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L. Papavero
58.3.4 Preparation, Planning, andPositioning
• MRI: sagittal slices: measure the distance between upper
border of the disk space and cranial rim of the fragment!
The translaminar hole will be centered on the halfway of
this distance. Axial slices: look at how much of the bulk of
the DH is underneath the thecal sac and how much is lateral of it or even intraforaminal. The translaminar hole is
centered on the lateral border of the thecal sac.
• Same positioning as for ILA.
• Important: the target lamina should be parallel to the
oor! This may require to tilt the OR table a little bit head
upward. The advantages of a horizontal target lamina are
twofold: the placement of the retractor blade and the drilling of the hole become easier (Fig.58.1).
• X-ray labeling: the needle should point to the maximum
bulk of the DH, which is usually halfway between the
upper border of the target disk space and the lower rim of
the cranial pedicle.
• At the beginning of the learning curve, the upper border
of the target disk space and the lower rim of the cranial
pedicle may be labeled separately and the skin incision
centered in between (Fig.58.8).
cranial direction, whereas the width of the isthmus decreases.
This means that the translaminar hole will be more medially
and more ovale-shaped in the cranial direction (Fig.58.9).
• Lamina: irrespective of the kind of speculum used, the
lateral border of the lamina should be visible underneath
the retractor valve. A dissector is placed onto the lamina
where the bulk of the DH is suspected and a uoroscopic
control is performed. At this point, the lamina should have
been tilted parallel to the oor so that the cutting burr can
be held more easily perpendicular to the lamina. With
slow circular movements, a round- (L5) or oval-shaped
(L4 and cranially) hole of about 10 mm in diameter is
performed (Fig.58.10). Three layers, “white” (outer cortical bone), “red” (spongy bone), and “white” (inner cortical bone), will be drilled off. For the sake of safety, the
inner cortical bone should be drilled with a diamond burr.
Remarks: (1) At least 3mm of the lateral border should be
spared in order to avoid a fracture of the pars interarticularis
(Fig.58.11). (2) Usually, the translaminar hole is located
just cephalad to the cranial insertion of the yellow liga-
58.3.5 Surgical Technique
The lamina can be approached via a subperiosteal (SP) or a
transmuscular (TM) route. The soft tissue approach mirrors
exactly that to the interlaminar space and has been already
described. Remember that the width and the overlapping of
the lamina in relation to the disk space increase in the caudal-
Fig. 58.8 Intraoperative uoroscopy: the needle (1) points to the upper
rim of the target disk, whereas the needle (2) points to disk fragment
just underneath the lower rim of the cranial pedicle
Fig. 58.9 Yellow numbers: length of the lamina; black numbers: width
of the lamina
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ment. So, after removal of the thin shell of inner cortical
bone with small punches, epidural fat will appear.
• Epidural dissection: up and down dissection of the fat
along the lateral border of the thecal sac. That should
be continued cranial up to the axilla of the exiting
root.
Fig. 58.10 Postoperative 3D-CT, which shows a translaminar hole L3
on the right side
• Management of the DH: Usually, an extruded or subligamentous disk fragment/s can be mobilized. After decompression, the root slips caudally into the visible eld
(Fig. 58.12). The root canal is probed with a doubleangled hook. If an extensive annular perforation is
detected, the disk space should be cleared. In our experience, that was required in merely 20% of the cases. The
rate of recurrence was 7%.
• Closure: Gelfoam soaked with long-acting steroid to ll
in the hole is optional, but it should be avoided if the disk
space has been cleared.
• Postoperative care: same as for ILA.
58.3.6 Complications
Tilting of the OR table in order to direct the lamina quite
parallel to the oor minimizes the risk of wrong level
surgery.
The particularly thin axillary dura should be handled very
carefully during dissection of adherent disk fragments. Due
to the narrow access, gluing a patch on accidental durotomy
is the best solution.
Although not a complication, enlarging the hole to con-
ventional laminotomy becomes necessary whenever a signicant annular perforation is detected on the caudal half of
the disk space, especially at the L5/S1 level.
