Percutaneous Cervical Discectomy
Daniel
Gastambide, M.D, orth. surg., Peyrou P.L., M.D., orth. surg *
Sang- Ho Lee, M.D.,Ph.D., neurosurg. **
Introduction
Percutaneous
cervical discectomy (PCD) is a surgical method for treating cervical disc
diseases. D. Gastambide introduced it in Europe in 1989 with Tajima, and performed
the first European procedure in 1990 [21]. The first Korean
procedure was performed in 1992. The goal is decompression of the spinal nerve
root by percutaneous removal and shrinkage of the nucleus pulposus and the
herniated mass under local or general anesthesia. Most of the patients
requiring surgery for cervical disc herniations can be successfully treated by
this method.
For soft
cervical disc herniation with a normal lordosis, simple anterior open discectomy
is generally considered [27] .The open anteromedial discectomy
without fusion is briefer and there are no complications from either allograft
or autograft. However, the operation could be followed by segmental
instability, loss of the physiological lordosis, collapse of the disc space, or
a posterior narrowing of the intervertebral foramen.[9,11,12,23]
The open
anteromedial discectomy with fusion requires usually to enter into the spinal
canal with the risk of complications such as an epidural bleeding,
peri-radicular fibrosis, transient or permanent myelopathy, bone graft related problems
(donor site morbidity, painful pseudarthrosis, graft extrusion or angular
collapse, kyphotic deformity, impacting of the graft into the body, dysphasia,
and hoarseness (temporary or permanent vocal cord paresis) [6, 8, 18, 29]
The PCD
with minimal invasive techniques under local anesthesia can possibly avoid
those complications, and offers an alternative to the open therapeutic methods
in cervicobrachial neuralgia or radiculopathy alone due to protruded soft
cervical hernia. In case of failure, this operation does not impede the further
conventional surgical approaches and it offers numerous advantages in addition
to the absence of the complications described above, the stability of the
intervertebral mobile segment is maintained, and the risk of recurrence is
reduced in performing an anterior discal window. Finally, the time spent in
operating room is reduced as well as the duration of hospitalization and the
patient can perform again his or her usual activities more rapidly.
The open microsurgical
anterior cervical foraminotomy [17] or the posterior foraminotomy [24]
with only partial discectomy maintains disc space height, but could approach
only lateral or foraminal herniation and they have big difficulty to treat paramedian,
central hernia and diffuse hernia.
The PCD
with preservation of disc space could approach and treat foraminal or lateral,
paramedian, central, and diffuse herniations.
1
Indications and
contraindications
The
indication of PCD is radicular pain not responding to conservative
treatment or sustained radiculopathy over three months. The best indication
seems to be a patient of less than 50 years old, with a provocation test positive,
without bony spur ≥ 2 mm, regardless hernia size, location (median,
paramedian or foraminal) and epidural leakage.
The contraindications
of PCD are extruded disc with myelopathy and severe spondylosis (< 3 mm
intervertebral height or ≥ 3 mm bone spur). The success rate for the
myelopathies is too low and the aggravation of neurologic signs may be
developed.
2
Preoperative
preparation
One has to
check patient's clinical and neurological status the day before surgery, to
review critically CT and MRI for the precise disc location, and to confirm the
level on a lateral radiograph. CT or MRI
have to be of less than 3 months, because of the possibility of sequester resorption by enzymes or
macrophagic cells and that the radicular pain become independent of the inflammation caused by the disc
fragment.
3
Prerequisites,
imaging and planning
3.1
The instruments
required for
percutaneous cervical discectomy comprise a guide needle adjusted with the
first 1 mm dilation tube (fig 1, A
and B) or a 18G spinal needle, a thin guide wire (fig 2), several dilators,
working tubes, an annulus trephine, various forceps with or without an irrigation
hole (fig 2 and 3), and a washing canula. The procedure should be performed
only with a clear view of the entire operative disc under lateral and A P
fluoroscopic projection has been obtained. The operating table must be radiolucent
(fig 4).
