Spinal Cord
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Anatomy and Neuroimaging
RITE Exam Review Lecture
Erik Beltran, MD MS
01/12/2015
Lecture Outline
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Basic Anatomy
Embryology
Vascular Supply
Grey Matter
White Matter
Clinical Cases & Neuroimaging
Spinal Cord
The Basics
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40-50 cm in length
1 – 1.5 cm in diameter
31 paired roots
Ends at the L1-L2 as the
conus medullaris
Cauda equina continues
as collection of
lumbosacral nerves
Filum terminale
C1-C7= Above vertebrae
C8 & below= Below
vertebrae
Spinal Cord
Embryology
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Formed from the caudal third of the neural tube w/
neuralization beginning day 17
Caudal neuropore closes by day 27
Alar Plate- Dorsal horns, afferent function
Basal Plate- Ventral & lateral horns, efferent function &
ventral roots
Spinal Cord
Embryology
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Growth increases during the 3rd embryonic month
Vertebral column and spinal cord initially grow at the same
rate
After 3rd month, spinal cord growth rate slows compared to
body and vertebral column
Net result- Cord ends at L1-L2, but nerve roots still exit at
corresponding vertebrae
Spinal Cord
Meninges
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Cord is covered by the
meninges
Dura matter- Tough outer
covering, dural sac ends at S2.
Arachnoid
Pia- Remains closely adherent
to the spinal cord. Filum
terminale anchors the cord to
the coccyx
Spinal cord is attached to the
dura by a series of lateral
denticulate ligaments
What are the layers traversed when performing a
lumbar puncture?
-Skin
-Subcutaneous Fat
-Supraspinous ligament
-Intraspinous ligament
-Ligamentum flavum
-Epidural fat
-Dura
-Arachnoid
Spinal Cord
Blood supply
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One anterior spinal artery
Supplies anterior 2/3 of the spinal cord
Arises from the vertebral arteries in the cervical region and from 510 larger radicular arteries (off aorta) in the lower cord
Spinal Cord
Blood Supply
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Two posterior spinal arteries
Supply the posterior 1/3 of the spinal cord
Arise from smaller radicular arteries at each level
Largest radicular artery is the artery of Ademkiewicz
Spinal Cord
Grey Matter
Spinal Cord
Grey Matter – Rexed lamina
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Defined by cellular
structure & location
I-VI – Dorsal horn
VII & X - Intermediate
zone
VIII & IX – Ventral
horn
Spinal Cord
Grey Matter – Rexed lamina I - V
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Lamina I (marginal nucleus of the spinal cord)
Lamina II (substantia gelatinosa)
Lamina III - V (nucleus proprius)
Found at all cord levels
Receive information from Lissauer’s tract (contains
ipsilateral pain and tempurature afferents, which
ascend 1-2 segments, then synapse
Spinal Cord
Grey matter - Rexed Lamina VI
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Lamina VI (Nucleus dorsalis/ Clark’s nucleus)
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Extends from C8 – T3/T4
Major relay center for unconscious proprioception
Receives information from muscle spindle and golgi tendon
organs and projects to the cerebellum via the dorsal
spinocerebellar tract
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Spinal Cord
Grey matter - Rexed Lamina VII
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Lamina VII (Intermediolateral nucleus & sacral
parasympathetic cell bodies)
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Extends from T1 – L2
Cell bodies of 1st order sympathetic neurons
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Sacral parasympathetic cell bodies: S2 – S4
Spinal Cord
Grey matter
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Lamina X – Anterior white commissure & central canal
Lamina VIII - Contains primarily interneurons
Spinal Cord
Grey Matter – Rexed Lamina IX
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Contains mainly motor neurons
Alpha motor neurons innervate a single motor unit
Dorsal motor neurons tend to innervate flexor muscles compared
to extensors, which tend to be more ventral
Gamma and beta motor neurons innervate muscle spindles
Cell bodies of the phrenic nerve (C3-C5)
Spinal accessory nucleus (C1-C6)
Onuf’s nucleus (S2-S4) – Motor neurons that are associated with
urethral and anal sphincters. Contribute to maintenance of
micturation and defecation continence.
