Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3918_Библиотеки_им_академика_М_И_Перельмана
.pdf
12
2.2.2 Type II Intramedullary
GlomusAVM
When a parenchymal or intramedullary lesion
has a nidus-like cranial AVM, it is classied as
type II. Intramedullary hemorrhage, in addition
to more common congestive myelopathy or SAH,
can also be the presenting symptom. This lesion
has multiple feeders from anterior as well as pos-
terior spinal artery.
Embolization is the rst line of treatment,
keeping in mind that complete obliteration may
never be achieved and both complete and partial
obliterations reduce the recurrences of symptoms
by decreasing the re-bleed rates [8]. Usual surgi-
cal excision of the nidus is obviously too risky to
be advised. In presence of inadequate obliteration
after embolization or presence of angiographic
high risks of embolization, a guided and planned
surgical excision may be offered.
Radiosurgery is a third modality, which has
been explored in these lesions. Stereotactic radio-
surgery has been used by researchers with docu-
mented success in motor symptom improvement
and partial obliteration of AVM nidus [8].
2.2.3 Type III Intramedullary
Juvenile AVM
When lesions appear metameric, i.e., multiple
vascular malformations appearing from the same
spinal metameric segment, it is sine qua non for
diagnosing this variant. Adolescent and young
adults are the usual sufferers. Fortunately, these
are rare variants. Complete obliteration is rarely
observed and never a target in planning treatment
of this variant. Terminating the progression of
neurological decits is considered the success of
treatment as genetic mutations are involved in
pathophysiology of the disease.
2.2.4 Type IV Perimedullary AVF
In the absence of intervening nidus, direct arte-
riovenous communication on the spinal cord pial
surface is the hallmark of this variant.
Perimedullary stula form more often on ventral
surface of the spinal cord and typically have a
midline location.
There are three different subtypes of this vari-
ant ranging from IVa to IVc depending on the
size, level of blood ow and venous drainage.
Type IVa single arterial feeder to the vein with
slow ow. Type IVb has multiple dilated arterial
feeders of intermediate size, while type IVc has
multiple dilated arteries and ectatic draining
veins. Type IVc has association with HHT, i.e.,
hereditary hemorrhagic telangiectasia, and
appear in younger patients, more often.
Type IVa perimedullary AVFs are more ame-
nable to microsurgery. Type IVb and IVc respond
favourably to endovascular treatment due to mul-
tiple feeding arteries and shunt volume. IVb may
require surgery for failed endovascular treatment.
2.2.5 Type V Extradural AVF
Congestive myelopathy is the clinical presenta-
tion, often indistinguishable from type I com-
monly located at lumbar level with frequent
bilateral epidural arterial supply. Distinction is
done by angiographically proving a direct stu-
lous communication between an extradural artery
and vein. Extradural AVFs were subdivided into
Subtypes Va- with intradural venous drainage
and Vb without intradural venous drainage.
Type A has a retrograde parenchymal drainage
with a perimedullary vein, which goes intradural
and leads to venous congestion leading to symp-
toms. Treatment consists of treating extradural
venous lake and this intradural perimedullary
vein. If the draining vein is large enough to give
an access, transvenous embolization can be done,
if there is single draining vein. With multiple
draining veins, meticulous coagulation and sepa-
ration of the epidural venous lake is advised type
Vb extradural AVFs are more amenable to endo-
vascular embolization.
2.2.6 Conus Medullaris AVM
This variant is a subtype of type II where a nidus
is clearly visible, added as a separate variant
since last two decades. As indicated by the name,
M. Panigrahi et al.
https://t.me/med1917
13
the anatomical location at conus is obvious, and
the nidus is both extra- and intramedullary.
Combined approach with both surgical and endo-
vascular treatments is recommended.
2.3 Clinical Presentation
Various case series have reported a male pre-
dominance with a M/F ratio of 4:1. A typical
patient with diagnosis of sDAVF is a male in his
fth decade of life. The most common (90–95%
of patients) presentation is chronic spastic
motor weakness, presenting as progressive
myelopathy. Sensory and sexual symptoms
with sphincter disturbances and lower back
pain mimicking sciatica can also be observed in
these patients.
