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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6009_Библиотеки_им_академика_М_И_Перельмана.pdf
Extramedullary Hematopoiesis
KEY FACTS
TERMINOLOGY
• Epidural ± paravertebral proliferation of hematopoietic
tissue in response to profound chronic anemia
• Minimally enhancing isointense thoracic intra- or paraspinal
masses with associated diffuse marrow hypointensity
IMAGING
• Midthoracic > cervical, lumbar
• CT
○ Soft tissue density, without bony erosion or calcification
• MR
○ T1: Isointense to cord
Neoplasms, Cysts, and Other Masses
○ T2: Iso- to mildly hyperintense to cord
TOP DIFFERENTIAL DIAGNOSES
• Epidural/paraspinal metastasis
• Spinal epidural lymphoma
• Paravertebral phlegmon/abscess
• Peripheral nerve sheath tumor
(Left) Sagittal graphic of
extramedullary hematopoiesis
(EMH) depicts hematopoietic
marrow extending into
prevertebral ſt and epidural
space . EMH is a common
compensatory phenomenon to
chronic hemolytic anemias.
(Right) Axial NECT through the
lower thoracic spine shows
paraspinal soft tissue masses
ſt and medullary expansion
of the vertebra and ribs .
With extramedullary
hematopoiesis there is marrow
expansion from severe anemia
and paraspinal masses as
extramedullary hematopoietic
elements.
• Epidural hematoma
PATHOLOGY
• Ectopic hematopoietic rests stimulated in response to
chronic anemic states
○ Intermediate β-thalassemia: Most common
○ Sickle cell anemia
○ Polycythemia vera
○ Myelofibrosis with myeloid metaplasia
CLINICAL ISSUES
• Asymptomatic
• Back ± radicular pain
• Treatment includes
○ Radiation therapy
○ Intravenous steroids
○ Decompressive laminectomy with surgical resection
○ Transfusions
○ Hydroxyurea
310
(Left) Coronal T1WI C+ FS MR
of the spine and paraspinal
tissues demonstrates deposits
of extramedullary
hematopoiesis extending from
the ribs st. Due to insufficient
production of blood elements
by the bone marrow,
hematopoietic tissues at other
sites proliferate to
compensate for the circulatory
demands for blood elements.
(Right) Axial T1WI MR reveals
foci of extramedullary
hematopoiesis breaking
through the vertebral bodies
into the neural foramina
from the ribs st.
Tumoral Calcinosis
KEY FACTS
Neoplasms, Cysts, and Other Masses
TERMINOLOGY
• Benign periarticular soft tissue hyperplasia, calcification
IMAGING
• Nonaggressive-appearing calcific mass centered about
large synovial joints
• Predilection for large joints
○ Hip
○ Shoulder
○ Elbow
○ Spinal involvement uncommon
• Radiographs/CT
○ Calcific mass with clustered calcific aggregates
surrounding joint
• T1/T2/STIR
○ Lobulated low-signal masses centered on facet joint
○ May extend into adjacent paraspinal soft tissue
○ Minimal enhancement
○ May extend beyond midline to involve dorsal elements,
ligamentum flavum
TOP DIFFERENTIAL DIAGNOSES
• Calcium pyrophosphate deposition disease
• Primary bone tumor
• Synovial chondromatosis
• Neuropathic joint
• Synovial cyst
PATHOLOGY
• Complication of chronic renal failure, on renal dialysis
• Familial tumoral calcinosis (FTC)
○ Normophosphatemic FTC
– Likely related to mutations in gene encoding for
SAMD9 protein
○ Hyperphosphatemic FTC
– Increased renal absorption of phosphate due to loss-
of-function mutations
(Left) Sagittal lumbar CT
shows mass-like calcifications
involving posterior elements
st. Calcified masses extend
into the bony canal causing
central canal encroachment
. Radiodense periarticular
masses are usually calcium
hydroxyapatite crystals
surrounded by foreign body
giant cell and histiocytic
reaction. (Right) Axial NECT
through the cervical spine
shows lobulated density ſt
surrounding the facet joint
with well-defined margins and
no soft tissue component.
(Courtesy N. Stence, MD.)
(Left) Axial bone CT reveals
central canal encroachment
ſt due to copious posterior
element calcifications. (Right)
Axial T2WI MR exhibits
hypointensity of these
posterior element calcified
masses st. There is moderate
mass effect upon the nerve
roots within the thecal sac ſt.
Tumoral calcinosis is usually
associated with hereditary
disorders of calcium
metabolism or renal dialysis. It
also occurs in degenerated
tissues in the absence of
systemic disorders.