Spinal Cord
Summary of grey matter
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Substantia gelatinosa – Relay center for spinothalamic tracts
Nucleus dorsalis – Relay center for proprioception
Intermediolateral nuclei – Sympathetic neurons
Motor neurons – Innervate motor units
Spinal Cord
White matter – Ascending & Descending pathways
Spinal Cord
White matter – Ascending pathways
Dorsal columns
 Spinothalamic tract
 Spinocerebellar tracts
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Spinal Cord
White matter – Ascending pathways
Dorsal Columns
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Somatotropically organized, medial to lateral:
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Sacral, Lumbar, thoracic, cervical.
Comprised of 1st order afferent axons containing well
localized fine touch and conscious proprioceptive
information.
Remain ipsilateral throughout spinal cord.
Synapse in nucl gracilis & cuneatus in the medulla.
Spinal Cord
White matter – Ascending pathways
Anterolateral System
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Lateral spinothalamic tract
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Contains contralateral pain and temperature
information.
2nd order neurons that have arisen from the posterior
grey matter (substantia gelatinosa, etc) and cross via
anterior commissure.
Medial to Lateral: C/T/L/S
Destination: mainly thalamus (VPL)
Also:
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Spinoreticular system (arousal to painful stimuli)
Spinotectal system (orient head & eyes to painful
stimuli)
Spinal Cord
White matter – Ascending pathways
Spinocerebellar Tracts
Division
From (peripheral
process)
Region
Dorsal spinocerebellar
Muscle spindles
(primary)
Ipsilateral trunk and legs
Ventral spinocerebellar
Gogli tendon organs
Ipsilateral trunk and legs
Cuneocerebellar
Muscle spindle
(primary)
Ipsilateral arm
Rostral spinocerebellar
Golgi tendon organs
Ipsilateral arm
Spinal Cord
White matter – Descending pathways
Lateral and anterior corticospinal tracts
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Motor pathways
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Anterior corticospinal tract:
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~ 10 % of descending motor axons, primarily truncal
muscles.
Ends by mid-thoracic cord.
Ipsilateral until axons cross to anterior horn at the level
of the synapse.
Lateral corticospinal tract:
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~ 90% of descending motor axons.
Contains contralateral axons.
Spinal Cord
White matter – Descending pathways
Rubrospinal Tract
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Contributes to control of large muscle movements in the
arms
Primarily modulates flexion movements of arms
Lesions above the Red Nucleus lead to decorticate
posturing
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Disinhibition of rubrospinal tract with disruption of lateral
corticospinal tracts = Flexion of upper extremities.
Decerebrate posturing results from a lesion below the red
nucleus.
Spinal Cord
White matter – Descending pathways
Vestibulospinal & Tectospinal Tracts
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Vestibulospinal:
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Alters muscle tone, position of limbs and posture in response to
movements of the head and body.
Medial tract acts to stabilize head and neck.
Lateral tract acts to stabilize extensors of the legs.
Tectospinal:
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Mediates reflex postural movements of the head & neck in response
to Visual & Auditory stimuli
Spinal Cord Cases
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A 34 year-old male is stabbed in the back after telling a
friend he was going to vote for Trump.
Your careful neurologic exam reveals:
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Right leg weakness with right extensor plantar response.
Loss of vibration and proprioception at the right toe and
ankle.
Loss of pain and temp of the left leg and left torso to T6.
Where is the lesion?
Brown-sequard syndrome
Spastic/weak leg w/ impaired
joint position sense, & loss of
contralateral pain/temp 2-3
segments below spinal lesion
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58 yo male with cardiac disease undergoes repair of
abdominal aortic aneurysm.
8 hours later, he wakes up with no movement of his legs, the
cardiothoracic surgeons swear it wasn’t them..
After obtaining a CT of the head, the primary team activates
the stroke pager…
Your neurologic exam finds:
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Paraplegia, hypotonia, areflexia at patella/achilles, absent pain &
temp to T11-T12, w/ preserved vibration and proprioception.
Where is the likely lesion and from what pathologic process?
Why did you find hypotonia and areflexia?
Anterior Spinal Artery Occlusion
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Anterior Cord syndrome.
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Lesion most likely due to insufficient arterial flow to the
anterior spinal cord at the artery of Adamkiewicz.
