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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6009_Библиотеки_им_академика_М_И_Перельмана.pdf
Myelomeningocele
KEY FACTS
TERMINOLOGY
• Posterior spinal defect lacking skin covering → neural tissue,
CSF, and meninges exposed to air
• Synonyms: Meningomyelocele, open spinal dysraphism,
spina bifida aperta, spina bifida cystica
IMAGING
• Lumbosacral (44%) > thoracolumbar (32%) > lumbar (22%)
> thoracic (2%)
• Preoperative: Posterior spinal defect lacking skin covering
→ neural tissue, CSF, and meninges exposed to air
• Postoperative: Dysraphism, low-lying cord/roots,
Congenital and Genetic Disorders
postoperative skin closure changes
TOP DIFFERENTIAL DIAGNOSES
• Dorsal meningocele
• Closed (occult) spinal dysraphism
• Postoperative pseudomeningocele
(Left) Sagittal graphic shows
ballooning of the meninges
through a dysraphic spinal
defect with a low-lying cord
ſt terminating in the red
neural placode . Axial insert
shows the origin of spinal
roots from ventral placode
and protrusion of the
meninges and placode through
the dysraphic posterior
elements st. (Right) Sagittal
T1WI MR shows a large
unrepaired lumbosacral
myelomeningocele sac ſt
protruding through a posterior
dysraphic defect. Neural
elements are seen protruding
into the sac .
PATHOLOGY
• Failure of neural tube closure
○ Placode may be segmental or terminal
• Association with maternal folate deficiency or abnormal
folate metabolism
• Usually accompanied by multiple neurological and
orthopedic complications
CLINICAL ISSUES
• Stable neurological deficits expected following closure
• Subsequent neurological deterioration prompts imaging
evaluation for tethered cord, dural ring constriction, cord
ischemia, or syringohydromyelia
DIAGNOSTIC CHECKLIST
• Cord retethering is most common spinal cause of delayed
deterioration
• Low-lying cord on MR does not always equate to clinical
tethering
100
(Left) Sagittal T2WI MR shows
typical posterior fossa Chiari 2
malformation changes. The
large myelomeningocele
lumbosacral sac ſt has not
been surgically repaired, and it
protrudes dorsally through a
large posterior dysraphic
defect. (Right) Axial T1WI MR
of an unrepaired lumbosacral
myelomeningocele confirms
an exophytic meningeal sac ſt
and extension of dysplastic
neural elements through
the osseous spinal dysraphic
defect into the
myelomeningocele.
Lipomyelomeningocele
KEY FACTS
Congenital and Genetic Disorders
TERMINOLOGY
• Lipomyelomeningocele, lipomyelocele, spinal lipomatous
malformation
IMAGING
• Subcutaneous fatty mass contiguous with neural
placode/lipoma through posterior dysraphism
○ Size varies from nearly imperceptible to large
• Posterior spinal dysraphism, enlarged canal at placode level
• Tethered, low-lying spinal cord ± meningocele inserts into
lipoma through dysraphic defect
TOP DIFFERENTIAL DIAGNOSES
• Terminal lipoma
• Intradural (juxtamedullary) lipoma
• Dorsal meningocele
• Myelocele/myelomeningocele
PATHOLOGY
• Premature disjunction of neural ectoderm from cutaneous
ectoderm → induction of mesenchyme to form fat (lipoma)
• Spinal cord always tethered
• Association with vertebral segmentation anomalies, sacral
dysgenesis, anorectal and genitourinary abnormalities
CLINICAL ISSUES
• Soft midline or paramedian skin-covered mass above
buttocks
• Back/leg pain, scoliosis, lower extremity paraparesis,
bladder/bowel dysfunction
• Incidence not impacted by folate supplementation to
pregnant women (unlike myelomeningocele)
• Closed dysraphism, so no Chiari II malformation
DIAGNOSTIC CHECKLIST
• Diagnosis of postoperative retethering primarily clinical;
use imaging to search for complications
(Left) Sagittal graphic of the
lumbosacral spine
demonstrates classic
lipomyelomeningocele
anatomy. The low-lying spinal
cord and cauda equina nerve
roots protrude through the
dysraphic posterior elements
into a dorsal meningocele sac
covered by skin and
subcutaneous fat. (Right) Axial
graphic of the lower lumbar
spine shows protrusion of the
nerve roots and neural
placode through the
dysraphic posterior elements
st into a skin-covered sac.
