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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6009_Библиотеки_им_академика_М_И_Перельмана.pdf
Heterotopic Bone Formation
KEY FACTS
TERMINOLOGY
• Definition: Bone development in abnormal location
• Occurs in 3 main scenarios: rhBMP-2 related, TDR related,
Complications
ACDF adjacent segment related
IMAGING
• Thin-section CT: High-attenuation bony osteophytes
extending into canal or neural foramen with narrowing
• MR for definition of neural/thecal sac compression
• May be difficult to identify on T1WI if it contains fatty
marrow mimicking adjacent fat signal
TOP DIFFERENTIAL DIAGNOSES
• Graft migration or extrusion
• Adjacent level degenerative change
• Myositis ossificans
PATHOLOGY
• Osteobiologic related: Lumbar surgery
(Left) Axial graphic shows
heterotopic bone formation in
a patient who has undergone
a posterior lumbar interbody
fusion. Bone formation is seen
within the epidural space ſt
with mass effect upon the
thecal sac. Heterotopic bone
formation is highly correlated
with the use of rhBMP-2.
(Right) Sagittal NECT shows
heterotopic ossification
extending inferiorly from the
C3 body ſt to cover superior
aspect of the C4 plate. This
superior margin of the plate is
malpositioned & extends to
the disc level .
○ Extradiscal/ectopic/heterotopic bone formation
presumably occurs when bone morphogenetic protein
leaks from carrier into epidural space
○ 75% incidence in 1 series of single-level posterior lumbar
interbody fusion (PLIF)
• Osteobiologic related: Cervical surgery
○ 11% of rhBMP-2 group vs. 6% in control group
CLINICAL ISSUES
• Majority of heterotopic ossification (HO) appears
asymptomatic but symptomatic foraminal stenosis
reported sporadically
• HO can be cause of new back pain and radiculopathy
DIAGNOSTIC CHECKLIST
• HO along PLIF or transforaminal lumbar interbody fusion
path may be difficult to identify on axial images because it
may be mistaken for normal pedicle
• Look closely at sagittal CT to identify bone projecting from
disc level
360
(Left) Initial CT myelogram
study shows a large
facetectomy defect on the left
at L5 ſt. Heterotopic bone
formation mimics the
appearance of facet joint in
this patient status post
facetectomy and posterior
fusion. (Right) CT myelogram
in the same patient performed
2 years later shows new
heterotopic bone filling in the
operative defect ſt, which has
the outline of the prior facet
joint margin. There is left
foraminal stenosis from
the heterotopic bone.
Recurrent Disc Herniation
KEY FACTS
Complications
TERMINOLOGY
• Recurrent protrusion/extrusion
• Failed back surgery syndrome
• Focal extension of disc material beyond endplate margins
at previously operated intervertebral disc level
IMAGING
• Nonenhancing, well-defined mass arising out of
intervertebral disc
• Disc material shows no enhancement
• May enhance peripherally after intravenous contrast
material due to granulation tissue or dilated epidural plexus
• Rare: Diffuse enhancement if associated with granulation
tissue or if postcontrast imaging delayed
• Fat suppression of T1WI (pre-/postgadolinium) may
increase sensitivity in detecting peridural fibrosis,
differentiating fibrosis from disc
TOP DIFFERENTIAL DIAGNOSES
• Peridural fibrosis
○ Immediate homogeneous postcontrast enhancement
• Hemorrhage
• Abscess
• Osteophyte
• Synovial cyst/ganglion cyst
• Vertebral body/epidural tumor
○ Homogeneous enhancement
CLINICAL ISSUES
• Revision microdiscectomy with posterior lumbar interbody
fusion/transforaminal lumbar interbody fusion vs. revision
microdiscectomy
○ 30-35% success rate for repeat surgery (range: 12-100%)
DIAGNOSTIC CHECKLIST
• Best reoperative result in patients with herniation at new
level away from operation site
(Left) Axial graphic of the
lumbar spine shows a left
laminotomy defect. A large
right paracentral herniation is
present, compressing the
thecal sac and roots adjacent
to the site of the prior
discectomy. (Right) Axial T1WI
MR shows right-sided
recurrent herniation as a focal
epidural mass of intermediate
signal with compression of the
thecal sac ſt. The exiting right
S1 root is obscured by the
herniation. Note the normal
position of the left S1 root .