Loss of reflexes and low tone are commonly seen due to
spinal shock in an acute injury.
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Reflexes may not return for days to weeks.
Eventual development of spasticity and hyperreflexia.
28 yo female presents to your clinic with severe
headaches exacerbated by sneezing, coughing, bending
over or defecation.
 Your careful neurologic exam notes diminished pain and
temperature over the bilateral C4 and C5 dermatomes…
 What is the pathologic process?
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Central Cord Syndrome
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Syringomyelia and
Chiari malformation.
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Loss of pain / temp in a
cape-like distribution.
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Preserved vibration /
posterior column
sensation and motor
systems until late in
disease course.
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45 yo male presents with low back pain, urinary retention, lower
extremity weakness.
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Your careful neurologic exam notes saddle anesthesia, brisk
patellar reflexes, increased tone in lower extremities, 4/5 strength
in lower extremities, increased anal sphincter tone.
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Likely localization and cause?
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Conus medullaris syndrome (lesion at L1-L2) from a
ruptured lumbar disc.
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Numbness and weakness tend to be symmetric.
Mixture of upper and lower motor neuron signs.
Urinary retention, erectile dysfunction, constipation (increased
anal sphincter tone).
Cauda equina syndrome
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More likely to be asymmetric
Only lower motor neuron signs.
Low anal sphincter tone and low urethral tone lead to early
urine and fecal incontinence.
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56 year-old male reports weakness of right arm for 6 months,
followed by weakness of right leg for 3 months.
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Neurologic exam notes 4/5 strength throughout RUE, 4+/5
strength in RLE, with right sided hyperreflexia, atrophy and
fasciculations.
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Amyotrophic lateral sclerosis
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Hallmark: Weakness & Wasting in the setting of
preserved or brisk reflexes.
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Important to note that while fasciculations derive from
LMN, they are not necessarily pathologic when seen in
isolation.
Spinal Cord Neuroimaging
Spondylolysis
Spondylolisthesis
Cervical disc herniation
Cord contusion is the best response because there is gross traumatic injury to the
spinal column with disruption of the C4-C5 ligamenta flava, interspinous ligaments,
and posterior longitudinal ligament. There is fracture deformity of C5 vertebra
consistent with a flexion teardrop fracture and fracture of C6. There is prevertebral
soft tissue edema, and the cord has T2 hyperintense signal at the C5 and C6 level
consistent with traumatic cord contusion with some intramedullary hemorrhagic
component. Neuromyelitis optica, ependymoma, abscess, and sarcoid myelitis are not
the best choices because the extensive vertebral column injuries are not consistent
with the typical presentation of any of these entities.
Spondylodiscitis with epidural abscess
The spinal lesion is multisegmental, elongated, and is in the lower cervical and thoracic levels.
The pattern and extent of this lesion is atypical for multiple sclerosis in its size and extent and
most characteristic of a form of transverse myelitis. The presence anti aquaporin antibodies
(NMO antibodies) is a diagnostic marker of neuromyelitis optica (also known as Devic disease)
which is a distinct form of demyelinating disease. The other choices would be highly unlikely to
have these auto-antibodies.
The arrows on the two images point to a semilunar nodule along the right anterior margin of
the right facet joint. This structure results in right lateral recess stenosis and is a frequent
etiology of radicular pain in the elderly. This structure arises continuous with the right facet
joint and is typical of a synovial cyst, likely partially calcified. A neurofibroma would be more
likely seen within the right neuroforamen arising along the nerve root. A large free fragment
with that dimension and that location is unlikely. The structure is adjacent to, but does not
appear to be continuous with the adjacent disc.
The figures demonstrate a diffuse heterogeneous appearance of the vertebrae, "salt and
pepper pattern". There is also a larger focal enhancing lesion extending into the pedicle
of L2 along with compression fractures. This pattern of diffuse osseus invasion can be
seen due to hematologic diseases and is most typical of multiple myeloma. Thalassemia
is associated with marrow reconversion with the repopulating of yellow marrow by
hematopoietic cells, but that would not be expected to show this salt and pepper pattern
or a focal lesion as in L2, nor would metastatic carcinoma. There are pathologic
compression fractures and some kyphotic posturing, but these would not be the best
answers.