(Left) Sagittal T1WI MR shows
the low-lying tethered spinal
cord ſt extending through a
dorsal dysraphic defect into
the subcutaneous fat to
terminate in a skin-covered
cyst . (Right) Axial T1WI MR
demonstrates protrusion of
the lipomyelomeningocele sac
with eccentric lipoma
through the parallel-oriented
dysraphic posterior elements
into the subcutaneous fat
(clinically evident as a skincovered fatty mass).
101
Lipoma
KEY FACTS
TERMINOLOGY
• Intradural (juxtamedullary, subpial) or terminal lipoma
IMAGING
• Lipoma intimately associated with spinal cord (intradural) or
distal cord/filum insertion (terminal)
• Lipoma follows fat signal intensity, density, and
echogenicity
TOP DIFFERENTIAL DIAGNOSES
• Lipomyelocele/lipomyelomeningocele
• Filum fibrolipoma
Congenital and Genetic Disorders
• Dermoid cyst
PATHOLOGY
• Follows premature separation (premature disjunction) of
cutaneous ectoderm from neuroectoderm during
neurulation
(Left) Axial graphic of the
thoracic spine demonstrates
incomplete closure of the
dorsal spinal cord around a
dorsal juxtamedullary conus
lipoma ſt, encompassing the
dorsal spinal nerve roots.
(Right) Axial T1WI MR reveals
the typical hyperintense
appearance of a conus
juxtamedullary (subpial)
lipoma ſt. Note the intradural
location and close relationship
with the dorsal conus
surface.
○ Surrounding mesenchyme enters ependyma-lined
central spinal canal, impedes neural tube closure open
placode
• Skin closed over malformation (closed neural tube defect)
• Proposed (2009) classification scheme proposes dividing
lipomas into 2 groups of lipomatous malformations based
on presence or absence of dural defect
○ Lipomas without dural defect
– Filum lipoma, caudal lipoma without dural defect,
intramedullary lipoma
○ Lipomas with dural defect
– Dorsal lipoma, caudal lipoma with dural defect,
transitional lipoma, lipomyelocele,
lipomyelomeningocele
CLINICAL ISSUES
• Symptoms referable to lipoma level, presence of spinal
cord compression
• Small lipomas may grow dramatically during infancy
102
(Left) Axial NECT following
intrathecal myelography
reveals a typical markedly
hypodense dorsal
juxtamedullary (subpial)
lipoma ſt. The lipoma
encircles and distorts the
spinal cord conus tip . Note
mild scalloping of the
posterior vertebral body.
(Right) Sagittal T1WI MR
demonstrates a low-lying
spinal cord with long
hyperintense filum lipoma ſt
that inserts into a
heterogeneous intraspinal
sacral dermoid tumor .