311
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SECTION 9
Vascular Disorders
Vascular Anatomy 314
Approach to Vascular Conditions
Type 1 Vascular Malformation (Dural Arteriovenous Fistula)
Type 2 Arteriovenous Malformation
Type 3 Arteriovenous Malformation
Type 4 Vascular Malformation (Arteriovenous Fistula) 330
Posterior Fossa Dural Fistula With Intraspinal Drainage
Cavernous Malformation
Spinal Artery Aneurysm
Spinal Cord Infarction
Subarachnoid Hemorrhage 335
Spontaneous Epidural Hematoma
Subdural Hematoma
Bow Hunter Syndrome
Vertebral Dissection
Carotid Dissection 340
Fibromuscular Dysplasia
338
320
324
328
329
331
332
333
334
336
337
339
341
Vascular Anatomy
Terminology
Abbreviations: Anterior spinal artery (ASA), posterior spinal
artery (PSA), artery of Adamkiewicz (AA)
Synonyms: Great anterior radicular artery, arteria radicularis
magna = AA radicularis magna = AA
Vascular Disorders
Imaging Anatomy
Vertebral Artery
The vertebra artery is divided into 4 segments. The 1st
segment (V1) of the vertebral artery extends from its origin to
the point of entrance into the foramen of the cervical
transverse process, which is usually the 6th body. The
vertebral artery is usually the most proximal and largest
branch off of the subclavian artery. Multiple variations in the
anatomic course and origins of the vertebral arteries have
been described. The most common variation in vertebral
artery origin is in the origination from the proximal subclavian
artery. The origin of the left vertebral artery from the aortic
arch between the left common carotid artery and left
subclavian artery has been described in 2.4-5.8% of cases.
When there is an origin of the vertebral artery from the arch,
the vertebral artery usually enters the foramen of the
transverse process of the 5th cervical vertebrae. With a
normal origin of the left vertebral artery from the subclavian
artery, the vertebral artery enters the transverse foramen of
the 6th cervical vertebrae in nearly 88% of cases. The site of
entrance at the level of C4 is seen in 0.5%, C5 in 6.6%, and C7
in 5.4%. Rare examples of origins of the left vertebral artery
from the left common carotid artery, or external carotid
artery, have been described. Also rare are variations in the
origin of the right vertebral artery (less than 1%) from the
aorta, carotid arteries, or brachiocephalic arteries.
The 2nd segment (V2) of the vertebral artery extends
superiorly through the foramen of the transverse processes in
a vertical course until it reaches the transverse process of C2.
The 3rd segment (V3) of the vertebral artery extends from
the exit of C2 to its entrance into the spinal canal. After
leaving the transverse foramen of C2, it courses laterally and
posteriorly to pass through the transverse foramen of C1. The
vertebral artery then extends posterior and medially in a
horizontal groove on the upper surface of the posterior arch
of C1. The vertebral artery turns abruptly as it nears the
midline and pierces the posterior atlantooccipital membrane
and enters into the vertebral canal. Anomalous connections in
this region are uncommon but include the proatlantal
intersegmental artery, which can communicate between the
internal or external carotid artery and the vertebral artery at
this level. Local duplication or fenestration of the V3 segment
can occur. The occipital artery also can arise from the V3
segment. A persistent 1st intersegmental artery can occur
where the vertebral artery courses below the C1 arch after
exiting the transverse foramen of C2 and enters the spinal
canal without passing through the C1 transverse foramen (34%). The origin of the posterior inferior cerebellar artery may
also be anomalously low between C1 and C2.
The 4th segment (V4) segment pierces the dura and extends
through the foramen magnum where it lies anterior to the
medulla and eventually joins the contralateral vertebral artery
to form the basilar artery. Major branches arising off the
vertebral artery include multiple muscular branches from the
extracranial segments to supply the deep muscles of the neck
and meningeal branches. The posterior meningeal branch
arises from the vertebral artery above the level of C1 and
314
below the foramen magnum and supplies the falx cerebelli
and the medial portion of the dura of the occipital posterior
fossa. Just before joining to form the basilar artery, each of
the vertebral arteries gives off a branch that will become the
ASA, which extends downward and medially to join in the
midline with a corresponding branch from the other vertebral
artery. The posterior spinal arteries can originate from the
posterior inferior cerebellar arteries or from the intracranial
portion of the vertebral arteries.