(Left) Axial T2WI MR shows
right-sided recurrent extrusion
ſt as a focal low signal mass
displacing the right S1 root
and right lateral margin of the
thecal sac. Note the normal
left S1 root . (Right) Axial
T1WI C+ MR shows typical
central lack of enhancement
of herniation ſt with
peripheral enhancement of
granulation tissue .
361
Peridural Fibrosis
KEY FACTS
TERMINOLOGY
• Scar formation within epidural space after lumbar surgery
• Part of failed back surgery syndrome (FBSS)
Complications
IMAGING
• Infiltration of epidural/perineural fat by enhancing soft
tissue density (intensity)
• Variable signal intensity on T2WI
• Immediate homogeneous postcontrast enhancement
TOP DIFFERENTIAL DIAGNOSES
• Recurrent disc herniation
• Epidural abscess/phlegmon
• Pseudomeningocele
• Postoperative hemorrhage
• Arachnoiditis
(Left) Axial T1WI MR shows a
right laminectomy defect and
extensive epidural fibrosis ſt
surrounding the right lateral
and dorsal aspect of the thecal
sac and the exiting root .
(Right) Axial T1WI C+ MR
shows a right
hemilaminectomy defect and
diffuse enhancement of
epidural fibrosis surrounding
the right lateral aspect of the
thecal sac ſt. The nerve root
is seen as a nonenhancing
structure within the fibrosis
. Enhancement continues
into the operative defect in
the disc st.
PATHOLOGY
• Postoperative scarring is part of normal reparative
mechanism
• May be asymptomatic; contribution to clinical symptoms
controversial
• Up to 1/4 of all FBSS cases
• Most patients with some degree of fibrosis are
asymptomatic
CLINICAL ISSUES
• Adult with gradual onset low back pain following initially
successful disc surgery
DIAGNOSTIC CHECKLIST
• Identification of only epidural fibrosis in FBSS patient is
contraindication to reoperation, yields poor reoperative
result
362
(Left) Axial T2WI MR a shows
hemilaminectomy defect and
absence of ligamentum flavum
. Epidural fibrosis
surrounding the left S1 root
shows slight increased signal
relative to adjacent disc
material ſt. (Right) Axial
T1WI C+ MR shows a left
hemilaminectomy defect . A
small amount of epidural
fibrosis surrounds the exiting
left S1 root, which diffusely
enhances ſt, as does the
operative defect in the
posterior anulus.
Arachnoiditis/Adhesions
KEY FACTS
Complications
TERMINOLOGY
• Postinflammatory changes usually involving cauda equina
IMAGING
• Thickening and clumping of nerve roots in cauda equina
• Adhesion of nerve roots to peripheral dura (empty sac sign)
• Soft tissue mass (pseudomass)
• Minimal to mild pial, dural enhancement
• Nerve root calcification (rare) or calcific mass (arachnoiditis
ossificans)
TOP DIFFERENTIAL DIAGNOSES
• Spinal stenosis
• Cauda equina neoplasms
• Carcinomatous meningitis
• Intradural metastases
PATHOLOGY
• Inflammatory, collagenous mass
• Historically related to trauma or spinal meningitis, now
more commonly associated with prior lumbar surgery
CLINICAL ISSUES
• Most common symptoms are chronic low back pain or leg
pain (radicular or nonradicular)
○ Simulates spinal stenosis and polyneuropathy
• Less common are paraparesis, hypoesthesia, gait disorder,
bowel/bladder dysfunction
• Treatment
○ Pain rehabilitation
○ Spinal cord stimulation
DIAGNOSTIC CHECKLIST
• Absent discrete nerve roots in thecal sac with clumping or
empty sac sign highly suggestive of lumbar arachnoiditis
• Radiological findings may be present without clinical
symptoms
(Left) Sagittal T1 C+ MR shows
clumping of the nerve roots of
the cauda equina ſt. There is
faint enhancement. A L2-L3
laminectomy defect is noted.
(Right) Sagittal CECT
myelography shows a large,
mass-like filling defect in the
caudal thecal sac
(pseudomass) st engulfing the
cauda equina due to chronic
changes of arachnoiditis.
(Left) Axial T2WI MR shows
diffuse thickening of the distal
dural sac and clumping of the
roots consistent with severe
arachnoiditis. Note the
thickening low signal dural
margin suggestive of calcific
arachnoiditis . (Right) Axial
T2WI MR in this patient with
ankylosing spondylitis shows
peripheral adhesion of the
nerve roots to the margins of
the thecal sac st, resulting in
the empty sac sign of
arachnoiditis. This pattern
may cause cauda equina
syndrome in patients with
longstanding
spondyloarthropathy.
