Spinal Cord Syndromes

Question 1

spinal root exits

Answer 1

C1-7 above C1-7 vertebrae; C8 between C7 and T1; T1-coccygeal below corresponding vertebrae; conus medullaris at L1 (spinal cord ends); dural sac and subarachnoid space end at S1

Question 2

dermatomes (by general area: 6)

Answer 2

no C1; C2-4 neck, C5-T1 arms; T2-L1 trunk (T4 nipple, T10 umbilicus); L2-S2 legs; S2-S5 perineum

Question 3

lateral corticospinal tract (alternate name, function, lesion causes what and why)

Answer 3

aka pyramidal pathway; controls voluntary movements of distal muscles (mainly flexors); inhibits muscle tone and DTRs (GABA) -> causes hyperflexia and spasicity if lesioned

Question 4

spinothalamic tract

Answer 4

detects pain, temp, light touch; A-delta and C nerve fibers (naked terminals of small, unmyelinated fibers)

Question 5

corticospinal tract pathway and somatotopic

Answer 5

UMN run from motor cortex through internal capsule then decussate at pyramids in lower medulla (90%) or continue ipsilaterally in anterior corticospinal tract (8% -> cross in anterior white commissure near termination level) or ipsilateral lateral corticospinal tract (2%), at level of termination synapse on anterior horn cells (LMN) or interneurons; somatotopic: arms medial and legs lateral (bows towards center)

Question 6

spinothalamic tract pathway and somatotopic

Answer 6

1st axon (soma in dorsal root ganglion) enter via dorsal root and split into ascending/descending branches that run longitudinally in Lissauer’s tract (posterolateral funiculus) for 1-2 segments, then synapse with dorsal horn cells, dorsal horn axons cross in anterior white commissure near level of entry (within 2 segments up or down) and then run vertically in contralaterally anterolateral funiculus and terminate in VPL, 3rd neuron in VPL projects to S1; arms medial and legs lateral (bows towards center)

Question 7

posterolateral funiculus

Answer 7

Lissauer’s tract (ipsilateral spinothalamic before crossing -> runs vertically 1-2 segments)

Question 8

anterolateral funiculus

Answer 8

spinothalamic tract contralateral (after crossing near level of entry)

Question 9

dorsal column pathway and somatotopic

Answer 9

1st axon (soma in DRG) enters via dorsal root and travels in dorsal column (fasciculus gracilis - leg; fasciculus cuneatus - arm); both fasciculi terminate in nuclei gracilis/cuneatus in lower medulla, 2nd axon decussates immediately and travels to VPL, 3rd neuron projects to S1; arms (FC) lateral and legs (FG) medial - bows away from center and towards dorsal horn

Question 10

sympathetic pathway

Answer 10

arise in hypothalamus, descend ipsilaterally to synapse on T1-L2 spinal nerves

Question 11

bladder control

Answer 11

reflex contraction occurs due to stretch receptors in bladder sending input to S2-4 LMN via dorsal roots; UMN inhibit this reflex; parasymp axons synapse on cell bodies in S2-4 ventral gray matter, causing detrusor muscle contraction

Question 12

atonic bladder

Answer 12

due to lesion of sacral dorsal roots or cauda equina/conus medullaris (aka LMN) -> flaccid, loss of sensations, overflow incontinence (constant dribbling)

Question 13

spastic bladder

Answer 13

due to lesion above conus and below pontomesencephalic micturition center b/c of UMN loss of inhibition on detrusor reflex; acutely caused acontractile bladder (urinary retention) and chronically causes reflex detrusor contraction and bladder emptying (incontinence)

Question 14

blood supply of spinal cord

Answer 14

anterior 2/3 supplied by anterior spinal a. (arises from vertebrals) - supplies corticospinal (motor) and spinothalamic (pain/temp) tracts; posterior 1/3 supplied by posterior spinal arteries - supplies DC/ML tract (propioception, etc.); midthoracic region in watershed and thus vulnerable to hypotension

