that is contralateral and 1-2 segments below the level of the lesion of spinal cord

Answer 22

lesion to spinothalamic tract

Question 23

Brown-Sequard syndrome is caused by?

Answer 23

• lesion or compression of 1/2 of spinal cord caused by trauma, neoplasm or herniated disk
• if complete hemisection–>lesion in UMN, descending hypothalamic axons, 1 or both dorsal column, spinothalamic and dorsal spinocerebellar tracts
• at level of lesion incoming dorsal and outgoing ventral roots may be lesioned

Question 24

patient with spinal cord hemisection or complete transection may undergo initial period of? and will be replaced by?

Answer 24

spinal shock

replaced by spastic weakness and UMN lesion signs

Question 25

spinal shock is characterized by?

Answer 25

flaccid paralysis of muscles below transection, loss of all reflexes, and loss of all sensation below level of lesion

may also have transient atonic/flaccid bladder-fills to capacity then dribbles out bc failed detrusor contraction and weak urethral sphincter (to become spastic)

Question 26

sudden occlusion of anterior spinal artery results in what?

Answer 26

bilateral spastic paresis and bilateral loss of pain and temp below level of lesion (perhaps following period of spinal shock)

**supplies ventrolateral parts of cord (corticospinal and spinothalamic)

Question 27

vitamin B12 (cobalamin) deficiency causes what and can result in what condition?

Answer 27

swelling of myelin sheath in dorsal columns and corticospinal tracts in thoracic or cervical regions

peripheral myelin may also be involved

subacute combined degeneration

Question 28

subacute combined degeneration is characterized by what symptoms?

Answer 28

bilateral spastic paresis and bilateral alteration of touch, vibration, and pressure sensations below the lesion sites

• if peripheral myelin involved, parethesias and impaired sensation in all 4 limbs