363
Arachnoiditis Ossificans
KEY FACTS
TERMINOLOGY
• Intradural ossification associated with postinflammation
adhesion and clumping of lumbar nerve roots
Complications
IMAGING
• Calcification morphology
○ Thin, linear
○ Mass-like, globular
• Calcific density on CT
○ Contrast may obscure calcifications on CT myelography
• T1WI: Areas of ossification are variable, mixed signal
○ Hypointense, isointense, or hyperintense
• T2WI: Linear or globular hypointensity if calcifications are
present
○ Larger areas of ossification can occasionally be
hyperintense on T2WI
• May exert mass effect on conus and cauda equina
(Left) Sagittal T2WI MR
through the lumbar spine
shows a nodular hypointense
signal along the margins of
the caudal thecal sac ſt due
to calcific arachnoiditis. Note
the prior multilevel anterior
fusions. (Right) Sagittal NECT
through the lumbar spine
more clearly shows the coarse
calcifications of the dura and
thecal sac ſt. CT also shows
intervertebral fusion at L3-L4,
L4-L5, and L5-S1.
PATHOLOGY
• Etiologies
○ Prior trauma
○ Spinal surgery
○ Subarachnoid hemorrhage
○ Pantopaque myelography
○ Spinal anesthesia
• Gross pathology: Calcified, inflammatory, collagenous mass
CLINICAL ISSUES
• No defining clinical symptomatology
○ Low back pain
○ Radicular or nonradicular leg pain
○ Paraparesis
○ Bladder and bowel dysfunction
364
(Left) Axial T2WI MR again
shows irregular hypointensity
about the margins of the
thecal sac st due to
dystrophic calcifications.
(Right) Axial NECT shows
coarse calcifications of the
caudal thecal sac st. Also
seen is a surgical defect of the
left L5 lamina .
Accelerated Degeneration
KEY FACTS
Complications
TERMINOLOGY
• Accelerated degeneration of disc space/facets at level(s)
adjacent to surgical fusion
• Transitional degenerative syndrome, accelerated
segmental degeneration, adjacent segment disease
IMAGING
• Degenerative disc/facet changes directly above or below
fusion
○ Also occurs adjacent to congenital segmentation
anomalies
• May show increased motion at degenerated level adjacent
to fused segment
○ Flexion/extension views for definition of instability
• Plain films most economical way to demonstrate presence
of adjacent segment degenerative changes and to serially
follow for progression
• MR best identifies soft tissue abnormalities that are occult
on plain film
TOP DIFFERENTIAL DIAGNOSES
• Disc space infection
• Pseudoarthrosis
• Spondylolysis
• Spondylolisthesis
• Normal postoperative changes
PATHOLOGY
• Produced by altered biophysical stresses from altered
normal spinal motion
• Solid fusion alters biomechanics at adjacent mobile levels
• More common with multilevel fusion but also seen
following single level fusion
• Presence of osteopenia at time of cervical surgery increases
risk of adjacent segment degeneration
DIAGNOSTIC CHECKLIST
• Pseudoarthrosis if extensive signal abnormality involving
anterior and posterior elements in horizontal fashion
(Left) Sagittal graphic shows
solid L4-L5 interbody fusion
and laminectomy. Note severe
disc degeneration at L3-L4
with spondylolisthesis, loss of
disc height, osteophytes and
central stenosis, and severe
degeneration at L5-S1 due to
altered biomechanics. (Right)
Sagittal T1WI MR shows a
solid fusion at C5-C6 with
normal fatty marrow signal.
There is disc degeneration at
C6-C7 with decreased disc
height and large disc extrusion
compressing cord ſt.
(Left) Sagittal T2WI MR shows
a patient post C4-C7 fusion
with anterior plating giving
low signal artifact . There is
a large synovial cyst showing
central hyperintensity at the
C3-C4 level ſt. (Right)
Anteroposterior myelography
(left) shows block to contrast
at L1-L2 ſt at the upper
margin of posterior fusion.
Lateral view (right) shows
contrast block and severe L1L2 degeneration .
365
Postsurgical Deformity
KEY FACTS
TERMINOLOGY
• Deformity: Abnormality of alignment, angulation, or shape
of vertebral column following surgery
Complications
○ May be associated with clinically significant findings such
as instability
TOP DIFFERENTIAL DIAGNOSES
• Infection
• Tumor
• Degenerative instability
• Isthmic spondylolisthesis
PATHOLOGY
• Risk factors for deformity
○ Age (pediatric at increased risk), number of levels
○ Location of laminectomy
○ Intramedullary disease
○ Facet joint involvement
○ Bone density
(Left) Sagittal NECT shows
severe kyphotic deformity at
site of anterior fusion ſt at
C5-C6 and adjacent segment
degeneration at C6-C7.