Question 15

complete cord transection symptoms

Answer 15

loss of all motor function and sensation below lesion (pinprick may be a few levels below lesion); bowel and bladder dysfunction (spastic chronically) and other autonomic dysfunction (orthostatic hypotension, anhidrosis, impotence, etc.); acutely will see flaccid plegia and urinary/fecal retention while chronically will see spasticity and incontinence; if C1-3/4 will need ventilatory support and if below C7 retains ability to independently transfer (arms intact)

Question 16

Brown-Sequard syndrome

Answer 16

hemisection of cord -> segmental LMN and sensory signs (flaccid at level), spastic below level (UMN), pain/temp contralateral a few levels below segment, propioception ipsilateral below segment

Question 17

syringomyelia

Answer 17

syrinx = cavity filled with CSF; starts centrally and spreads centrifugally; first affects spinothalamic tract (capelike loss of pain/temp), followed by LMN bodies in anterior horn (flaccid at level)

Question 18

tabes dorsalis

Answer 18

posterior column syndrome; impaired vibration and position sense leading to sensory ataxia (worse in dark -> positive Romberg sign); caused by untx syphylis (10-20 yrs) -> lancinating leg pains, absent leg reflexes, sphincter dysfunction, Argyll Robertson pupils, possible blindness

Question 19

Argyll Robertson pupils

Answer 19

accomodate but don’t react (small, miotic)

Question 20

syphilis

Answer 20

causes tabes dorsalis -> posterior column syndrome (sensory ataxia)

Question 21

posterolateral column syndrome

Answer 21

dsyfunction of both dorsal column and corticospinal tract (causing sensory ataxia and spasticity w/ hyperactive reflexes); causes by B12 deficiency -> myelin degeneration w/o inflammation

Question 22

B12 deficiency

Answer 22

causes posterolateral column syndrome -> both dorsal column and cortiocspinal tract; peripheral neuropathy can also be present causes hyporeflexia (confusing - look for Babinksi sign to confirm)

Question 23

causes of anterior horn cell disease

Answer 23

SMA (inherited: SMA and Kennedy’s, acquired: PMA), infectious (polio, WNV, enterovirus 71, coxsackie, echoviruses

Question 24

SMA

Answer 24

autosomal recessive LMN syndrome (attacks anterior horn cells) -> varies in severity from death occurring with 18 mo to adult onset w/o life shortening

Question 25

Kennedy's disease

Answer 25

X-linked mutation in androgen receptor, causes (among other things) anterior horn cell disease

Question 26

ALS

Answer 26

combined UMN + LMN in corticospinal tract

Question 27

anterior spinal artery occlusion

Answer 27

blocks bilateral corticospinal tract and spinothalamic tract (spastic weakness below lesion, pain/temp loss a few levels below lesion), blocks anterior horn (flaccid weakness at level of lesion), impaired bowel/bladder control, preservation of DC/ML (proprioception, etc.); occurs most commonly in lower thoracic region (watershed) -> due to aortic dissection, atherosclerosis, hypotension

Question 28

intramedullary lesion causes (5)

Answer 28

ependymoma, astrocytoma, glioblastoma, myelitis, abscess

Question 29

intradural extramedullary lesion causes (2)

Answer 29

schwannoma, meningioma

Question 30

extradural lesion causes (5)

Answer 30

disc disease, epidural metastasis, primary bone tumor, lymphoma, epidural abscess

Question 31

lumbar disc herniation symptoms

Answer 31

below spinal cord -> LMN lesion of compressed nerve roots and dermatomal sensory loss (hyporeflexia), radicular pain, no bladder/bowel involvement

Question 32

cauda equina syndrome

Answer 32

radicular lesion of multiple roots L4 and below -> severe radicular pain, flaccid weakness in legs with hyporeflexia. saddle region sensory disturbance (S3-5), bowel/blader dysfunction and impotence --- immediate surgical decompression necessary to save bladder fn

Question 33

causes of cauda equina syndrome

Answer 33

lumbar disc herniation, spinal stenosis, tumor