Spinal Arteries
The spinal cord circulation is derived from segmental branches
off of the vertebral arteries as well as multiple radicular
arteries arising from segmental vessels. These segmental
vessels include the descending cervical, deep cervical,
intercostal, lumbar, and sacral arteries. The ASA arises at the
junction of the intradural segment of the vertebral arteries,
caudal to the basilar artery. The ASA descends in the midline
without interruption from the foramen magnum to the filum
terminale. The ASA supply is reinforced by multiple segmental
feeders. The segmental feeders give rise to sulcal, or central
branches, which supply the anterior 2/3 of the cord. The
anterior 2/3 includes the anterior horns, spinothalamic tracts,
and corticospinal tracts. The ASA lies in the midline on a
ventral aspect of the cord in the groove of the anterior
median fissure. The posterior spinal arteries arise from the
posterior rami of the vertebral artery or from the posterior
inferior cerebellar artery.
The PSAs are a paired longitudinal system of vessels on the
dorsal cord medial to the dorsal roots. These form a plexiform
and variable network between the 2 dorsal arteries. The PSA
supplies the posterior 1/3 of the cord, which includes supply
to the posterior columns and a variable supply to the
corticospinal tracts. Continuation of both the ASA and PSA
supply is derived from segmental anastomoses. These
segmental vessels arise as dorsal rami from vertebral,
subclavian, thoracic intercostal, and lumbar intercostal
arteries. The dorsal rami enter the canal through the neural
foramen and then penetrate the dura and divide into 2 main
branches: The dural artery, which supplies the nerve root
sleeve and the dura, and the radiculomedullary branch. The
radiculomedullary branch then divides into a radicular artery,
which penetrates the subarachnoid space to supply the
anterior and posterior roots. There is also a variable medullary
artery branch, which joins the ASA and PSA. The radicular
arteries arise from the division of the radiculomedullary
arteries along the anterior and posterior nerve roots. The
anterior radicular artery extends along the anterior surface of
the spinal cord, while the posterior radicular artery likewise
extends along the posterior cord surface.
The multiple fetal segmental vessels will regress with
adulthood, leaving 2-14 (average 6) anterior radicular arteries
persisting in the adult and 11-16 posterior radicular arteries in
the adult. The major cervical radicular feeders to the spinal
cord occur between the C5-C7 levels. There are 2-3 anterior
cervical cord feeders that measure 400-600 microns in size.
There are also 3-4 posterior cervical cord feeders, which are
smaller in size, on the order of 150-400 microns. The V3
segment never gives rise to radiculomedullary branches. In the
thoracic spine, there are 2-3 anterior thoracic cord feeding
segmental vessels. These are usually left-sided and are on the
order of 550-1200 microns in size. Small ventral feeding
vessels may also be present on the order of 200 microns.
There is an inverse relationship between the number and
Vascular Anatomy
caliber of ventral radicular vessels. There "pauci-segmental"
anatomy can occur with fewer vessels (< 5) with larger caliber
or "plurisegmental" anatomy with more vessels with smaller
caliber. The dominant thoracic anterior radicular artery is also
called the AA. The AA tends to have a left-sided origin (73%)
and arises from T9-T12 (62%), with less common origins in the
lumbar region (26%) and from T6-T8 (12%). A major
segmental feeder may also occur in the upper thoracic spine,
often at the T5 level. This has been termed the artery of von
Haller. The number of posterior thoracic cord feeding vessels
varies from 9-12, with an average of 8. The posterior thoracic
feeding vessels have no right-to-left lateralization. These
vessels are on the order of 150-400 microns in size. The
lumbosacral and pelvic regions have from 0-1 major feeding
vessels to the spinal cord. The ASA ends at the conus with
communicating branches (rami cruciantes) to the PSA. The
posterior division of the iliac artery gives rise to the inferior
and superior lateral sacral branches, which give rise to the
spinal arteries via the anterior sacral foramen. The anterior
division of the iliac artery gives rise to the inferior gluteal
artery, which supplies the sciatic nerve. The posterior division
of the internal iliac artery gives rise to the iliolumbar artery,
which supplies the femoral nerve at the iliac wing level.
Spinal Veins
The veins of the spinal cord parallel the spinal arterial pattern.
There is a very symmetrical pattern of venous drainage
(compared with the highly asymmetrical arterial supply) with
minimal anterior-to-posterior, right-to-left segmental
variation. There are 2 sets of intrinsic radial draining veins,
which drain into the anastomoses on the cord surface. The
central group of veins provides for return of the anterior
horns and surrounding white matter and drain into the central
veins in the anterior median fissure. This forms the anterior
median vein. Peripheral dorsal and lateral cord drainage is via
the small, valveless radial vein plexus, which extends to the
coronal venous plexus on the cord surface and then drains to
the epidural venous plexus of Batson. The epidural plexus
consists of anterior and posterior internal vertebral plexus
components and connects with the superior and inferior vena
cava, azygos and hemiazygos systems, and the intracranial
dural sinuses. There are from 30-70 medullary radicular veins.