Fig. 58.11 The supercial cortical bone of the lamina is drilled off with a cutting burr (left), the inner cortical bone with a diamond dust–coated
burr (center), keep at least 3mm safety zone at the lateral border of the pars interarticularis (right)
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L. Papavero
Fig. 58.12 Epidural dissection on the right side: the intra-axillary disk
fragment pushes the root upward to the lower rim of the pedicle (left);
the epidural capsule has been removed from the DH (center); after the
removal of the space occupying disk fragment, the root becomes visible
58.4 Extraforaminal Approach (EFA)
[6, 13, 14]
58.4.1 Indication
• Disk fragment located at least two-thirds lateral to the
pedicle.
58.4.2 Contraindication
• Foraminal disk herniations located more than two-thirds
inside the root canal.
58.4.3 Technical Requirements
• The same as for TLA.
58.4.4 Preparation, Planning, andPositioning
in the surgical eld (left). Red line: lateral border of the thecal sac; yellow line: axilla of the exiting root; blue line: lower border of the exiting
root
• For safety reasons, the patient should be belted on the gluteal region: the OR table has to be tilted 20–30° away
from the surgeon in order to get a better oblique view of
the extraforaminal compartment. Especially, obese
patients may risk to “roll over” on their own fat.
• Lateral view (X-ray labeling): insert a spinal needle one
nger’s breadth lateral to the spinous process, perpendicularly to the skin, and projecting toward the lower border
of the affected disk space. Draw a horizontal line at this
level (A). Switch the C-arm into the AP-view: Two horizontal lines are drawn: (1) the lower border of the affected
disk space should be identical with the previous marking
in the lateral view (A) and (2) the lower border of the
transverse process above the affected disk (B). Two vertical lines are also drawn: (1) the midline (row of the spinous processes) (C) and (2) a line about 4cm off to the
midline, marking the lateral boundary of the pedicle
above and below the affected disk (D). The distance
between the two horizontal lines (AB) is the skin incision
and will be 3–4cm in length and about 4cm paramedian
(Fig.58.14).
• MRI: sagittal slices: cave! Usually, they are not scanned
lateral enough, that is, lateral to the root canal, and miss
the EFDH.Axial slices: compare the amount and distribution of the extraforaminal fat tissue on both sites. Coronal
slices: although rarely performed, they are of invaluable
help to show the spatial relationship among exiting root,
root canal, and extraforaminal compartment (Fig.58.13).
• Same positioning as for ILA.
58.4.5 Surgical Technique
• The transmuscular blunt splitting approach to EFDH at
the level L4/L5 or more cranially can be performed with
an expandable tubular retractor or with a miniaturized
speculum combined with medial and lateral counterretractor blades (Fig.58.15). At the level L5/S1, the author
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Fig. 58.13 (From left to right) Inapparent paramedian slices due to
faulty scanning (center) omitting the extraforaminal areas, especially
on the left side (arrow); the coronal view shows that the left-sided L4
Fig. 58.14 Labeling of the lines of reference on the intraoperative lateral (Left) and AP (right) view
root is severely impinged by an extraforaminal DH (arrow). The disk
fragment is also clearly visible on the axial slice (right, arrow): compare the different distribution of the extraforaminal fat
Fig. 58.15 Blunt splitting of the muscles pointing to the medial third of the transverse process cranial to the target disk (left), 3D-CT depicting
the access (center), target point (asterisk) of the transverse process (right)
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Fig. 58.16 Surgical eld to approach L5/S1 on the left side: the upper
blade rests on the facet joint, the left one on the transverse process L5
recommends the use of two counterretractors inserted
perpendicular to each other. That allows to choose four
blades of different lengths matching with the following
structures: facet joint (medial), transverse plane (lateral),
transverse process (cranial), and ala (caudal) (Figs.58.16
and 58.17). Furthermore, the use of the microscope “skin
to skin” is advised.
• Skin: 3cm in length, 4cm off the midline.