Fig 1a
Fig 1b
A: needle, drift, first dilation tube, separated (up) and fitted (down). See
the beveled guide needle and the first beveled dilation tube with its notch
allowing the adjustment to the guide needle edge, so that the both bevel edges,
at the tip, are in continuity, adjusted altogether like an unique bevel
B: Complete set: see the second dilation tube; the working tube; the trephine
with its inverted interior thread with aspiration effect, allowing automatic
extraction of the disc; the cutting dissecting forceps; the toothed dissecting
forceps, and the washing canula. (ACO France)
Advantage of these tools is the few number of operating times, without using
Kirschner wire; and trephine particular efficiency which makes the forceps
practically useless
Bigger working tubes for endoscopic laser are optional.
Disadvantages are: the absence of incorporated suction system in the dissecting
forceps and possibility of leakage during discography if both needle and first
dilation tube are not strictly fitted during manufacturing
Fig 2
The cutting dissecting forceps is presenting a suction system; one and two
millimeters dilation tubes , three, four and five millimeters working tubes
allowing endoscopic laser; annulus trepan. Disadvantages are the absence of
trephine with inverted interior thread and necessity of using a Kischner wire
after discography (Medsys, Belgium)
Fig 3
Complete set: there is no trephine , which is made useless by the laser (Wooridul
Spine Hospital kit, Storz)
Fig 4
3.2
Preparation and
Anesthesia
Preoperative
antibiotics
(usually cefazoline 1 gram) should be given the day before operation, for
antibiotics impregnation of the poorly vascularized disc to decrease the risk
of infection. Preoperative sedatives are recommended. Anterior neck skin
preparation and showers with iodized antiseptics are usual.
The PCD
must be performed in operating room with a strict asepsis. The PCD is
performed in supine position of the patient with the neck mildly extended on a
radiolucent table. The anesthesiologist has to be told to put the perfusion on
the surgeon opposite side. The forehead is fixed by an Elastoplast on midline.
A 7 cm thickness short rolled drape is put under the neck. The shoulders are sloped down with an Elastoplast
fixed on the table. For strict patient immobilization, anterior knee right and
left knee supports are associated with plantar distal fixed supports. The two
arms lie along patient’s trunk. Fluoroscopic C-arm, lying on surgeon opposite
side, is put in antero-posterior, then in lateral view, and the area to operate
is carefully marked on the skin with a felt-pen using a metal instrument on
front and profile. The lesion site is marked in counting the cervical vertebra cephalad
then “caudalad”. For a better visualization of the disc C6-C7, a slight slope
of the fluoroscope can be necessary. The felt-pen marks the internal edge of
the sternocleidomastoid muscle, the median axis of neck, the upper edge of the
sternum and marks the periphery of the cutaneous area to asepticize. The skin
is distempered with an antiseptic. The fluoroscope is covered with a sterile
field, then the face is surrounded with a plastic field which will be hold up
only on the head of the patient in order for anesthesiologist to observe the
patient and speaks with him (Fig 4), or a normal sterile drape will be hanged
on the opposite side of the operator (the surgeon has to be able of going
cephalad and caudal around the C-arm when in lateral position).
If local
anesthesia with neuroleptanalgesia is chosen, the conversation of the operator
with the patient is possible during the PCD. Then the changes of the patient's
symptoms and signs can be immediately noted, particularly if the discography
with provoked pain test is necessary. If general anesthesia is chosen, the
patient is intubated.
Usually, a
solution of xylocaine 2% with adrenaline is used to infiltrate the skin and
subcutaneous tissues. In order to
minimize the thickening of underlying tissues and to allow a minute palpation
of the spinal axis, we prefer to not infiltrate more deeply with xylocaine.
4
Surgical Anatomy
of the Neck
All the operation
is based on the fact that all the prevertebral content is very mobile due
to compartmentalization of the neck by direct reach for the herniated portion.
The visceral axis (thyroid, trachea, Pharynx, larynx, and esophagus) is easily
displaced on the opposite side of the operator from the lesion with one or
two fingers (fig. 5 A and B), and it is removed from critical neural structure.
The cervical spine can even be palpated with the index and/or middle finger
while the vascular axis (carotid artery, internal jugular vein) is displaced
outside.
Fig 5a
Fig 5b
Because the
esophagus lies slightly to the left of the spine at C7 in most patients, we
prefer anterior approach to the disc from right side at an acute angle to the midline,
on the skin incision. Tools penetrate middle of the disc, in strict avascular zone.