Exception to this classical presentation is
always to be kept in mind because approximately
15% of the patients report in atypical fashion. Rare
instances of acute deterioration of motor power
due to hemorrhage or due to Foix- Alajouanine
syndrome can also be seen. These acute episodes
are supposed to be secondary to acute thrombosis
of the pathological veins draining the stula caus-
ing hyperacute venous hypertension, and clinical
deterioration becomes erratic and acute. Episodes
of remissions in between acute attacks of motor
power deterioration have also been noticed.
2.4 Diagnosis
MRI and spinal angiography (both subtracted and
unsubtracted) are the modalities used in diagnos-
ing sDAVF.MRI of the spine is usually the rst
imaging modality that gives a clue to the diagno-
sis. Multiple serpiginous ow voids in the sub-
arachnoid spaces (arterialized pial veins) seen in
T1W and T2W images direct the observer toward
suspecting sDAVF.Flow in dilated, tortuous ves-
sels of the arterialized coronal venous plexus is
the cause of this signal void. These pial veins may
focally indent the cord surface and give a scal-
loped appearance on sagittal T1W images.
Normal CSF ow voids also give this pattern;
therefore, MRI alone with the ndings mentioned
above is not sufcient to conclude the diagnosis.
Evidence of venous hypertensive myelopathy
should be searched for and documented for
sDAVF to be established as diagnosis.
This evidence comes in the form of swollen
cord (usually cauda) with T2 hyper-intense sig-
nal within the cord substance associated with
peripheral T2 hypo-intense signal, which indi-
cates that the central T2 high signal is secondary
to venous hypertensive myelopathy, and not due
to tumor, edema, or any other cause. This
peripheral hypo- intensity on T2 images of the
spinal cord is a consistent and specic diagnos-
tic feature of venous congestion associated with
dural AVF.
Without doubt, the spinal angiography is the
investigation of choice for diagnosing and clas-
sifying sDAVF. It gives anatomical details and
angioarchitecture of the stula with condence;
therefore, a proper management plan can be
made out.
This angiographic evaluation should not only
assess the stula site but should contain thorough
assessment of the whole spinal vasculature that
includes vertebral arteries, thyrocervical trunk
intercostal, lumbar arteries of the aorta, and the
internal iliac arteries. The intercostal artery is
numbered by the rib under which it runs. This
helps diagnose associated lesions (missed on
non-angiographic evaluation) or other feeders in
compound stulae with multiple sites of feeding
vessels.
2.5 Management
The main target of treatment in sDAVF is com-
plete elimination of venous congestion. This can
be achieved only after total block of shunting,
discussed in pathophysiology. Achieving this tar-
get only gives a chance for recovery of the spinal
cord. Excision, obliteration, or disconnection of
the stula, which can be accomplished surgically
or endovascularly. It is important to keep in mind
that obliteration of this stulous connection leads
to resolution of T2 hyper-intensities seen on spi-
nal MRI, only weeks to months after surgery or
intervention.
2 Types ofSpinal Vascular Malformations
https://t.me/med1917
14
2.5.1 Surgical Treatment:
Microsurgical Technique
ofPial Resection
Posterior approach is the most straightforward
corridor to reach the pathology. Preferential lami-
nectomy, laminoplasty, or hemi-laminectomy can
be performed based on surgeon’s selection.
The main goal in surgery is to identify the
arterialized medullary vein. The most certain
way (after midline dural opening) to identify this
is to look for vein’s dural piercing at the site of
dural penetration of posterior nerve root.
Conrmation of the target vein that needs to be
disconnected can be done with the use of com-
parison between anatomy and angiography.
Surgeon should always try to look for a vein that
is large and arterialized and look for the vein that
is crossing the subarachnoid space to join the
dilated coronal venous plexus. Once the target
vein is identied, it is cauterized using bipolar
cautery and cut using a micro-scissors.
Immediately after this, the color of venous plexus
changes from red to blue after a minute or so. Use
of micro-Doppler is an important aid while dis-
connecting the stula, as it demonstrates a change
in ow pattern in arterialized vein, before and
after disconnection.
Two things should always be kept in surgeon’s
mind: rstly, overzealous stripping of venous
plexus from the surface of cord will only exacer-
bate the venous hypertension in cord, thus lead-
ing to poor outcome. Secondly, change in color
of the vein may not always be apparent, immedi-
ately after disconnecting. Therefore, it should not
be used as a guide for surgical success
per-operatively.