• Transmuscular route: after incision of the fascia of m.
erector spinae, the muscle is dissected bluntly using the
index nger along the cleavage plane between the multidus and the longissimus muscle (Fig. 58.15). If this
brous separation cannot be palpated, the muscle is split
downward to the medial third of the transverse processes.
The selected retractor is then introduced so that the tips
rest rmly on the lower half of the upper transverse process and on the upper half of the lower one. The lateral
surface of the pars interarticularis represents the medial
border of the surgical exposure. A uoroscopic check at
this point of the procedure is essential (Fig.58.18).
• Extraforaminal compartment: tilting the OR table by
15–20° away from the surgeon gives a better view of the
area lateral of the pedicle. Drilling off bone is usually not
necessary, except in the case of an extremely hypertrophied facet joint or at the L5/S1 level. The medial half of
the intertransverse muscle is incised and pushed laterally,
thereby exposing the intertransverse membrane, also
called the “intertransverse ligament.” After its incision,
the fat surrounding the nerve appears. Because of the
proximity of the nerve, the accompanying vessels, and
DH, the sucker should also be used as a nerve retractor.
However, beware of an excessive retraction of the dorsal
ganglion in order to minimize the incidence of postoperative burning dysesthesias! Branches of the radicular artery
L. Papavero
Fig. 58.17 Intraoperative uoroscopic control L5/S1: (1) medial blade
on the facet joint, (2) lateral blade, (3) cranial blade a bit cephalad to the
transverse process L5, (4) blade on the ala sacri, dissector pointing to
the DH (arrow)
should be dissected carefully and spared whenever possible. The accompanying veins can be cauterized if they
hinder the access to the disk fragment.
• Management of the DH: Typically, we nd the nerve and
the ganglion pushed laterally and cranially by the mostly
free disk fragment. As a rule, removal of the fragment
alone is sufcient. If an extensive perforation of the annulus is evident, clearing of the disk space should be considered. After probing the root canal with a double-angled
blunt hook for residual fragments, the nerve may be covered with a Gelfoam soaked with crystalline steroid.
• Closure: placing a drain is optional and, in our experience,
seldom necessary. Musculature requires no suturing.
• Special considerations for the L5/S1 level: because of the
particular anatomical relationship among disk space,
transverse process L5, and ala, the microsurgical musclesplitting approach at the lumbosacral level should be
practiced by a surgeon who is already familiar with the
technique at the more cranial levels. Repeated intraoperative uoroscopic checks may also be necessary. If difculties should arise, switching to the conventional
“macroapproach” should be considered.
• Postoperative care: as previously described.
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Fig. 58.18 Intraoperative uoroscopic control in AP view for
approaching a left-sided extraforaminal DH L3/L4. Note the concave
curve of the degenerative scoliosis. Close-up view of the medial third of
the transverse process (asterisk) (bottom right)
58.4.6 Complications
Reex sympathetic dystrophy occurs in 1–2% of the patients,
mostly within 1 week after surgery, especially at the L5/S1
level. It is characterized by burning discomfort of the shiny leg,
which becomes very sensitive to touch. Due to the intracanalicular location of the ganglion, every manipulation of the nerve in
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the extraforaminal compartment stretches the ganglion, which
may cause postoperative causalgic disturbances. Therapy:
codeine, sympathetic block (Marcaine 1%), and physiotherapy.
References
1. Mixter WJ, Barr JS.Rupture of the intervertebral disc with involve-
ment of the spinal canal. N Engl J Med. 1934;211:210–2015.
2. Caspar W. A new surgical procedure for lumbar disc herniation
causing less tissue damage through a microsurgical approach. Adv
Neurosurg. 1977;4:74–7.
3. Yasargil GM. Microsurgical operation of herniated lumbar disc.
Adv Neurosurg. 1977;4:81–5.
4. Williams RW.Microlumbar discectomy: a conservative approach to
the virgin herniated lumbar disc. Spine. 1978;3(2):175–82.
5. Abdullah AF, Ditto EW, Byrd EB. Extreme-lateral lumbar disc
herniations: clinical syndrome and special problems of diagnosis.
J Neurosurg. 1974;41(2):229–34.