Dorsal Dermal Sinus
KEY FACTS
Congenital and Genetic Disorders
TERMINOLOGY
• Synonyms: Dermal sinus tract (DST)
• Midline/paramedian stratified squamous epithelial-lined
sinus tract
• Extends inward from skin surface for variable distance
IMAGING
• Sinus tract easily identified superimposed on background of
cutaneous fat
• Terminus usually conus medullaris (lumbosacral) or central
spinal canal (cervical, thoracic)
TOP DIFFERENTIAL DIAGNOSES
• Low coccygeal midline dimple
• Pilonidal sinus
• (Epi)dermoid tumor without dermal sinus
PATHOLOGY
• Focal incorporation of cutaneous ectoderm into neural
ectoderm during disjunction at circumscribed point only →
focal segmental adhesion
• Spinal cord ascends relative to spinal canal, stretches
adhesion into long, tubular tract
CLINICAL ISSUES
• Infancy → 3rd decade
• Presentation either asymptomatic (incidentally noted skin
dimple) or infection, neurological deficits 2° to cord
tethering or compression
DIAGNOSTIC CHECKLIST
• Must differentiate DST from simple sacral dimple or
pilonidal sinus
• Identify sinus course, termination for surgical planning
(Left) Sagittal graphic shows a
dermal sinus extending from
the skin surface into the spinal
canal to terminate at conus
with epidermoid cysts. A skin
dimple with capillary angioma
and hairy tuft (cutaneous
marker) indicates sinus
opening. (Right) Sagittal T2WI
MR shows hypointense dermal
sinus ſt extending through L5
posterior elements and
coursing intradural to tether
the low-lying hydromyelic
conus st at L2-L3. A vitamin E
capsule has been placed to
mark the skin opening of the
sinus .
(Left) Sagittal T1WI MR shows
low to isointense signal
intradural masses (epidermoid
cysts) at L2-L3 and L5sacrum ſt. There is a dermal
sinus tract extending dorsally
from the low sacral region st.
(Right) Sagittal T1WI C+ MR in
a patient with a dorsal dermal
sinus tract st and clinical
meningitis demonstrates
diffuse abnormal pial and
cauda equina enhancement
. Note minimal rim
enhancement of the sacral ſt
and lumbar epidermoid
cysts.
103
Simple Coccygeal Dimple
KEY FACTS
TERMINOLOGY
• Synonym: Sacral dimple
IMAGING
• Low sacral dimple connecting to coccyx by fibrous tract
○ Usually resides within intergluteal cleft
○ No intradural extension by definition
• Variable size; deeper dimples usually evoke more physician
and parental concern
TOP DIFFERENTIAL DIAGNOSES
• Dorsal dermal sinus
Congenital and Genetic Disorders
• Pilonidal sinus
PATHOLOGY
• Congenital
• Tract usually atretic; may occasionally be patent with fluid in
lumen
(Left) Sagittal graphic of the
lumbosacral spine
demonstrates a low sacral
dimple (marked by a vitamin E
capsule ), which is
connected to the coccyx tip by
a fibrous tract ſt. There is no
intradural extension, and the
conus/intradural structures
are normal. (Right) Sagittal
T2WI MR demonstrates a deep
low sacral dimple with a
vitamin E marker capsule
placed. The conus terminates
at normal L1 level. The dimple
and tract ſt connect directly
to the coccyx st with no
intradural extension.
CLINICAL ISSUES
• Often asymptomatic discovery by parents during diaper
change or bathing
○ Dimple becomes less conspicuous as patient grows
○ No specific treatment indicated; reassure parents
• Occasionally present with acute inflammation or purulent
discharge
DIAGNOSTIC CHECKLIST
• Important to distinguish from dorsal dermal sinus, which
requires surgical excision
○ Low dimple opening within intergluteal cleft usually but
not always coccygeal dimple
○ High dimple position, leaking of fluid more likely dorsal
dermal sinus
• Look for hypointense tract surrounded by bright fat on MR
• Always mark skin dimple ostium with MR visible marker
104
(Left) Sagittal T1WI MR
reveals a deep sacral dimple
marked for imaging with a
vitamin E capsule . The
conus terminates at normal L1
level. The dimple shows typical
"spot-welded" proximity to the
coccyx via a short fibrous tract
. (Right) Axial T1WI MR
confirms that the sacral
dimple, marked with a vitamin
E capsule , and tract
connect directly to the coccyx
without intradural
extension.