2.5.2 Endovascular Treatment
With the ease with which the surgical discon-
nection is performed, and a relatively higher
recurrence rate with endovascular intervention,
operative treatment has become a preferred
treatment for sDAVF. Without doubt, with
availability of better catheters and embolic
materials, with better understanding of spinal
angiography, the results of endovascular treat-
ment are much better than the recent past. Still
the usual and major causes of failure include
angiographically occult stulae, multiple feed-
ers, and failure of microcatheter to reach stula
or failure of embolic agent to hit the target vein.
The key to long-term successful endovascular
treatment is a good penetration of embolization
agent into draining vein. Success rates for
endovascular and surgical treatment ranges
between 25% to 75% and 98%, respectively.
Rates of denitive embolization have wide
range, depending in part on the embolic agent
used and the use of variable stiffness
microcatheters.
2.5.2.1 Preferred Endovascular Agent
Endovascular therapy with liquid embolic
agents - N-butyl-cyanoacrylate (NBCA) and eth-
ylene vinyl alcohol copolymer dissolved in
dimethyl sulfoxide (Onyx, Medtronic, CA, USA
and Squid, Balt, Montmorency, France) are pre-
ferred for treatment of sDAVF and perimedullary
stula (arteriovenous stula). Liquid embolic
should be injected super selective catheterization
of the feeding artery using ow guided micro-
catheter. The concentration of the NBCA (glue)
must be adjusted depending on the ow volume
of the shunt and the distance between the tip of
the catheter and the shunting zone. A slow con-
tinuous injection of much dilute glue (15% glue
and 85% lipiodol) has a higher chance of reach-
ing the draining vein and obliterating the stula.
Ethylene vinyl alcohol copolymer can be
used when a longer, more controlled injection
with better penetration of the vascular bed is
needed in spinal AVM.
In low ow rate glomerular AVMs, PVA par-
ticles yield a stable result if venous stagnation
occurs. Obliteration of arterial or venous aneu-
rysms which are the source of the hemorrhage in
spinal AVM should also be accomplished with
liquid embolic agents or coils during endovascu-
lar treatment [9].
M. Panigrahi et al.
https://t.me/med1917
15
ab
c
d
e
Fig. 2.1 Spinal DAVF. (a) Sagittal T2W image of the
lumbar spine shows increased signal intensity, cord
edema, and perimedullary ow voids and expansion of the
lower thoracic cord and conus. (b) Unsubtracted AP view
of the left D10 intercostal artery supplies an sDAVF
beneath the left D10 pedicle and dilated radiculomedul-
lary vein ascending to dilated perimedullary veins. (c)
Selective left D10 distal intercostal artery injection show-
ing the stula. (d) The stula was treated with onyx embo-
lization and coils (coil in intercostal artery was deposited
for facilitating microcatheterization of the feeding radicu-
lar artery). Onyx cast shown in unsubstracted image. (e)
Immediate repeat angiography showed complete closure
of stula
2.5.3 Radiosurgery
Zhan etal. in a systematic review done in 2018
reported that among arteriovenous malforma-
tions, 16% showed nidus to be obliterated,
decreased, and unchanged in 44.6%, and 39.3%,
respectively, at an average follow-up of
46.8months [10]. Lack of extensive research in
radiosurgery in the management of spinal AVMs
is the reason for its limited use.
Illustrative Cases
Case 1: Dorsal sDAVF
A 50-year-old male presented with subacute
onset of progressive weakness of both lower limbs
and urinary incontinence over a 9-month period.
MRI and angiography are shown in Fig. 2.1.
Importance of heavily weighted T2 sequence con-
structive interference in steady state (CISS) in
better delineating the ow voids of the perimedul-
lary vein can be seen in Fig.2.2.