6. Reulen HJ, Pfaundler S, Ebeling U. The lateral microsurgical
approach to the “extracanalicular” lumbar disc herniation. A technical note. Acta Neurochir. 1987;84:64–7.
7. Mayer HM. Lumbar disc herniations: the microsurgical interlami-
nar, paramedian approach. In: Mayer HM, editor. Minimally invasive spine surgery. Heidelberg: Springer; 2005. p.284–96.
8. Di Lorenzo N, Porta F, Onnis G, etal. Pars interarticularis fenestra-
tion in the treatment of foraminal lumbar disc herniation: a further
surgical approach. Neurosurgery. 1998;42:87–90.
9. Bernucci C, Giovanelli M. Translaminar microsurgical approach
for lumbar herniated nucleus pulposus (HNP) in the “hidden zone”:
clinical and radiologic results in a series of 24 patients. Spine.
2007;32(2):281–4.
10. Papavero L.Lumbar disc herniations: the translaminar approach. In:
Mayer HM, editor. Minimally invasive spine surgery. Heidelberg:
Springer; 2005. p.304–14.
11. Soldner F, Helper BM, Wallenfang T, et al. The translaminar
approach to canalicular and cranio-dorsolateral lumbar disc herniations. Acta Neurochir. 2002;144:315–20.
12. Vogelgesang JP.The translaminar approach in combination with a
tubular retractor system for the treatment of far cranio-laterally and
foraminally extruded lumbar disc herniations. Zentralbl Neurochir.
2007;68(1):24–8.
13. Papavero L. Lumbar disc herniations: the extraforaminal
approach. In: Mayer HM, editor. Minimally invasive spine surgery.
Heidelberg: Springer; 2005. p.297–303.
14. Tessitore E, de Tribolet N. Far-lateral lumbar disc hernia-
tion: the microsurgical transmuscular approach. Neurosurgery.
2004;54(4):939–42.
Microsurgical Decompression
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FrankGrochulla
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59.1 Introduction and Core Messages
Degenerative lumbar spinal canal stenosis is a frequent
disease of the “aging spine,” leading to mono- or bilateral leg symptoms that are often described as spinal
claudication [1–3]. The primary goal in treatment is to
relieve the patients’ leg symptoms. Surgery for lumbar
spinal stenosis is generally accepted when conservative treatment has failed or if progressive neurological
decits occur [4]. In the past, laminectomies are considered to be the treatment of choice in lumbar spinal
stenosis without instability [3, 5, 6]. Due to the risk of
destabilization after laminectomy, limited approaches
and less invasive techniques for decompression have
been proposed by several authors [7–10]. Today, laminotomy under microscopic guidance is the preferred
surgical technique in lumbar spinal stenosis presenting
without additional deformity or segmental instability.
During the past decade, approaches and techniques for
laminotomy have been modied in different manners.
In this chapter, the ipsilateral interlaminar approach
for microsurgical decompression of the ipsilateral and
contralateral spinal canal in the so-called over-the-top
technique is described.
59.2 Indications
• Acquired degenerative central and lateral spinal canal stenosis with clinical symptoms (e.g., spinal claudication),
veried by MRI or CT scan
• Failed conservative treatment
• No symptoms/signs for segmental instability
59.3 Contraindications
• Unstable lumbar degenerative scoliosis
• Spondylolisthesis grade I or higher with dominant lowback pain
• Severe and/or dominant low-back pain
• Absolute contraindications for general anesthesia
59.4 Technical Prerequisites
• Microscope
• Microsurgical instruments (e.g., Bayonet-shaped
instruments)
• Tubular retractor system (e.g., Caspar retractor)
• High-speed drill
• Fluoroscopy
F. Grochulla (*)
Metropol Medical Center, Clinic for Orthopedics, Trauma Surgery
and Spinal Surgery, Nuremberg, Germany
e-mail: frank.grochulla@mmc-nuernberg.de
© Springer-Verlag GmbH Germany 2023
U. Vieweg, F. Grochulla (eds.), Manual of Spine Surgery, https://doi.org/10.1007/978-3-662-64062-3_59
59.5 Planning, Preparation, andPositioning
The patient is placed prone for this procedure on a Wilson
frame or alternatively placed on a special operating table in
the knee-chest position (mecca position) (see Fig.59.1). In
this positioning, the abdomen is free, thus relieving pressure
on the abdominal venous system and decreasing venous
backow into the spinal canal through Batson plexus.