Dermoid Cysts
KEY FACTS
Congenital and Genetic Disorders
TERMINOLOGY
• Synonyms: Dermoid tumor, "dermoid"
• Benign spinal mass composed of cells embryologically
comprising skin and its appendages
IMAGING
• Lumbosacral or cauda equina CSF isointense/isodense mass
± interspersed fat signal intensity/density
○ Lumbosacral (60%), cauda equina (20%)
• Focal osseous erosion, spinal canal widening, flattening of
pedicles and laminae at spinal level of mass
• Less likely to show diffusion restriction than epidermoid
cyst
TOP DIFFERENTIAL DIAGNOSES
• Arachnoid/meningeal cyst
• Neurenteric cyst
○ Intradural cyst; usually ventral to cord
PATHOLOGY
• Congenital or acquired origin
○ Congenital cysts arise from dermal rests or focal
expansion of dermal sinus
• Cyst filled with thick cheesy, buttery, yellowish material
(desquamated keratin, lipids)
• Associated anomalies include dermal sinus, vertebral
segmentation anomalies, closed dysraphism
CLINICAL ISSUES
• Most commonly asymptomatic or presentation with slowly
progressive compressive radiculopathy/myelopathy
• Infectious meningitis in association with dermal sinus
• Acute chemical meningitis 2° to rupture, discharge of
inflammatory cholesterol crystals into CSF
DIAGNOSTIC CHECKLIST
• Often difficult to diagnose on CT and MR; presence of fat
helpful to suggest diagnosis
(Left) Sagittal graphic of the
cervicothoracic spine
demonstrates a large dorsal
dermoid cyst ſt in association
with a dermal sinus tract .
There is marked spinal cord
compression. (Right) Sagittal
T2WI MR (myelopathy)
demonstrates a hyperintense
dermoid tumor with an
intramedullary component ſt
contiguous with an
extramedullary component
following a dermal sinus tract
to the skin surface.
(Left) Sagittal T1WI shows a
variant case of intradural
teratoma , with mixed fat
and soft tissue mass at the
level of multiple vertebral
body segmentation
abnormalities ſt. The conus is
also low lying st. (Right)
Sagittal T2WI shows an
unusual case of mature
intradural teratoma seen
as a lobulated mass involving
the distal thoracic cord. The
teratoma occurs at the site of
vertebral body segmentation
abnormalities ſt. The
tethered cord is apparent st.
105
Epidermoid Cysts
KEY FACTS
TERMINOLOGY
• Benign nonneoplastic spinal mass embryologically derived
from epidermal (skin) elements
IMAGING
• Lumbosacral or cauda equina CSF isointense/isodense mass
○ 40% intramedullary, 60% extramedullary
○ Acquired epidermoid cysts nearly always occur at cauda
equina
TOP DIFFERENTIAL DIAGNOSES
• Arachnoid cyst
Congenital and Genetic Disorders
• Neurenteric cyst
PATHOLOGY
• Congenital (60%)
○ Arise from epidermal rests or dermal sinus
• Acquired (40%)
(Left) Sagittal graphic of the
thoracolumbar spine shows a
pearly white epidermoid cyst
ſt located within the cauda
equina at the conus, a typical
location for post lumbar
puncture acquired epidermoid
cyst. (Right) Sagittal T1WI MR
demonstrates a hypointense
intradural extramedullary
mass ſt within the cauda
equina in a patient who
previously had a lumbar
puncture as an infant. Signal
intensity is slightly
hyperintense to CSF, and there
is no hyperintense lipid
content to indicate that
dermoid cyst is conspicuous.