2 Types ofSpinal Vascular Malformations
https://t.me/med1917
16
b
a
b
Fig. 2.2 When comparing a routine T2 TSE (a) sequence
and a heavily T2-weighted (3D CISS) sequence (b), the
former depicts the cord edema better, whereas the latter is
better suited to demonstrate the perimedullary ow voids,
as seen in this patient
Case 2: Role of Catheter Angiography and
Advantages over MR Angiography in Spinal
AVM (Fig.2.3)
Case 3: High Cervical sDAVF (Fig.2.4)
Case 4: Intramedullary Thoracic AVM
(Fig.2.5)
Case 5: Dorsal sDAVF (Fig.2.6)
Case 6: Type I Perimedullary Fistula (L2)
(Fig.2.7)
Case 7: Intramedullary Glomerular AVM
(Cervical) (Fig.2.8)
M. Panigrahi et al.
https://t.me/med1917
17
a
c
d
b
e
Fig. 2.3 Comparison of MR angiography with catheter
angiography in a patient with spinal AVM. (a) Selective
left D5 intercostal injection showing spinal AVM. (b) The
coronal MIP images of contrast-enhanced MR angiogra-
phy display the craniocaudal extent of the dilated peri-
medullary vein draining the AVM. (c) The magnied MR
angiographic image depicts the arterial feeder of the AVM
(arrow). (d) Early phase image of the catheter angiogra-
phy examination veried the location of the AVM. Note
that only the catheter angiography images can reveal the
small network of vessels of the stula (d) and depict the
dynamic drainage pattern (e). (b) MRA helps in depicting
the extent of venous drainage such that limited DSA can
be obtained
2 Types ofSpinal Vascular Malformations
https://t.me/med1917
18
a
de
b
c
Fig. 2.4 Cervical sDAVF. (a) DSA showing sDAVF at
C6–D1 level fed by inferior division of left costocervical
trunk on left subclavian injection. (b) Angiogram with
microcatheter positioned in costocervical trunk. (c) Left
costocervical trunk showing coil, which was deposited for
facilitating microcatheterization of the feeding radicular
artery. (d) Unsubtracted image post-embolization show-
ing onyx cast in the distal feeding radicular artery, spinal
DAVF, and the draining radicular vein. (e) Post-
embolization angiogram shows no lling of stula
M. Panigrahi et al.
https://t.me/med1917
19
a
cd
e
b
Fig. 2.5 Intramedullary thoracic AVM. (a) Sagittal
T2-weighted MR image shows serpentine ow voids and
long segment cord edema in thoracic region. (b) Selective
angiogram of right D8 intercostal artery shows lling of
the posterior spinal artery supplying the AVM. Posterior
spinal artery lling noted from a vessel at different level
(right T10 intercostal artery). (c) Angiogram with micro-
catheter positioned just proximal to the stula. (d) Check
angiogram following embolization of right D10 intercos-
tal artery with glue shows no lling of stula. (e) Sagittal
T2-weighted MR image 2months after treatment shows
that the enlarged perimedullary veins and intramedullary
abnormal signal intensity have reduced signicantly
2 Types ofSpinal Vascular Malformations
https://t.me/med1917
20
a
bc
d
Fig. 2.6 (a) Sagittal T2-weighted MR image of postop-
erative case of right D11 sDAVF shows that the enlarged
perimedullary veins and intramedullary abnormal signal
intensity are persisting. (b) Postoperative spinal angiogra-
phy with selective catheterization of the right T11 seg-
mental artery showing residual DAVF. (c) Angiogram
with a large FOV shows the extensive venous drainage
into spinal perimedullary veins. (d) Right T11 intercostal
artery late-phase angiogram following closure of the feed-
ing artery with glue shows no residual stula
M. Panigrahi et al.
https://t.me/med1917
21
a
d
e
bc
Fig. 2.7 Spinal perimedullary stula type I at L2 level on
the left side. (a) Selective angiogram of the left T11
intercostal artery early phase (a) shows slightly enlarged
artery of Adamkiewicz and anterior spinal artery lling
the shunt at L2 level. (b) Late phase, showing the serpen-
tine perimedullary veins lling in descending fashion.
(c) The stula is embolized with onyx with the cast
shown in the unsubtracted image. (d) After onyx embo-
lization, the anterior spinal axis is still opacied, while
the venous ectasia and the stula are obliterated. (e)
However, following procedure, patient was found to be
unresponsive. CT of the brain showed diffuse subarach-
noid hemorrhage
2 Types ofSpinal Vascular Malformations
https://t.me/med1917
Соседние файлы в папке Библиотека им академика М.И. Перельмана