Furthermore, the amount of lumbar lordosis is decreased,
and the interlaminar spaces are widened. Thus, it is easier to
enter the spinal canal for decompression.
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Fig. 59.1 (a) Knee-chest
(mecca) position, situation in
the OR and illustration (b),
and as an alternative prone
positioning (c)
F. Grochulla
a
b
c
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Fig. 59.2 The target level is localized with an inserted needle under
lateral uoroscopy control
For positioning, some special aspects have to be considered in (mostly elderly) patients with acquired spinal canal
stenosis: patients can have limited mobility of the joints
(shoulder, hip, knee) and of the cervical spine (avoid head
rotation!).
Localization: The target level(s) is localized with an
inserted needle under lateral uoroscopy control, and the
approach is planned and marked (see Fig.59.2). It is important to place the supercial approach exactly over the lumbar
segment of interest because of the limited extent of the
microsurgical approach.
59.6 Surgical Techniques
• The author recommends the application of the surgical
microscope from the beginning of the surgical
procedure.
• The skin incision is up to 5–10mm lateral to the spinous
process on the affected side and typically 2–3cm in length
for one level. In the presence of bilateral symptoms, a
left-sided approach is preferred for right-handed
surgeons.
• A semicircular paramedian incision is made in the thora-
columbar fascia. The length of this incision can be longer
than the skin incision (see Fig.59.3).
• Subperiosteal dissection of the paravertebral muscles is
carried out, and a self-retraining speculum retractor
(Caspar, Aesculap,- or metrx retractor, Medtronic) is
inserted (see Fig. 59.4). It is necessary to control the
force of the retractor during surgery to avoid pressure
necrosis of the surrounding cutaneous and musculature
tissue.
• The laminae of the adjacent vertebrae and the interlami-
nar space are exposed.
Fig. 59.3 Skin incision 5–10mm lateral to the spinous process on the
affected side and typically 2–3cm in length for one level
Fig. 59.4 Caspar tubular retractor system
• With a high-speed burr (see Fig.59.5a, b), the decompression of the ipsilateral spinal canal is started with the
removal of lower half of the cephalad lamina until the origin of the ligamentum avum is exposed (see Fig.59.6).
The ligamentum avum will be seen to thin out at the
cephalad lamina and is detached from the lamina with a
dissector. At this point, epidural fat and the dura can be
identied (see Fig.59.7). The extension of the interlaminar space is completed by resection of the cephalad part
of the caudal lamina and by resection of a portion of the
medial part of the facet joint (medial facetectomy).
• After complete exposure of the ipsilateral ligamentum avum, it can be removed with rongeurs. Adhesions of the
dura to the ligamentum avum are dissected carefully in
order to avoid dural laceration.
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Fig. 59.5 Angular handpiece for high-speed drill
F. Grochulla
Fig. 59.6 Partial removal of the lamina and exposure of the ligamen-
tum avum
Fig. 59.7 The ligamentum avum is detached from the lamina with a
dissector. Epidural fat and the dura can be identied
• An adequate ipsilateral subarticular decompression has
been accomplished when the medial part of the pedicle and
the lateral border of the nerve root are identied—and when
the traversing nerve root can be easily mobilized (Fig.59.8).
Fig. 59.8 Exposure of dura and nerve root after ipsilateral decompres-
sion. D dura, NR nerve root
Fig. 59.9 Undercutting of the lamina with a high-speed burr. L lamina,
LF ligamentum avum, D dura
• The contralateral decompression is initiated by a tilting of
the table away from the surgeon, and the microscope is
adjusted to obtain a clear eld of vision across the midline. Utilizing a high-speed burr, the undercutting of the
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