There had been prior
laminectomy and posterior
fusion. (Right) Sagittal NECT
shows near normal alignment
after 2 stages of surgery. The
1st stage was posterior
osteotomies; the 2nd stage
was anterior vertebrectomies
with strut graft with
plate/screws. The 3rd stage
was posterior instrumented
fusion (not shown).
• Preexisting degenerative disease risk factor for cervical
deformity
○ 30% incidence of kyphosis in patients with straight spine
• Thoracolumbar junction
○ Particularly susceptible to deformity
• Spinal deformity reoperation complications as high as 33%
○ Implant failure
○ Adjacent segment degeneration (10%)
○ Pseudoarthrosis
CLINICAL ISSUES
• Surgery for progressive neurological decline, intractable
pain, cosmetic appearance
DIAGNOSTIC CHECKLIST
• Thresholds for optimal correction of adult deformity
include sagittal vertical axis < 50 mm, pelvic tilt < 25°, and
pelvic incidence-lumbar lordosis < 10°
366
(Left) Sagittal NECT shows
severe multilevel
spondylolisthesis ſt with
multilevel laminectomy defect
st. (Right) Sagittal CT shows
increased kyphotic angulation
in this patient following
posterior laminectomy and
corpectomy. Note the
angulation of the cage with
the displacement of the
posterior superior margin into
the canal .
Radiation Myelopathy
KEY FACTS
Complications
TERMINOLOGY
• Chronic progressive radiation myelitis
• Delayed radiation myelopathy
IMAGING
• Spindle-shaped cord swelling with irregular, focal rind of
enhancement (early)
• Focal cord atrophy (late)
• Clinical signs may reflect longer segment of damage than
demonstrated on MR
TOP DIFFERENTIAL DIAGNOSES
• Transverse myelitis
• Multiple sclerosis
• Spinal cord infarct
• Astrocytoma
• Syrinx
PATHOLOGY
• Demyelination, lipid-laden microphages, swollen astrocytes,
endothelial damage, necrosis, local Ca⁺⁺ deposition,
hyalinosis of intramedullary vessel walls
CLINICAL ISSUES
• Onset of progressive numbness and weakness ± sphincter
dysfunction 1 month → several years after fractionated
radiotherapy
• Relentless progression without significant improvement in
most cases
DIAGNOSTIC CHECKLIST
• Late focal atrophy at sites of previous enhancement
• Fatty marrow replacement in treatment field provides clue
to etiology
• Pathologic cord changes not always visible on MR imaging
(Left) Sagittal T2WI MR in a
patient following radiation
therapy for head and neck
squamous cell carcinoma
demonstrates abnormal
intramedullary T2
hyperintensity in conjunction
with fatty marrow
replacement, characteristic of
postradiation vertebral and
spinal cord changes. (Right)
Sagittal T1WI C+ MR confirms
abnormal spinal cord
parenchymal enhancement in
the area of greatest radiation
myelopathic injury. Note also
the marked T1 shortening in
the vertebral marrow
reflecting fatty replacement.
(Left) Sagittal T2WI MR
following radiation treatment
for melanoma shows extensive
radiation myelopathy
involving the cervical and
thoracic cord with diffuse cord
hyperintensity ſt. (Right)
Sagittal T1 C+ MR in this
patient with extensive
radiation myelopathy
involving cervical and thoracic
cord following treatment for
melanoma shows ill-defined
mild enhancement of the
upper thoracic cord from T1 to
T3 .
367
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SECTION 11
Remote Complications
Remote Complications Overview 370
Donor Site Complications
Deep Venous Thrombosis
Pulmonary Embolism
Aspiration Pneumonia
Acute Myocardial Infarction 376
Cerebral Infarction
Cerebellar Hemorrhage
Intracranial Hypotension
Extraaxial Hematoma, Brain
Retroperitoneal Hemorrhage 381
Retroperitoneal Lymphocele
Ophthalmic Complications
Esophageal Perforation
Acute Pancreatitis
Pseudomembranous Colitis (Clostridium dicile) 386
Rhabdomyolysis
Bowel Perforation
Ureteral Trauma
372
373
374
375
377
378
379
380
382
383
384
385
387
388
389