If paramedian approach, 2 to 5 mm from anterior border disc midline, is
preferred, one has to know that the way to homolateral foraminal zone can be
blocked by the homolateral uncus. Consequently, a paramedian approach on the
opposite side of a foraminal hernia can be preferred in the goal to pass
diagonally better behind the controlateral uncus, as far as possible of
medullar axis. A left anterior approach can
be chosen in case of right foraminal or
posterolateral herniation although the risk of esophageal puncture might be
slightly increased, but usually visceral axis is enough “mobilizable” to
authorize anterior border disk penetration on the middle with right side skin
incision.
On the cadaver dissection there is
about 2mm of safe zone which consist of epidural subdural subarachnoïdal space
before reaching the spinal cord parenchyme.
5
Surgical
Technique
When the
forefinger of the operator pushes the trachea or the larynx toward opposite
side to clear a way which opens the vasculo-visceral axis on the patient, he
perceives perfectly the beats of the carotid artery outside. The carotid artery
can be protected under the other fingers. The index and long fingers are used
to palpate the anterior aspect of the vertebra in the cleavage between trachea
and carotid artery (fig. 5 A and B)
The pulp of
index finger of the operator then slips inside towards the front of vertebral
body and perceives the prominence of the anterior edge of the disc to be
treated, between two depressions corresponding to the concavity of adjacent
vertebral bodies.
The entry
point is usually 1.5 cm lateral to the lateral margin of the visceral
axis. After a short skin incision, the
operator passes the guide needle together with the first dilation tube or an 18
gauge spinal needle at the edge of the forefinger. The guide needle penetrates
the disc just in the middle, controlled by the AP view, oriented at about 25 °
to the opposite side. After a last check of the front scopy, a slight pressure
makes the needle enter the anterior wall of the disc. C-arm of the fluoroscope
is placed in profile, the good level is checked and the needle is entered on
around 5mm to the midline under lateral radiographic view.
The discography
and the provocation test may be performed in order to differentiate the type
or presence of the soft disc hernia and know the origin of pain [1, 25].
0.5 ml to 1ml of contrast media can be injected to opacify the posterior part
of the disc (fig. 6). If the provocation test shows positive response, it
is a very good indication of PCD. The guide needle is pulled alone, leaving
in place the first 1 mm dilation tube which has been introduced altogether
with the needle (fig 1A) or a Kirschner wire is pushed through the 18 G needle
and the needle is pulled. If you have used a single use needle, you can cut
its distal part and use it like a Kirschner wire.
Fig 6: Discography allows showing hernia exact contour on lateral C-arm fluoroscopic
view :
The operator may have confirmed the
pulsation of carotid artery far out of the working tube or wire
The second 2-mm dilation tube
and/or third 3-mm dilation tube then are introduced against the annulus for
progressive dilation under guidance of fluoroscopy in the lateral projection.
Small movements of axial rotation and some pressure applied on the first 1-mm
metallic tube allow a passage through the anterior wall of the disc on 1 or 2
mm. An intradiscal hyperpressure can drive back and make leave out from the
disk the instruments if a firm pressure is not applied. The working tube or
sheath is introduced over the dilation tube. Sometimes anterior bony spur
impedes the insertion of instrument, so that we must use a hammer with
attention to hit the tube. A 1.7 mm rigid endoscope with saline irrigation may
be used to see and confirm no other tissue except the disc.
Fig 7 A, B, and C: Discal hernia fragments taken only with the trephine; 7A:
trephine tip with teeth and inside threading; 7B: white disc fragments in
saline; 7C: discal substance cores of another disk, aligned in order from
left to right ; the last are reddish, near the vascularized disk edge .
A core of
discal substance is pulled using the inside threading trephine (fig
7A) entered through the working tube to cut the annulus. The internal spire of
trephine with interior thread allows automatic extraction of several "carrots"
of disc [23]. You try to take five cores of 5 (fig 7B) to 15 mm long
(fig 7C), and stop when the discal substance seems too reddish, meaning that we
are on the uncus or near the epidural space.
Verify with
the small forceps that all free discal fragments are taken off.
Try to
extract the tail of the hernia mass, which is more fibrotic and collagenous.
Do not try to remove the anterior
part of disc in order to avoid the localized kyphosis. We rinse the intradiscal
space with saline fluid mixed with cefazoline.