The anterior median vein continues caudally along the filum
terminale to the end of the dural sac. The coronal and median
veins drain to the medullary veins, which leave the intradural
space at the root sleeve and extend into the epidural plexus.
Medullary veins have a functional valve-like mechanism at the
dural margin, which prevents epidural reflux into the
intradural space. There are no intradural valves present.
Embryology
The embryogenesis of the vertebral artery begins at
approximately day 32 and is completed by day 40. The
vertebral artery is formed from fusion of the longitudinal
anastomosis that links cervical intersegmental arteries, which
branch off of primitive paired dorsal aorta. The
intersegmental arteries regress, except for the 7th vessel,
which will come to form the proximal portion of the
subclavian artery, including the origin of the vertebral artery.
As the connections to the primitive dorsal aorta disappear, the
vertebral artery takes shape and initially has a more beaded
anastomotic appearance and a tortuous course. The basilar
artery is formed by fusion of the 2 primitive vertebral arteries.
Spinal cord vessels originate from a capillary network on the
ventral lateral surface of the cord connected with segmental
Vascular Disorders
aortic branches. Two primitive longitudinal systems are
formed. By the end of the 2nd month, the ventrolateral
systems transform into the longitudinal solitary anterior
median ASA. The plexus-like pattern remains more prominent
on the dorsal surface of the cord. The ASA formation is
followed by a variable regression of segmental feeding vessels
(initially 31) and is completed by the 4th month of gestation.
The reduction is most pronounced in the thoracic and lumbar
areas. Segmental arteries persist as intercostal and lumbar
arteries. In the cervical spine, dorsal intersegmental
anastomoses persist as components of the vertebral arteries.
The ventral anastomoses persist as the thyrocervical trunk.