○ Iatrogenic, follows implantation of viable epidermal
elements after lumbar puncture or surgery
(myelomeningocele closure)
• Striking white, pearly sheen capsule containing creamy,
waxy, pearly material
CLINICAL ISSUES
• Asymptomatic or slowly progressive compressive
radiculopathy/myelopathy
• Symptoms slowly progress if untreated
• Complete surgical resection offers best opportunity for
good neurologic outcome
DIAGNOSTIC CHECKLIST
• Epidermoid cysts may be congenital or acquired
• Acquired epidermoid cysts nearly always occur in cauda
equina
106
(Left) Sagittal T2WI MR in a
patient who had a lumbar
puncture as an infant reveals a
well-circumscribed intradural
extramedullary mass ſt
within the cauda equina. The
cauda equina is distorted and
anteriorly displaced by the
cyst. Signal intensity is slightly
hypointense to CSF. (Right)
Axial T1WI MR demonstrates
that the epidermoid cyst ſt
nearly fills the spinal canal
and displaces the cauda
equina anteriorly. This
location is typical of a post
lumbar puncture acquired
epidermoid cyst.
Tethered Spinal Cord
KEY FACTS
Congenital and Genetic Disorders
TERMINOLOGY
• Synonyms: Tethered cord syndrome, tight filum terminale
syndrome
IMAGING
• Stretched, thinned cord with low-lying conus, thickened
filum
• ± fibrolipoma/terminal lipoma, dysraphism, vertebral
segmentation anomalies
• ↓ spinal cord motion
TOP DIFFERENTIAL DIAGNOSES
• Normal variant low-lying conus
• Open or closed spinal dysraphism
• Postsurgical low-lying conus
PATHOLOGY
• Tethering stretches nerve fibers, arterioles, and venules →
impairs oxidative metabolism of conus and nerve roots →
syringohydromyelia, myelomalacia
• Tethered filum histologically abnormal, even if conus
terminates at normal level
CLINICAL ISSUES
• Low back and leg pain, gait and sensory abnormalities,
urinary bladder dysfunction
• Symptomatic presentation most common during rapid
somatic growth (adolescent growth spurt, school age 4-8
years), or 2° to kyphosis (elderly)
• Gait spasticity, weakness, muscular atrophy
DIAGNOSTIC CHECKLIST
• Tethered cord syndrome is clinical diagnosis
○ Imaging role is detection of low-lying conus/thick filum,
associated anatomic abnormalities for surgical decision
making
○ Clinical tethering may be present despite normal conus
level
(Left) Sagittal graphic of the
lumbosacral spine depicts
composite tethered cord
syndrome (TCS) findings of
low-lying, hydromyelic
tethered cord with thickened
filum and fibrolipoma
inserting into a terminal
lipoma that is contiguous with
subcutaneous fat through
dorsal dysraphism. (Right)
Sagittal T2WI MR (clinical TCS)
demonstrates an elongated
low-lying spinal cord
extending to the S2 level,
where it ends in a small
terminal lipoma st. Focal
sacral posterior dysraphism is
also present.
(Left) Sagittal T1WI MR
(clinical TCS symptoms)
confirms an elongated lowlying spinal cord extending to
the S2 level and ending in a
small terminal lipoma .
Focal sacral posterior
dysraphism is also
conspicuous. In general,
lipomas are considerably more
conspicuous on T1WI than
T2WI. (Right) Axial T1WI MR
at the lumbosacral transition
reveals that the abnormal
elongated, low-lying spinal
cord continues to the
sacral level.
107
Segmental Spinal Dysgenesis
KEY FACTS
TERMINOLOGY
• Segmental spinal dysgenesis (SSD), caudal regression
syndrome (CRS)
IMAGING
• Localized segmental lumbar or thoracolumbar vertebral,
spinal cord dysgenesis or agenesis
• Congenital acute angle kyphosis or kyphoscoliosis
• Distal spinal osseous architecture usually normal (unless
concurrent CRS)
TOP DIFFERENTIAL DIAGNOSES
Congenital and Genetic Disorders
• Multiple vertebral segmentation disorders
• Congenital vertebral displacement
• Medial spinal aplasia
• Caudal regression syndrome
PATHOLOGY
• Characteristic segmental vertebral, cord anomalies
(Left) Sagittal graphic
demonstrates lower lumbar
segmental spinal dysgenesis
(SSD) with posterior
subluxation of the upper
lumbar spine relative to the
segment below the dysgenetic
level ſt. (Right) Sagittal T1WI
MR (lumbosacral SSD) depicts
complete disconnection of the
spinal canal at the dysgenetic
level ſt. Note that the distal
spinal cord st is separate
from, not connected to, the
proximal thoracic spinal cord.