If discography is done the contrast
image of protruded disc beyond the posterior body line become visible on the
C-arm monitor, so, it is good indicator of depth for small disc forceps to remove
herniated fragment of the disc close to the posterior longitudinal ligament
If the patient is not intubated, we
ask him directly and confirm if the abnormal pain disappears or decreases. Mostly,
the cervicobrachial neuralgia decreases or disappears simultaneously with PCD. The
amount of removed disc is 200 to 1590mg (920mg in average), but success rate is
not proportional to removed disc weight.
At the end
of the operation, an abundant rinsing is performed in using a washing canula or
a needle. After the instrument is removed, a slight compression can be applied
with fingers on the surgical area for a few time to prevent hematoma. The skin
closure can be made with stitch or adhesives. The average duration of the PCD
is about 45 min. Cervical brace such as
6 Optional Holmium-YAG
laser associated with endoscopy in the same fiber (fig 8)
Fig
8 Endoscope with one way for optical fibers for associated light, vision and
laser, and two ways for saline irrigation (Storz)
A working
scope with passage of the laser probe or thin instruments can be used : laser
is more delicate, works precisely with 0.3-0.5 mm cutting depth in the
continuous saline irrigation and safely ablates the tissue near or inside the
hernia mass close to posterior longitudinal ligament so that it can protect
spinal cord or nerve root from energy transmission. In order to ablate the tissue near or inside
the hernia mass instead of endplate and posterior longitudinal ligament you
should see inside disc with small endoscope.
You shoot the laser beam as posteriorly
as possible to ablate and shrink directly the herniated part of the discs
against the posterior longitudinal ligament in the set of 0.5-0.8 Joule of 10Hz
under control of 1.7 mm endoscope with saline irrigation and fluoroscopy. You
decompress and partially vaporize large contained subligamentous fragments (fig
9A). In A-P x-ray projection the laser probe should be correctly positioned
toward herniated portion. Total energy of laser is about 5000 Joule. You may
see inside the disc, the ablated defect of the posterior disc and annulus under
the pumping irrigation of the normal saline 1000 cc mixed with cefazoline 2
grams. When the endoscopic laser does not meet any resistance in the posterior
part of the disc or can not see the hernia mass anymore under posterior
longitudinal ligament, the intervention is finished.
Fig 9a 
Fig 9b
Fig 9 A and B Before PCD sagittal MRI of a C6C7 hernia: A:; B:control 3 months after PCD showing hernia complete disappearing; note disk height minimal lessening
6
Postoperative
Management
The patient
is observed for 3 to 24 hours in the clinic for seeing if he or she is developing
any complications. The patients can be permitted to go home on the same day.
The patients do not need bed rest more than one night.
Postoperative
antibiotics and analgesics are recommended per oral for three to ten days.
Cervical collar is recommended for 3 to 14 days according to patient
improvement. Physical therapy such as head traction in mildly flexed neck and
TENS might be helpful to recover faster within two weeks postoperatively if the
cervicobrachialgia did not disappear completely.
Rehabilitation
exercise for neck muscle strengthening and improvement of neck motion range
is recommended two times a week for three months after four to six weeks postoperatively.
Fig 10: Roentgenographic evidence of spontaneous fusion and marked collapse
of the interspace at operated level 1 year after open surgery, facilitating
emergence of hernias below and above the C5C6 level.
7
Errors and
potential hazards
-
Incision
One has to be able of making a new short
incision if the first incision is not appropriate for needle course
-
Complications
(21) (table
1)
The
complications of PCD were mainly potential.
Immediate
complications to be postulated were:
1)
vascular
injury (1 case)- right carotid artery perforation due to inability to detect
carotid pulsation through the patient‘s thick and short neck. The artery was
sutured after conversion to open discectomy-,
2)
prevertebral
hematoma, laryngeal edema,
3)
esophageal
perforation,
4)
lesion
of recurrent nerve (1 case)(transient hoarseness due to deep Xylocaine
infiltration around laryngeal nerve which became normal after several hours),
or lesion of superior laryngeal nerve or of large hypoglossal nerve.
5)
cervical
cord compression with neurological disorders (1 case: transient pyramidal
symptoms due to compressing the cord from passing the pituitary forceps beyond
the posterior vertebral body lines. He recovered immediately after conversion
to open discectomy with fusion)
Secondary
complications could be postulated;
1)
worsening
of the initial symptoms: delayed aggravation of herniation which needed open discectomy one month after
PCD (1 case)
2)
subacute
discitis and epidural abscess with neurological disorders.