Selected References
1. Gailloud P: The artery of von Haller: a constant anterior radiculomedullary
artery at the upper thoracic level. Neurosurgery. 73(6):1034-43, 2013
2. Eskander MS et al: Vertebral artery anatomy: a review of two hundred fifty
magnetic resonance imaging scans. Spine (Phila Pa 1976). 35(23):2035-40,
2010
3. Becske T et al: The vascular anatomy of the vertebro-spinal axis. Neurosurg
Clin N Am. 20(3):259-64, 2009
4. Bell R et al: Neurovascular anatomy: a practical guide. Neurosurg Clin N Am.
20(3):265-78, 2009
5. Debette S et al: Cervical-artery dissections: predisposing factors, diagnosis,
and outcome. Lancet Neurol. 8(7):668-78, 2009
6. Goyal MS et al: The diagnosis and management of supraaortic arterial
dissections. Curr Opin Neurol. 22(1):80-9, 2009
7. Johnson MH et al: Vascular anatomy: the head, neck, and skull base.
Neurosurg Clin N Am. 20(3):239-58, 2009
8. Kim YK et al: Cervical artery dissection: pathology, epidemiology and
management. Thromb Res. 123(6):810-21, 2009
9. Tubbs RS et al: Surgical anatomy and quantitation of the branches of the V2
and V3 segments of the vertebral artery. Laboratory investigation. J
Neurosurg Spine. 11(1):84-7, 2009
10. Wang S et al: Anomalous vertebral artery in craniovertebral junction with
occipitalization of the atlas. Spine (Phila Pa 1976). 34(26):2838-42, 2009
11. Bagheri SC et al: Penetrating neck injuries. Oral Maxillofac Surg Clin North
Am. 20(3):393-414, 2008
12. Chen JW: Cervical spine injuries. Oral Maxillofac Surg Clin North Am.
20(3):381-91, 2008
13. Turan TN et al: Treatment of intracranial atherosclerotic stenosis. Rev Neurol
Dis. 5(3):117-24, 2008
14. Schmidt WA: Takayasu and temporal arteritis. Front Neurol Neurosci. 21:96104, 2006
15. Nelson PK et al: Vertebrospinal angiography in the evaluation of vertebral
and spinal cord disease. Neuroimaging Clin N Am. 6(3):589-605, 1996
315
Vascular Disorders
Vascular Anatomy
Right common carotid artery
Ascending cervical artery
Right thyrocervical trunk
Right costocervical artery
Right subclavian artery
Right vertebral artery origin
Innominate artery
Ascending aorta
External carotid artery
Left internal carotid artery
Anterior segmental artery
Left common carotid artery
Left vertebral artery origin
Left internal mammary artery
Left subclavian artery
Descending aorta
Thoracic aorta
316
Thoracic segmental
(intercostal) artery
Postcentral branch to
vertebral body
Radiculomedullary (spinal)
artery
Intercostal artery
(Top) AP graphic shows the aortic arch and arterial great vessels in red. The vertebral arteries give rise to the anterior and posterior
spinal arteries. The ascending cervical arteries (branches of the thyrocervical trunks) give off anterior and posterior segmental
medullary arteries that anastomose with the anterior spinal artery and posterior spinal artery on the cord surface. Complete spinal
angiography includes evaluation of all these vessels. (Bottom) Axial graphic shows an overview of the arterial supply to the vertebral
column and its contents, depicted here for the lower thoracic spine. A series of paired segmental arteries (cervical region arises from the
vertebral and thyrocervical arteries, thoracic region are intercostal arteries, and lumbar region are lumbar arteries) divide into anterior
and posterior branches. The posterior branch gives rise to a muscular branch, a branch to the vertebral body, and the radiculomedullary
artery. The radiculomedullary artery enters the vertebral canal via the neural foramen.
Anterior spinal artery
Dorsal branch of segmental
artery
Ventral branch of segmental
artery
Muscular artery
Vascular Anatomy
Vascular Disorders
Posterior spinal arteries
Anterior spinal artery
Posterior radiculomedullary
artery
Ventral branch of segmental
artery
Postcentral branch to
vertebral body
T10 segmental artery
Aorta
Medullary branches
Artery of Adamkiewicz
Anterior radiculomedullary
artery
Muscular branch
Dorsal ramus
Intercostal artery
Intercostal artery
Anterior spinal artery
Posterior branch of segmental
Postcentral branch to
vertebral body
Medullary arteries
Muscular branch
(Top) Oblique axial graphic rendering of T10 depicts segmental intercostal arteries arising from the lower thoracic aorta. The artery of
Adamkiewicz is the dominant segmental feeding vessel to the thoracic cord, supplying the anterior aspect of the cord via the anterior
spinal artery. Note its characteristic hairpin turn on the cord surface as it 1st courses superiorly, then turns inferiorly. (Bottom) Anterior
and posterior radiculomedullary arteries anastomose with the anterior and posterior spinal arteries. Penetrating medullary arteries in
the cord are largely end arteries with few collaterals. The cord watershed zone is at the central gray matter.
artery
Ventral radiculomedullary
artery
Radiculomedullary artery
Dorsal radiculomedullary
artery
Posterior spinal arteries
317
Vascular Anatomy
Vascular Disorders
Right intradural vertebral
Right vertebral artery
(segment V3) within C1
transverse foramen
Right vertebral (segment V2)
Right vertebral artery
Right thyrocervical trunk
Right subclavian artery
Opisthion
(segment V4)
(segment V1)
Occipital condyle
C1 lateral mass
Vertebral artery enters C6
transverse foramen
Left vertebral artery
Left subclavian artery
C1 lateral mass
Posterior arch C1
C1 transverse foramen
C2 lateral mass
C2 transverse foramen
C3 transverse foramen
(Top) AP volume-rendered image of a CTA shows the course of the vertebral arteries entering the transverse foramen and ascending to
the foramen magnum. Both vertebral arteries in this patient enter the C6 level, but this can show wide normal variation. Left vertebral
arteries arising from the arch enter more cephalad at C5. (Bottom) Lateral volume-rendered CTA shows the course of the distal left
vertebral artery passing through C1 and horizontally oriented C2 transverse foramen.
C2 spinous process
C2 pars interarticularis
Left vertebral artery
318
Branch to vertebral body
Anterior spinal artery
Vascular Anatomy
Vascular Disorders
Artery of Adamkiewicz
Catheter
Left T8 intercostal artery
Dorsal muscular branch
Vertebral venous channels
Basivertebral vein
Anterior median vein of spinal
cord
Medullary veins
Dorsal coronal venous plexus
of spinal cord
(Top) AP view of a left T8 intercostal injection gives rise to the characteristic hairpin turn of the major segmental feeding vessel to the
thoracic cord, the artery of Adamkiewicz. Extending inferiorly from the top of the hairpin turn is the anterior spinal artery, which
supplies the anterior 2/3 of the cord. (Bottom) Magnified graphic of the internal vertebral venous plexus is shown. The radicular veins
course along the dorsal and ventral rami, eventually draining into components of the anterior or posterior internal plexus and
subsequently the segmental veins, which will drain into the superior or inferior vena cava.
Anterior internal vertebral
venous plexus
Segmental vein
Radicular vein
Posterior internal vertebral
venous plexus
319