○ Normal upper spinal cord
○ Hypoplastic or absent spinal cord, vertebral dysgenesis at
gibbus apex
○ Bulky, thickened, low-lying cord segment within spinal
canal below dysgenesis
CLINICAL ISSUES
• Thoracic or lumbar kyphosis
• Palpable bone spur at gibbus apex
• Spastic paraparesis or paraplegia
• Rarely present with normal or mildly impaired lower
extremity function → subsequent deterioration
DIAGNOSTIC CHECKLIST
• SSD and CRS probably represent 2 different phenotypes
along single malformation spectrum
• Morphologic severity correlates with residual spinal cord
function, severity of clinical deficit
108
(Left) Sagittal T2WI MR (mixed
SSD, caudal regression) shows
relatively low dysgenetic level.
The dysmorphic vertebral
bodies produce acute angle
focal kyphosis. Note the
truncated, squared-off conus
ſt. (Right) Coronal T2WI MR
(severe lumbosacral SSD)
shows separation of the distal
spinal cord component st
from the thoracic spinal cord
(not shown) above the
dysgenetic level. The
cephalad-directed nerve roots
ſt are commonly observed in
lumbosacral SSD.
Caudal Regression Syndrome
KEY FACTS
Congenital and Genetic Disorders
TERMINOLOGY
• Caudal regression syndrome, sacral agenesis, lumbosacral
hypogenesis
IMAGING
• Constellation of caudal developmental growth
abnormalities and associated soft tissue anomalies
• Spectrum ranges in severity from absent coccyx to
lumbosacral agenesis
• 2 main types
○ Group 1: Distal spinal cord hypoplasia, severe sacral
osseous anomalies
○ Group 2: Tapered, low-lying, distal cord elongation with
tethering, less severe sacral anomalies
TOP DIFFERENTIAL DIAGNOSES
• Tethered spinal cord
• Closed spinal dysraphism
• Occult intrasacral meningocele
PATHOLOGY
• Group 1: More severe caudal dysgenesis with high-lying,
club-shaped cord terminus (decreased number of anterior
horn cells)
• Group 2: Less severe dysgenesis with low-lying, tapered,
distal cord tethered by tight filum, lipoma,
lipomyelomeningocele, or terminal myelocystocele
CLINICAL ISSUES
• Clinical spectrum ranges from neurologically normal →
severely impaired
• Symptomatic patient presentation spans mild foot
disorders → complete lower extremity paralysis and distal
leg atrophy
DIAGNOSTIC CHECKLIST
• Look for caudal spine anomalies in patients with
genitourinary or anorectal anomalies
(Left) Sagittal graphic of the
lumbosacral spine in severe
group 1 caudal regression
syndrome (CRS) shows high
truncation of the sacrum
and medial position of the iliac
wing st. The conus ſt
terminates abnormally high in
a blunt wedge shape. (Right)
Sagittal T2WI MR (group 1
CRS) reveals severe truncation
of the sacrum and
abnormally high termination
of the spinal cord at the T12L1 vertebral body level with a
typical blunted, wedge-shaped
conus ſt.
(Left) Axial T2WI MR of the
pelvis (severe group 1 CRS)
demonstrates bilateral
abnormal hypoplastic iliac
wings closely
approximated in the midline
secondary to complete
absence of a normal sacrum at
this level. (Right) Sagittal
T1WI MR (group 2 CRS)
depicts mild sacral dysgenesis
and posterior spinal
dysraphism, with the
abnormal low-lying tapered
spinal cord terminating ſt
into a large terminal lipoma
.
109