Late
complications is worsening of osteoarthritis, accelerated by disc height
diminution (mean 15%) (21)
8
Special problems:
recurrence
If the patient has been already
operated for cervical discal hernia at the same side or the other side, at the
same level or at an other level, either with percutaneous (2 personal cases) or
open surgery (3 personal cases), there is no special risk of operative
complication if the visceral axis has a normal mobility.
9
Results
On one
series of more than 170 patients, the mean preoperative duration of symptoms
was 22 months (range 1-240 months).
There were 76%
of cervicobrachial neuralgias (dominant radiculalgia 55%, dominant cervicalgia
21%), 18% of isolated radiculalgia, 6% of isolated cervicalgia.
The
vertebral levels of soft cervical disc herniations ranged from the C3-C4
level to the C6-C7 level. 127 patients had 1 level operated (5 C3C4, 13 C4C5,
83 C5C6, 25 C6C7, 1 C7D1), 42 patients had 2 levels operated (5 C3C4 + C4C5, 15
C4C5 + C5C5C6, 17 C5C6+C6C7, 5 C4C5+ C6C7), 1 had 3 levels operated (C3C4 +
C4C5 + C6C7).
The mean
duration of the operation was 45 min.
Provocating
pain test by injecting 1/2cc of non ionic dye is very significant for a good
result if positive (reproduction of the same topography of pain). Epidural
leakage, initial size and location of the hernia, presence of bony spurs ≤
2 mm do not modify significantly the results. An important size lessening of
the hernia improves significantly the results (21)
The mean
follow-up was 37 months (1 to 13 years)
The rate of
success is 92% (81% excellent and good, 11% fair. Among the 14 poor results
(8%), 4 were reoperated by fusion after 3 to 24 months.
10
Comparison with
open surgery
The
clinical success rate is the same in open and percutaneous procedures.
Complication rate seems to be quite different, favoring PCD in table 1. PCD
complications occurred in four patients of our series (1 carotid wound,
1 reversible recurrent nerve impairment, 1 transient pyramidal syndrome, 1
secondary symptoms worsening). There were no infection, no pulmonary embolism,
no thromboplebitis, no perforation of esophagus and no death.
Another advantage of PCD is avoidance
of disc space collapse after discectomy.(fig 8)
In open
surgery, there are the same complications (4 recurrent nerve impairments, 3
transient pyramidal syndromes, 2 secondary symptoms worsening), and 3 other
types of complications (Claude Bernard Horner syndrome: 2, superficial
complications on cervical incision or on donor site: 17, graft mobilizations:
12, graft collapse: 18). The ratio of complications between open surgery and
percutaneous procedures is 9,44. In other words, there are near ten times more
complications in open surgery.
11
Discussion
The
advantages of this cervical percutaneous surgical procedure are numerous:
-
Performed
either under neuroleptanalgesia associated with local anesthesia, or under
general anesthesia,
-
confirmation
of symptomatic level during the same operation time if performed under local anesthesia.
-
Reduced
operation time
-
No
epidural bleeding
-
No
post-operative periradicular fibrosis
-
No
risk of instability, nor postoperative kyphosis, nor complications of donor
site, graft migration or collapse
-
Reduced
risk of discal hernia relapse on anterior percutaneous surgical window
-
ablation
of hernia mass with inverted trephine, forceps,
and eventually with the endoscopic Ho:YAG laser,
-
No
difficulty if further open approach
-
Complications
rate high reduction compared with open surgery (table 1)
-
Hospital
staying shortened to 24 hours or less
-
Faster
return to work
-
Better
cost/efficiency ratio
Per-operative
complications fears, particularly oesophagal lesions or hematoma, are not
confirmed in our series of 227 surgeries. This percutaneous cervical discectomy
widens and broadens indication of percutaneous cervical approach and might
become the treatment of choice in future because of possibility of direct
ablation of the hernia mass with less serious complication.
In the treatment of soft cervical hernias, when the surgeon chooses a simple discectomy procedure, without graft nor arthrodesis, the first choice is the minimal invasive approach of percutaneous cervical discectomy, followed, in case of failure, by open anterolateral approach.
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